# Improve Your Soundstage for $2



## Patrick Bateman

Some people asked me to post this info, so here goes:

How to improve your soundstage for two bucks.

If you've ever listened to a set of audiophile mini-monitors, you may have noticed that they throw a really amazing soundstage. The reason that they do this is that the enclosure is very small.

But we can replicate this effect with a much larger enclosure by reducing diffraction. Here's how this works:

When the sound from your speaker hits *anything*, it creates a reflection. These reflections are perceived by your ears as a secondary sound source. So for instance, if you take a set of mini monitors and place them six inches away from a wall, the reflection off that wall will muddy the image. That's why speakers sound better when you pull them away from a wall.

What's interesting about this phenomenon is that it's VERY time dependent. A reflection that occurs an inch or two from your speaker is 10x worse than a reflection which occurs a foot away.

Having established that reflections are a BAD thing, how do we address that? Here's a few options:


Use a waveguide to 'funnel' the sound in one direction. I do this in most of my projects. It's a LOT of work 
Absorb the sound. You can do this with sound absorbing pads, like they use in a studio. Not really practical in a car.
Diffuse the sound. This works really well. Despite all the work I've investigated in waveguides, I'll admit that it works nearly as well, and it's a hell of a lot less work.

With sound diffusion, we're basically taking that reflection, and spreading it waaaaaaaay out in frequency in time. So instead of a big ol' nasty reflection at one spot and one frequency, we're spreading it out over an octave or two, over a few milliseconds.

Here's a couple pics of some speakers which use diffusion to improve their soundstaging abilities.



















Subjectively, the speaker becomes more difficult to localize when it's in a spherical enclosure. The soundstage becomes more diffuse, and seems to float "around" the speakers instead of being tied to them. The sound is also sweeter and less fatiguing.

And this is only common sense of course. Imagine a sound wave striking a sharp edge, diffracting violently:










Now imagine the same sound wave in a spherical enclosure. The energy is the same, but the sound is diffused gently across the smooth surface. The improvement in the polar response is measurable, and the subjective improvement is obvious.

In part two I'll describe how to do it...


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## Patrick Bateman

In part one I described why reflections are a BAD thing, some options for controlling them, and how this will improve your soundstage.

Now the practical part, how to build it.

Let's say we wanted to diffuse sound down to 100hz. The speed of sound is 13500in/second. So to diffuse sound down to 100hz, we'd need a spherical enclosure that's 42.98" in diameter. Here's the equation:

required sphere radius = 13500 / lowest frequency / 2 / pi
required sphere radius = 13500 / 100 / 2 / 3.14159

Hmmm that's not gonna work is it? 

Psychoacoustic studies have shown that matching frequency response above 1khz is more important than *below* 1khz.

Based on that we could reduce our sphere from almost four feet to a little over four inches. At that size, it starts to get practical to do this in the car.

My local craft store sells some clear plastic spheres, I have no idea what they're for, but they work for spherical enclosures. They're 8cm in diameter and they're less than a buck. An 8cm sphere will control diffraction down to 1365hz.

Here's a picture of a vifa ring radiator in one of these 99 cent spheres:



















So there's the math above, and they're readily available at craft stores. In the pic I'm using half a sphere. You'd want to take the entire sphere and cut it down to a point where it blends seamlessing with the diaphragm. The way that B&W does it is just about ideal:










The teardrop shape is better than a sphere; it flattens out the frequency response and reduces diffraction. My local craft store has egg shapes, but they're not big enough for this application. YMMV


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## Patrick Bateman

I found a better pic of what diffraction looks like:










click on the link to watch the animated version:

http://www.silcom.com/~aludwig/images/diffdem.gif

Note how the sound diffracts off the tweeters edge and off the baffles edge. That's why tweeters are carefully recessed.

If you look at the math above, you can see that it's practical to reduce diffraction from a tweeter down to 1365hz for a buck. Better yet, put that spehere about six inches away from the dash and the windshield, and you'll eliminate or reduce ALL reflections down to 470hz. If you take it that far, your tweeters will literally disappear. No amount of electronic manipulation or DSP can do this. There isn't a magic amplifier that can do this. Replacing your head unit won't do this.

But a 99 cent plastic sphere can.


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## Patrick Bateman

Here's some articles on diffraction from guys that are a lot smarter than me:

Diffraction from baffle edges

Baffle Step Compensation

I post a lot of measurements of my car online. The first thing that people notice is that the response isn't particularly flat. That's because they're accustomed to response graphs from manufacturers, who measure speakers on a big ol' flat baffle. To give you an idea of why that's misleading, here's what happens to a speaker when you put it in a box:










and in a sphere:


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## iyamwutiam

Good job patrick --more power to you.


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## Patrick Bateman

And I saved the best for last.

Have you ever noticed that your speakers sound good at moderate levels, but grow fatiguing at high volumes? You crank them up for a minute or three, but quickly you want to reduce the volume. This is particularly common with people using horn loaded compression drivers in the car. They sound great for a few minutes, but grow fatiguing quickly.

According to research by Earl Geddes, the perception of diffraction is level dependent. That's one of the reasons you're speakers sound fatiguing at high levels. You could use the most expensive speakers from Dynaudio or Focal, with vanishingly low distortion, along with the most expensive electronics. But if you ignore the diffraction issue, they'll still be fatiguing. 

Here's the quote:

_"The paper that Lidia and I just did on the perception of very small time delayed signals, such as would occur for diffraction in a waveguide or off a cabinet edge, is also enlightening for its proof that these effects are strongly dependent on the playback sound pressure level. The ear appears to mask these effects at low levels, while they rapidly become perceptible at higher SPLs. This basically puts much of the previous work on the perception of diffraction and very early reflections into a questionable light since playback level was seldom a controlled or control variable."_

http://www.audioxpress.com/magsdirx/voxcoil/addenda/media/mowry1008.pdf


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## Austin

Very interesting. I will keep this in mind when i build my home theater speakers. I may even rebuild my tweeter pods in my car.


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## JediMentality

Very good info. Thanks Pat!


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## Patrick Bateman

Austin said:


> Very interesting. I will keep this in mind when i build my home theater speakers. I may even rebuild my tweeter pods in my car.


Thanks! I've been doing horns and waveguides for almost two decades now, and the improvement that I've seen from adressing diffraction (almost) has me considering "conventional" components again. The improvement in soundstaging is just ridiculous.

I first noticed it with the Anthony Gallo speakers a few years back at CES. They use ridiculously cheap drivers, and they're basically a glorifed Bose system, yet they sound a million times better than they should. Considering the junky components you'd think they'd sound like crap, but they sounded better than speakers that cost ten times as much.

Really made me think about how they sound so good.


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## splicer

I've been thinking about sticking my seas neos (which are small format tweeters) in kind of a softball-sized sphere in the kicks to deal with the diffraction issue. As a bonus it would really blend in with the interior theme. I would just need to vinyl up a foam ball. 

mini interior

either that or put the tweets on the A-pillars like I have been considering...


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## Quickshift

Would you not want the tweeters in a sphere that's somewhat larger than the diameter of the faceplate so you have a smooth curved sides round the outside of the faceplate rather than a sharp 90 degree transition at the edge as you would get with a small hemisphere as you show in the photo?

I think one of the other reasons for using a spherical enclosure is to try to reduce standing waves to a minimum.

there are some good tools for simulating baffle diffraction on the FRD consortium site IIRC.

Another technique that helps reduce baffle diffraction is to surround the drivers with fairly thick felt, I remember reading some studies on it although it didn't always look that neat in the examples.

You can buy fairly large polystyrene eggs and spheres, maybe it would be possible to use one as a template for a fibreglass enclosure and then dissolve out the polystyrene.

<<edit http://www.speakerdesign.net/felt_amelioration/feltssenter.html stuff about using felt>>


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## 94VG30DE

I noticed this with a friend's car. He had a bunch of Apple iMac sphere speakers like are shown in the link below, and we were basically trying to use them as car speakers. 

Shown here: iMac G4 Sphere Speakers 

I was immediately surprised by how good they sounded for the size and how they seemed to be constructed. One might even be able to remove the original tweeter inside and mount something else in it. I would be interested to see an RTA plot on one of those. 

edit: better pics here: http://www.cubeowner.com/forums/index.php?showtopic=13516


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## splicer

Patrick Bateman said:


> I first noticed it with the Anthony Gallo speakers a few years back at CES. They use ridiculously cheap drivers, and they're basically a glorifed Bose system, yet they sound a million times better than they should. Considering the junky components you'd think they'd sound like crap, but they sounded better than speakers that cost ten times as much.


I have been thinking about building some spherical speakers recently out of something like the Tang Band 3-4" drivers. Haven't found the right 'enclosure' yet. I was eyeing some hemispherical wood bowls at IKEA.

They come in 5,8,and 11 inch diameters. 
IKEA | Serve | Serving dishes & bowls | BLANDA MATT | Serving bowl


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## Steak

is this principle the main reason why subwoofers are hard to localize?


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## goodstuff

Patrick Bateman said:


> Here's some articles on diffraction from guys that are a lot smarter than me:
> 
> Diffraction from baffle edges
> 
> Baffle Step Compensation
> 
> I post a lot of measurements of my car online. The first thing that people notice is that the response isn't particularly flat. That's because they're accustomed to response graphs from manufacturers, who measure speakers on a big ol' flat baffle. To give you an idea of why that's misleading, here's what happens to a speaker when you put it in a box:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> and in a sphere:


So I guess I don't need an EQ quite as much as I need a couple of red rubber balls covered in fiberglass, lol.


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## Babs

Subscribed.. FINALLY.. The idea of sphericals anywhere near the letters DIY.
I've been contemplating ideas on enclosure construction for a better-than driver in something that hopefully ends up about the same size and shape as an Orb or a Gallo.

I was thinking layered sandwiched MDF maybe, or some craft material, etc.. A couple small bowls molded together with a baffle attached/cut-out, etc. But keeping in mind the important thing of smooth and angled all the way to the edge of the driver.

Hoping for some good DIY's of sphericals with some good wide-banders. Aura's, tangs, etc.


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## Patrick Bateman

Quickshift said:


> Would you not want the tweeters in a sphere that's somewhat larger than the diameter of the faceplate so you have a smooth curved sides round the outside of the faceplate rather than a sharp 90 degree transition at the edge as you would get with a small hemisphere as you show in the photo?
> 
> I think one of the other reasons for using a spherical enclosure is to try to reduce standing waves to a minimum.
> 
> there are some good tools for simulating baffle diffraction on the FRD consortium site IIRC.
> 
> Another technique that helps reduce baffle diffraction is to surround the drivers with fairly thick felt, I remember reading some studies on it although it didn't always look that neat in the examples.
> 
> You can buy fairly large polystyrene eggs and spheres, maybe it would be possible to use one as a template for a fibreglass enclosure and then dissolve out the polystyrene.
> 
> <<edit David Ralph's Speaker Pages - Felt Effects on Baffle Diffraction stuff about using felt>>


The problem with felt is it doesn't operate very low; below 15khz it doesn't make much of a difference.

A roundover operates down to 1/4 wavelength of the roundover's radius.

That's another thing too; it doesn't *have* to be a sphere. Anything that's done to reduce diffraction will yield an audible and measurable improvement.

You could look at this as a series of stages, and each stage is cumulative. IE, do some of them, or all of them for full effect.


Use a roundover with a radius that's equivalent to one quarter of the frequency you need to cover. For instance, to go down to 2000hz you'd use a roundover with a radius of 1.6875".
Go all the way and use a sphere. A sphere is basically a roundover on all sides.
Add a waveguide to the face, and round THAT over.

If you look at the profile of the B&W, you can see the woofer's cone itself forms a waveguide. For a tweeter you'd need to build one. Even *without* a waveguide on the tweeter, the enclosures shape reduces diffraction.

And reducing diffraction makes the speakers disappear.


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## Patrick Bateman

Steak said:


> is this principle the main reason why subwoofers are hard to localize?


Subwoofers are easy to localize, but the mechanism that we use to localize subs is different than the one we use to localize high frequencies. At low frequencies the pathlength is paramount. That's due to the length of the soundwaves. A 500hz soundwave is twenty seven inches long. Low frequencies are so long, we're unable to detect a difference from one ear to the other. (google interaural time delay.)

The reason that subwoofers are localized is generally due to being too far or too close, and localization via the 2nd and 3rd order harmonic distortion which they produce.


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## Patrick Bateman

splicer said:


> I have been thinking about building some spherical speakers recently out of something like the Tang Band 3-4" drivers. Haven't found the right 'enclosure' yet. I was eyeing some hemispherical wood bowls at IKEA.
> 
> They come in 5,8,and 11 inch diameters.
> IKEA | Serve | Serving dishes & bowls | BLANDA MATT | Serving bowl


yowza, nice find!

These would be perfect. I used the plastic spheres from the craft shop for my latest project, and split one with my drill. The Ikea bowls would work much better.


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## The Drake

very interesting read. If you have a enclosure already built, could you reshape the internal space of the enclosure to be spherical to get the same results?


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## Babs

The Drake said:


> very interesting read. If you have a enclosure already built, could you reshape the internal space of the enclosure to be spherical to get the same results?


Diffraction distortion happens on the outside of baffle/enclosure.









The internal space around the driver (inside of the front baffle, etc) would mainly affect driver ventilation and early reflections but I think the main issue to be resolved here is on the exterior surface.


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## jbowers

Subscribed - good stuff!


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## ItalynStylion

Patrick, great work applying this to car audio! It's a tough thing to accomplish but I think it's a great idea. I've known about this diffraction idea for a while but I've never thought about applying it to car audio. Ironically, this is probably the BEST place it could be applied since objects that cause reflections are much closer to the drivers. 

This idea was why I spent so long doing the baffles on my frugal horns. I initially thought I could cut a circle, do a roundover, and I'd be good to go. Then Dave at Planet 10HiFi explained to me the reason it was so important. That's when I went the extra mile (4 hours) of sanding. As a result, these things image like CRAZY! I've been told that the ideal shape is that of a tear drop much like what B&W has on the tower you posted above.


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## Patrick Bateman

ItalynStylion said:


> This idea was why I spent so long doing the baffles on my frugal horns. I initially thought I could cut a circle, do a roundover, and I'd be good to go. Then Dave at Planet 10HiFi explained to me the reason it was so important. That's when I went the extra mile (4 hours) of sanding. As a result, these things image like CRAZY! I've been told that the ideal shape is that of a tear drop much like what B&W has on the tower you posted above.


Thanks! I basically discovered it the same way. Here are *my* home speakers, note the ridiculous roundover:










(the horn on top is just to demonstrate the scale)

One afternoon I was waiting for some stuff to dry on my current car project, and added a roundover to an old set of HLCDs that I had laying around, and measured them. Took literally fifteen minutes. And then I listened to them, when the measurements were WAY improved, and was startled by the transformation. Never heard them sound so good. It was actually kind of depressing LOL, since the speakers that I applied the roundover on were never competitive with my own DIY designs. But once the roundover was applied, they sounded 10x better.


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## ItalynStylion

^is that a sonotube sub I see in the corner


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## KARPE

With those ikea bowls, they probably aren't fully round, but flat on bottom so they stay standing. Would that defeat the idea of diffusion?

I'm a bit confused on how to pick the size of the cup/ hemisphere, If I'm using a 3.5 FR88 full range driver, what specs would I use to calculate what i would need?


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## Austin

ItalynStylion said:


> ^is that a sonotube sub I see in the corner


Haha looks like it.


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## Austin

KARPE said:


> With those ikea bowls, they probably aren't fully round, but flat on bottom so they stay standing. Would that defeat the idea of diffusion?


Your gonna have to make an edge somewhere to mount it. I think the main idea is to focus around the front part of the enclosure. The back part isnt as critical as the front edge.


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## [email protected]

KARPE said:


> With those ikea bowls, they probably aren't fully round, but flat on bottom so they stay standing. Would that defeat the idea of diffusion?
> 
> I'm a bit confused on how to pick the size of the cup/ hemisphere, If I'm using a 3.5 FR88 full range driver, what specs would I use to calculate what i would need?


I believe they are talking about the outside of the enclosure not the inside.


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## Arc

Thanks for this Pat. I have a sheet somewhere that had the frequency response for a supra baffle somewhere around here, I'll see if I can find it.

Are those the Nathans or Summas?


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## Melodic Acoustic

You I was reading about this about a month or so ago. It now makes more sense. Great info and I had already been thinking of ways to make it work in my up coming build, now I have a better understand on how it works and I have a pretty good idea of how I'm going to do it now.


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## braves6117

BeatsDownLow said:


> I believe they are talking about the outside of the enclosure not the inside.


x2 , IMO


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## Austin

KARPE said:


> With those ikea bowls, they probably aren't fully round, but flat on bottom so they stay standing. Would that defeat the idea of diffusion?





BeatsDownLow said:


> I believe they are talking about the outside of the enclosure not the inside.



I think KARPE was talking about the flat surface on the bottom of the bowl on the outside (backside). Like this:
http://www.davidlauffenburger.com/i...l with bark inclusion on bottom and rim 2.jpg

Except without the lip..because i dont think the ikea bowls have the lip, it just transitions into the flat part.


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## splicer

KARPE said:


> With those ikea bowls, they probably aren't fully round, but flat on bottom so they stay standing. Would that defeat the idea of diffusion?
> 
> I'm a bit confused on how to pick the size of the cup/ hemisphere, If I'm using a 3.5 FR88 full range driver, what specs would I use to calculate what i would need?


for purposes of reducing diffraction, a larger sphere is always better. The idea is that for a given volume (which you need for an enclosure) it should be as smooth as possible. It does not need to be perfectly smooth but you definitely want to keep sharp edges quite a distance away from high frequency sources.


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## ItalynStylion

Arc said:


> Thanks for this Pat. I have a sheet somewhere that had the frequency response for a supra baffle somewhere around here, I'll see if I can find it.


I believe you are looking for this good sir. It is attached at the end of the frugal horn plans that Dave and Scott have graciously provided.


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## KARPE

braves6117 said:


> x2 , IMO


so how do you determine the necessary radius of the enclosure and after that peak points above and below the driver does it matter if the sphere is continued? or could it be flat?


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## Patrick Bateman

Arc said:


> Thanks for this Pat. I have a sheet somewhere that had the frequency response for a supra baffle somewhere around here, I'll see if I can find it.
> 
> Are those the Nathans or Summas?


Those are the big kahunas, a set of Summas handbuilt by Dr Geddes himself. If anyone is in the PNW I'm going to be bringing them up to Mercer Island for the PNW Audio Fest later this month.


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## t3sn4f2

Question, would the objects around a typical install location (ie dash, defrost vents, pillar angles, glass, ect.) affect the response the same way as baffle shape would? If so then couldn't the changes that a less then optimum baffle bring actually correct the overall response once the surrounding objects own changes are summed in?

In other words, what if my pillar creates a dip where the stock baffle steps it back up to where it sounds better?


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## t3sn4f2

Also I think B&W used _Tapering Tubes_ more for the internal benefits then the added bonus of it having the same external shape.

"The sound of silence. Not all sound generated by speaker drive units is good sound. The kind that emerges from the back of a working driver, into a conventional box cabinet, can bounce around and make a mess of the good sound coming out of the front. B&W’s trailblazing Nautilus™ speaker found a way around boxes. Tapering tubes filled with absorbent wadding soaked up the wayward sound energy and reduced resonances to an insignificant minimum. 

Nautilus™ Tapering Tubes are fitted to nearly all B&W speakers, even when they’re not visible to the eye. Sound is channeled through a hollow pole magnet, away from the diaphragm, and disappears into the tail.. So all the sound you hear is good sound."

"When a driver is loaded by a tube of a similar diameter to the diaphragm, sound propagates down the tube as a series of simple plane waves. When the sound reaches the other end of the tube it is reflected back up the tube towards the driver. If it reaches the driver it causes delayed radiation that time-smears the original signal, blurring the clarity of the sound. If, however, you fill the tube with absorbent material and the tube is long enough, you can dissipate the energy before it reaches the end of the tube. The sound from the driver then remains clean and true to the input signal. Tapering the tube enables you to make it shorter for the same level of absorption. It acts like a horn in reverse - reducing the sound level instead of increasing it.

The limit of this type of loading is reached when the wavelength gets small enough to be comparable with the diameter of the tube. Above a certain frequency, the sound ceases to propagate as a simple plane wave and a series of cross-mode resonances are set up which can re-radiate through the driver diaphragm. To maintain the effectiveness of tube loading, you must restrict the bandwidth of each driver. This is one reason why the Nautilus loudspeaker is divided into a 4-way system. A more complex type of loading is required to cover a wider bandwidth and the sphere/tube enclosure was developed for the Nautilus™ 800 Series."


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## Patrick Bateman

KARPE said:


> With those ikea bowls, they probably aren't fully round, but flat on bottom so they stay standing. Would that defeat the idea of diffusion?


Check out the jpg that ItalynStalion posted; it's not the shape itself that's uber-important. It's the lack of sharp edges.

In the jpg he posted, you'll notice that the sphere and the hexagonal enclosure worked the best. The cylinder worked ok when the driver is mounted on the curved side, but the results are ATROCIOUS when mounted on the flat side. And that's the general theme:

sharp edge = lots of diffraction

Just make your enclosures look like a Ford Taurus and you'll be OK










Ideally the enclosure should be tear drop shape, like an airplane wing, or a B&W 801. But *anything* that you do to reduce sharp edges will reduce diffraction.



karpe said:


> I'm a bit confused on how to pick the size of the cup/ hemisphere, If I'm using a 3.5 FR88 full range driver, what specs would I use to calculate what i would need?


If you're using a sphere, the radius of the sphere is calculated like this:
_required sphere radius = 13500 / lowest frequency / 2 / pi_

If you're using a simple roundover, the radius of the roundover is calculated the exact same way. That's because we're basically taking a sphere and "quartering it."
_required roundover perimeter = 13500 / lowest frequency / 2 / pi_

You can work from the other direction too. For instance, if you're at Home Depot, looking at PVC, and trying to figure out what size is adequate, here's the calculation.

_Lowest frequency = 13500 / 2 / pi / radius of roundover_

For instance, you're standing at Home Depot, and trying to figure out if 2" PVC pipe will do the job. First, you have to take that pipe and quarter it, so that it give you a roundover with a radius of 1". A PVC pipe with a diameter of 2", chopped into four pieces, will give you a roundover with a radius of 1" and a perimeter of 1.57. _( pi / radius / 2)_
Plugging those numbers into our equation, we find that a 2" PVC pipe, quartered, will reduce diffraction down to 1368hz. _(13500 inches per second / 2 / 3.14159 / 1.57"_

Does that answer the question? You can approach it from either direction. Either purchase some PVC pipe, or some Ikea salad bowls, and calculate the lowest frequency that they'll diffuse the sound. Or calculate what size you require.

Psychoacoustic research demonstrates that the roundover is most effective at high frequencies. If you're not convinced, grab a tweeter, buy a sphere for a buck, stuff a sock in it, and listen to them.

I think you'll be pleased by how the tweeters "disappear" in a sphere.


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## rockinridgeline

I've been thinking a lot about how I want to shape the a-pillars for my closed back Dyn mids and F#1 tweets (they don't need enclosures). I think this thread has given me food for thought. I am thinking that since the tweets are crossed over from 4K up that they would be fine in a sphere a little over 1" and the mids would work in 4" sphere. somebody let me know if I am missing something. Is diffraction going to be as big an issue with the mids?


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## splicer

t3sn4f2 said:


> Question, would the objects around a typical install location (ie dash, defrost vents, pillar angles, glass, ect.) affect the response the same way as baffle shape would? If so then couldn't the changes that a less then optimum baffle bring actually correct the overall response once the surrounding objects own changes are summed in?
> 
> In other words, what if my pillar creates a dip where the stock baffle steps it back up to where it sounds better?


Yes, other objects will contribute to the frequency response but there are two important things to keep in consideration:
1. the closer the sharp edge is to the driver, the more it matters, especially at high frequencies. 
2. diffraction doesn't just screw up the frequency response, it does it differently for each listening angle. That is why you can't effectively EQ out diffraction effects. If you EQ to make it better in one position, it makes it worse in another. 

It is useful to think of this like water flowing in a stream or ripples in a pond. A smooth and large rock will have the water flow smoothly around it. One with lots of edges creates all kinds of turbulence. If you put a bunch of jagged rocks in the stream you may be able to create an area where the flow is smooth, but you can't do that without making it rough in other places.


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## Patrick Bateman

rockinridgeline said:


> I've been thinking a lot about how I want to shape the a-pillars for my closed back Dyn mids and F#1 tweets (they don't need enclosures). I think this thread has given me food for thought. I am thinking that since the tweets are crossed over from 4K up that they would be fine in a sphere a little over 1" and the mids would work in 4" sphere. somebody let me know if I am missing something. Is diffraction going to be as big an issue with the mids?


Diffraction is an issue at all frequencies, but it's particularly audible above 1khz. But listen for yourself; go to the craft store, buy some spheres for a buck, and cram a sock in there to seal it off. I think you'll be surprised how quickly the speakers "disappear."

If you want to go the extra mile, buy some rope caulk from Home Depot. It's $5. It's used to seal plumbing, it's in the insulation section. That will seal the sphere completely, and it's removable.

So you can experiment with the spheres, and see if they make an audible improvement.

I think you'll be amazed...


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## BigRed

I remember reading about how Biggs from Jbl used a diffraction ring on the mids in his kicks. is it just the exterior surrounding the driver that is most important with a particular angle on the edge or the actual sphere shape behind the speaker, or both?


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## ItalynStylion

BigRed said:


> is it just the exterior surrounding the driver that is most important with a particular angle on the edge or the actual sphere shape behind the speaker, or both?


I'm guessing here but I think it has more to do with the area closest to the edge of the speaker. Reason being is that those edges will get more sound bouncing off them than the rear of the enclosures.


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## Patrick Bateman

BigRed said:


> I remember reading about how Biggs from Jbl used a diffraction ring on the mids in his kicks. is it just the exterior surrounding the driver that is most important with a particular angle on the edge or the actual sphere shape behind the speaker, or both?


Just take a look at the pic, it should be obvious:










Diffraction off the rear of the enclosure is a bigger problem at low frequencies than at high frequencies. At 5khz a wavelength is 2.7" long. So diffraction off the front is a bigger problem than diffraction off the back. But at 500hz a wavelength is 27" long, so diffraction off the rear of the enclosure is a much bigger issue.

The solution that Biggs used achieves the same goal, the main difference is that the wooofers are flush-mounted. In my experience, a spherical enclosure "disappears" better than a baffle, because the baffle re-directs most of the energy towards you. A spherical enclosure diffuses the sound in all directions.

That's not a knock on Biggs; IMHO diffraction is more audible at high frequencies than at low frequencies.


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## Arc

ItalynStylion said:


> I believe you are looking for this good sir. It is attached at the end of the frugal horn plans that Dave and Scott have graciously provided.



You are quite correct. I have that pic saved somewhere, thanks for reminding me where I got it and providing it :beerchug:

I was looking for it because I wanted to see the effects of a camfered baffle like the Avalons use.


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## WLDock

Good read here folks!

I have wanted to do some type of spherical or egg shaped enclosure for awhile now. My thinking is....a spherical enclosure along with a mat might be about the best way to get a small mid on the dash.....as it has to be one of the toughest places in the car to put drivers....reflections everywhere. However, when you have a car with a wide and long dash it is worth a try to put speakers there as there are benefits to dash mounting as well.

I was looking at some of the Gallo and Orb sets to play with. However, I ended up picking up a set of the KEF KHT1000 "egg" speakers in the Picofote1 IPOD dock. Mated with a sub, these are some nice sounding small speakers. The enclosure and the Uni-Q driver do a nice job in these....even more so in the larger models.



> They may look cute - but they sound anything but. Experiencing a movie or favorite album through KHT1005.2 is like seeing an old friend after a makeover: fresh, involving, more intense.The centre and satellite speakers all have KEF’s stunning 75mm (3in.) Uni-Q driver - the smallest ever made, its 15mm (0.6in.) metal dome tweeter and double neodymium magnets deliver the extended bandwidth you normally get with much larger units.
> 
> *The curvy die-cast aluminium enclosures eliminate the diffractions and internal resonances that so often blur the output of conventional small speakers, so the sound is cleaner and crisper.*




































I hope to do some type of sphere or egg shape enclosure for some 3" fullranges to be mounted on the dash...will see...


----------



## t3sn4f2

splicer said:


> Yes, other objects will contribute to the frequency response but there are two important things to keep in consideration:
> *1. the closer the sharp edge is to the driver, the more it matters, especially at high frequencies.
> 2. diffraction doesn't just screw up the frequency response, it does it differently for each listening angle. That is why you can't effectively EQ out diffraction effects. If you EQ to make it better in one position, it makes it worse in another.
> *
> It is useful to think of this like water flowing in a stream or ripples in a pond. A smooth and large rock will have the water flow smoothly around it. One with lots of edges creates all kinds of turbulence. If you put a bunch of jagged rocks in the stream you may be able to create an area where the flow is smooth, but you can't do that without making it rough in other places.


I see, thanks. 

Edit: Although, objects around the tweeter in almost every install location are going to be nearer in proximity then the edge of a standard width baffle would be to the tweeter and more diffracting even due to the crazy shapes.


----------



## ItalynStylion

Patrick Bateman said:


> Diffraction off the rear of the enclosure is a bigger problem at low frequencies than at high frequencies. At 5khz a wavelength is 2.7" long. So diffraction off the front is a bigger problem than diffraction off the back. But at 500hz a wavelength is 27" long, so diffraction off the rear of the enclosure is a much bigger issue.


Thanks for clearing that up Patrick!


----------



## SSSnake

Patrick,

A couple of quick points to make sure that I am on the same page:



> Better yet, put that spehere about six inches away from the dash and the windshield, and you'll eliminate or reduce ALL reflections down to 470hz.


The case stated above eliminates or reduces *diffraction* down to 470 hz as the boundary surfaces are not now acoustically part of the baffle. However, reflections still occur (particularly in the omnidirectional radiation frequencies). I would agree that they are of secondary importance to diffraction but they do occur and color the sound (hence the reason room treatments are still important).



> Lowest frequency = 13500 / 2 / pi / *radius* of roundover
> 
> For instance, you're standing at Home Depot, and trying to figure out if 2" PVC pipe will do the job. First, you have to take that pipe and quarter it, so that it give you a roundover with a radius of 1". A PVC pipe with a diameter of 2", chopped into four pieces, will give you a roundover with a radius of 1" and a *perimeter *of 1.57. ( pi / radius / 2)
> Plugging those numbers into our equation, we find that a 2" PVC pipe, quartered, will reduce diffraction down to 1368hz. (13500 inches per second / 2 / 3.14159 / 1.57"


In this section you use "radius" and "perimeter" interchangably. I believe that perimeter is correct but I haven't been able to find an authoratative source to confirm.

As many have noted this is great stuff. I just wanted to make sure that I and others are reading the post are on the same page.


----------



## slade1274

Cool, even coming a bit late to the discussion I get to add something of value... check out this solution to finding (making) enclosures.

Parts Express DIY Project


----------



## Patrick Bateman

SSSnake said:


> Patrick,
> 
> A couple of quick points to make sure that I am on the same page:
> 
> 
> 
> The case stated above eliminates or reduces *diffraction* down to 470 hz as the boundary surfaces are not now acoustically part of the baffle. However, reflections still occur (particularly in the omnidirectional radiation frequencies). I would agree that they are of secondary importance to diffraction but they do occur and color the sound (hence the reason room treatments are still important).
> 
> 
> 
> In this section you use "radius" and "perimeter" interchangably. I believe that perimeter is correct but I haven't been able to find an authoratative source to confirm.
> 
> As many have noted this is great stuff. I just wanted to make sure that I and others are reading the post are on the same page.


Yes, you are correct. I was going to edit my original post last night, then realized I'm supposed to be on vacation 

(Typing this from an airport in Nevada...)

Also, I had the same issue, trying to find a formula for this online was a p.i.t.a. The forumula that I posted is based on a single wavelength.

My measurements seem to demonstrate that a roundover is partially effective at even a fractional wavelength. In other words, in the real world, a roundover has an effectiveness that appears to increase with frequency. Yet it's even effective at frequencies where the formula indicates it shouldn't be, albeit not as effective as it is at higher frequencies.

Then again, we need it the most at high frequencies, as we're naturally more sensitive to polar response above 1khz then below.


----------



## captainobvious

Patrick, thank you for taking the time to lay this out for us. This is some great reading material, and will certainly change my approach with this installation.


----------



## psycle_1

Nice thread.

How exactly would one execute this with tweeters in the A-pillars?


----------



## 94VG30DE

I was thinking that myself. I guess you wouldn't really be able to to a whole sphere as the back of the a-pillar is flush against the glass. It seems like the goal would be to get the a-pillar to resemble a cylinder as much as possible, and then mount the correctly-sized tweeter on tangent to the front face, flush with the face. Seems like this would be easier as the tweeter size got smaller. You'd have to do the math though to pick the right tweeter size for your a-pillar diameter. Or at the very least, that would help predict the result.


----------



## Jim85IROC

Interesting concepts, but in reality I think a lot of them fall short. diffraction occurs right at the point where the front baffle breaks the perpendicular from the direct radiation pattern... i.e. as soon as you get to the "edge" of the flat part. With a normal home speaker, this is the edge of the baffle, or if it's got a round-over, it's right at the very beginning of that roundover. What occurs beyond that initial fixed point is secondary. Plenty of research has been conducted that proves that a roundover will help this... the bigger the roundover, the smoother the response... so far this all agrees perfectly with what Patrick has said. The problem is that your "solution" ignores everything that you've demonstrated. For a circular enclosure to be beneficial, you need to have a smooth and large initial radius at the point where the enclosure tapers back from the tweeter faceplate, but simply dropping the tweeter into a cup that's got a rounded back isn't doing that. Likewise, the pods shown in the pic of Earl Z's car don't address that situation either. All of these create a worst-case scenario... a sharp baffle edge that's equidistant from the radiating source all the way around. At least with a conventional baffle you can reduce the diffraction effects by placing the driver in such a position that the left, right, top & bottom edges are all at different distances. 

One comment on the B&W midrange enclosure too... The enclosure shape of those enclosures are the shape they are primarily because of the effects they have on the sound inside the enclosure, not the outside. That teardrop shape is designed primarily to absorb and dissipate the acoustic energy radiating from the backside of the cone.

I also can't help but wonder whether any of this diffraction stuff would be relevant with conventional car-audio tweeters that sit in a mounting cup, or at the very least, have a dome that's recessed in the plastic housing with the grill covering it. My guess is that the housing is going to represent the "edge" and due to the tweeter dome edge being slightly recessed, will make anything beyond that largely invisible.

The issue of fatigue at higher volumes may be partially associated with diffraction, but the primary reason for this is largely assumed to be non-linear harmonic distortion. If diffraction has any impact on listener fatigue, I suspect it's very minor.

I would also imagine that comb filtering from windshild reflections are going to have a far greater impact on what you hear than a couple dB of diffraction effects.


----------



## Patrick Bateman

Jim85IROC said:


> Interesting concepts, but in reality I think a lot of them fall short. diffraction occurs right at the point where the front baffle breaks the perpendicular from the direct radiation pattern... i.e. as soon as you get to the "edge" of the flat part. With a normal home speaker, this is the edge of the baffle, or if it's got a round-over, it's right at the very beginning of that roundover. What occurs beyond that initial fixed point is secondary.


Keep in mind I'm a complete freak about imaging, when it comes to a good stereo, that's the first thing I notice. You are proposing that diffraction occurs when the baffle breaks from perpendicular.

That's true, but it's only part of the story.

As the sound wave travels from the source, any change in slope will cause diffraction. The greater the change in slope, the greater the diffraction.

So that's why I invest so much effort in waveguides, spherical enclosures, and the like. It's an effort to eliminate early reflections. (and control directivity also.)

You suggest that what happens beyond the baffles edge is "secondary." That would only be true if the sound wave ceased to exist after crossing the baffle. Based on what I've studied, diffraction is an issue for the first 10 milliseconds of travel, at least. Sound travels eleven feet in 10 milliseconds. This is also one of the reasons that home speakers frequently image better than car speakers. At home we have the luxury of pulling them away from the sidewalls. The reflections are still there, but they're not in that critical 10 millisecond window (if we're lucky.)



Jim85IROC said:


> Plenty of research has been conducted that proves that a roundover will help this... the bigger the roundover, the smoother the response... so far this all agrees perfectly with what Patrick has said. The problem is that your "solution" ignores everything that you've demonstrated. For a circular enclosure to be beneficial, you need to have a smooth and large initial radius at the point where the enclosure tapers back from the tweeter faceplate, but simply dropping the tweeter into a cup that's got a rounded back isn't doing that. Likewise, the pods shown in the pic of Earl Z's car don't address that situation either. All of these create a worst-case scenario... a sharp baffle edge that's equidistant from the radiating source all the way around. At least with a conventional baffle you can reduce the diffraction effects by placing the driver in such a position that the left, right, top & bottom edges are all at different distances.


Yes, to control diffraction properly you would want the shaped to blend smoothly all the way to the diaphragm... Just like B&W did.

Zausmer's pods don't have any sharp edges.



Jim85IROC said:


> One comment on the B&W midrange enclosure too... The enclosure shape of those enclosures are the shape they are primarily because of the effects they have on the sound inside the enclosure, not the outside. That teardrop shape is designed primarily to absorb and dissipate the acoustic energy radiating from the backside of the cone.
> 
> I also can't help but wonder whether any of this diffraction stuff would be relevant with conventional car-audio tweeters that sit in a mounting cup, or at the very least, have a dome that's recessed in the plastic housing with the grill covering it. My guess is that the housing is going to represent the "edge" and due to the tweeter dome edge being slightly recessed, will make anything beyond that largely invisible.


"largely invisible?" There's tons of research that demonstrates that reflections during the first few milliseconds reduce intelligibility, alter the perception of the acoustic space, etc... And that doesn't even consider the effect of reflections on frequency response.

Even if we reduce the window down to a single millisecond, that's still 13.5 inches. Anything even close to the radiator is a problem. We can't eliminate the reflections but we can diffuse them.



Jim85IROC said:


> The issue of fatigue at higher volumes may be partially associated with diffraction, but the primary reason for this is largely assumed to be non-linear harmonic distortion. If diffraction has any impact on listener fatigue, I suspect it's very minor.
> 
> I would also imagine that comb filtering from windshild reflections are going to have a far greater impact on what you hear than a couple dB of diffraction effects.




The studies on diffraction and listener fatigue are emerging. I even stumbled across a Nasa paper on this. (Your tax dollars at work.)

But let's ignore all the studies for a moment and just think about this from a common sense perspective. All waves are affected by diffraction and reflections. Doesn't matter if it's a radio wave, an ocean wave, or a sound wave. The problem we face is that the intelligibility of our speakers, along with the perception of the soundstage, is dependent on reflections and diffraction. So anything we can do to control them will improve things for us. And coming back to the studies, it's particularly critical for those first few milliseconds.


----------



## douggiestyle

I knew I'd seen this somewhere...

BERYLLIUM BMW 323ci. - Page 10 - CARSOUND.COM Forum


----------



## Nitin

so will this here work for the purpose of whats being discussed in this thread ie using tennis balls instead of plastic spheres 










i was using this to see if changing direction that the speakers face would have any effect ie in terms of axis - but it seems like from whats being said in this thread it could serve a dual purpose 

also would those spheres need to be any bigger than how i have them there


----------



## Austin

^^Thats a good idea. What size tweets are those?


----------



## ItalynStylion

^PERFECT IMO! Not only are they perfect hemispheres but they're also soft!


----------



## Fixtion

Nitin said:


> so will this here work for the purpose of whats being discussed in this thread ie using tennis balls instead of plastic spheres
> 
> i was using this to see if changing direction that the speakers face would have any effect ie in terms of axis - but it seems like from whats being said in this thread it could serve a dual purpose
> 
> also would those spheres need to be any bigger than how i have them there


make better cuts, spray paint the surface black, and cover it in grille clothe.
good to go!


----------



## Nitin

Austin said:


> ^^Thats a good idea. What size tweets are those?


they are supposed to be 28mm tweeters though i would tend to think that this figure refers to the voice coil diameter - the actual diameter of the tweeter is 62.2 mm - they are dynaudio MD102's that come with any dynaudio esotec component set now - you can find all the details at this link here 

Dynaudio - Authentic Fidelity



> ^PERFECT IMO! Not only are they perfect hemispheres but they're also soft!


so is it better having them soft or would it be better to actually remove the yellow mat and cover the rubber with a few layers of fibreglass ??



> make better cuts, spray paint the surface black, and cover it in grille clothe.
> good to go!


yeah - this was just temporary just to experiment with - i did have a few plans on how i could still have used the idea with a little refinement going forward but those involved a bit of fibreglass - now it depends on whether the entire structure should remain soft or whether its fine to fibreglass it and cover it with a carpet so that the carpet actually partially absorbs any potential reflections - i was wanting to actually use leather for cosmetic considerations but that would probably be very reflective ?


----------



## boltupright

If I understand it correctly, it seems the tennis ball edge would have to contact the outside edge of the speaker without having any sharp edge between the speaker and the tennis ball. That metal circle you have on the outside of the speaker has a sharp edge all the way around it, so I don't think it would work.


----------



## invinsible

Can a dome tweeter crossed at 3200hz can benefit from this spherical enclosure?
I understand that the midrange would be highly benefited. I always had this in mind of using a spherical enclosure for the drivers and even sub for that fact but din't know it could benefit at such a great extent. Have a sphere enclosure for a 10" sub has always been on mind. Haven't taken the time out to go ahead with it. Plus, need to determine how big it might turn out to be. 

Patrick will the sub benefit from a sphere enclosure design?


----------



## Babs

Nitin said:


>


I've seen it all now. 

That's using the noodle! Good job.


----------



## ItalynStylion

invinsible said:


> Patrick will the sub benefit from a sphere enclosure design?


My guess is no. Think about how big that sphere would be. 
13500 / 30hz / 2 / pi= 72" radius

That works out to be 12ft across! Put that in your trunk! 

Besides, frequencies below 80hz are very hard to locate anyways. They are considered to be omni-directional.


----------



## Patrick Bateman

ItalynStylion said:


> My guess is no. Think about how big that sphere would be.
> 13500 / 30hz / 2 / pi= 72" radius
> 
> That works out to be 12ft across! Put that in your trunk!
> 
> Besides, frequencies below 80hz are very hard to locate anyways. They are considered to be omni-directional.


Yep. Our hearing mechanism is dominated by path length differences below 1khz. Above that point it's very point it's very important to match the frequency response on the left and the right speakers. Reducing diffraction improves the frequency response off axis, which is why it helps speakers "disappear."

The 1khz frequency isn't "set in stone" either, it's a transition that covers about 500hz to 2khz.

Anyways, long story short, path lengths are the top priority at low frequencies.


----------



## invinsible

Patrick Bateman said:


> Yep. Our hearing mechanism is dominated by path length differences below 1khz. Above that point it's very point it's very important to match the frequency response on the left and the right speakers. Reducing diffraction improves the frequency response off axis, which is why it helps speakers "disappear."
> 
> The 1khz frequency isn't "set in stone" either, it's a transition that covers about 500hz to 2khz.
> 
> Anyways, long story short, path lengths are the top priority at low frequencies.


Well if that's the case than what makes companies like Morel, KEF, B&W come up with Sphere shape enclosure for their subwoofers. Noticed that they crossed high upto 160hz or so. 

Morel Loudspeakers - Home Audio - SoundSpot Satellite System - SoundSpot Components - SoundSub 9
HTB Series
B&W PV1 Subwoofer

As per the doing up the tweeter, have Morel Hybrid ovation running in front with Mt-22 tweeter and here's what I plan to do. I had an old Home theatre system with 5 2" size full range speaker in Sphere shape which are not in use anymore. I plan to use two of their enclosure to mount the the MT-22 tweeter. It has an opening of 2", with some fabrication I suppose I may be able to mount them in it and they look neat. Here's some pics on it. 

I would like to know how much difference will this make on the dome tweeter and if it's worth doing it ? I would be placing them on the dash.


----------



## Nitin

> Well if that's the case than what makes companies like Morel, KEF, B&W come up with Sphere shape enclosure for their subwoofers. Noticed that they crossed high upto 160hz or so.


in the instance of subwoofers - as was explained above it wont really have much influence on the difraction due to the wavelengths of subsonic frequencies 

but sometime back when Moe Sabourin (at that time president of IASCA) visited South Adrica he revealed in a workshop/seminar that he conducted here that many serious SPL competitors believe that you need to reduce turbulence within the enclosure to get a subwoofer tuned to a vehicles resonant frequency so a smooth enclosure with no edges will perform this feat hence a spherical shape is best for that purpose - in this instance its not about whats going on outside the enclosure but whats going on inside the enclosure 

also in theory a spherical shape would create more even pressure on the cone and make it more evenly damped than a rectangular box would and also the spherical shape on paper reduces the chances of standing waves as well 

i could be incorrect about any or all of the above but that is how i understand it


----------



## Jim85IROC

Patrick Bateman said:


> Keep in mind I'm a complete freak about imaging, when it comes to a good stereo, that's the first thing I notice. You are proposing that diffraction occurs when the baffle breaks from perpendicular.
> 
> That's true, but it's only part of the story.
> 
> As the sound wave travels from the source, any change in slope will cause diffraction. The greater the change in slope, the greater the diffraction.
> 
> So that's why I invest so much effort in waveguides, spherical enclosures, and the like. It's an effort to eliminate early reflections. (and control directivity also.)
> 
> You suggest that what happens beyond the baffles edge is "secondary." That would only be true if the sound wave ceased to exist after crossing the baffle. Based on what I've studied, diffraction is an issue for the first 10 milliseconds of travel, at least. Sound travels eleven feet in 10 milliseconds. This is also one of the reasons that home speakers frequently image better than car speakers. At home we have the luxury of pulling them away from the sidewalls. The reflections are still there, but they're not in that critical 10 millisecond window (if we're lucky.)
> 
> 
> 
> Yes, to control diffraction properly you would want the shaped to blend smoothly all the way to the diaphragm... Just like B&W did.
> 
> Zausmer's pods don't have any sharp edges.
> 
> 
> 
> "largely invisible?" There's tons of research that demonstrates that reflections during the first few milliseconds reduce intelligibility, alter the perception of the acoustic space, etc... And that doesn't even consider the effect of reflections on frequency response.
> 
> Even if we reduce the window down to a single millisecond, that's still 13.5 inches. Anything even close to the radiator is a problem. We can't eliminate the reflections but we can diffuse them.
> 
> 
> 
> 
> 
> The studies on diffraction and listener fatigue are emerging. I even stumbled across a Nasa paper on this. (Your tax dollars at work.)
> 
> But let's ignore all the studies for a moment and just think about this from a common sense perspective. All waves are affected by diffraction and reflections. Doesn't matter if it's a radio wave, an ocean wave, or a sound wave. The problem we face is that the intelligibility of our speakers, along with the perception of the soundstage, is dependent on reflections and diffraction. So anything we can do to control them will improve things for us. And coming back to the studies, it's particularly critical for those first few milliseconds.


You're kinda missing my point. I'm not arguing that the entire enclosure isn't going to have an effect... I'm sure it does, but my comment is that you're missing the forest for the trees here. Sure, what's going on halfway behind the enclosure is probably having an audible effect, but my argument is that the single biggest source of audible diffraction (the sharp edge at the edge of the baffle) isn't really being dealt with properly in Earl's car nor in this tweeter pod idea. That first edge is where the vast majority of your diffraction comes from is still a very sharp transition, so you're going to get a very bumpy frequency response measurement with or without that cup. You've got measurement equipment... stick the tweeter in that little pod and measure it. I'll bet that you get some fairly severe diffraction ripple... worse than what you'd get on a flat baffle with a 1/2" roundover. 

If I can find time to get my soundeasy rig set up and make some sawdust this weekend, I'll try to take some measurements and put them up too. This will be a lot easier for me to describe with some actual measurements.


----------



## jsun_g

I am so glad I stumbled upon this thread.

I did a hybrid approach to my tweeter pods which are attached to the A-pillars...the pods look kind of similar to the pics in the quoted thread.
This is the thread I got the idea from: http://www.diymobileaudio.com/forum...justable-easily-replaceable-tweeter-pods.html

By hybrid approach, I implemented the technique in this thread by using two 2" ID PVC end caps (the ends are rounded) and clamshelled them together & drilled a 1-3/4" diameter opening in the end of one side, yielding about a 5/8" roundover. I am using TangBand tweeters Parts-Express.com:Tang Band 25-1166SJ 1" Neodymium Tweeter | tweeter dome tweeter fabric dome neodynium tang band tb speakers which are kind of laid-back sounding, which works out great for me being A-pillar mounted.
I ended up shaving the flange off the tweeters and flush-mounting them into the clamshell PVC pods. One tweeter didn't survive though...it is reading infinite DCR...I must have fkkd it up while dremmeling the flange or soldering the wires. Until a replacement comes in, I am using a mismatched tweeter set.

IMPRESSIONS:
the non-fkkd up tweeter is on the passenger's side and I can notice a difference with this "diffraction reducing" setup. I can't tell that HF sounds are coming from the tweeter...many sounds are coming from behind it, above it, or outside the A-pillar. I am liking this! I can't wait to get the replacement tweeter for the driver's side.

I am struggling with understanding something though regarding this roundover subject...the higher the frequency that is playing, the more it is attenuated off-axis. We are talking about 90-degrees off axis when looking at the plane a speaker is mounted to. I am not quite understanding how high frequencies which attenuate so much off axis would be affected by a rounded vs. straight edge. I can tell a difference with my new setup, but what is the story behind this...does the fact that there is a baffle (even though it is at 90-degrees off axis) cause those greatly attenuated waves to be amplified (kind of like a waveguide) such that they may be as loud as (or at least noticible) the primary on-axis wave?



invinsible said:


> Morel Loudspeakers - Home Audio - SoundSpot Satellite System - SoundSpot Components - SoundSub 9
> HTB Series
> B&W PV1 Subwoofer


----------



## Notloudenuf

Nitin said:


> in the instance of subwoofers - as was explained above it wont really have much influence on the difraction due to the wavelengths of subsonic frequencies
> 
> but sometime back when Moe Sabourin (at that time president of IASCA) visited South Adrica he revealed in a workshop/seminar that he conducted here that many serious SPL competitors believe that you need to reduce turbulence within the enclosure to get a subwoofer tuned to a vehicles resonant frequency so a smooth enclosure with no edges will perform this feat hence a spherical shape is best for that purpose - in this instance its not about whats going on outside the enclosure but whats going on inside the enclosure
> 
> also in theory a spherical shape would create more even pressure on the cone and make it more evenly damped than a rectangular box would and also the spherical shape on paper reduces the chances of standing waves as well
> 
> i could be incorrect about any or all of the above but that is how i understand it


Almost every build log on termpro.com has the builder using 1/4's of PVC pipe, sonotube or wood cut on 45's to smooth out the corners. Your reasoning is the reason they claim for doing this.


----------



## Dakota548ci

Go to Lowes and pick up one of these. Would make for a great mold. These are the same ones James loudspeakers use to house their outdoor speakers. $19 at Lowes.










Portfolio at Lowe's: 35-Watt Black Spotlight Landscape Lighting

James Loudspeaker version:










http://www.jamesloudspeaker.com/land3.gif

This Pdf will show you a picture of the driver mounted in the enclosure:
http://www.jamesloudspeaker.com/lit/ACF1A3.pdf

Shane


----------



## thehatedguy

L'Cleach round over got you thinking about horn termination?


----------



## invinsible

Nitin said:


> also in theory a spherical shape would create more even pressure on the cone and make it more evenly damped than a rectangular box would and also the spherical shape on paper reduces the chances of standing waves as well


+1 that's exactly what I had in mind. Am sure it may not make difference as much as it would make the higher frequencies, but with standing waves being the issue even in sealed enclosure which would get smoothen out with a sphere enclosure. In a rectangular box some sub do tend to get boomy once crossed higher than 80hz, I believe the same will have different character crossed higher, may be get less boomier than the regular boxes. But again then it's the volume than matters which may make sub sound boomy or tight. But, some of the resonance and standing wave may reduce with sphere enclosure and help making the sub sound more smoother. The only challenging part will be size of the enclosure in sphere form.


----------



## tmans

learned alot


----------



## boltupright

invinsible said:


> +1 that's exactly what I had in mind. Am sure it may not make difference as much as it would make the higher frequencies, but with standing waves being the issue even in sealed enclosure which would get smoothen out with a sphere enclosure. In a rectangular box some sub do tend to get boomy once crossed higher than 80hz, I believe the same will have different character crossed higher, may be get less boomier than the regular boxes. But again then it's the volume than matters which may make sub sound boomy or tight. But, some of the resonance and standing wave may reduce with sphere enclosure and help making the sub sound more smoother. The only challenging part will be size of the enclosure in sphere form.


Wouldn't putting some pieces of foam inside the enclosure break up the waves? Maybe just glue some pieces to the sides...or put some of that fiberfill stuff in the box?


----------



## aztec1

What happens if there's no baffle at all, spherical or otherwise?


----------



## ItalynStylion

aztec1 said:


> What happens if there's no baffle at all, spherical or otherwise?


I tried it back in the day while tuning the car atop a large mountain. The results were so awful the mountain exploded in sheer disgust. Most of you know this event as the eruption of Mt. St. Helens in 1980.


----------



## WLDock

douggiestyle said:


> I knew I'd seen this somewhere...
> BERYLLIUM BMW 323ci. - Page 10 - CARSOUND.COM Forum


Hey! thanks for bringing that thread up. I forgot about that one...that build started early last year and that post is still going. At first, I was not too sure how I liked his ball pods but I guess that was about the best one could do given the shape. Awesome install there.


----------



## Abaddon

splicer said:


> I've been thinking about sticking my seas neos (which are small format tweeters) in kind of a softball-sized sphere in the kicks to deal with the diffraction issue. As a bonus it would really blend in with the interior theme. I would just need to vinyl up a foam ball.
> 
> mini interior


Black Vinyl with Red stitching... DO IT!


----------



## aztec1

ItalynStylion said:


> I tried it back in the day while tuning the car atop a large mountain. The results were so awful the mountain exploded in sheer disgust. Most of you know this event as the eruption of Mt. St. Helens in 1980.


 Thanks, I'll be sure to leave that off of my "try this" list.


----------



## Patrick Bateman

aztec1 said:


> What happens if there's no baffle at all, spherical or otherwise?


Then the frame of the woofer forms the baffle. Due to interference from the back side of the speaker, the low frequency output begins to decay at a frequency which is dictated by the width of the cone.

Check out linkwitzlab.com and quarter-wave.com for more info on how this works.


----------



## lechuck

Scientifics who design stereo sound reproduction never meant it to be only 2 channels. At least 3 channels should be used. Left right and center. With a good processor and 3 speakers you have a good imaging capabilities where ever you stand in the room. With only two channels, you could spend a million bux on the speaker design, but when you are not right in the middle axe, facing straight ahead your expensive speaker, it doesn't matter what you do, you don't get the right imaging.

Try this with your loved stereo sound system, pan you head from right to left and already you cannot hear a stable image.

A center channel with a processor with gather the center information so you hear clearly the image no matter what position you face, and where you are between the speakers.

I always love the stereo illusion with two speakers, its like magic, but it is so constraining that when you try an audiophile processor with 3 speakers, you can't look back.

Is it only me but I think the diffraction issue is overrated? The diffraction sound is a fraction of the sound produced by the speaker itself. You may reduce the difraction by putting the tweeter in a plastic sphere but the you don't deal with any other problems generated by doing this. Traditional enclosure have that diffraction issue but real brand names deal with this issue with carefull manufacturing, B&W in my humble opinion puts too much money on fancy shaped enclosure... Dealing with enclosure diffraction is not the badest problem in speakers design. The speaker doesn't disapear my god, its the diffraction that is reduced, the sound should come out of the speaker or you got it unplugged


----------



## rockinridgeline

ItalynStylion said:


> I tried it back in the day while tuning the car atop a large mountain. The results were so awful the mountain exploded in sheer disgust. Most of you know this event as the eruption of Mt. St. Helens in 1980.



:laugh:


----------



## Oliver

ItalynStylion said:


> I tried it back in the day while tuning the car atop a large mountain. The results were so awful the mountain exploded in sheer disgust. Most of you know this event as the eruption of Mt. St. Helens in 1980.


I remember that:laugh:


----------



## Babs

Forgot about this company, so thought I'd share some spherical enclosure pron for you guys this morning. I have an itchy suspicion these speaks sound awesome...

















The enclosure they say on the site is two opposing fiberglass h-spheres filled with a proprietary sand mixture.. The filler is something I saw on Gallo's site also in their A'Diva's.. Apparently I think Gallo uses it for low-end extension possibly??? Anyway, nice speaks here by Proclaim.


----------



## Patrick Bateman

lechuck said:


> Scientifics who design stereo sound reproduction never meant it to be only 2 channels. At least 3 channels should be used. Left right and center. With a good processor and 3 speakers you have a good imaging capabilities where ever you stand in the room. With only two channels, you could spend a million bux on the speaker design, but when you are not right in the middle axe, facing straight ahead your expensive speaker, it doesn't matter what you do, you don't get the right imaging.


Creating a stable soundstage isn't rocket science. It's basically two steps:


Match the frequency response from approximately 1khz to 20khz, on the left and the right. This is the range where soundstaging cues are dominated by frequency response.
Match the pathlengths from approximately 20hz to 1khz. This is the range where soundstaging cues are dominate by pathlengths.

The hardest part about getting the first part right are reflections and diffraction. Reflections create phantom images, confusing the cues which define the soundstage. Diffusion or absorbtion of those reflections doesn't eliminate the problem, but it reduces it a great deal. It allows a speaker to "disappear."

The hardest part about getting the second part right is simply finding places to locate the speakers.



lechuck said:


> Try this with your loved stereo sound system, pan you head from right to left and already you cannot hear a stable image.
> 
> A center channel with a processor with gather the center information so you hear clearly the image no matter what position you face, and where you are between the speakers.


IMHO, a discussion of going to a three-speaker system is beyond the scope of this thread.



lechuck said:


> I always love the stereo illusion with two speakers, its like magic, but it is so constraining that when you try an audiophile processor with 3 speakers, you can't look back.
> 
> Is it only me but I think the diffraction issue is overrated? The diffraction sound is a fraction of the sound produced by the speaker itself. You may reduce the difraction by putting the tweeter in a plastic sphere but the you don't deal with any other problems generated by doing this. Traditional enclosure have that diffraction issue but real brand names deal with this issue with carefull manufacturing, B&W in my humble opinion puts too much money on fancy shaped enclosure... Dealing with enclosure diffraction is not the badest problem in speakers design. The speaker doesn't disapear my god, its the diffraction that is reduced, the sound should come out of the speaker or you got it unplugged



If you care about imaging, then diffraction is a problem. The difference in soundstaging between a speaker in a box and a speaker in a diffraction-free enclosure is breathtaking.


----------



## aztec1

Patrick Bateman said:


> Then the frame of the woofer forms the baffle. Due to interference from the back side of the speaker, the low frequency output begins to decay at a frequency which is dictated by the width of the cone.
> 
> Check out linkwitzlab.com and quarter-wave.com for more info on how this works.


Lots of great reading on those sites, thanks. I guess my question about no baffles was more geared toward tweeters because I thought it was less important for the back wave to be separated at high frequencies, even though it looks like Linkwitz designs can get excellent midrange response with an open baffle.

For a tweeter though, why would putting it in a sphere necessarily sound better than just hanging one from a wire in midair? Would that depend on the physical construction of the tweeter itself?


----------



## lechuck

improve your soundstage with more than 2$ = improve your soundstage with a processor and 3 speakers.

You are right, it is out of subject on this thread. But IMHO guys like BW are wasting their time with expensive enclore like that










The winner is cabasse for sound source coherence and diffractio elimination 










But cabasse is using active filtering and amplification for their spheres, there must be a good reason for this!

My heart goes to Meridian for being the most honest and full of integrity in the entire audio industry (anyone heard their TRIFIELD processor?) It is the best thing man invented since hi rez audio playback!


----------



## mikey7182

That Nautilus is beautiful. I find it ironic that the enclosures that do the best job at making the source "disappear" also seem to draw the most attention to themselves.  "Hey Bill- what are those massive blue seashells on the sides of your tv??"


----------



## LegendJeff

Awesome thread.. thanks for posting this info


----------



## Patrick Bateman

aztec1 said:


> Lots of great reading on those sites, thanks. I guess my question about no baffles was more geared toward tweeters because I thought it was less important for the back wave to be separated at high frequencies, even though it looks like Linkwitz designs can get excellent midrange response with an open baffle.


Yes, there is no backwave with a tweeter. Linkwitz uses dual tweeters for this very reason, to create a backwave.



aztec1 said:


> For a tweeter though, why would putting it in a sphere necessarily sound better than just hanging one from a wire in midair? Would that depend on the physical construction of the tweeter itself?



The reason that it sounds better is that diffraction is created by sharp edges. Suspending a tweeter from a wire in midair would practically be a worst-case scenario. The sharp edge near the tweeter would generate gobs and gobs of diffraction.

About the only good thing about suspending a tweeter from a thread in mid air is that the diffraction would be generated almost instantaneously, because the edge is located so close to the diaphragm.

So the diffraction would reduce the intelligibility of your stereo, but the imaging would be affected to a lesser degree, since the secondary source is so close to the primary source.

But wouldn't you rather have your cake and eat it too? It's inexpensive and easy to reduce diffraction, particularly with tweeters.


----------



## lechuck

lechuck said:


> Scientifics who design stereo sound reproduction never meant it to be only 2 channels. At least 3 channels should be used. Left right and center. With a good processor and 3 speakers you have a good imaging capabilities where ever you stand in the room. With only two channels, you could spend a million bux on the speaker design, but when you are not right in the middle axe, facing straight ahead your expensive speaker, it doesn't matter what you do, you don't get the right imaging.
> 
> Try this with your loved stereo sound system, pan you head from right to left and already you cannot hear a stable image.


The reason two channel stereo won the consumer market is because it was cost wise more reasonable to produce two way vinyls, two way cartridge, two way amps, and so on... back in the day

Three channels stereo is the real thing!


----------



## splicer

mikey7182 said:


> That Nautilus is beautiful. I find it ironic that the enclosures that do the best job at making the source "disappear" also seem to draw the most attention to themselves.  "Hey Bill- what are those massive blue seashells on the sides of your tv??"


actually, in-wall could be better for diffraction than anything shown here, because it is effectively an infinite baffle, and a plane is the surface of a sphere of infinite size.


----------



## aztec1

Patrick Bateman said:


> Yes, there is no backwave with a tweeter. Linkwitz uses dual tweeters for this very reason, to create a backwave.
> 
> The reason that it sounds better is that diffraction is created by sharp edges. Suspending a tweeter from a wire in midair would practically be a worst-case scenario. The sharp edge near the tweeter would generate gobs and gobs of diffraction.
> 
> About the only good thing about suspending a tweeter from a thread in mid air is that the diffraction would be generated almost instantaneously, because the edge is located so close to the diaphragm.
> 
> So the diffraction would reduce the intelligibility of your stereo, but the imaging would be affected to a lesser degree, since the secondary source is so close to the primary source.
> 
> But wouldn't you rather have your cake and eat it too? It's inexpensive and easy to reduce diffraction, particularly with tweeters.


This is perfectly clear now, thanks. I guess the near 180 degree edge of many tweeter edges is the worst kind of sharp surface, I appreciate it you putting into terms I can understand.  Although blowing up Mt St Helens should have been description enough!

I'm running Seas neos, the edges slope down a bit which may perfectly lend them to a tennis ball mount. I'm excited to try this, my driver side tweet has been the bane of my install from day one because of the angle it makes with the window...methinks this will help a lot.


----------



## cycfari

This thread is inspiring me to re-do my A-Pillars. I'm now running 3 way active with the Tweeters & Mids fibre glassed to the A-Pillar. However I feel my soundstage sounds really bad 

So I intend to re-fibre glassed the tweeters & mids in a Spherical or Conical enclosures. This round, I'll have them to be on axis too. Should I house the Tweeters & the mids in a single enclosure or in 2 seperate Spherical/Conical enclosures?


----------



## 94VG30DE

cycfari said:


> So I intend to re-fibre glassed the tweeters & mids in a Spherical or Conical enclosures. *This round*, I'll have them to be on axis too. Should I house the Tweeters & the mids in a single enclosure or in 2 seperate Spherical/Conical enclosures?


"This round" haha :rimshot:


----------



## chithead

This thread is making me wonder if the flat face my tweeters are always mounted on is what is causing the harsh sound that makes me not want to use tweeters... Again Mr. Bateman has the gears in my head turning.


----------



## lechuck

if the diffraction problem was that huge like everyone here seems to believe, how come the respected Thiel didn't even bother with it's premium 3000$ tweeter?


----------



## Babs

If the tweet flange is flush with the front baffle, the diffraction I would think would occur at the edges of the cabinet or rather the next sharp edged steps on the face of the cabinet. Any links to the particular Thiel speaks using this tweet?

Looks like a different tweet in their current floor-stander, but from the looks of the front baffle shape around that tweet, they're fully aware of reducing diffraction...


----------



## lechuck

Sorry, here in europe we use Thiel/accuton, but in US you must know the Accuton drivers, not to be mistaken with Thiel speaker! different drivers!

the first speaker that used the diamond tweeter was from Sunray 200 000$









and Avalon made their eidolon with it for only 50000€ did you say bargain?!









boy those Thiel must sound good, I better trust Thiel. 

Diffraction is a problem know since a long time, that is why Meridian build only narrow faced speaker, but I must see to believe (hear actually) an A/B test with the same tweeter, same crossover and so on... to see if the diffraction problem is such that it is worth the cabinet design trouble!

How on earth would one make a spherical enclosure out of thick damped material??? MDF and plywood doesn't come spherical!


----------



## cycfari

94VG30DE said:


> "This round" haha :rimshot:


i'll start to hack my pillars tomorrow. Hmm.. maybe i'll just do 2 seperate conical enclosures for the tweet & mids. Madonna sounds better in Conical tips :laugh:


----------



## Patrick Bateman

cycfari said:


> This thread is inspiring me to re-do my A-Pillars. I'm now running 3 way active with the Tweeters & Mids fibre glassed to the A-Pillar. However I feel my soundstage sounds really bad
> 
> So I intend to re-fibre glassed the tweeters & mids in a Spherical or Conical enclosures. This round, I'll have them to be on axis too. Should I house the Tweeters & the mids in a single enclosure or in 2 seperate Spherical/Conical enclosures?


Diffraction occurs when the sound crosses a sharp boundary. That's why they typical rectangular enclosure causes so much of it. The most "bang for the buck" is found by putting a roundover on the front of the enclosure. After that's done, putting a roundover on the rear of the enclosure has benefits too. And after that's done, moving the speakers away from the sidewalls will yield an improvement.

A spherical enclosure will sound fairly similar to an enclosure with a roundover on the front and the back, since the shapes are somewhat similar.

The reason I'm posting this is that I don't think you'll see a huge benefit from throwing your mids and tweeters in spheres. Based on the pictures, the front already has a roundover.

I'm not saying it *won't* improve things, but it's not going to be a night and day difference, considering you *already* have a roundover on the front.

If you're image is too close to the driver's side, you're likely suffering from the Hass Effect.

Try lowering the level of the driver's side tweeter by 3-6db, while leaving the midrange at the same level. If that improves things, then the Haas Effect is screwing up your image.


----------



## Patrick Bateman

chithead said:


> This thread is making me wonder if the flat face my tweeters are always mounted on is what is causing the harsh sound that makes me not want to use tweeters... Again Mr. Bateman has the gears in my head turning.


Diffraction can add a bit of harshness to a speaker's response. Having said that, the biggest audible improvement from reducing diffraction is an improved soundstage.

Of course _reflections_ can make a speaker sound harsh; for instance if there's a boundary that's 3.5" away from a tweeter, it will often generate a peak at 2khz, which is quite audible. (A 2khz sound wave is seven inches long. 3.5 inches is half a wavelength. When the sound hits the boundary that's 3.5 inches away, it's reflected back to the source. By the time the reflection reaches the source, it's in phase, and creates a peak at 2khz.)

A microphone can help a lot to find harshness in a system.

Also, a speaker that's running out of excursion can sound harsh, of course. If the harshness is noticeable at moderate volumes, it could be a reflection.


----------



## cycfari

Patrick Bateman said:


> Diffraction occurs when the sound crosses a sharp boundary. That's why they typical rectangular enclosure causes so much of it. The most "bang for the buck" is found by putting a roundover on the front of the enclosure. After that's done, putting a roundover on the rear of the enclosure has benefits too. And after that's done, moving the speakers away from the sidewalls will yield an improvement.
> 
> A spherical enclosure will sound fairly similar to an enclosure with a roundover on the front and the back, since the shapes are somewhat similar.
> 
> The reason I'm posting this is that I don't think you'll see a huge benefit from throwing your mids and tweeters in spheres. Based on the pictures, the front already has a roundover.
> 
> I'm not saying it *won't* improve things, but it's not going to be a night and day difference, considering you *already* have a roundover on the front.
> 
> If you're image is too close to the driver's side, you're likely suffering from the Hass Effect.
> 
> Try lowering the level of the driver's side tweeter by 3-6db, while leaving the midrange at the same level. If that improves things, then the Haas Effect is screwing up your image.



Thanks Pat for the advice. The round part is actually the speakers grill. I'm already playing my driver's side tweeter by -3dB & still doesn't seem to enjoy my soundstage. I've a set of spare pillars & will try to mould individual spheres to the mids & tweets. Also I have the feeling that my drivers are firing across each other & may be detrimental to the Soundstage. My next trial is going to have them on axis too.


----------



## PRTG

Hello Patrick,

Back to the very beginning. By "horn loaded compression drivers that sound fatiquing in high levels" you mean drivers that have some kind of horn in their construction or usually low Qts high efficiency drivers designed to sound best when horn-loaded?

Regarding improvement of sounstage in a car - as most of cars usually haven't got much of a space to put drivers a bare feet from windshield, I don't see a point by using ball shaped enclosures.

Perhaps old trick mounting tweeters horizontally with reflection from windshield can be good enough to open up the soundstage. Baffle in this case isn't really cube, rather wide flat surface. Still small "bumps" made on this surface as foundation where drivers are actually mounted perhaps could make it even more precise and not only reflect from windshield, but also pull some of high frequencies directly towards the listener if that seems desirable.

Now about my $2 investment. I had a pair of somewhat harsh sounding no-name silk dome tweeters. Instead of desperate throwing-them-faraway action I decided to get rid of waveguides first as they looked a bit unreasonable shaped. I did it by softening glue with hot air gun first (carefully from magnet side) and then using strong knife and pliers to separate both parts. Waveguide removal alone improved the sound magnificently, at least the harsh resonanses around ~4 and ~8 kHz were significantly reduced.

Liberated speakers were mounted on car front panel under factory mesh (my oldy-goldy Volvo 850 has them) facing upwards. Simple 1-st order crossover consisting of only 1.2uF condenser was used to get somewhat high rolloff point (~7kHz perhaps). I chose condenser value judging by ear, getting to the balance point where harshness seem to cease, but sound level still isn't too low.

In car these tweeters now are just balancing soundstage and filling in the missing upper frequencies. The sound image now is really coming from the front, which for me is just more pleasant way of listening, also it is more balanced among both front-sitters. Also, high levels of listening are not fatiquing at all as most of bad stuff is filtered out.

Making these tweeters sit on teardrop shaped podiums is now next what comes in mind (I alway fancied these Nautilus B&Ws), so thanks for inspiring reminder


----------



## Patrick Bateman

PRTG said:


> Hello Patrick,
> 
> Back to the very beginning. By "horn loaded compression drivers that sound fatiquing in high levels" you mean drivers that have some kind of horn in their construction or usually low Qts high efficiency drivers designed to sound best when horn-loaded?


The problem isn't the compression drivers, the problem is the horn or the waveguide that they're mounted to. In particular, it seems that the transition from the mouth to the room needs to be exceptionally gentle.

Keep in mind, waveguides and horns are "my thing", so I'm apt to obsess about these things more than most do.

With any luck, I should have the 2nd channel of my waveguides hooked up and running today; if anyone is in the Pacific Northwest and wants to hear it, I'm hoping to demo it here:

Pacific Northwest Audio Society

I have about two weeks to get in buttoned down.

Here's the thread:

Creating a Soundstage with Waveguides and Psychoacoustics - diyAudio


----------



## Ge0

After reading this thread its really making me think twice about selling these.

http://www.diymobileaudio.com/forum/classifieds/62254-fs-little-french-balls-fury.html

Hmm, painted to match my interior and mounted on goose necks :bulb::bulb::bulb:

Ge0


----------



## Niebur3

Okay, I think I get all of this, but my only problem is that in all the pics of the home audio systems that incorporate this design, they are in open rooms with large open space around it.....so, if I put a sphere on my dash surrounded by a flat dash and angled flat windshield among various other obstacles, wouldn't diffraction happen off the edge of whatever the sphere comes into contact with?


----------



## Ge0

lechuck said:


> How on earth would one make a spherical enclosure out of thick damped material??? MDF and plywood doesn't come spherical!


High durometer rubber???

Ge0


----------



## Ge0

Niebur3 said:


> Okay, I think I get all of this, but my only problem is that in all the pics of the home audio systems that incorporate this design, they are in open rooms with large open space around it.....so, if I put a sphere on my dash surrounded by a flat dash and angled flat windshield among various other obstacles, wouldn't diffraction happen off the edge of whatever the sphere comes into contact with?


I like that you have thought this out. BINGO!!!

Perhaps a wave guide is more3 appropriate for auto?

Ge0


----------



## Brechin

I read this like three days ago. I wanted to try it with my home audio system. I have some Insignia indoor outdoor drivers that I did this to just to see if it made a difference. I can certainly see the difference when I 1. Backed by speakers off the wall. 2. when I made the bowl. It no longer starts distorting at 50% power its taking 80% for it to distort now. Making one of those believe it or not was really simple but takes a day or two. All you need is some news paper, chicken wire, screen (from like a window) and some fiberglass resin or bondo type products,glue and some tape and some sand paper of course.. 

Step 1. take the chicken wire mold it to the size and shape you desire. 

Step 2. then layer it with news paper. Tape the news paper from the chicken wire side. 

Step 3. Lay your screen in there about 3 or 4 layers, put your fiberglass resin in there, and let it dry. 

Step 4. sand the inside down by hand no sander. 

Step 5. remove the chicken wire carefully and put a layer of some more resin on the outside to give it a smooth outside surface. 

It wasn't a perfect shape but it was more of just something to try to see how well it worked for me. It was a fun little project thank you pat for opening my eyes. 

Reason for me thinking it can be done like this is because fiberglass resin is EXTREMELY durable when it gets dry. All I have to do now is make another one but this time with a more durable product. Like make a box with wood then repeat that process on the inside then you have a bowl on the inside tricky part would be to make it rounded on the outside. You could actually put some dynamat on the inside on top of the fiberglass resin. maybe I could do the same thing on the outside?


----------



## Patrick Bateman

Niebur3 said:


> Okay, I think I get all of this, but my only problem is that in all the pics of the home audio systems that incorporate this design, they are in open rooms with large open space around it.....so, if I put a sphere on my dash surrounded by a flat dash and angled flat windshield among various other obstacles, wouldn't diffraction happen off the edge of whatever the sphere comes into contact with?


You're correct. The psychoacoustic books indicate that the first 10-20ms have the greatest effect on our perception of the soundstage. That's why pulling speakers away from the walls improves the soundstage.

At the same time, we've all noticed that some reflections are more obnoxious than others. For instance, put your home speakers against a wall, and all sense of width disapears. Move them out from the wall, and the width comes back.

If we can even eliminate reflections in the first millisecond, that equates to 13.5".

Now moving your tweeters 13.5" away from the windows isn't practical; but a spherical enclosure of the same circumference is just 2.15 inches in diameter.

As with all this stuff, it's cheap and easy to experiment. If you hear an improvement in intelligibility and soundstaging, then stick with it.

Or just go listen to the Gallo or B&W speakers. They're easy to find, they're a very common brand.

The measurements already demonstrate an improvement.


----------



## Brechin

Ok so now I'm seeing a problem with my design, I dropped the driver back into my box with the home made bowl... I come to believe it would sound better if I just made a box like that no?


----------



## jon w.

dear mr. bateman,

i admire your technical aspirations. perhaps you'd like to check out my front monitors, which embody most of what's been discussed. perhaps others will find my engineering efforts interesting. visit the whitledge designs website, then click on the link to the publicity section. there one may download my series of *.pdf articles.

best regards,
jon


----------



## I800C0LLECT

Ge0 said:


> I like that you have thought this out. BINGO!!!
> 
> Perhaps a wave guide is more3 appropriate for auto?
> 
> Ge0



Just hang'em from the mirror like dice


----------



## 72buicklark

awesome


----------



## rockinridgeline

Hey Jon W. Nice to see you on here! Your sprinter van has inspired me in many ways. I have been reading "patrick's" posts, knowing that you took these principles into consideration for your "worlds greatest car stereo". I have some plans for my dynaudios that have been inspired by your work.


----------



## jon w.

hey rockinridgeline,

thanks. i'm glad you found my work helpful. i found the effects of minimizing diffraction (as patrick discussed) to be profoundly helpful. it made my stage less susceptible to minor movements of one's head in the listening position and increased center focus. perhaps you'll find a way to radius your enclosures generously to minimize diffraction. if you start like i did, with a simple square-edged baffle plate, take a listen, then add large curves to the front baffle, you'll see hear the effects as i did.

best,
jon

ps. nice build log - i love the non-metallic conduit.


----------



## goodstuff

rockinridgeline said:


> Hey Jon W. Nice to see you on here! Your sprinter van has inspired me in many ways. I have been reading "patrick's" posts, knowing that you took these principles into consideration for your "worlds greatest car stereo". I have some plans for my dynaudios that have been inspired by your work.


I second this. Very happy to see you here Jon. I've been reading the sprinter van articles, rereading and then reading them again. I hope to apply some of the same principals you used in my next install. You've inspired me to get serious about improving the listening environment. Still struggling with some of those equations though. Wish I was a rocket scientist, they might make more sense.  Thanks. (Sorry about the thread jack Patrick.)


----------



## aztec1

Patrick Bateman said:


> Diffraction can add a bit of harshness to a speaker's response. Having said that, the biggest audible improvement from reducing diffraction is an improved soundstage.
> 
> Of course _reflections_ can make a speaker sound harsh; for instance if there's a boundary that's 3.5" away from a tweeter, it will often generate a peak at 2khz, which is quite audible. (A 2khz sound wave is seven inches long. 3.5 inches is half a wavelength. When the sound hits the boundary that's 3.5 inches away, it's reflected back to the source. By the time the reflection reaches the source, it's in phase, and creates a peak at 2khz.)
> *
> A microphone can help a lot to find harshness in a system.
> 
> *Also, a speaker that's running out of excursion can sound harsh, of course. If the harshness is noticeable at moderate volumes, it could be a reflection.


Can you please elaborate on using a mic to find harshness? I have a nasty harshness at around 5k on my driver's side tweet that I can EQ out, but it makes it sound really bad. I assumed it was a reflection, because it's on axis to my headrest and it's only a couple of inches at most from the window. 

How can I tell the difference between diffraction and reflection with a mic? I'd love to find out before I make some new pods, thanks.


----------



## ItalynStylion

aztec1 said:


> How can I tell the difference between diffraction and reflection with a mic? I'd love to find out before I make some new pods, thanks.


Maybe try some foam where you think the reflection is coming from; then measure. If it goes away you've pinpointed the source. A few trials of that could help find if it's a reflection.


----------



## Patrick Bateman

aztec1 said:


> Can you please elaborate on using a mic to find harshness? I have a nasty harshness at around 5k on my driver's side tweet that I can EQ out, but it makes it sound really bad. I assumed it was a reflection, because it's on axis to my headrest and it's only a couple of inches at most from the window.
> 
> How can I tell the difference between diffraction and reflection with a mic? I'd love to find out before I make some new pods, thanks.


The easiest way to find reflections in the car is to just look at where the speakers are mounted. For instance, if you mount a speaker two inches in front of a hard surface (ie, the window) there will be a reflection like this:

_There will be a dip at one quarter wavelength of the distance. For instance, if the distance is 2", there will be a dip at 1688hz. (speed of sound / distance / 4)
There will be a peak at one half wavelength, which will be less severe than the dip. For instance, if the distance is 2", there will be a peak at 3366hz._

As you can imagine, a peak and a dip will basically ruin the sound of your tweeters. And it's difficult to EQ, because cutting the peak lowers the dip, and boosting the dip raises the peak! You just can't win 

The dip occurs because the sound reflects back to the tweeter out-of-phase, and the peak occurs because the sound reflects back to the tweeter in-phase. The peak is less severe than the dip because it's maximum power is +6db.

One of the cool things about throwing your tweeter in a sphere is that it doesn't have to be very big to eliminate that reflection. A sphere with a diameter of 2" will diffuse diffraction and reflections all the way down to 2150hz.

You can also attack the problem from the other direction, which is to measure the response, and then try to figure out what's causing it. Both methods are valuable, but the first one is faster and doesn't require a mic.

The easiest way to find the source of diffraction is to look at where the speaker is mounted. Diffraction occurs anywhere that the wave is bent, so sharp edges are the biggest culprits. For instance, if you listen to a tweeter that's unbaffled, it will sound thin and weird. Pop it into a baffle, and it sounds a million times better. That's baffle step diffraction at work. If you want to reduce diffraction in your tweeters, mount them so that there aren't any sharp edges nearby.

I use clay weatherstripping obsessively, you'll see it in the pics of my system. Note that grey stuff in the throat? Clay weatherstripping.

It makes an audible and measurable difference in high frequency response. It's great stuff.








The weatherstripping can be especially effective if your tweeters aren't perfectly flush with their mounting point.

You can also see reflections and diffraction in a speaker's impulse response. It's difficult to see in a car, due to the volume of reflections.


----------



## Gill

Can you post the formula(corrected one).Examples with pics of enc will be of great help for a dumb like me.


----------



## aztec1

ItalynStylion said:


> Maybe try some foam where you think the reflection is coming from; then measure. If it goes away you've pinpointed the source. A few trials of that could help find if it's a reflection.





Patrick Bateman said:


> The easiest way to find reflections in the car is to just look at where the speakers are mounted. For instance, if you mount a speaker two inches in front of a hard surface (ie, the window) there will be a reflection like this:
> 
> There will be a dip at one quarter wavelength of the distance. For instance, if the distance is 2", there will be a dip at 1688hz. (speed of sound / distance / 4)
> There will be a peak at one half wavelength, which will be less severe than the dip. For instance, if the distance is 2", there will be a peak at 3366hz.
> 
> As you can imagine, a peak and a dip will basically ruin the sound of your tweeters. And it's difficult to EQ, because cutting the peak lowers the dip, and boosting the dip raises the peak! You just can't win
> 
> The dip occurs because the sound reflects back to the tweeter out-of-phase, and the peak occurs because the sound reflects back to the tweeter in-phase. The peak is less severe than the dip because it's maximum power is +6db.
> 
> One of the cool things about throwing your tweeter in a sphere is that it doesn't have to be very big to eliminate that reflection. A sphere with a diameter of 2" will diffuse diffraction and reflections all the way down to 2150hz.
> 
> You can also attack the problem from the other direction, which is to measure the response, and then try to figure out what's causing it. Both methods are valuable, but the first one is faster and doesn't require a mic.
> 
> The easiest way to find the source of diffraction is to look at where the speaker is mounted. Diffraction occurs anywhere that the wave is bent, so sharp edges are the biggest culprits. For instance, if you listen to a tweeter that's unbaffled, it will sound thin and weird. Pop it into a baffle, and it sounds a million times better. That's baffle step diffraction at work. If you want to reduce diffraction in your tweeters, mount them so that there aren't any sharp edges nearby.
> 
> I use clay weatherstripping obsessively, you'll see it in the pics of my system. Note that grey stuff in the throat? Clay weatherstripping.
> 
> It makes an audible and measurable difference in high frequency response. It's great stuff.


Thank you for this excellent advice guys. I'm going to try the foam trick as well as measuring with both a tape and a mic and see where that leads...I've been fighting my tweets for soooo long.

Patrick, have you ever tried setting a tweeter a bit "inside" a sphere and rounding those edges too? Kinda like a mini-horn inside a sphere? I'm wondering if it would make the response better or worse.


----------



## kappa546

that would be more or less a mini WG.


----------



## Patrick Bateman

Gill said:


> Can you post the formula(corrected one).Examples with pics of enc will be of great help for a dumb like me.


Ideally, you would want to put the driver in a sphere whose circumference is equal to the length of the frequency that you want to diffuse. For example, if you have a tweeter and you want to diffuse the sound radiation down to 2000hz, you would use a sphere with a circumference of 6.75". (speed of sound / 2000)

It's not always practical to throw your speakers in a sphere, and you will realize most of the benefits by simply using a roundover on the left and on the right. The roundover will be one quarter of the length above, and you'll need it on the left and right. Top and bottom is nice too, but left and right is more important. In the example above, you would use PVC pipe with a diameter of 2.14".

And obviously, it doesn't have to be exact, I would simply use 2" PVC pipe and "quarter it."

This is also why you see roundovers on $107,000 loudspeakers. It looks like it's there for cosmetics, but it's 100% functional.








When you first look at a system like this, you might think that the drivers are what's important, but that cabinet is every bit as important as what's inside of it.


----------



## rockinridgeline

After reading the input about quarter wavelength peaks, which I had heard before, I thought that I would take a quick look on my eq settings to see where I had made cuts using the RTA and determine if they agreed with the predictions from physical dimensions. I try not to go crazy with the eq, and look to make cuts where their are peaks and use as little boost as possible.

To set this up, my midbass are about 62" apart from each other, and there is a center console under the dash (it doesn't extend to the seat but does create a pronounced foot well on each side). The distance form the kick to the console is about 22", and it is a little farther than that from the door speaker to the console.

Based on these measurements, I should have a dip around 54 hz, but the RTA doesn't measure that low very well. I am going to play some test tones to get a db reference at that and surrounding frequencies.

I should have a peak around 106 hz according to the physicall measurements. I checked my eq, and I have a cut of -3 db on both midbass at 100 hz! 

I also have a cut of - 5 db at 300 hz. do the math for the distance to the center console and it says that I should have a peak right around 300 hz!

It reinforced for me that the rta is doing a decent job of picking up linearity issues. Now it is a different matter to determine what I can do physically with speaker placement to try and remedy the issues instead of the eq band-aid that I am using now. Good stuff Patrick, keep it coming!


----------



## Domino187

thanks pat very good information


----------



## nonogo

I would also like to say thanks pat, your information has been invaluable


----------



## ihartred

i have these in black that i just pulled out of the closet. i bought them for like $12 at the drug store. maybe?
one inch speaker


----------



## Aaron'z 2.5RS/WRX

Patrick Bateman said:


> Thanks! I basically discovered it the same way. Here are *my* home speakers, note the ridiculous roundover:
> 
> 
> 
> (the horn on top is just to demonstrate the scale)
> 
> *One afternoon I was waiting for some stuff to dry on my current car project, and added a roundover to an old set of HLCDs that I had laying around, and measured them. Took literally fifteen minutes. And then I listened to them, when the measurements were WAY improved, and was startled by the transformation. Never heard them sound so good. It was actually kind of depressing LOL, since the speakers that I applied the roundover on were never competitive with my own DIY designs. But once the roundover was applied, they sounded 10x better*.


Any chance I could get a pic of what you did with this? I will be installing HLCD's here shortly and I know they can be difficult to tame down... I'd be interested in any more you had on this.. 

Would there be any benefits to using something like a CCF inside of the horn to help relieve any harshness? 

Thanks!


----------



## timelord9

Patrick Bateman said:


> Ideally, you would want to put the driver in a sphere whose circumference is equal to the length of the frequency that you want to diffuse. For example, if you have a tweeter and you want to diffuse the sound radiation down to 2000hz, you would use a sphere with a circumference of 6.75". (speed of sound / 2000)





Patrick Bateman said:


> One of the cool things about throwing your tweeter in a sphere is that it doesn't have to be very big to eliminate that reflection. A sphere with a diameter of 2" will diffuse diffraction and reflections all the way down to 2150hz.


Hi Patrick

Brilliant stuff, and the best part about it is that it is very, very easy to try out. 

If it doesnt work (and theory plus your practice suggests it will) then I will be out about $5 and 20mins of mucking around. Coupled with the understanding of diffraction gained by the discussion in this thread, and I smell a win coming along. 

I am, however, a bit lost with your calculations. The first one you posted up was: 
- speed of sound/required diffraction frequency/2/pi
- 13500 / Hz / 2 / 3.14159

but the quotes above have left me a bit confused. Any hints? 

Also, I found these on eBay: 
10 Polystyrene Foam Balls 65mm - eBay, Other Crafts, Crafts. (end time 16-Oct-09 12:08:01 AEDST)

10 x 65mm polystyrene balls for $5. Add a couple of Hybrid L1V2's: 









which should flow quite nicely onto the sphere, a quick coat of resin and paint, and bingo?

I calculated that a 65mm sphere should difuse frequencies down to 1k, however, even if its only 2k (with X/O at 4k-12db) things should sound pretty good...

unless I've cocked it up. which is quite possible!


----------



## timelord9

something like this...where the pod either sits on the dash, or is (somehow??) raised up from the dash.


----------



## Patrick Bateman

Aaron'z 2.5RS/WRX said:


> Any chance I could get a pic of what you did with this? I will be installing HLCD's here shortly and I know they can be difficult to tame down... I'd be interested in any more you had on this..
> 
> Would there be any benefits to using something like a CCF inside of the horn to help relieve any harshness?
> 
> Thanks!


Sure, pics are here:

The HOMster! (or How I Learned How to Fix a Horn) - diyAudio

It's literally a piece of PVC duct taped to the horn. We're talking five minutes invested, and a dollar worth of plumbing.









The waveguide with PVC and foam









These are polar measurements. The ones at the top are the untreated horn. The ones at the bottom are treated with foam and a roundover. There's a ton of reflections in the car, so if you've never seen an in-car measurement, it might be shocking if you're accustomed to anechoic measurements.​
At first they look similar. If you look closely you'll notice the following:


There's a dip at 1900hz, and a peak at 2900hz. This is really common in car audio. When a sound wave reflects, the reflected energy is _in-phase_ at half a wavelength, and _out-of-phase_ at one quarter wavelength. The result is a peak and a dip, and it's almost impossible to EQ. Because if you fix the peak, you make the dip worse, and vice versa.
As you move off axis, the frequency response gets peakier
The treated response, which is the curve at the bottom, exhibits improvements off-axis, and the peak and the dip are nearly eliminated.

Not too shabby for a buck.


----------



## Patrick Bateman

timelord9 said:


> Hi Patrick
> 
> Brilliant stuff, and the best part about it is that it is very, very easy to try out.
> 
> If it doesnt work (and theory plus your practice suggests it will) then I will be out about $5 and 20mins of mucking around. Coupled with the understanding of diffraction gained by the discussion in this thread, and I smell a win coming along.
> 
> I am, however, a bit lost with your calculations. The first one you posted up was:
> - speed of sound/required diffraction frequency/2/pi
> - 13500 / Hz / 2 / 3.14159
> 
> but the quotes above have left me a bit confused. Any hints?
> 
> Also, I found these on eBay:
> 10 Polystyrene Foam Balls 65mm - eBay, Other Crafts, Crafts. (end time 16-Oct-09 12:08:01 AEDST)
> 
> 10 x 65mm polystyrene balls for $5. Add a couple of Hybrid L1V2's:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> which should flow quite nicely onto the sphere, a quick coat of resin and paint, and bingo?
> 
> I calculated that a 65mm sphere should difuse frequencies down to 1k, however, even if its only 2k (with X/O at 4k-12db) things should sound pretty good...
> 
> unless I've cocked it up. which is quite possible!


The speed of sound is 13500 inches per second, so sound travels 13.5 inches in one-thousandth of a second.

In the first example, I mentioned that a sphere with a *circumference* of 6.75" will diffuse the sound down to 2000hz.

In the second example, I mentioned that a sphere with a *diameter* of 2" will diffuse the sound down to 2150hz.

A sphere with a diameter of 2" has a circumference of 6.28", so they're virtually identical in size.

Ideally, you want to use a sphere which has a circumference that's equal to one wavelength at the *lowest* frequency you're going to be playing. Unfortunately, spheres are a bit of work, and a simple roundover will give you most of the results, in half of the space. But a sphere is ideal.


----------



## Patrick Bateman

ihartred said:


> i have these in black that i just pulled out of the closet. i bought them for like $12 at the drug store. maybe?
> one inch speaker


The problem with multimedia speakers is that they can't get loud, unfortunately. China has made neodymium motors inexpensive and ubiquitous, so we see a lot of wideband drivers for sale that weren't practical ten years ago. But their power handling is terrible, and efficiency is very low.

Most of these "multimedia" speakers use aluminum cones, and that drops the efficiency into the low 80s. Combined with low power handling, you wind up with a speaker that will blow up if it's pushed above 90db.

IMHO, the most interesting drivers are the ones that combine neodymium motors with light cones. That combination gives you massive efficiency, since neo motors are so powerful. The midranges in my car are Tang Band two-inchers, but they're the paper coned version. With a paper cone, a two inch tangband is more efficient than a four inch Dynaudio. ( Light cone + big motor =  )

I have a set of these in the garage, and they take this recipe to the EXTREME:










Parts-Express.com:Tang Band W4-1805S 4" Neodymium Midrange Driver | Tang Band W4-1805S 4" midrange tb speakers neodymium driver line array point source midrange home theater computer speaker center channel set tube amplifier cone mid

The cone is so light, they actually include a grill so you don't destroy it 
We're talking about a cone that weighs virtually nothing, coupled to a neodymium motor that's big enough for a subwoofer that's four times the size.










This tiny little midrange is basically a scaled down version of the subwoofers that Alma Gates used back in the 90s, except with a better motor and lower distortion

Tang Band FTW!


----------



## Aaron'z 2.5RS/WRX

Thank you Very Much Mr. Bateman.. lol.. now please, put the ax down... lol.. 

Now, have to figure out how to integrate this into my install.. 

Can the "tubes" protrude into the mouth enough so I don't increase the height of the mouth of the horn (looking at it, just like you pictured?)

My HLCD's are also mini-bodies, this complicates things even more, yes?


I'm reading your HOMonster link now... interesting.. it's just going to be integrating it into my install.. lol.


----------



## Patrick Bateman

_Someone emailed me, asking about good locations for mounting speakers. I *personally* prefer mounting the midranges first, and then basing everything else off the midrange locations.

Thought I'd take a couple of minutes to explain why I don't go the conventional route. IE, why I don't use kick panels.

Anyways, here's why I use the speaker locations that I use:
_

There's a myth that people aren't able to localize low frequencies. Bose's marketing department spread that, in an effort to sell their Acoustimass systems, and the myth got traction.

The truth is that it's VERY easy to localize low frequencies, but we're more sensitive to their *distance* than their angle.

Think about this one for a second:

Have you ever been at a movie theatre, and could hear the subwoofer from another movie in *your* auditortium? In other words, the bass from another movies was "bleeding" into the room? And was there any doubt about the location? I mean, you didn't think the sound was coming from the same room, or from under your seat, right?

That's a quick example of how easy it is to localize bass. At very low frequencies, we can perceive the distance of a sound easily, and as frequency increases, less so. At high frequencies, we're very sensitive to the intensity of sound.

This has some ramifications for the placement of subs and midranges. For instance, I drive a coupe, and because the back seat is basically a joke, the subwoofer would be less than THREE feet away if it was in an infinite baffle in the trunk. Yet my midranges are over FIVE feet away, under the dash.

Time delay can't do a thing to fix this either. You can delay the signal so that it's in sync with the midranges, but your PERCEPTION of the location is based on the interaural time delay between your ears. And time delay can't relocate your ears 

Now get out a tape measure, and measure the distance between your ears. For me, that distance is eleven inches. The speed of sound is 13500 inches per second. Which means that an eleven inch wavelength is 1227hz.

THAT frequency, 1227hz, is the most critical for imaging. At that frequency, I am sensitive to both interaural time delay, and intensity differences.

That frequency will vary from person to person, and is based on the distance between your ears. Above that frequency, your imaging cues are dominated by frequency response. Below that frequency, it's dominated by ITD (interaural time delay.)

When I first learned this stuff, it was hideously confusing, because it's basically the opposite of what most people do. After studying this, I've realized that putting subs up front is a terrible idea, unless you can get them under the dash, because the distance is all wrong. And that tweeters don't necessarily have to be on, or even near the doors. And most importantly, that the most important soundstaging cues in our stereos aren't coming from the tweeters, they're coming from the midrange, at a frequency that's equal to the distance between our ears.

This is probably one of my most confusing posts, and a lot of this psychoacoustics stuff is controversial, so I invite anyone to study it further... It's probably the most important thing you can learn to improve your system.


----------



## Patrick Bateman

_There's a fairly decent summary of our spatial perception of sounds here:

Spatial sound perception

_

*C.6Spatial sound perception*


Classic psychoacoustic experiments showed that, when excited with simple sine waves, the hearing system uses two strong cues for estimating the apparent direction of a sound source. Namely, interaural intensity and time differences (IID and ITD) are jointly used to that purpose. IID is mainly useful above 1500Hz, where the acoustic shadow produced by the head becomes effective, thus reducing the intensity of the waves reaching the contralateral ear. For this high-frequency range and for stationary waves, the ITD is also far less reliable, since it produces phase differences in sine waves which often exceed 360. Below1500Hz the IID becomes smaller due to head diffraction which overcomes the shadowing effect. In this low-frequency range it is possible to rely on phase differences produced by the ITD.


----------



## slomofo

awesome info guys, a little too technical for this layman at times but nonetheless


----------



## chithead

Actually makes perfect sense. Explains why I enjoy full range speakers minus tweeters more than I do tweeters plus midrange.


----------



## Patrick Bateman

chithead said:


> Actually makes perfect sense. Explains why I enjoy full range speakers minus tweeters more than I do tweeters plus midrange.


Yep.

One thing that's great about the internet is that we can collaboratively figure out why some things sound good, and others do not. In the 90s I used to read Stereophile cover-to-cover, and got it in my head that you had to spend $10,000 to have a great stereo. But thanks to the internet, we can *collaboratively* figure out what those $10,000 systems are doing right, and clone it for pennies.

Full range speakers are a good example. You're not going to find many "hi-end" speakers that use a single driver*, because there isn't much of a profit to be found in a speaker which uses a single component. But removing the crossover from the midrange and putting it in a well-built enclosure will frequently sound remarkably good, even superior to a well-engineered two-way.

Combine that with quality electronics, and you have a very listenable system, for not a lot of money.

* admittedly, single driver systems are gathering steam year after year, but it's still uncommon in the high end.


----------



## chithead

I like it. 4" full range with 8" midbass delivers nice impact on everything from snares to kick drum back to Elle Fitzgerald's powerful voice back to the the forceful tuba blasts in the Marine Corp Hymn.


----------



## rockinridgeline

Patrick Bateman said:


> because there isn't much of a profit to be found in a speaker which uses a single component.


Mr Bose's bank account would disagree. Although you did preface the statement with "high end". Just couldn't help but think about Acoustimass systems flying off the shelves.

I think it was more about the WAF than anything else.

Wife Acceptance Factor


----------



## ihartred

Patrick Bateman said:


> The problem with multimedia speakers is that they can't get loud, unfortunately. China has made neodymium motors inexpensive and ubiquitous, so we see a lot of wideband drivers for sale that weren't practical ten years ago. But their power handling is terrible, and efficiency is very low.
> 
> Most of these "multimedia" speakers use aluminum cones, and that drops the efficiency into the low 80s. Combined with low power handling, you wind up with a speaker that will blow up if it's pushed above 90db.


Actually i meant just the enclosure! The speakers are meant to run off an ipod and have a 1 watt rms. The speaker mounting hole is one inch and would easily fit most tweeters, but I wasn't sure if the design was meeting the point of the thread


----------



## zerodistortion

Does anyone here have any pictures of these sphere enclosures installed in a car? Very interesting topic btw. I'm sure it's not a problem with smaller tweets, but I'm running large format tweets, so not sure how I could get it to work without it being an eye sore.


----------



## rockinridgeline

zerodistortion said:


> Does anyone here have any pictures of these sphere enclosures installed in a car? Very interesting topic btw. I'm sure it's not a problem with smaller tweets, but I'm running large format tweets, so not sure how I could get it to work without it being an eye sore.


on page three of this thread that you are reading there is this link:

BERYLLIUM BMW 323ci. - Page 10 - CARSOUND.COM Forum


----------



## zerodistortion

Thanks!!! I'll give it a try.


----------



## Cruxis

Nice!!


----------



## Gill

rockinridgeline said:


> on page three of this thread that you are reading there is this link:
> 
> BERYLLIUM BMW 323ci. - Page 10 - CARSOUND.COM Forum


Link is not working. post a pic rather, that would be of a help.


----------



## Gill

FOCAL BERYLLIUM BMW 323ci.
Checked the pics on this link. Now the question is how to find the diameter of sphere?Lets say MD102 crossed at 2.2khz.. what should be the size then..


----------



## 94VG30DE

Gill said:


> FOCAL BERYLLIUM BMW 323ci.
> Checked the pics on this link. Now the question is how to find the diameter of sphere?Lets say MD102 crossed at 2.2khz.. what should be the size then..


The formula was stated more than once higher up in the thread.


----------



## Gill

Patrick Bateman said:


> If you're using a simple roundover, the radius of the roundover is calculated the exact same way. That's because we're basically taking a sphere and "quartering it."
> _required roundover perimeter = 13500 / lowest frequency / 2 / pi_


Acc to the above method:-

Perimeter of sphere:-13500/2200/2/3.14=0.977.

where am i commiting a mistake?It can't be that small.


----------



## Notloudenuf

Well since I really have nothing to add to this thread I do know of this company CIC Ball| Plastic balls | Hollow Plastic Balls | Rubber Balls | Metal Balls| they have all different materials and sizes of balls that would fit about any application you guys could dream up. They do have a minimum order so a few of you might need to get together to make it worthwhile.

And yes I said balls......


----------



## 94VG30DE

Gill said:


> Acc to the above method:-
> 
> Perimeter of sphere:-13500/2200/2/3.14=0.977.
> 
> where am i commiting a mistake?It can't be that small.


Re-read what you just quoted. The equation shown is for the _radius _of a roundover, which in this case is effectively half the diameter of sphere. So that sphere would be about 2" in diameter, which I'm thinking seems a little more reasonable.


----------



## saymon7

I´d like to know what do you guys (especially patrick bateman  ) think about Acoustic Lens Technology which is used by Bang Olufsen in their home speakers but also in audi and aston martin cars. I think it might be more useful than those spheres because it takes away all windshield reflections and radiates the same sound in 180° angle. so what do you think.... ?


----------



## audiorailroad

Notloudenuf said:


> Well since I really have nothing to add to this thread I do know of this company CIC Ball| Plastic balls | Hollow Plastic Balls | Rubber Balls | Metal Balls| they have all different materials and sizes of balls that would fit about any application you guys could dream up. They do have a minimum order so a few of you might need to get together to make it worthwhile.
> 
> And yes I said balls......


did you guys see the size of the hollow ones.................31 inches. thats good for some pretty good bass imho.


----------



## clekchau

this is great info


----------



## andy335touring

I've made some 4.5" diameter sphere(ish) enclosures for my Trinity WB mids and i'm going to get them flocked.

Does flocking help reduce *diffraction* and reflections ?

I think you can can get different thicknesses of flocking ? So thicker the better ?

*flocking is going to be applied over the edge of the enclosure and on to the mounting flange of the speaker*

A pic might help, there's still a bit of an edge by the speaker :uneasy:


----------



## Patrick Bateman

saymon7 said:


> I´d like to know what do you guys (especially patrick bateman  ) think about Acoustic Lens Technology which is used by Bang Olufsen in their home speakers but also in audi and aston martin cars. I think it might be more useful than those spheres because it takes away all windshield reflections and radiates the same sound in 180° angle. so what do you think.... ?


A speaker on a flat baffle radiates sound in 180 degrees, but begins to narrow at high frequencies, and there's a baffle step at low frequencies.

The B&O lens redirects the energy in all directions. It still suffers from a baffle step.

The waveguides in my car direct all the energy towards the listeners, and use the windshield to extend the mouth of the waveguide.

The B&O lens has two problems. There's a bunch of diffraction generated at the edge of the lens, and it sends a great deal of energy back towards the windshield, where it will be reflected towards you.

In a home environment, I think the B&O solution makes a lot of sense. As long as you can get the enclosure away from the sidewalls you won't get distracting reflections.

But in the car? I wouldn't use it.

Having said that, I've only heard the home version of it.

Check out Duvel - they do the same thing, but with better drivers than B&O. Listening to the Duvel was actually what sparked my interest in the BMS 4540ND, which is what I use in my car. Duvel uses it in one of their models that's around $4000 IIRC.


----------



## Patrick Bateman

andy335touring said:


> I've made some 4.5" diameter sphere(ish) enclosures for my Trinity WB mids and i'm going to get them flocked.
> 
> Does flocking help reduce *diffraction* and reflections ?
> 
> I think you can can get different thicknesses of flocking ? So thicker the better ?
> 
> *flocking is going to be applied over the edge of the enclosure and on to the mounting flange of the speaker*
> 
> A pic might help, there's still a bit of an edge by the speaker :uneasy:


This looks fantastic. Why change a thing?

And what's flocking? Do you have a pic?


----------



## andy335touring

Thanks, it's just finished in grey primer and a clear coat to seal it at the moment but the colour matches the dash fairly well.

The main reason is hopefully flocking will make the pods a bit less obvious and hide the odd bumpy bits in the paint finish that's not so apparent in the picture.

Most likely i'm being over optimistic if the flocking going to have much audioble effect as it's too thin but i'll see if they can make it thicker/longer coat/fiber ?

There's a link to the place i'm going to use below, not the best website but it's just down the road from me.

SBP - What Is Flocking, Flocking Explained, How To Flock


----------



## Patrick Bateman

andy335touring said:


> Thanks, it's just finished in grey primer and a clear coat to seal it at the moment but the colour matches the dash fairly well.
> 
> The main reason is hopefully flocking will make the pods a bit less obvious and hide the odd bumpy bits in the paint finish that's not so apparent in the picture.
> 
> Most likely i'm being over optimistic if the flocking going to have much audioble effect as it's too thin but i'll see if they can make it thicker/longer coat/fiber ?
> 
> There's a link to the place i'm going to use below, not the best website but it's just down the road from me.
> 
> SBP - What Is Flocking, Flocking Explained, How To Flock


It sounds like you're hoping for some diffusion of the sound. The problem is that wavelenghts are exceptionally long, so the surface would have to be VERY rough for it to work. We're talking about peaks and valleys that are a few centimeters in height, not a fraction of a millimeter.

This site kind of explains how that works:

QRD Diffuser Well Depth Calculator

Anyways, the sphere itself is going to do all the heavy lifiting; the flocking may improve cosmetics, but it can only diffuse veeeeeery high frequencies. My calculator says it would have an effect around 30khz or so.

No worries though - the spheres look very good. Wish I could here it!


----------



## ilkercom

I thought that, only I was using the kitchen cup  for ring adiator tweeters


----------



## ilkercom

and the last case


----------



## mark1478

awesome info. thanks from a NOOB.


----------



## RE_gawker

Would walmart have these balls? I don't know of any craft stores that are close 

Also, this talk about diffraction makes me think...what about grill covers for tweeters and mid ranges, would that cause diffraction?
edit: Another question, Is the radius in the equation the minimum required size by the sphere or does the sphere have to be that size?


----------



## bruther

That is an amazing install


----------



## ajhill

Cool!


----------



## Codeblue

andy335touring said:


>


 Nice. Is that an E34? Do you have a build thread or more pics?


----------



## andy335touring

Yes, it's an E34.

Sorry i don't have a build thread as i didn't take many build pics, if you want any info drop me a PM so this thread doesn't go off topic.


----------



## Patrick Bateman

One thing I hate about full range speakers is that they can't get very loud. It's very difficult to fix this, because a small speaker simply has a limited excursion.

Here are a few things I've seen people try:







Strap a huge motor to a relatively small cone, like Lowther does. The big motor increases efficiency. You're still limited by excursion, unfortunately.







Use a small cone, but with much greater excursion. This actually works quite well, but requires a lot of power, due to low efficiency. I'd take this $50 woofer over a $500 Lowther any day. Of course the tube amp aficionados would disagree  (This woofer is way too inefficient to work with a tube amp.)







Use an array. Kind of tricky in the car.

Here's a solution that I haven't seen in cars very much: *Use a dipole.*

I've often noticed that a woofer sounds better outside of a box, than *in* a box. Unfortunately, there's no bass. But with a carefully sized baffle, we can fix that to an extent.

When it comes to infinite baffles, one thing that people overlook is that it's actually a LOT more efficient. At some frequencies we're getting SIX db more output. Because we're getting output from both sides of the cone, the efficiency of a 4" woofer in an open baffle is close to the efficiency of a 6" woofer in a sealed box. *Note that this only applies at certain frequencies - the baffle must be sized properly.*

Here's a demonstration of what I mean:







First, we pick a woofer. For this simulation, I've chosen the Dayton ND105.

A spherical enclosure reduces diffraction, which improves the polar response of our driver. Subjectively, it makes the speaker "disappear." There's a very simple reason that spherical speakers sound so good, and that is because we are EXTREMELY sensitive to imaging cues in the first five milliseconds after a sound is radiated. Sound travels 68 inches in the first five milliseconds. Ideally we would control all diffraction and reflections in a 68 inch radius of the driver.

In a car, we can't do that, but a sphere does it a lot better than almost anything else. (Waveguides are nice too.)







Here's our sphere, a serving bowl from Ikea. WalMart also sells something comparable. The WalMart once is called "Canopy Acacia Wood Bowl." You could probably find a candidate at Target too. I'm going to do my sims with the Ikea bowl.







Here's some pics from someone else who did this. He said the sound was very good, but that it didn't get very loud. With a bit of clever fabrication, we should be able to increase the efficiency by almost six dB, while retaining the good directivity of the sphere.

A side bonus is that dipoles have a pleasant sense of "space", due to reflections. (Reflections in the first 5ms are bad, but after that, they improve intelligibility and soundstaging. I can link to the papers if anyone's curious.)

I'll post sims shortly...


----------



## andy335touring

So is the back of the bowl is open ?

Where would you mount a 5" bowl as i struggled with a 4" sphere to get it in between the A-piller and dash binicle(sp?) on the drivers side ?

My full range speakers get plenty loud enough off a 60wrms amp to keep up with my SLS 8" due to them being on axis and mounted on the dash, i think if you tried to use them in the kicks they might not be loud enough, plus if you can't get them on(or near) axis your probobly going to need use a tweater with them.

Sorry for all the questions, i'm just trying to learn.


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## timelord9

my attempts at spherical tweeter pods. 

1. Purchase polystyrene balls in bag of 10 from ebay

2. Cover in 2 layers of 5 minute epoxy resin (araldite etc). Sand runs in between layers

3. Cut out face and hollow out inside just enough to fit tweeter. Sand face til flat. Use more epoxy to cover face, then use body filler. 

4. Drill holes for threaded rod or t-nut, or however you're going to mount it.

5. test fit.

6. To trim, paint on exterior PVA (heat and UV resistant - the normal stuff melts in the sun on your hot dash) mixed with black laser cartridge toner, then sprinkle on flocking powder. Leave to set for 24h or more.

5. ???

6. Profit.


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## katodevin

Timelord: could you hook me up with an ebay link to the balls that you purchased? I've done some searches on there with no luck.


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## timelord9

Polystyrene Foam Balls, Crafts items at low prices on eBay.com.au

and just cause I'm a nice guy and you americans have never heard of that place called "overseas"...

polystyrene balls, great deals on Crafts on eBay!


As for $2? I don't think so.

expoxy resin - $6
balls!- $5.50
pva - $8
flocking - $18
sandpaper - $5

Hybrid Audio L1V2's? ........ priceless.

:lol:

(note prices are in Australian Pesos)


----------



## Patrick Bateman

timelord9 said:


> my attempts at spherical tweeter pods.
> 
> 1. Purchase polystyrene balls in bag of 10 from ebay
> 
> 2. Cover in 2 layers of 5 minute epoxy resin (araldite etc). Sand runs in between layers
> 
> 3. Cut out face and hollow out inside just enough to fit tweeter. Sand face til flat. Use more epoxy to cover face, then use body filler.
> 
> 4. Drill holes for threaded rod or t-nut, or however you're going to mount it.
> 
> 5. test fit.
> 
> 6. To trim, paint on exterior PVA (heat and UV resistant - the normal stuff melts in the sun on your hot dash) mixed with black laser cartridge toner, then sprinkle on flocking powder. Leave to set for 24h or more.
> 
> 5. ???
> 
> 6. Profit.


Awesome fabrication!

How's it sound?


----------



## timelord9

Patrick they sound fantastic. In my original pods, the sound was very raw and "in your face", or "hot", with a large amount of sibilance and harshness at around 5-10kHz (hard to tell without measurements). A combination of the pods themselves as well as tuning (phase, rather than EQ) and the ability to change their aiming has resulted in a much more relaxed, listenable sound. For the first time ever, I actually drove for 5 hours (on the way home from nationals) without dicking about with crossover slopes, phase, eq, time alignment, levels etc etc etc etc. For those of you with a high level processor like the hxd2 or similar, this is no mean feat. 

I just simply listened to the music. 

I am certainly an advocate for this type of enclosure, especially because of the low cost of fabrication. I count myself in the bottom 5% in terms of DIY fabricators (couldn't fabricate my way out of a paper bag) and even I managed to come up with something that I'm proud of. 

it took a bit of trial and error - mainly error - however once I got the hang of it I can churn them out very quickly - the longest part is waiting for the glue/epoxy to dry.

In terms of cost, once you have the epoxy, glue and flocking, they are very cost effective to produce lots of.

My next trial will be finding a cabinet maker to make me up some spheres turned from oak or similar, then laquered to match the internal wood trim of the merc. That would be cool...

Thanks Patrick! You have been the absolute inspiration behind this build, and I've learnt heaps about diffraction as well as fabrication (don't use poly resin on polystyrene kiddies) along the way.


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## timelord9

ooooh!

like these!

Craft-Supplies Balls Half Balls Ball Knobs Beads


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## katodevin

Timelord: Do you have these on or off axis?


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## timelord9

off axis, pointing up towards the light above the middle of the dash. I have a fairly vertical windscreen compared to most modern cars however, so you gotta do what sounds right in your car.


i tried them on axis last night and it didn't sound right at all, however I'm not necessarily going to give up. I haven't seen the off axis plots for these tweeters though, so I get the feeling I might be missing a large amount of information...

the depth and image is just so much nicer off axis (scored 15/15 for depth at nationals, which is unheard of, as well as a 10/10 for width) so I'm a bit loath to mess with that sort of outcome...!


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## eng92

You should be able to get polystyrene balls in the craft section of most dollar stores. The local one to me sells packs of 2 @ 4" or 4 @ 3" for $1.

I followed a similar procedure to timelord9 as far as the epoxy coating goes except I sleeved mine with a piece of ABS pipe. A Dyn MD102 is a perfect press fit into a piece of 2".

I mounted them temporarily on ball swivels so I could adjust the aiming.

Here are a couple of pics.

















This first set was a little crudely made. I am doing up another set in the near future for a set of L1 Pro SEs that just arrived.


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## timelord9

those ball swivels are awezome! where did they come from?


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## eng92

local camera shop or 

OMNI PAN/TILT DIGITAL CAMERA BALL/SWIVEL HD MOUNT 1/4" - eBay (item 230359894264 end time Dec-19-09 07:33:42 PST)

You could probably find all plastic ones a lot cheaper


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## Patrick Bateman

timelord9 said:


> Patrick they sound fantastic. In my original pods, the sound was very raw and "in your face", or "hot", with a large amount of sibilance and harshness at around 5-10kHz (hard to tell without measurements). A combination of the pods themselves as well as tuning (phase, rather than EQ) and the ability to change their aiming has resulted in a much more relaxed, listenable sound. For the first time ever, I actually drove for 5 hours (on the way home from nationals) without dicking about with crossover slopes, phase, eq, time alignment, levels etc etc etc etc. For those of you with a high level processor like the hxd2 or similar, this is no mean feat.
> 
> I just simply listened to the music.


That's awesome that it worked so well! And the thanks should go to Geddes, I'm shamelessly ripping off his ideas here.

We've had three or four people try this, all with good results, so let's do a quick recap on how and why this improves the sound of a speaker.

Sound travels 13.5 inches in a single millisecond. Our hearing mechanism is extraordinarily sensitive to events which occur in the first five millisecond window. For instance, if you listen to a set of speakers at home, and you move them away from the wall, the tonality in the midrange improves, and soundstaging improves too. Ideally, we'd keep the speakers at least 68" away from anything reflective.

One thing that's not obvious is that _the enclosure itself_ generates reflections and diffraction. For instance, if the edges of your enclosure have a sharp edge, diffraction will be generated off of every single edge. This is why very small enclosures image so well. They have diffraction, but the diffraction occurs very quickly after the initial wavefront, so it "blends" in. Ironically, you can make a very large enclosure sound good by simply rounding over the edges. (This reduces diffraction off the cabinet edges.)

So far so good, right?

In the car, it's impractical to move the speaker 68" away from any boundary. That leaves us four options:


Move the speaker as far away from boundaries as possible. This isn't a very good solution because it looks weird and it reduces the size of your soundstage a great deal.
Create an enclosure that diffuses the sound that's radiated from the driver. This works nicely. For instance, if we want to diffuse the first millisecond of sound, we need an enclosure with a diameter of just 8.6".
Use a waveguide. It accomplishes the same thing.
All of the above. There's nothing to stop you from "mixing and matching" these techniques. For instance, if you don't have room for a sphere with a diameter of 8.6", you could use a smaller one, and move it away from the windshield. The effect will be comparable to using a larger one. (Not quite as good though - bigger is better.)

If you're interested in exploring this further, check out some of the links I posted earlier. Start by reading up on The Haas Effect. Note that the Haas Effect focuses on the first five milliseconds. It is my personal belief that five milliseconds isn't a "hard cutoff"; I believe the effect is more pronounced as we get close to zero milliseconds, and less pronounced at 5ms. I haven't seen that documented though.

There's another thing that's worth experimenting with, and that's the fact that narrow directivity works better in a car than in the home. For instance, home speakers are generally designed for very wide dispersion. But in a car, that's the *last* thing we'd want. Wide directivity means tons of reflections off the windshield, the dash, the floor, ceiling and doors. The SpeakerWorks Grand National and the Biggs Regal controlled directivity with horns and waveguides, but there are other solutions also. A big driver will "beam" at a lower frequency than a small driver. At home, we might not want that, but in the car, we do.














Here's a pic of a conventional soft dome, and the polar response. In the polar response, you can see that it's beginning to beam at about 6khz. Based on it's diameter, we would expect it to be about 6dB down at 45 degrees off-axis at 13500khz. (speed of sound/diameter of piston)
The measured polar response demonstrates that it's behaving as expected.














Here's a pic and the polar response of a 2" computer speaker. In the polar response, you can see that it's starting to beam about an octave lower, at 3khz. Based on it's diameter, we would expect it to be about 6dB down at 45 degrees off-axis at 6750khz. (speed of sound/diameter of piston.) Like the soft dome tweeter, this computer speaker is well-behaved, and is beginning to beam where we'd expect it to.

It's kind of tricky to see the difference in these graphs, because the scale is so large. Pay close attention to what's going on at 5khz in the graphs. In the tweeter the off-axis response is identical to the on-axis respone. The off-axis response of the computer speaker is down 3dB at 5khz. That doesn't sound like a lot - but it's the equivalent of cutting the power by *half.* This effect isn't unique to small woofers - it works on all pistons. Just remember that the speaker will beam at a frequency that's equivalent to the speed of sound divided by the diameter of the driver. (This is a simplficaition; it ignores the effect of cone shape, damping, etc... Check the spec sheet of the driver in question, or better yet, buy them and measure them.)

Anyways, now that people are getting good results, I hope this provided some "food for thought." We can really take this to "the next level" by narrowing directivity even further, then increasing efficiency to improve dynamics.


----------



## benny

My wife actually brought me home some bags of polystyrene balls to use as tweeter mounts. (she digs good car sounds, too ) 









I might have to try some whittling this afternoon, I'll be using Seas TFFNC/G tweets in PVC pipe caps. I plan on just hollowing out a cup to flush the pipe cap into, then trying the tweeters with different aimings.

Things currently look like this:


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## Patrick Bateman

I'm going to swing by Ikea today and pick up some of the semi-spherical salad bowls. Should be easier to work with than the plastic spheres from the craft stores.

WalMart sells some similar ones too.


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## benny

Here are my tweeter spheres after a half hour with my Dremel tool and a small sanding drum:


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## 94VG30DE

Those balls look sweet benny. Looks like the radius of the dome is almost perfectly matched to the radius of the ball, like they were made for each other. Good choice.


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## timelord9

My build tutorial is here: 

Tutorial: Cheap,easy tweeter pods - Mobile Electronics Australia

you'll have to register though....:computer:


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## benny

Got some semi-finished spheres Velcro'd on my dash:


















Sounds good so far...


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## timelord9

hey Benny, are you going to paint? If not, i'd recommend flocking. Super easy and cheap. See my tute for more details.


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## cubdenno

Interesting. I AM USING THE bg nEO 3PDR and am wondering about doing this.....


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## Patrick Bateman

Someone emailed me with some specific questions about soundstaging, so thought I'd do a "brain dump" here, in case anyone else is dealing with the same issues...

Here goes:


To get a good image, you have to think about how we hear things. In the soundstaging thread I threw out some book recommendations that might help. The most important thing is to understand that our hearing mechanism behaves differently *below* 1khz and *above* 1khz. This is due to the distance between our ears. (You can get out a ruler and literally measure the distance; it varies from person to person.)

Anyways, above 1khz, frequency response is *everything*. If you want a good soundstage, you MUST get the left and the right tweeter to match. If not, forget it, you won't have a soundstage to speak of. It will basically be a big amorphous blob, and it will vary depending on what's being played. (IE, the blob will "float" around.)

Because matching the left and right is so critical, I personally prefer a single driver on each side covering the range of 1khz and up. In my car, I am using a BMS 4540ND on a waveguide. The waveguide controls reflections for the first millisecond or so.

What this basically means is that my left and right tweeters sound the same. That's a big part of the magic.

If waveguides aren't your thing, I personally recommend using a single tweeter, and do something to control early reflections. A spherical enclosure "sprays" the reflections in every direction, which reduces their audibility.

Basically reflections are unavoidable, so if you have to live with them, at least diffuse them about the cabin. The worst possible thing for your soundstage is a strong early reflection. Yet that's exactly what happens in 75% of the cars out there.

Once you have the tweeters sorted, then you work on the midbass. Ideally, you want them as far and as wide as possible. You also need some serious woofers, as cabin gain raises the efficiency of our subwoofers. If you don't have some serious midbasses, the subwoofers will drown out the midbass at most volumes, and you end up with a sluggish bass-heavy presentation, which is typical of an "average" install.

For instance, there are $300 subwoofer packages that can hit 120dB, yet you'd need two THOUSAND watts to hit 120dB with the average car audio midbass. (And that's assuming no power compression.)

Long story short, getting the midbass right is the most difficult thing in a car IMHO.

I personally don't like having speakers in the doors, because it drags the soundstage forward. If you must put speakers in the doors, I would only use them as secondaries, with the primary midbasses further out. For instance, you could have a set of 4" midbasses under the dash, with sevens in the doors. In this scenario, the doors would be attenuated so that they don't dominate the sound.

There are formulas for how much they should be attenuated; google "haas effect." You can literally calculate the attenuation based on the distance from one to the other.

In the real world, you can probably reduce the attenuation to some degree, because of the highly reflective environment of a car. (IE, reflections color the sound already, so the second set of midbasses aren't as audible as they would be if you were listening in an anechoic environment.)

Hope that helps...


----------



## Patrick Bateman

Someone emailed me with some specific questions about soundstaging, so thought I'd do a "brain dump" here, in case anyone else is dealing with the same issues...

Here goes:


To get a good image, you have to think about how we hear things. In the soundstaging thread I threw out some book recommendations that might help. The most important thing is to understand that our hearing mechanism behaves differently *below* 1khz and *above* 1khz. This is due to the distance between our ears. (You can get out a ruler and literally measure the distance; it varies from person to person.)

Anyways, above 1khz, frequency response is *everything*. If you want a good soundstage, you MUST get the left and the right tweeter to match. If not, forget it, you won't have a soundstage to speak of. It will basically be a big amorphous blob, and it will vary depending on what's being played. (IE, the blob will "float" around.)

Because matching the left and right is so critical, I personally prefer a single driver on each side covering the range of 1khz and up. In my car, I am using a BMS 4540ND on a waveguide. The waveguide controls reflections for the first millisecond or so.

What this basically means is that my left and right tweeters sound the same. That's a big part of the magic.

If waveguides aren't your thing, I personally recommend using a single tweeter, and do something to control early reflections. A spherical enclosure "sprays" the reflections in every direction, which reduces their audibility.

Basically reflections are unavoidable, so if you have to live with them, at least diffuse them about the cabin. The worst possible thing for your soundstage is a strong early reflection. Yet that's exactly what happens in 75% of the cars out there.

Once you have the tweeters sorted, then you work on the midbass. Ideally, you want them as far and as wide as possible. You also need some serious woofers, as cabin gain raises the efficiency of our subwoofers. If you don't have some serious midbasses, the subwoofers will drown out the midbass at most volumes, and you end up with a sluggish bass-heavy presentation, which is typical of an "average" install.

For instance, there are $300 subwoofer packages that can hit 120dB, yet you'd need two THOUSAND watts to hit 120dB with the average car audio midbass. (And that's assuming no power compression.)

Long story short, getting the midbass right is the most difficult thing in a car IMHO.

I personally don't like having speakers in the doors, because it drags the soundstage forward. If you must put speakers in the doors, I would only use them as secondaries, with the primary midbasses further out. For instance, you could have a set of 4" midbasses under the dash, with sevens in the doors. In this scenario, the doors would be attenuated so that they don't dominate the sound.

There are formulas for how much they should be attenuated; google "haas effect." You can literally calculate the attenuation based on the distance from one to the other.

In the real world, you can probably reduce the attenuation to some degree, because of the highly reflective environment of a car. (IE, reflections color the sound already, so the second set of midbasses aren't as audible as they would be if you were listening in an anechoic environment.)

Hope that helps...


----------



## 94VG30DE

The idea of having all your staging cues coming from a single driver makes sense, and also partly explains why my stage sucks when I'm crossing my tweeter so high (~3500). I love reading these brain dumps. 

On an unrelated note, is the autodupe feature back? I keep seeing it in different threads, and I'm getting all nostalgic.


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## katodevin

Question - Should we be preserving the flanges of tweeters, or triming them to make as smooth and gradual of a transition to the "diffuser"/ball housing as possible? 

For example - Should i leave the flange as is, or throw that sucker on a lathe, and trim it down closer to the dome.


----------



## 94VG30DE

katodevin said:


> Question - Should we be preserving the flanges of tweeters, or triming them to make as smooth and gradual of a transition to the "diffuser"/ball housing as possible?
> 
> For example - Should i leave the flange as is, or throw that sucker on a lathe, and trim it down closer to the dome.


Yeah I was wondering that too. Some tweeters have more pronounced rims than others, and would require some heavy-duty work to get the enclosure shape flush with the actual dome.


----------



## katodevin

Here is my effort using Seas Neo tweeter.

I found 3 different sized balls @ Michael's (arts and crafts store by me). 









I decided to go with the smallest one for my tweeter. 









I first trimmed the ball using a dremel, getting it close to the opening size I needed. I then took a flat block of wood, and laid a piece of sandpaper on it. On top of that I moved the ball in a circular motion until I got it the exact size I wanted. 

















Drilled a hole for the wire, stuffed it with some polyfill, and I'm ready to go test aiming positions.









Took about 1/2 an hour per each enclosure. I plan on using some resin to permanently affix the halves, and to also sand down the outside to ~ 600-1000 grit before painting. This will all happen once I decide on a mounting position. I will report on listening impressions after tomorrow. BTW, those aren't cracks. It's hotglue.


----------



## 3fish

OK. So I found this company in Germany which produces a WIDE range of machined metal (aluminum?) sphere's for car audio use. Their latest edition is that which has tapered end:very sexy indeed. 

Site is in German, you can use babblefish to translate if necessary. I wrote to the company letting him know that there were DIY'ers here in the US that at the least would want to learn more about about. This company produces these housings for specific tweeters. 

Very sexy.


----------



## Gill

website is...?


----------



## rockinridgeline

Those small plastic spheres are only going to limit diffraction well in a 3 way with the tweets crossed over pretty high. If that is a tweeter in a 2 way the sphere should be a bit larger. PB covered that earlier in the thread.


----------



## 3fish

Gill said:


> website is...?


 oops!

Adrenalin-Carhifidesign


----------



## lycan

Another great thread  Thanks Patrick!


----------



## Babs

3fish said:


> oops!
> 
> Adrenalin-Carhifidesign


Those enclosures look bangin! Stealthy? Not in the least, but I like 'em.


----------



## rexxxlo

oh great 9 pages of the best caraudio reading ive done in years and i cant add this as a project for at least a few months 


i have a simple question however 

were does the diffraction start and how small of a lip is audible?

in the morel tweeter in the picture above there are screw holes should they be filled with clay ?

i have a tweeter with a 1/4" aluminum grill that screws on to the body and in order for me to do this i would have to 
1 loose the grill and risk damage 
2 build a ramp up to and around the tweeter
3 recess it into the mounting surface 

i have them flush mounted in my door just like in the picture with the cardboard taking shipping is the same as the interior door skin 

in some of my books at home on acoustics i remember reading where teh author would make concentric rings that sort of make a staircase up to the tweeter 

this couldn't work in a car however i was thinking that making a sort of doughnut around the tweeter might help?

i could cut a circle on the drill press out of mdf and round it over on the inside and outside













this is also making me think about my home speakers and what to do to them 

thanks as if i dont have enough to do hahah
i love this hobby


----------



## buckingam

thank you, this is very interesting.


----------



## lucas569

i really like reading all this but then it comes down to how it looks(for me at least)...alot of these would look silly in a car...


----------



## Patrick Bateman

rexxxlo said:


> oh great 9 pages of the best caraudio reading ive done in years and i cant add this as a project for at least a few months


Don't thank me, I'm shamelessly stealing ideas from others 
A year and a half ago I bought a set of Gedlee Summas and it really got me thinking about why 90% of the speakers out there sound like crap. It's not a coincidence that I started posting like crazy on this forum around that time - it was due to a 'reset' of my thinking about audio, via these speakers.



rexxxlo said:


> i have a simple question however
> 
> were does the diffraction start and how small of a lip is audible?[


That's a great question. Diffraction begins right at the diaphragm. So the shape of the diaphragm itself is important.

Geddes said that a flat piston is ideal for his waveguides. Then again, we aren't using a waveguide here. (Or are we? The sphere is definitely altering the radiation angle of the piston.)

Here's one of his patents which deals with this:
Phase plug with optimum aperture shapes - Google Patent Search

You could easily spend the entire weekend reading the other twenty, but that one is a good start. Audioxpress also published a number of his articles from the AES. Any large public library will have the AES papers. I studied them at the Seattle Public Library.



rexxxlo said:


> in the morel tweeter in the picture above there are screw holes should they be filled with clay ?
> 
> i have a tweeter with a 1/4" aluminum grill that screws on to the body and in order for me to do this i would have to
> 1 loose the grill and risk damage
> 2 build a ramp up to and around the tweeter
> 3 recess it into the mounting surface
> 
> i have them flush mounted in my door just like in the picture with the cardboard taking shipping is the same as the interior door skin
> 
> in some of my books at home on acoustics i remember reading where teh author would make concentric rings that sort of make a staircase up to the tweeter
> 
> this couldn't work in a car however i was thinking that making a sort of doughnut around the tweeter might help?
> 
> i could cut a circle on the drill press out of mdf and round it over on the inside and outside
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> this is also making me think about my home speakers and what to do to them
> 
> thanks as if i dont have enough to do hahah
> i love this hobby


You are definitely "getting it." You are correct, the screw holes on the tweeter WILL cause diffraction. The effect would occur at a very high frequency, due to the small dimensions of the holes. But it *would* have an effect, and fixing it requires about two cents worth of clay.

I think the thing I like most about your post is that you're seeing what will cause diffraction, and you are thinking about how to fix that. The spheres are an attractive option, but a flush mount gets you "in the ballpark."

The most important thing by far is to avoid ALL SHARP EDGES. So if your tweeters are already recessed in the doors or in the A-Pillars, and there is a lip, just use some clay to smooth out the transition from the edge of the tweeter to whatever it's mounted in.







This is quite good. The tweeter is nicely flush mounted. Ideally it would be nice to get the tweeter further from the glass, since a reflection will be generated off of it. The other option is to move it VERY close to the glass, which will drive the reflection up in frequency, and make it less audible.







This is terrible. The sharp edge close to the diaphragm will generate diffraction as the angle transitions from 180 degree to 360 degrees. Remember, the key is to have the most gentle transition from one angle to another.

The other reason that this baffle is atrocious is that it's round. Round baffles are terrible because the edge is equidistant from the diaphragm. Due to that, there will be a notch at one specific frequency, and a peak as well. (If the baffle was square you'd still have problems, but those problems would be spread out in frequency, severity, and in time.)

When you download a spec sheet from Madisound, those measurements are done on a baffle that's wider than your entire car. That's why the response graphs are so smooth. We don't have the luxury of using a huge flat baffle in the car, so we have to compensate in other ways.


----------



## Patrick Bateman

Oh I forgot to answer your question about removing the grill. I personally don't recommend it, because the grill is very VERY close to the diaphragm. When you have a reflection in front of a speaker it will create a dip at one-quarter wavelength, and a peak at one-half wavelength. The reason that grills aren't a problem is that the frequency of those peaks and dips are inaudible _as long as the distance is very small._

This is also why most tweeters will sound and measure better when they're very VERY close to the windshield, rather than further away. You'd think that moving them away from the glass would improve things, but it's generally the opposite. Increasing the distance moves the peak and the dip lower in frequency, where it's more audible.


----------



## invinsible

Well, finally I went ahead with making the sphere enclosure of the Morel Tweeter I have. Used the Tennis ball with a fabricated metal stand to hold it. I covered one of them with the speaker grill cloth.
I tested these and there is definitely some difference. Placed them on the dashboard. I tried one stuffed with little polyfill and the other without it. Din't notice much of difference. Wat's the deal? stuff them with little polyfill or not?
I am not to sure if the design looks fine. Any opinion?


----------



## kkant

invinsible said:


> I tried one stuffed with little polyfill and the other without it. Din't notice much of difference. Wat's the deal? stuff them with little polyfill or not?


Looks like a sealed tweeter you've got there. So polyfill doesn't matter. Polyfill only makes a difference if the diaphragm is moving the air within the tennis ball, which in this case it is not.


----------



## invinsible

kkant said:


> Looks like a sealed tweeter you've got there. So polyfill doesn't matter. Polyfill only makes a difference if the diaphragm is moving the air within the tennis ball, which in this case it is not.


Well I have actually removed the back casing / original mounting of morel, the magnet is exposed to the internal air volume of the sphere. There might be little bit of heat exchange after adding the polyfill when the tweeters are running. 
Tweeters will be crossed at 3.2khz with 6db slope.


----------



## Fast1one

invinsible said:


> Well I have actually removed the back casing / original mounting of morel, the magnet is exposed to the internal air volume of the sphere. There might be little bit of heat exchange after adding the polyfill when the tweeters are running.
> Tweeters will be crossed at 3.2khz with 6db slope.


Removing the back casing is definitely something you don't want to do, especially when crossing over lower. Excursion will be significantly increased at lower frequencies and the response will change in the lower octaves. What concerns me more is the 1st order slope.

Be very careful that you don't cook those things...


----------



## kkant

invinsible said:


> Well I have actually removed the back casing / original mounting of morel, the magnet is exposed to the internal air volume of the sphere. There might be little bit of heat exchange after adding the polyfill when the tweeters are running.
> Tweeters will be crossed at 3.2khz with 6db slope.


Have you exposed the diaphragm to the enclosure? The magnet exposure alone doesn't matter, what matters is whether the dome's backwave is sealed up like stock. As Fast1one said, I would not open up the internal airspace of the dome. Especially at such a low xover point with such a shallow slope.


----------



## kkant

As far as the heat transfer question-- that won't make a difference with polyfill. Polyfill is a good insulator, which is why it's used in quilts and sleeping bags.


----------



## matt1212

Is this the reason my tweets came with a teardrop housing???? Or shoud i consider giving them a new home?


----------



## I Need Bass

...very nice info...now if I could just do that with all my car speakers


----------



## timelord9

you don't need to do that with all your car speakers though...

the midrange and the tweeters are a good start. Check out the Beryillium BMW for an idea or two.


----------



## cheesehead

I saw these yesterday and immediately thought of this thread. I figured for $2.95 they might be worth experimenting with!











Here's the link to millionbuy.com if any one is interested.

(2.95) COBY CSP-14 <br>Personal Mini Stereo Speaker System


----------



## joms

I am having my Hertz MLK165 installed exactly like this using the same tweeter pods. Can you comment if the pods are right? Is the apillar design bad because of the edge it has? or is the edge part far enough? Thanks


----------



## Patrick Bateman

Reflections in the first ten milliseconds are going to create phantom imaging cues. To my ears, reflections are more obnoxious the closer that you get to zero. If you agree with that, then the first millisecond is particularly important. Sound travels 13.5" in a millisecond.

So do the math - if you can get the diaphragm 13.5" away from anything, that's a good start.

You can experiment with this yourself. Put your tweeters in a sphere, pull them away from the windows, and listen. I think you'll find that the tweeters are more difficult to localize when you do that. It's the _reflections_ that make it easy to locate the tweeter, not the tweeter itself.

As documented in another thread, I now have my tweeters about 18" away from the side windows, and it's working nicely. There are a lot of good reasons to get your tweeters away from the windows.

Note that a lot of this depends on directivity and your crossover points; you can "cheat" these rules if you're using your tweeters in a range where they're beaming.


----------



## ngsm13

So, if I were to employ this in Home Audio, but want to utilize my existing rectangular enclosure, I could essentially install the spheres into the enclosure?

Also, it's a good idea to have the rear of the enclosure be a sphere, but also have a curved baffle in front I imagine? (Basically like taking a bagel, cutting it in half horizontally and laying that flat side on the flat baffle the speaker is mounted to with the speaker/tweeter aimed through the hole?) I was thinking to create a ring (cylinder) out of green potting foam, and gradually smooth/sand it away until the desired shape is attained. (Half bagel, lol) Then you can fiberglass over top of it and blend it into the enclosure.

Currently, I'm working with a 2way setup, so for my mid I'd probably need to make the back sphere sufficient enough to act as an actual enclosure I imagine. Though, I have oversized rectangular enclosures now, with solid fillers inside to decrease internal volume. So would my idea of installing the sphere attached to the back of the flat baffle work, then use my foam/fiberglass to make my ring on the front of the baffle?

Interesting read, seems simple enough of a project to try out!

nG


----------



## Patrick Bateman

ngsm13 said:


> So, if I were to employ this in Home Audio, but want to utilize my existing rectangular enclosure, I could essentially install the spheres into the enclosure?


No.

Conventional loudspeaker simulations, like WinISD, do not account for baffle shape. So everyone tinkers with it, and obsesses over the low frequency cutoff, because WinISD assumes that the baffle is flat and it's infinite.

But that's not how things work in the real world. In the real world, the shape of the baffle and the enclosure itself will introduce peaks and dips on the order of 6dB. This is HUGE, and very audible.

That's only half the problem though.

The shape of the baffle and the enclosure will affect the polar response. For instance, the sharp edge on a conventional rectangular enclosure will cause problems with the off-axis response. Even worse, these problems won't be obvious unless you do polar measurements, but they're VERY audible.

So putting a sphere INSIDE the box won't fix these things; you have to modify the shape of the enclosure and the baffle itself.

Linkwitz has a decent article on baffle diffraction on his site. IMHO, he underestimates the affect, because it gets worse in a complex environment like a car. (At home you can just pull the box away from the walls, we don't have that luxury.)



ngsm13 said:


> Also, it's a good idea to have the rear of the enclosure be a sphere, but also have a curved baffle in front I imagine? (Basically like taking a bagel, cutting it in half horizontally and laying that flat side on the flat baffle the speaker is mounted to with the speaker/tweeter aimed through the hole?) I was thinking to create a ring (cylinder) out of green potting foam, and gradually smooth/sand it away until the desired shape is attained. (Half bagel, lol) Then you can fiberglass over top of it and blend it into the enclosure.









At this point I am starting to think that a semi-sphere or a semi-cylinder is superior to a sphere. This is because a sphere is perfectly symmetrical. I measured three different enclosure types recently, and the sphere sounded very VERY good, but there was a peak and a dip caused by it's symmetry. The flat baffle used by Revel in the pic above, combined with the curved back, gives us the benefit of a sphere while breaking up the symmetry that causes peaks and dips.



ngsm13 said:


> Currently, I'm working with a 2way setup, so for my mid I'd probably need to make the back sphere sufficient enough to act as an actual enclosure I imagine. Though, I have oversized rectangular enclosures now, with solid fillers inside to decrease internal volume. So would my idea of installing the sphere attached to the back of the flat baffle work, then use my foam/fiberglass to make my ring on the front of the baffle?
> 
> Interesting read, seems simple enough of a project to try out!
> 
> nG


Experimentation is definitely important. I've found that the spheres have a way of "disappearing" into the stage that's breathtaking, but there are other shapes which may be superior (ie a semi-sphere.)

Note that these advantages are much more audible with tweeters than woofers.


----------



## ngsm13

Patrick Bateman said:


> No.
> 
> *So putting a sphere INSIDE the box won't fix these things; you have to modify the shape of the enclosure and the baffle itself.
> *
> At this point I am starting to think that a semi-sphere or a semi-cylinder is superior to a sphere. This is because a sphere is perfectly symmetrical. I measured three different enclosure types recently, and the sphere sounded very VERY good, but there was a peak and a dip caused by it's symmetry. The flat baffle used by Revel in the pic above, combined with the curved back, gives us the benefit of a sphere while breaking up the symmetry that causes peaks and dips.
> 
> Experimentation is definitely important. I've found that the spheres have a way of "disappearing" into the stage that's breathtaking, but there are other shapes which may be superior (ie a semi-sphere.)
> 
> Note that these advantages are much more audible with tweeters than woofers.


I'm unsure as why the bolded part wouldn't work. Keep in mind I'm still speaking for my Home Audio, essentially it would be like taking sealed spheres and having a rectangular enlcosure around them, just different aesthetically? 

Here's a feeble paint drawing of what I'm speaking of, this is a side cut-away view of what I was suggesting. Two way speaker with mid and tweeter respectively, drivers mounted to the baffle, with the curved rings I suggested making. 










Would this not accomplish the same/similar effect?

nG


----------



## benny

The spheres inside the cabinets wont do anything with repect to baffle step. That is an effect of the OUTside of the enclosure.


----------



## ngsm13

So, the spheres are not for the backwave/behind the speaker at all? The round, smoothly curved/tapered rings around the mid/tweeter be effective at all on the baffle?

nG


----------



## timelord9

nG - what is your understanding, so far, of what is trying to be achieved by using a spherical baffle for tweeters? not trying to be rude, I'm just trying to see what you're thinking so that we can clear up any misunderstandings


----------



## ngsm13

timelord9 said:


> nG - what is your understanding, so far, of what is trying to be achieved by using a spherical baffle for tweeters? not trying to be rude, I'm just trying to see what you're thinking so that we can clear up any misunderstandings


Indeed I did misunderstand at first, that's why I asked my questions. I initially interpreted the benefit was two fold front/back wave, and I took off running with the backwave. Does it not benefit from the sphere at all?

Understanding that the focus is on the radiating front wave, and still wanting to have some sort of benefit with what I currently have in my home, would the curved ring (half donut shape) provide any benefit at all to break up my flat front baffle? Seems like a simple modification/addition to my front baffle, and could be painted to match. 

Thanks for the input. 

nG


----------



## invinsible

Finally managed to get the Morel MT22 tweeter in the sphere enclosure. Result, well they sound much more smoother compared to when they were in Apiller almost 90 off axis, but spheres havn't made them sound just smoother but altogether can more details out of it. They seem to disappear, its hard to locate where the tweeters. But, most importantly there is added space, it feels like listening in more larger room than before. The Path length distance is same as the midwoofer from listening position. 
For now am enjoying this, until I decide to place them in center of dashboard in future. Thanks Patrick


----------



## Patrick Bateman

ngsm13 said:


> Indeed I did misunderstand at first, that's why I asked my questions. I initially interpreted the benefit was two fold front/back wave, and I took off running with the backwave. Does it not benefit from the sphere at all?
> 
> Understanding that the focus is on the radiating front wave, and still wanting to have some sort of benefit with what I currently have in my home, would the curved ring (half donut shape) provide any benefit at all to break up my flat front baffle? Seems like a simple modification/addition to my front baffle, and could be painted to match.
> 
> Thanks for the input.
> 
> nG



In a sealed enclosure the back wave of the driver is contained by the enclosure.*

If you were using a dipole you'd want to pay attention to the shape of the front AND the back of the woofer. But in a sealed box you only need to worry about the shape of the baffle and the enclosure itself.

When we look at a speaker it seems intuitive that the sound is directed towards us, but this really isn't the case. The wavefront is shaped by the cone, the baffle, the enclosure, and anything close to it.

This is particularly true at frequencies which are less than the length of the cone. For instance, if you have a five inch woofer, the shape of the baffle will be particularly important for all frequencies below 2700hz.**

_* You can get a modest improvement in frequency response by paying attention to the opening of the baffle on the inside of the box. But the effect is nowhere near as pronounced as what's going on OUTSIDE of the box. 

** speed of sound / diameter = (13500 inches per second / 5") = 2700hz_


----------



## ngsm13

Thanks for the information. So, the curved ring addition to the front of my baffle will do nothing?

nG


----------



## saymon7

Does the sphere material matter?? I have made mine of wood and then decided to cover it with acoustic foam and I believe they sound better now. But it could be just mine delusion.


----------



## thechainrule

When using a product like this would much more work be required other than finding a way to mount the tweets? Would removing that screw flange be beneficial? Sorry for the noob question just trying to cut a corner if I can. 

Parts-Express.com:Vifa NE25VTT-04 1" Titanium Dome Tweeter | Vifa NE25VTT-04 titanium tweeter NE series dome neodymium waveguide hf high frequency mtm horn loaded tymphany09


----------



## squeak9798

I was screwing around on Eclipse's Japan site this morning, and couldn't help but think of this thread when I saw their speaker offerings;
ECLIPSE Speakers


----------



## Babs

If they marketed the good stuff besides just one decent deadhead in the states maybe they'd actually SELL something here instead of pulling out. Looks like they DO have some good stuff, though not quite stealthy.. Still I dig the little wide-bander and tweet pods. They're usable.


----------



## aztec1

I found these cheapo pods. They looked nice to me. A bit of dremel and voila! I haven't mounted them yet, still playing with placement. They instantly fixed many issues I'm struggling with, especially on the driver's side at around 8kHz, just by holding them with my hand in the place where my old "pods" were. I'm sure with some placement tweaking they will really widen the soundstage and get rid of lots more harshness. Really amazing stuff, if you're on the fence about this just do it...the improvement is staggering! Thanks Patrick!


----------



## yischrax

Makes SMS to me Ann who am I kidding I can't post my new thread till I comment on 4 more threads


----------



## vactor

great reading yet again PB!!! thanks!! i am planning my system in my new car and i think it will be a 2.5 way. 3" fostex mids in a properly shaped diffraction-minimized baffle/enclosure in the kick panels, 10" subs in the doors and MAYBE some 12-15" IB subs in the trunk for the last octave (probably not though) and 250 watts to each driver. i and gonna see what a lowly 3 incher can do (heck if i can do it for the ladies, why can't 3" do well for sound too??) ... again, great reading and a lot of food for thought. nothing beats a sound understanding of the fundamentals and using the science we know to get the most from the hardware. it doesn't have to cost a mint to sound like a million bucks!


----------



## TAMUmpower

Heres my idea that I threw together while I am in the middle of installing my new system.

I got these "dense" styrafoam eggs at hobby lobby for 2 bucks each. I just sawed the front off them and hollowed them out with a jewlers flat head screwdriver. Maybe my dremel would have been cleaner, but it was easy enough to just pick at it, took maybe 6min each to complete. They also sand very smooth if I have to paint them. I want to try to cover them in suede, however it will be tough to do it without rinkles. 

I am going to mount them using either clothes hanger wire or something a bit thicker. Ill make it decorative some how making it loop off of the egg in a few places, it will be nice too because I am using Hybrids swivel cups and since the wire will be bendable I will be able to adjust the positioning indefinently once I finish everything up.


----------



## NSTar

very interesting.

Can we collect or create another thread on solutions for all the speaker sizes? The tenis ball looks good but is there enough volume to match the speaker?

currently, I'm looking for a solution for my 3.5" midbass.

How about subwoofer? can you do a round housing and a sphere or half circle bottom?


----------



## NSTar

The egg thing above... isn't the tweeter sealed from the back? Also, if not, then couldn't you just mold something else using that shape?

If the shape in front is what matters, then what about the cover that is causing defraction? shouldn't you remove that?

So if I have an 10" sub, and I want an egg shape, base on defraction, I'd want a very large egg that is cup near the front tip with 8" opening?


weird.

For cars, it'll have to protrude out of the doors.


----------



## TAMUmpower

NSTar said:


> The egg thing above... isn't the tweeter sealed from the back? Also, if not, then couldn't you just mold something else using that shape?
> 
> If the shape in front is what matters, then what about the cover that is causing defraction? shouldn't you remove that?
> 
> So if I have an 10" sub, and I want an egg shape, base on defraction, I'd want a very large egg that is cup near the front tip with 8" opening?
> 
> 
> weird.
> 
> For cars, it'll have to protrude out of the doors.


I would read the first few pages to better understand everything. The idea is that the rounded outer shape helps to reflect the sound waves more randomly than a sharp edge, which by some magic sound expert formula, causes the speaker to appear more hidden. You dont need to do this for a sub and bass is already hard to pinpoint the source location.

From what Ive read you are more trying to remove the sharp corner rather than needing a 100% curved surface. Some of the examples just have a rounded edge on an otherwise square enclosure.

Whether the tweeter is sealed doesnt really matter as they dont need sealed enclosures, not sure what you were asking in regards to that.

I am a newbie on this topic though, I just read a few pages, and since I was installing a new system, thought I would try something out.


----------



## Patrick Bateman

NSTar said:


> The egg thing above... isn't the tweeter sealed from the back? Also, if not, then couldn't you just mold something else using that shape?
> 
> If the shape in front is what matters, then what about the cover that is causing defraction? shouldn't you remove that?
> 
> So if I have an 10" sub, and I want an egg shape, base on defraction, I'd want a very large egg that is cup near the front tip with 8" opening?
> 
> 
> weird.
> 
> For cars, it'll have to protrude out of the doors.


The entire shape of the enclosure matters, in fact even the shape of the cone matters. (I can dig into the latter part if anyone's curious; the effect of cone shape on directivity isn't well documented.)

The reason it's not relevant for subwoofers is the frequency. For instance, a 2khz sound wave is 6.75" long. Due to that length, a modest roundover is very effective. For instance, if you use a roundover of less than 2" on either side of the cone, you get an audible and measurable improvement in the polar response.

On the other hand, try to do the same thing with a 10" subwoofer. Let's say you want to control diffraction at 60hz. 60hz is TWO HUNDRED AND TWENTY FIVE inches long.

See how the dimensions get ridiculous in a hurry? 

So you could definitely create a diffraction-free enclosure for a subwoofer, but the enclosure wouldn't fit in the car 

On the other hand, doing it for a tweeter is downright trivial, inexpensive, and easy.


----------



## Patrick Bateman

aztec1 said:


> I found these cheapo pods. They looked nice to me. A bit of dremel and voila! I haven't mounted them yet, still playing with placement. They instantly fixed many issues I'm struggling with, especially on the driver's side at around 8kHz, just by holding them with my hand in the place where my old "pods" were. I'm sure with some placement tweaking they will really widen the soundstage and get rid of lots more harshness. Really amazing stuff, if you're on the fence about this just do it...the improvement is staggering! Thanks Patrick!


I'd have to say that's the *best* candidate for a spherical mount that I've ever seen. I thought the Vifa DQ25 was a good one, but that Seas is even better. The transition from the dome to the sphere is almost perfect. I have some Vifa XT19s here, and one of the things that make them difficult is that the face plate is so huge - almost four inches across.

If anyone's interested in trying this, here's where to get 'em:

SEAS Prestige 27TAFNC/G (H1397) 1" Aluminum Dome Tweeter from Madisound








SEAS Prestige 27TAFNC/G (H1397) 1" Aluminum Dome Tweeter

Compact neodymium magnet tweeter for high quality speaker design in small cabinets and automobiles.

Aluminum/magnesium alloy diaphragm with pistonic behavior throughout the audible frequency range, resulting in a good dispersion also above 10kHz.

Wide roll Sonomex surround together with a double chamber magnet system results in a low resonance frequency.

The critically designed diffusor compensates for a slight axial roll off towards 20 kHz and reduces resonances above 20kHz.

Very low magnetic stray fields makes this unit suitable for A/V systems.

Voice coil immersed in magnetic fluid, allowing high power handling capacity and simplified crossover design.

Seas does not provide mounting hardware for this tweeter. It can be mounted by press fit, mounting from behind or using a modified mounting cup. The back of the tweeter is threaded for an M4 bolt for fastening from behind. LPG tweeter mounts will also work with slight modification. You will have to drill a couple holes through the back of the plastic mount for proper fit. Use an adhesive to glue the tweeter into the mount. The Vifa tweeter mounts will not work for this tweeter.


----------



## NSTar

So I went around looking for a solution for my midbass 3.5" (handles 100wrms)... can't find a pod that is sturdy enough to handle the bass but also shaped like an egg. To me, if I can get the tip to be around 3.5" that'll be perfect to defract some wave. 

I don't think I can use foam in my case.


----------



## NSTar

invinsible said:


> Finally managed to get the Morel MT22 tweeter in the sphere enclosure. Result, well they sound much more smoother compared to when they were in Apiller almost 90 off axis, but spheres havn't made them sound just smoother but altogether can more details out of it. They seem to disappear, its hard to locate where the tweeters. But, most importantly there is added space, it feels like listening in more larger room than before. The Path length distance is same as the midwoofer from listening position.
> For now am enjoying this, until I decide to place them in center of dashboard in future. Thanks Patrick


You mounted it like that in your car? if you are gonna do that, might as well move it further away from the window and a-pillar some more...and also paint the stand black so it doesn't stand out.


Even better, use a very strong thin wire so it'll be invisible....the stand..well, just stands out.


----------



## TAMUmpower

Yea we should have an install gallery for this thread. Heres my styrofoam egg pods from earlier finished in microsuede


----------



## katodevin

TAMUmpower said:


> Yea we should have an install gallery for this thread. Heres my styrofoam egg pods from earlier finished in microsuede


Could you hook it up with some advice on the fabric wrapping? I haven't wrapped anything this round before and am having some trouble.

Thanks so much.


----------



## TAMUmpower

katodevin said:


> Could you hook it up with some advice on the fabric wrapping? I haven't wrapped anything this round before and am having some trouble.
> 
> Thanks so much.


Well the more stretch the fabric has the better. My microfiber is much stretchier one way than the other, which isnt ideal but its workable.

Since my shape is oblong I wrapped it like rolling a pencil. The seam is not a straight line, it is curved like an stretched out S diagnally on one side. You also need mega sticky glue like 3m super 77, which you can get at walmart. I just started on one side and worked my way around. Just keep stretching it every which way to take out wringles and mess with lining up everything on the last little bit. Any excess near the narrow end just pinch the excess into a fold and cut the fold off creating to ends that should line up and hide the cut. Doing it in black helps hide imperfections better than any other color too.

If you are doing anything sphere shaped you probably cant use microfiber. I would just get any material that is stretchy like rubber, because that is all that is really going to work.


----------



## NSTar

found this but so expensive to buy and gut out.

Polk Atrium Sat30 2 way single chestnut outdoor satellite speaker Dynamic Balance at Vanns.com

it's exactly 3.5 speaker inside and the same two screws to hold it. I just want the shell.


----------



## TAMUmpower

NSTar said:


> found this but so expensive to buy and gut out.
> 
> Polk Atrium Sat30 2 way single chestnut outdoor satellite speaker Dynamic Balance at Vanns.com
> 
> it's exactly 3.5 speaker inside and the same two screws to hold it. I just want the shell.


Contact polk and tell them you have damaged your enclosure and wanted to purchase a new enclosure. You might get a lead


----------



## katodevin

TAMUmpower said:


> If you are doing anything sphere shaped you probably cant use microfiber. I would just get any material that is stretchy like rubber, because that is all that is really going to work.


Bad news to me 

I was trying to use some grill cloth, but it is proving to be extremely difficult, haha.

I really don't want to paint this. I'll have to think of another idea.


----------



## invinsible

NSTar said:


> You mounted it like that in your car? if you are gonna do that, might as well move it further away from the window and a-pillar some more...and also paint the stand black so it doesn't stand out.
> 
> 
> Even better, use a very strong thin wire so it'll be invisible....the stand..well, just stands out.


There is good amount of gap from the windscreen. Both the tweeters are running off axis. I kept the stand as it is as of now having brushed aluminium look but incase I do get bored surely gonna paint it black in matt finish.


----------



## timelord9

katodevin said:


> Could you hook it up with some advice on the fabric wrapping? I haven't wrapped anything this round before and am having some trouble.
> 
> Thanks so much.


I would investigate flocking. It's easy to do yourself and can look pretty trick. 

my tutorial on pod building and flocking is here:

Tutorial: Cheap,easy tweeter pods - Mobile Electronics Australia


----------



## NSTar

LOL, I emailed them, no reply.


----------



## Babs

I still say I wish someone would try some orbs (orbaudio) in a car crossed to run the top side of a two-way and report findings.


----------



## NSTar

Just a quick off topic... Babs? are those spherical?  *ahem...avatar*


----------



## Sptsmed

If I am stuck using forward placement on the door panels, would it still benefit me from using a closed rear on the tweets and mids with the hope of rounding the exposed face on the door panel?


----------



## thechainrule

Making some spherical enclosures tonight. How far forward from the windshield should tweeters be mounted typically? I dont have much room and it looks like the ideal spot for me would have the pod almost touching the glass. Thoughts?


----------



## Fantaxp7

So TAMU, how are those Styrofoam eggs soundin'? I am thinking of going that route.


----------



## TAMUmpower

Fantaxp7 said:


> So TAMU, how are those Styrofoam eggs soundin'? I am thinking of going that route.


Well, to be honest I am not sure as I cant compare how the tweeters would have sounded before. This was a new installation with HAT Clarus components. The sound stage is pretty good with the eggs pointed about 45 degrees off axis. The only issue is that they are in an e36 M3 and the interior is small so the eggs being half way up the pillars is annoying when looking out the windshield. 

Since the eggs sand very easily and smoothly, I think I am going to try to reduce the depth by 50%. Since it is only the front of the egg up to 90 degrees that matters, the back being curved shouldnt make a difference. I'm just going to sand it to where its closer to small sphere so that they dont come into my vision as much.


----------



## Sptsmed

I am looking at doing the same thing in my M3 vert, although was in hopes of maybe still using the door spot maybe with part of the egg exposed, but not sure, really dont want to play with the A pillar if I can avoid it.


----------



## RattyMcClelland

I was recommended by a fellow TA'er to get some outdoor lights from B&Q here in the UK as they are perfect size for L1pro & the SE.

So today i went out and bought some.

Perfect doesnt begin to describe it.










Probably wont use the glass screw cover. Will use body filler around the thread before i paint these so they look flush. The tweeters fit just inside but loosly so i think some sort of gasket or stickyness will be required to hold these in place.


















Drivers side aimed at the centre of the car.


















Close up on the passenger side.


















As for mounting it to the car i could use the small stick that you can see on the left and attatch it witha boilt to the apillars itself or the flat part of the dash where the bottom of the tweeter sits but the stick part is like welded on so i may have to drill out the nut thats in their and fit a fresh bolt and drill another hole for speaker wires to pass though. The blue tak is for support.



























But whats good is that the tweeters sit further away mounted in the cups than they would sitting flushish in the pillars but they are closer together.

Just got to dill out the nut stick part now and see if i can bolt it to the dash or pillar.

I have apillar baffles as well as these so i can do an AB comparison to see the difference.


----------



## NSTar

over 300 bux for a tweeter @ 20 watt? seriously, is it worth it? What if you put it in the back of the car ...would it sound bad? I got plenty of space in the rear panel.


----------



## TAMUmpower

Those cups dont look like they are going to do anything based on what was said in this thread. The idea is that from the face of the speaker the surround comes out and thn the corner is curved. You still have a sharp angle. The rear of the speaker housing being curved doesnt do much, its the front you are looking for.


----------



## RattyMcClelland

Maybe your right but these will be running from 8k upwards so the diameter doesnt need to be wider as im not going to low frequencies like 2000hz. Will see how these compare anyway to apillars anway.


----------



## Juanhanded

I want to re-read this thread because there is so much damn info,but...

What is the optimal (practical) mounting location for an egg-shaped tweeter enclosure,where looks and styling are of no concern?

Where would be optimum for mid-range speakers to be located?

What would be optimum for mid bass,are in the doors OK? And what would be the practical rounding/transitioning to the door panel?

Are we talking a 3-way system,idealy?

Does a sub play into any of this? (or is it more likely to screw the whole thing up?)

And is a HU with active crossovers going to be a great help?

Is the egg/ball shape considered to be the way to go,as there seems to be a brief mention of mounting to the side of a cylinder.


----------



## Juanhanded

Juanhanded said:


> I want to re-read this thread because there is so much damn info,but...
> 
> What is the optimal (practical) mounting location for an egg-shaped tweeter enclosure,where looks and styling are of no concern?
> 
> Where would be optimum for mid-range speaker..............
> 
> Is the egg/ball shape considered to be the way to go,as there seems to be a brief mention of mounting to the side of a cylinder.


My apologies for the noob questions,I have read more of Patrick's related threads to know that there is a bit more complexity in all of this...however...How do you see the principles applied here in this thread (to a tweeter) applied to the rest of a conventional install? Such as midrange or fullrange done similarly on the dash?


----------



## Yuck.

How could I do this in a newer civic sedan dashboard using the stock tweet locations as a foundation of sorts with a HAT imagine tweeter? I was thinking those little apple egg speaker pods, but does the lip curve out enough? I Imagine diffraction is extra awful because of the sound bouncing off the windshield, people say it smooths the sound, but would you let your speakers bounce off the window in your house to improve the sound, doesn't sound optimal. I'm now actually starting at the hk 695-01's at this computer and thinking they might work, which they won't, but now I'm thinking in the right direction at least, haha


----------



## terranova

good read thanks


----------



## Babs

NSTar said:


> Just a quick off topic... Babs? are those spherical?  *ahem...avatar*


I'd say elliptical probably.


----------



## TAMUmpower

I am scrapping my egg pods I posted about earlier. There just isnt enough space on an e36 windshield for pods. I got tired of the drivers side one catching my vision and sitting so close to the wheel. I am just going to mold them into the pillars and round the edges as much as I can.


----------



## rhystard

i'm going to be trying some of the ideas here soon. bought some cheap tweeters to complete my components, but i'm worried that they seem a little bright upon first "dangline from the wire" testing :laugh::laugh:

luckily no mountains blew up.

i just really don't want big visible eggs taking up space on my pillars or on top of my dash.

hopefully just flush mounting them to the roundest thing i can aesthetically get away with will help.

the wealth of information on this forum is staggering.


----------



## benny




----------



## Patrick Bateman

rhystard said:


> i'm going to be trying some of the ideas here soon. bought some cheap tweeters to complete my components, but i'm worried that they seem a little bright upon first "dangline from the wire" testing :laugh::laugh:
> 
> luckily no mountains blew up.


When you suspend a driver in free air without a baffle, you get a ton of diffraction off the edge. According to the research from Geddes and Lee, diffraction sounds really offensive, so that's likely what you are hearing.



rhystard said:


> i just really don't want big visible eggs taking up space on my pillars or on top of my dash.


It doesn't have to be an egg or a sphere, based on the sims and measurement I've done, a little bit of diffraction treatment goes a long way, especially at high frequencies. So if you don't have the space for a full sphere, just put the driver in a conventional baffle but round over the edges. Pay attention to the back side of the enclosure too; sound will "wrap around" the baffle.



rhystard said:


> hopefully just flush mounting them to the roundest thing i can aesthetically get away with will help.
> 
> the wealth of information on this forum is staggering.


This one's a personal choice. Personally, I like the sense of "air" and "space" that you get by pulling the tweeters off the doors or the A-Pillars.

I mean, think about it: Do your speakers at home image better on stands, or pushed all the way up against the wall?


----------



## rhystard

oh, i know what you're saying completely.

it's just that the car is a daily driver, and aesthetics and a somewhat stealth install are higher on the priority list that absolutely perfect sound, you know what i mean?

i will try some different things and see how far i can go to get the best sound possible, without making it look like a showcar/spaceship inside


----------



## JayGold

I've been reading this entire thread and want to try going the sphere route in my tweeter install.

Some advice is required as I'm utilizing a fairly vintage set of Canton Pullman RS3 components consisting of a 1" hard dome driver.

How do you suggest I go about designing a sphere for what looks like a nipple grill




























The connections are very close to the outer edge of the magnet.


----------



## tyort1

Too bad the B&W speakers sound so terrible.


----------



## wadejg

Metal spheres can be found from McMaster Carr:

McMaster-Carr

Regards,
Justin


----------



## Chris C

tyort1 said:


> Too bad the B&W speakers sound so terrible.


LMAO:laugh:


----------



## igo4bmx

this is a cool project i can work on- more stuff to do with the car!


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## derickveliz

.
*I really want to try this,* 

I found these images on FaceBook from "Fan photos from Hybrid Audio Technologies"



















.

*Looks like all these really makes sense.*

D.


----------



## katodevin

looks like mine, but more fancier.


----------



## JLawsonz

The small and medium size globes avail inthe home improvement center for makeup lights and ceiling fan light kits seems like a good piece to launch a project for cheap.


----------



## derickveliz

I would like to get 5 in ball with 3.5 midrange and a smaller for tweeters then mount and attach to the A-Pillars, but I was wondering about visibility, I test fit and it really doesn't bothers me but what about legal? is it going to pass the inspection?

What if I only use 60% of the sphere and chop the back/side where attaches to the A-pillar?

The important shape/surface is the curve that goes away from the speaker, right? correct me if I'm wrong or it's better if I keep a full sphere?

Thank you.

DERICK,
I'm enjoying every word in this thread, I love pictures...










.


----------



## igo4bmx

aztec1 said:


> I found these cheapo pods. They looked nice to me. A bit of dremel and voila! I haven't mounted them yet, still playing with placement. They instantly fixed many issues I'm struggling with, especially on the driver's side at around 8kHz, just by holding them with my hand in the place where my old "pods" were. I'm sure with some placement tweaking they will really widen the soundstage and get rid of lots more harshness. Really amazing stuff, if you're on the fence about this just do it...the improvement is staggering! Thanks Patrick!



because of you i bought the same kinyo speakers and then cut the speakers out and put in the textile seas prestige speakers
i will be installing them today when i get home from work


----------



## derickveliz

I found this in the Robb Report Collection Magazine...


----------



## HK_M3

Those Gallo Strada's look to be incredible. I have never loved the sound of B&W though.


----------



## Vince_K

igo4bmx said:


> because of you i bought the same kinyo speakers and then cut the speakers out and put in the textile seas prestige speakers
> i will be installing them today when i get home from work



I also have the Seas tweets. These Kinyo enclosures seem to be quite a nice fit. 

Neweggmall.com - Portable USB Speaker (NB-005B)

Post your final mounted pics! I'm about to jump on these as well. Thanks!!


----------



## Notloudenuf

I'm working on my version of the speaker balls. here is where I am now.









The mounting screw locations is what is bothering me now. Do I need to do something with this flange or can it stay.
something along the lines of this?


----------



## 94VG30DE

Bend over mounting tabs, put your screws through them if you want, then use NHMC to smooth edges.


----------



## CraigMBA

I'm building a setup kind of like this one. I'd claim to be building a total ripoff clone of it, but I had it all built before I saw the picture save the defraction ring which I plan to add.

Doug Winkler's JBL2118 kick pannel.

Is there any way I can incorporate a half sphere to the back of the tweeter and improve it, or am I stuck hanging it out there in the wind, waiting for Mt. Saint Hellens to become active again?

Anybody else have any suggestions?


----------



## derickveliz

*I'm working on it!*


----------



## derickveliz

derickveliz said:


> *I'm working on it!*


Done!



















.


----------



## Notloudenuf

Just so people know at Staples they sell a heavy plastic sphere the same size or slightly larger ~80mm full of paper clips for $1ea. In my local Staples they are right at the front with all of the $1, $2, $5 bargain bins. These at Staples felt heavier and thicker than the ones I bought at Michaels.


----------



## TAMUmpower

derickveliz said:


> Done!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> .


Who did you order your dash mat from. Is that suede or velour? I getting one soon but I'm not sure if suede kills reflections as good as carpet...but I'd hate to put carpet on the dash of a BMW. Input?


----------



## ReticulatingPigeonElf

TAMUmpower said:


> Who did you order your dash mat from. Is that suede or velour? I getting one soon but I'm not sure if suede kills reflections as good as carpet...but I'd hate to put carpet on the dash of a BMW. Input?


I'd consider fiberglassing some thin dash panels and gluing closed-cell foam on them... dumb idea?


----------



## derickveliz

TAMUmpower said:


> Who did you order your dash mat from. Is that suede or velour? I getting one soon but I'm not sure if suede kills reflections as good as carpet...but I'd hate to put carpet on the dash of a BMW. Input?


I got the Ltd edition! looks ok, and takes good care of the reflections.

The black one I have is really black but the camera changes the color a little bit, I went with black because it has no sun reflexions like the gray & smoke.

I got a bunch of samples and did a lot of testing. I believe Carpet has a better fit, but I don't like the way carpet looks like.

Dash Mat






































D.


----------



## Jprice2708

Would there be much difference between choosing a sphere the same diameter as the speaker (say 4" for a 4" speaker) and having just a dome rear, vs choosing a larger sphere than the speaker (say 6" sphere for a 4" speaker) and having the speaker mounted on a more curved front surface? I'm assuming the extra volume in the enclosure would probably be good, but would there be much in the way of other benefits? Also for a Focal 4w2 would it be better to port the ball or have it sealed (if anyone knows - I can't find any technical specs on the 165w2 set online at all)


----------



## Patrick Bateman

Jprice2708 said:


> Would there be much difference between choosing a sphere the same diameter as the speaker (say 4" for a 4" speaker) and having just a dome rear, vs choosing a larger sphere than the speaker (say 6" sphere for a 4" speaker) and having the speaker mounted on a more curved front surface? I'm assuming the extra volume in the enclosure would probably be good, but would there be much in the way of other benefits? Also for a Focal 4w2 would it be better to port the ball or have it sealed (if anyone knows - I can't find any technical specs on the 165w2 set online at all)


Yes, size matters. [insert joke here]

A roundover reduces diffraction down to a certain frequency, and then it's ceases working. So the bigger your woofer is, the bigger roundover you need. That's why I started this thread with a tweeter - you get the most "bang for the buck" with a tweeter roundover, since it doesn't have to extraordinarily large to make an audible difference.

The math on the how big the roundover should be is in the first couple pages.


----------



## 94VG30DE

Earlier explanation on how to calculate your size: Post #17 Page 1



Patrick Bateman said:


> The problem with felt is it doesn't operate very low; below 15khz it doesn't make much of a difference.
> 
> A roundover operates down to 1/4 wavelength of the roundover's radius.
> 
> That's another thing too; it doesn't *have* to be a sphere. Anything that's done to reduce diffraction will yield an audible and measurable improvement.
> 
> You could look at this as a series of stages, and each stage is cumulative. IE, do some of them, or all of them for full effect.
> 
> 
> Use a roundover with a radius that's equivalent to one quarter of the frequency you need to cover. For instance, to go down to 2000hz you'd use a roundover with a radius of 1.6875".
> Go all the way and use a sphere. A sphere is basically a roundover on all sides.
> Add a waveguide to the face, and round THAT over.
> 
> If you look at the profile of the B&W, you can see the woofer's cone itself forms a waveguide. For a tweeter you'd need to build one. Even *without* a waveguide on the tweeter, the enclosures shape reduces diffraction.
> 
> And reducing diffraction makes the speakers disappear.


----------



## Jprice2708

Patrick Bateman said:


> If you're using a sphere, the radius of the sphere is calculated like this:
> *required sphere radius = 13500 / lowest frequency / 2 / pi*
> If you're using a simple roundover, the radius of the roundover is calculated the exact same way. That's because we're basically taking a sphere and "quartering it."
> *required roundover perimeter = 13500 / lowest frequency / 2 / pi*
> You can work from the other direction too. For instance, if you're at Home Depot, looking at PVC, and trying to figure out what size is adequate, here's the calculation.
> 
> *Lowest frequency = 13500 / 2 / pi / radius of roundover*
> For instance, you're standing at Home Depot, and trying to figure out if 2" PVC pipe will do the job. First, you have to take that pipe and quarter it, so that it give you a roundover with a radius of 1". * A PVC pipe with a diameter of 2", chopped into four pieces, will give you a roundover with a radius of 1" and a perimeter of 1.57*. _( pi / radius / 2)_
> Plugging those numbers into our equation, we find that a 2" PVC pipe, quartered, will reduce diffraction down to 1368hz. *(13500 inches per second / 2 / 3.14159 / 1.57"*[/font][/size]


I'm assuming this is the equation you mentioned Patrick, but it has me confused, as it looks in the explanation like you are using perimeter and radius interchangably and they are very different measurements if I remember my maths properly  It has been many loooong years since high school lol, but any clarification would be great.


----------



## Scooter-Man

I went from dash mounted PG RSD tweeters (that were probably producing some disfraction due to install) to this set up. This really smoothed out the harsh upper freqs, especially at louder volumes. Overall, I'm very pleased with the results.



















Old Tweeter Set-up


----------



## rexxxlo

these have to be some of the coolest pictures i have seen 

i like how the focus is really sharp where it counts and kinda fuzzy around the edges

i bet it sounds as good as it looks


TAMUmpower said:


> Who did you order your dash mat from. Is that suede or velour? I getting one soon but I'm not sure if suede kills reflections as good as carpet...but I'd hate to put carpet on the dash of a BMW. Input?


----------



## derickveliz

rexxxlo said:


> these have to be some of the coolest pictures i have seen
> 
> i like how the focus is really sharp where it counts and kinda fuzzy around the edges
> 
> i bet it sounds as good as it looks


Thank you, yes they sound pretty good, I'm about to move the Mids, my stage is not where I want it, also I'm experimenting with the woofer up front!

Here is my BUILD, 

Thanks again.

.


----------



## douggiestyle

Hi Patrick,

I've gone over this whole thread a few times and still have some questions. I'll post them here as I think they will help others down the line.

1. Your big point is to eliminate sharp edges to reduce diffraction. The orb shape helps the sound "curve" around which essentially aids longer sound waves. Based on this, is there a scenario where speheres DON'T make sense?

For example, with Derick's (great) pods 









or katodevin's here









wouldn't diffraction still occur where the orbs meet the pillars/dash? Would moulding these into the a-pillars while eliminating sharp curves be a better way to eliminate diffraction? Examples such as:

Mikamouse (tweets)









dvflyer









gutz









In other words, is the key word to this really two parts:
1. eliminate sharp edges, and
2. spheres are a CHEAP and EASY and EFFECTIVE way to accomplish this


----------



## douggiestyle

Also (sorry I have a bunch of Q's)

1. for katodevin's mid pods, does the implementation cause diffraction at the edge since it is more of a half-circle w/ sharp edges all the way around. It's been raised a few tims but never directly addressed by you.

2. Along the same lines, using your formula to find the needed radius, doesn't that depend on the speaker size? For example, if running a tweeter down to 2000hz, a radius of 1.07inches is needed. But using a .75" tweeter vs. a 1.25" tweeter will change the spot at which to cut the orb... so that should change certain parameters, right?

3. When using a super tweeter like I intend to, say 6000hz, only a .36 radius sphere is needed (.716 diameter). The tweeter I'm using, LG26nfa, has a flange making it 2" wide. Is there any benefits of an orb in this case?










4. Finally, for the mid, if diffracting down to 1000hz, a 4" diameter sphere is needed. However (if sealed) internal volume before displacement is only .55 liters while the recomended is .75l enclosure for F3 of 150hz. I plan to cross these down to 200hz, would the diffraction benefits outweigh the compromise of an optimum enclosure?

Sorry for the list of questions, and thanks again for sharing your insight!


----------



## 9mmmac

Patrick Bateman said:


> Thanks! I've been doing horns and waveguides for almost two decades now, and the improvement that I've seen from adressing diffraction (almost) has me considering "conventional" components again. The improvement in soundstaging is just ridiculous.
> 
> I first noticed it with the Anthony Gallo speakers a few years back at CES. They use ridiculously cheap drivers, and they're basically a glorifed Bose system, yet they sound a million times better than they should. Considering the junky components you'd think they'd sound like crap, but they sounded better than speakers that cost ten times as much.
> 
> Really made me think about how they sound so good.


This is cool, but it also really freaks me out. I keep thinking of War of The Worlds. Is it going to melt my face with a plasma death ray? OTH, I see floor and desk lamps here. Can I get some at my fave thrift shop, run the cables up like the power wire and put some nice pods in the lamp housing? Hmmmm.


----------



## MDubYa

So hypothetically I could put my tweeters in a tennis ball and they would image better?

Edit: Nevermind... I just read tge whole article... Well I feel like a horses pa-toot!


----------



## MDubYa

Patrick,
I've been reading and now I have a question, most people in this section are putting their tweeters in the A pillars or near the dash... Would the sphere idea still work if I mounted my tweeters in a sphere and mounted the sphere in my door panel????


----------



## Patrick Bateman

douggiestyle said:


> Hi Patrick,
> 
> I've gone over this whole thread a few times and still have some questions. I'll post them here as I think they will help others down the line.
> 
> 1. Your big point is to eliminate sharp edges to reduce diffraction. The orb shape helps the sound "curve" around which essentially aids longer sound waves. Based on this, is there a scenario where speheres DON'T make sense?
> 
> For example, with Derick's (great) pods
> 
> 
> 
> 
> 
> 
> 
> 
> 
> or katodevin's here
> 
> 
> 
> 
> 
> 
> 
> 
> 
> wouldn't diffraction still occur where the orbs meet the pillars/dash? Would moulding these into the a-pillars while eliminating sharp curves be a better way to eliminate diffraction? Examples such as:
> 
> Mikamouse (tweets)
> 
> 
> 
> 
> 
> 
> 
> 
> 
> dvflyer
> 
> 
> 
> 
> 
> 
> 
> 
> 
> gutz
> 
> 
> 
> 
> 
> 
> 
> 
> 
> In other words, is the key word to this really two parts:
> 1. eliminate sharp edges, and
> 2. spheres are a CHEAP and EASY and EFFECTIVE way to accomplish this


Here's my take on your questions. I've been interested in audio for a couple of decades. For the majority of that time, I had "upgradeitis." I was constantly replacing amplifiers, re-arranging my room, and swapping loudspeakers. It wasn't uncommon to purchase two sets of loudspeakers in one year.

About three years ago I splurged and bought me a set of Summas, and I now listen to them for about 10 hours a day. (I work at home.)

So a lot of the threads that I start are experiments based on using some of the design principles in the car.

So, back to your question. *Is there a scenario where spheres don't make sense?*

I'll throw out a quote from Geddes to answer that one. "Only agregious amounts of distortion in a loudspeaker are an issue. Once these are brought down to reasonable levels then its other things, like polar response, diffraction and dynamics that are the significant issues."*

I think that statement sums up loudspeaker design fairly well. If you want a loudspeaker that you can live with, focus on polar response, diffraction, and dynamics.

It takes a helluva large enclosure to get world-class directivity - here's a picture of Geddes with his speakers to give you an idea of how big they are. They're hyoooooge:










So, admittedly, directivity control in the car is a challenge.

That leaves diffraction and dynamics. And the great thing about battling the diffraction problem is that it's fairly easy to do. Especially at high frequencies, it really doesn't take much of a roundover to make an audible effect.

As for whether mounting them in the A Pillar, versus putting them into spheres is superior? I'd say put 'em in spheres and try various locations in the car. The thing that I've noticed with spherical tweeters is that you can frequently get a *wider* and *deeper* stage by pulling them away from the windshield. Experimentation is key. (And it's fun too!)

As for the third pillar of loudspeaker design, I'd say dynamics is worthy of a whole 'nother thread.

It would also be interesting to discuss which pillars are the most audible. Diffraction? Dynamics? Polar response?

_* New White Paper posting - Page 19 - diyAudio_


----------



## keep_hope_alive

thanks for the idea. i read this thread yesterday and made this today. Hobby Lobby had solid wood spheres (with one flat side with a predrilled hole) for $1.69. i didn't want to use styrofoam or plastic.

I used a hole saw to make the initial opening
then used a paddle bit to clean out the inside
my paddle bit was too small so i used a dremel to finish it out
i used the dremel to perfect the opening size
i drilled a hole for the speaker wire
...all in about 15 minutes

had some older 3/4" Alpine tweeters laying around

i like my first attempt.

will be doing this with Hertz Mille tweeters tomorrow
























































two sizes









i have a stand-off idea using a machine screw and hollow brass tubing. 

then paint and cover with grill cloth or not, or whatever.


----------



## rugdnit

keep_hope_alive said:


> thanks for the idea. i read this thread yesterday and made this today. Hobby Lobby had solid wood spheres (with one flat side with a predrilled hole) for $1.69. i didn't want to use styrofoam or plastic.
> 
> I used a hole saw to make the initial opening
> then used a paddle bit to clean out the inside
> my paddle bit was too small so i used a dremel to finish it out
> i used the dremel to perfect the opening size
> i drilled a hole for the speaker wire
> ...all in about 15 minutes
> 
> had some older 3/4" Alpine tweeters laying around
> 
> i like my first attempt.
> 
> will be doing this with Hertz Mille tweeters tomorrow
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> two sizes
> 
> 
> 
> 
> 
> 
> 
> 
> 
> i have a stand-off idea using a machine screw and hollow brass tubing.
> 
> then paint and cover with grill cloth or not, or whatever.


That looks really cool, but isn't the real benefit of the sphere the internal enclosure?


----------



## keep_hope_alive

not the internal enclosure. the tweeter isn't vented into the cavity, the tweeter cavity is closed off. only a few tweeters on the market (Hertz Mille) allow you to remove the cavity to leave it open. 

for an open back cone midrange, you need the cavity. you could do this with a dome midrange if you wanted (if it was large enough)

if you read the first page of this thread, you will understand why.  it's all about eliminating the diffraction off of the tweeter baffle.

the B&W example is one where the shape is diffraction and cavity. but automotive tweeters aren't open. they have a cavity and a magnet on the back.


----------



## keep_hope_alive

and i have an awesome idea for mounting it to the apillar. i'll share the Hertz Mille tweeter sphere install for a 2005 Scion tC build. Slated for tomorrow morning.


----------



## rugdnit

I understand the diffraction part and have read the first page ( as well as the following pages ). I have also read that a sphere enclosure is ideal as well due to back wave reflections ( it was some time ago, so I don't have a link etc etc ).


----------



## keep_hope_alive

rugdnit said:


> I understand the diffraction part and have read the first page ( as well as the following pages ). I have also read that a sphere enclosure is ideal as well due to back wave reflections ( it was some time ago, so I don't have a link etc etc ).


Valid for a open back midrange or tweeter. These aren't open back.

These will benefit from more mass and no resonance. Thin walls resonate and you want that frequency to be well below your intended response.


----------



## Eastman474

So explain to me how you go about placement of the diffraction? Same theory as Gary Biggs regal right? With the flower looking diffraction ring?


----------



## keep_hope_alive

the sphere is merely reducing the baffle edge diffraction. you still have reflections and diffraction from the mount, the apillar edges, etc. you still have reflections that arrive delayed and cause phase interference (or comb filtering). you want to minimize all of that. recognize that anything 10dB below a signal is not adding to the signal - so if you could get all of your reflections 10dB below the original (direct) signal - you would essentially just have the original signal (ideally). aiming the tweeters so the window and windshield are off axis enough to attenuate those reflections is one method and how i plan on approaching this. absorbing those reflections is another method, but we can't make the glass absorptive. i am still concerned about reflections off the opposite window - giving the opposite ear too much information (left ear getting right channel information). that's natural in everyday life and our brain can handle it - but it uses those IID and ITD cues to determine source localization. essentially, that is what our goal is for imaging - using psychoacoustics to our advantage with non-ideal speaker placement. 

this is what i love about car audio - it is so difficult and a great challenge. i mean, in a home you just buy Wilson Audio speakers and let the installer do the work... and acoustically treat the room.


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## keep_hope_alive

not totally familiar with Bigg's flower - if anything, he was trying to make the diffraction diffuse - break it up so many times that nothing was dominant. that would also distribute energy and possibly reduce the effect. a flower shape would do just that. 

the sphere is trying to eliminate the phenomenon altogether. the thread references home audio and the Loudspeaker Design Cookbook. I saw that sphere diffraction study in there, but never thought about applying it to tweeters (where you don't rely on the sphere as a cavity). i am very appreciative to Patrick for bringing this to our attention. the length of this thread, the all positive and constructive responses, and the images make this one of the better threads on DIYMA (IMO).


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## Eastman474

Yes this is a pretty cool thread, i can't wait to finish reading through all of it to get the most from it


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## TOOSTUBBORN2FAIL

Curious how well this works for a tweeter crossed around 6.5kh. The calculation shows I need .34" radius for that frequency, but would a larger radious work as well?


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## ErinH

That radius is a minimum needed. Anything larger will result in a lower frequency/diffraction. So, it's a good thing. Also, keep in mind just because you're crossed at a given frequency, you still have content played below it unless you have an extremely steep slope on the crossover.


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## ErinH

keep_hope_alive said:


> not totally familiar with Bigg's flower - if anything, he was trying to make the diffraction diffuse - break it up so many times that nothing was dominant.


I believe his rings were more an attempt at lessening beaming. But, that may be incorrect...been a while since I've seen any discussion on the subject.


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## CraigMBA

bikinpunk said:


> I believe his rings were more an attempt at lessening beaming. But, that may be incorrect...been a while since I've seen any discussion on the subject.


Biggs made them famous, but Doug Winkler came up with them (Mark Eldridge also credits DW somewhere on the Carsound forum). Doug posts here from time to time, you can find his post on the topic 
here.



> Yes, it what Gary used in his Regal, but due to the crossover points and size of his mids, it was more for points that sound. The technique I used only works when trying to mate a large speaker with a tweeter. If I had the room, I would have run the 2118 with a 2105 and then the Scan tweet, but I did not have the room. *So unless you are going to run an 8 in a 2 way setup, don't waste your time trying this*.


Bolding mine for the moneyshot.


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## ErinH

^ (bold) I can imagine. There's really no reason for anyone to have to 'break down' beaming because most people are crossing outside of that point anyway. Heck, I'm sure with a nicely placed crossover, one could even use part of that effect to boost just a touch more of the upper end of their mid before bringing in the tweeter.


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## rugdnit

​


keep_hope_alive said:


> *Valid for a open back midrange or tweeter. These aren't open back.*
> 
> These will benefit from more mass and no resonance. Thin walls resonate and you want that frequency to be well below your intended response.


I hate it when I try to do three things at the same time. For some reason I missed the tweeter part... sorry about that.


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## keep_hope_alive

a different tweeter inset, two different sphere sizes


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## keep_hope_alive

rugdnit said:


> ​
> I hate it when I try to do three things at the same time. For some reason I missed the tweeter part... sorry about that.


no problem, sorry if i came off as being short, i was also trying to do a couple of things at once. 

our date with the Scion this morning fell through due to family needs (he's not coming over). I'll still get it done and share the final product with the group.

my plan to stand off the ring is a hollow threaded tube with a solid brass (or nickel) tube over that. wire routed through the threaded tube, and that tube would screw into the wood sphere and use nuts to hold it to the apillar. the brass tubing would simply hide the threads. 

we were looking at the camera mounts so we could play with aiming, but we have a good idea where we want them anyway, and the mounts will allow for some rotation.


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## keep_hope_alive

bikinpunk said:


> That radius is a minimum needed. Anything larger will result in a lower frequency/diffraction. So, it's a good thing. Also, keep in mind just because you're crossed at a given frequency, you still have content played below it unless you have an extremely steep slope on the crossover.


Did I miss an explaination why circumference = wavelength is the equation? At least, that is what I get for a derivation of the equation.


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## Wesayso

Here's an idea to create a custom pod for your tweeter.
The firm Shapeways is a 3D printing firm that can print your 3D design. I think I'm going to try them to make a tweeter spacer for my doors. I have a cylindrical spacer right now to aim the tweeters a bit. I used Inventor to create a more rounded spacer to try and get rid of some of the difraction. Here's my 3D model for a Hertz Space One tweeter:








The tweeter will directly fit in this spacer, no need for a mounting ring etc.

Here's the same model uploaded as STL to Shapeways:









You can print it in several different materials. I'm thinking of using a black nylon, from their website:

_PA 2200
Strongest material
Flexible
PA 2200, Selective-Laser-Sintered (SLS)
This is the strongest nylon material that we have and it has a good heat resistance. The most interesting is that you can use the material for living hinges and springs. SLS is not suitable for molding.
Using the model in White, Strong and Flexible as a lost pattern will leave rests after burning. Be aware that this is a porous material, so it will absorb miniscule polution particles in the air. Please keep in mind that your object will turn yellowish when you put it in direct sunlight. 

The design and thickness of your model will affect the flexibility of this material._

It doesn't fit in this thread cost wise though , one print of this model would set me back about $33,-. The cost is based on volume.
I'm sure there are a lot more firms that can do this stuff cost effective. This one is in the Netherlands. Just an idea.

I'll let you guys know if I follow trough.


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## derickveliz

That's really cool,

I'm much better drawing 3D stuff than playing with glass! jeje


.


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## asawendo

This is fantastic thread to read. 

I'm doing my project right now.....still experimenting the best material for my scanspeak R2904 tweeter (fiber/ plastic / wood / ceramic). 

Best regards

Wendo


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## keep_hope_alive

More with the tweeter spheres, this time for Hertz ML28 tweeters. Driver side is the same.














































aiming




































We have brass tubing to cover the threaded shaft that we will paint silver. we'll either paint or fleece the sphere. the tweeter logo will be horizontal and upright. wire is through the threaded rod and will terminate in a plug or terminal. end product should look good.


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## asawendo

keep_hope_alive said:


> More with the tweeter spheres, this time for Hertz ML28 tweeters. Driver side is the same.
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> We have brass tubing to cover the threaded shaft that we will paint silver. we'll either paint or fleece the sphere. the tweeter logo will be horizontal and upright. wire is through the threaded rod and will terminate in a plug or terminal. end product should look good.


That's cool Bro...

What kind of wood did you use for that thing?!


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## keep_hope_alive

Wood - check the previous page(s) for more info on those wooden spheres. $1.60 for them. Given our 1.3kHz crossover point, the equation yields a 1.7" diameter required. These spheres are "good" down to 2kHz. We'll listen and see if we want larger spheres. For now, we just want to listen to them.


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## ErinH

now, if only someone could find a way to integrate these things where they stand far enough off the pillar/dash to not have the baffle coincident with it and still hide them or at least make them look decent.


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## Wesayso

keep_hope_alive said:


> More with the tweeter spheres, this time for Hertz ML28 tweeters. Driver side is the same.


What diameter did you end up using for the ML28?


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## keep_hope_alive

We used spheres with a diameter of 2-1/4". 1910Hz is the "diffusion cutoff" or where the wavelength = circumference


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## asawendo

After experimenting some material and also speakers, I just want to shared my little project....










Cheap Tweeter that sound very good with sphere. 










Monacor SPH 30X Midrange and Scanspeak 2904/R70000 Tweeter. Very good tonal balance, great imaging, smooth as silk and extended high range without any harsh. 

The sound is come all around my dashboard as if the speaker itself not producing any sound! 

Thx a lot to PB and all great people in DIYMA!

Best Regards

Wendo


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## derickveliz

But the round edges are missing!


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## asawendo

derickveliz said:


> But the round edges are missing!


Thx for your input maybe I can work on it Bro.....

But it still much better sound than previous installation

Best Regards

Wendo


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## Ultimateherts

Don't know if this site has been mentioned in this thread at all:

Barnard Ltd. - Ornaments - Plastic Balls - *CLEAR TRANSPARENT PLASTIC 2 PIECE SPHERE 40 GAUGE

They basically sell plastic spheres in two half so that retailers can put signage inside of them and they are relatively cheap. The question I have is that they rate them in size, but also in gauge sizes. Is the gauge size a term for thickness of the plastic used???


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## 60ndown

asawendo said:


> Wendo


3" midrange + 6" tweeter?

very unusual


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## wannabesq

Good read, interesting stuff. And here I was thinking that all those round speakers were just cosmetic... Now to go re buy my whole setup....


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## AccordUno

it's not really a 6" tweeter the face might be, but it looks more like a 3/4" - 1" radiator tweeter.. If he would have flushed the mid and made it round instead of the square-ish it would have not seems out of place.. 

How is it mounted to the glass? How much is in the way? got more picture of the full dash?


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## peg_legs

I just spent the morning redoing my tweets, up on the dash and in styrofoam balls from Hobby Lobby. I got styrofoam, wood and plastic balls from there. $15 total. I started with styrofoam for a quick install and planned to redo them in wood if I really like it. The tweets were in the sail panels and sound much better now in the balls. I have to retune everything, but it already sounds much better. I used 2 inch balls and the tweets are Seas Neos. Thank you Patrick! I really enjoy all of your posts


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## 60ndown

peg_legs said:


> I just spent the morning redoing my tweets, up on the dash and in styrofoam balls from Hobby Lobby. I got styrofoam, wood and plastic balls from there. $15 total. I started with styrofoam for a quick install and planned to redo them in wood if I really like it. The tweets were in the sail panels and sound much better now in the balls. I have to retune everything, but it already sounds much better. I used 2 inch balls and the tweets are Seas Neos. Thank you Patrick! I really enjoy all of your posts


can you give us 3 concrete examples of how and why it 'sounds better' ?

after sails for a while and now your balls  im interested in hearing what you have to say about what your hearing, most people seem to take months to change anything and cant even remember the old sound.

you can tell me/us, exactly what the difference is, try not to just repeat whats already been said, in your own words, in your car, how is the sound different? 

im happy with my sound, but if your reply is good enough i may have to get some balls in my face.


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## ErinH

I still have yet to really understand the purpose of this. The biggest advantage I'm seeing here is that most people are now using them on axis.
So, that alone - going from off-axis to on-axis - would likely be a huge improvement.
Who has gone from on-axis w/o sphere mount to sphere mount, same firing angle? 

To me, the issue is that the flange itself dictates the baffle step/diffraction fo when not mounted to a baffle which is typically how you could think of most car audio installs being on the dash), matching the same diameter sphere to the flange diameter doesn't seem to be beneficial to me. 

I'd like to see measurements on this. Heck, if someone can take the time to send me a tweeter with and without the sphere (and maybe of different size spheres) I'll be happy to measure the response so we can get a clear understanding of how the sphere size vs tweeter/midrange flange size affects response. For diffraction to be minimized you'll have to at least use a sphere larger than the flange size of the driver used. Otherwise you're at the mercy of the driver's flange.
If I'm wrong on this, please let me know. I'm just not seeing how there's any true gain with a sphere the same size of the tweeter/mid flange and I'm banking that the noticeable gain in response is mostly due to those who had tweeters firing across the dash, now firing on axis (and thus reducing comb filtering issues).

I dunno... my random $.02.


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## 000zero

Awesome thread


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## peg_legs

60ndown said:


> can you give us 3 concrete examples of how and why it 'sounds better' ?
> 
> after sails for a while and now your balls  im interested in hearing what you have to say about what your hearing, most people seem to take months to change anything and cant even remember the old sound.
> 
> you can tell me/us, exactly what the difference is, try not to just repeat whats already been said, in your own words, in your car, how is the sound different?
> 
> im happy with my sound, but if your reply is good enough i may have to get some balls in my face.


Sure will, but it may sound much like Bikinpunk's response below yours. Let me start with info on me. I'm no expert. Never competed, but do love music.I am an engineer and play and record music. My first car stereo was built in the late 1980's. Alpine, MB Quart, Soundstream. This is my first time going active and using time alignment.
so on to the request..
I went from the stock location in the sails to on axis on the dash in balls. the stock location pointed straight across and down towards the gear shifter. I never could get this to sound good. No stage, slurring, lack of clarity and voids in certain frequencies. The tweets (Seas Neos) never wanted to play well with the woofers (Dayton RS180). I believe I may have had a phase issue (wish I had tried that). Now I'm on Axis, and the tweets blend well with the woofers. The depth of stage increased, much more clarity showed up to the party, I don't notice any vast areas of missing frequencies. 
of note, I had to turn the gains down a lot on the tweets after moving them, and was able to drop the crossover point back down to 2200 hz without the problems that made me raise it to 3.1k. Those problems were not limitations of the drivers, but the drivers not playing well together. 

I believe that at least 98% of the gains were from moving to on axis and possibly correcting a phase issue or comb filtering. This thread was enough motivation to go try something new and the end result was well worth the effort. I have a few other threads that I want to try like the one on time alignment with noise tracks, and the soundstage that ate my dash


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## 60ndown

peg_legs said:


> Sure will, but it may sound much like Bikinpunk's response below yours. Let me start with info on me. I'm no expert. Never competed, but do love music.I am an engineer and play and record music. My first car stereo was built in the late 1980's. Alpine, MB Quart, Soundstream. This is my first time going active and using time alignment.
> so on to the request..
> I went from the stock location in the sails to on axis on the dash in balls. the stock location pointed straight across and down towards the gear shifter. I never could get this to sound good. No stage, slurring, lack of clarity and voids in certain frequencies. The tweets (Seas Neos) never wanted to play well with the woofers (Dayton RS180). I believe I may have had a phase issue (wish I had tried that). Now I'm on Axis, and the tweets blend well with the woofers. The depth of stage increased, much more clarity showed up to the party, I don't notice any vast areas of missing frequencies.
> of note, I had to turn the gains down a lot on the tweets after moving them, and was able to drop the crossover point back down to 2200 hz without the problems that made me raise it to 3.1k. Those problems were not limitations of the drivers, but the drivers not playing well together.
> 
> I believe that at least 98% of the gains were from moving to on axis and possibly correcting a phase issue or comb filtering. This thread was enough motivation to go try something new and the end result was well worth the effort. I have a few other threads that I want to try like the one on time alignment with noise tracks, and the soundstage that ate my dash


thank you

and im reasonably sure a few weeks with this and some more tuning and things will start to get very exciting.

theres been a few occasions where ive heard something outside my vehicle, when re playing the track there it is again, about 2 feet outside the vehilce, if a system could be made to image like that a lot it would be interesting/fun/weird.

ive sat in and listened to dozens of 'high end' cars, ive never heard imaging like it tho ?


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## Bayboy

bikinpunk said:


> I still have yet to really understand the purpose of this. The biggest advantage I'm seeing here is that most people are now using them on axis.
> So, that alone - going from off-axis to on-axis - would likely be a huge improvement.
> Who has gone from on-axis w/o sphere mount to sphere mount, same firing angle?




Agreed! Patrick's info has opened my eyes very well, but at the same time implementation (at least for me) is nowhere near easy. That's due to some other factors which may not allow me to utilize it... 

Anyway I'm not seeing a whole lot, if any, good examples where the driver was simply put into a sphere or utilized the proper round-over with the appropriate transition from flange to edge, but kept at the same axis. I would like to see some feedback from just that aspect alone before other techniques were applied.


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## Pr_007

Hi everybody, I have a Morel Supremo Tweeter, the one with a 4 inch face plate.

I am planning to make a spherical enclosure for the same.

I am considering Christmas decoration balls made out of paper-mache. I have attached a picture of the ball. Just suggest if this will work out. The balls will be coated with 3 layers of Fiber glass in the inner side of the sphere.

My question is will the balls made of paper-mache be able to hold it or will it break off??


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## 60ndown

Pr_007 said:


> Hi everybody, I have a Morel Supremo Tweeter, the one with a 4 inch face plate.
> 
> I am planning to make a spherical enclosure for the same.
> 
> I am considering Christmas decoration balls made out of paper-mache. I have attached a picture of the ball. Just suggest if this will work out. The balls will be coated with 3 layers of Fiber glass in the inner side of the sphere.
> 
> My question is will the balls made of paper-mache be able to hold it or will it break off??


paper mache and fiberglass will be be very strong, have no fear.

i would fiberglass the inside of the balls as well.


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## peg_legs

bikinpunk said:


> Who has gone from on-axis w/o sphere mount to sphere mount, same firing angle?


Just had a thought.. dangerous, I know . I can pick up some PVC caps (cylinder shape) to mount the tweeters in and bring the balls, and we can switch back and forth in your driveway. My ears are nowhere near as good as yours and I only live 30 minutes away from you.


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## ErinH

I'd rather measure them if we could and post the data. People are more likely to accept that than my opinion... though, judging by the data I've posted thus far... maybe not. :/

I actually have an itty bitty tweeter (vifa 3/4") and a few balls I picked up from hobby lobby to toy with. Just gotta find the time. 


PS: I might be at your building Wed. I'll give you a heads up if I come out there.


----------



## peg_legs

bikinpunk said:


> I'd rather measure them if we could and post the data. People are more likely to accept that than my opinion... though, judging by the data I've posted thus far... maybe not. :/
> 
> I actually have an itty bitty tweeter (vifa 3/4") and a few balls I picked up from hobby lobby to toy with. Just gotta find the time.
> 
> 
> PS: I might be at your building Wed. I'll give you a heads up if I come out there.


Hit me up if you come by.
Great idea on measuring them. It's a shame how the recent driver reviews turned out. 
We can try several shapes, but I'm betting flat baffle, sphere and cylinder would be enough.
I can throw together some govt approved test plans, procedures and test reports..  jk

I would need at least a week. Both my 13 yr old daughter and girlfriend had surgery last week and are keeping me on my toes caring for them.

I have been kicking myself for not buying those scan speak tweets at the GTG.


----------



## ErinH

I think Kirk still has those tweeters. 

I'd like to test flat baffle of X size. Round baffle of same outer size as the X baffle size and then maybe a couple other spheres larger and smaller than the tweeter flange. i think that would be a good representation of how the various sizes compare to the tweeter itself.

We can flush mount the tweeter on something like a 2x2" baffle, then surface mount it on the same baffle, then mount it in a sphere with 2" wide diameter, and then start trying various sized spheres to see how it all works out.
We can use Edge to model the predicted response on the square baffle.

I'm actually pretty busy myself with getting the house prepped for selling, but maybe I can get something going this weekend.


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## SSSnake

I have similar thoughts to Erin on this one... If the ball is no larger than the flange then you may be better served with a recessed surface mounting. Keep in mind the suggestion of the balls is to reduce diffraction. Balls aren't the only solution here. Proper edge termination on a dash, a pillar, or sail panel (tougher to do here) will provide benefits as well and may provide a lower usable xover point for the tweet (vs a ball not much larger than the tweeter flange). Another solution to consider with a dash moutned tweet is acoustic foam in the dash to a pillar intersection. This area is typically pretty a nasty geometry and creates tons of reflections.


----------



## Wesayso

Wesayso said:


> Here's an idea to create a custom pod for your tweeter.
> The firm Shapeways is a 3D printing firm that can print your 3D design.
> 
> _PA 2200
> Strongest material
> Flexible
> PA 2200, Selective-Laser-Sintered (SLS)
> This is the strongest nylon material that we have and it has a good heat resistance. The most interesting is that you can use the material for living hinges and springs. SLS is not suitable for molding.
> Using the model in White, Strong and Flexible as a lost pattern will leave rests after burning. Be aware that this is a porous material, so it will absorb miniscule polution particles in the air. Please keep in mind that your object will turn yellowish when you put it in direct sunlight.
> 
> The design and thickness of your model will affect the flexibility of this material.
> _
> 
> I'll let you guys know if I follow trough.


The prints are in... Model changed a bit to create a smooth transition to my door panel, the model in an STL file:









And this came with UPS today:

















I'll try and mount them in the coming days/weekend.

My old tweeter mount (at that point still with Pioneer tweeter):


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## Bayboy

Pretty nice piece you got there. Make sure you do a before and after review if possible.

After reading through this and looking at a few tweeters to try this with I found it very easier to do with a few common tweeters @ partsexpress which also happen to be less expensive to play with. I say easier because of their relative size and mounting design (less flange and some already curved to flow into a roundover). Their size would also make the sphere or needed roundover less atrocious on the dash. What you think:

Dayton Audio ND16FA-6 5/8" Neodymium Dome Tweeter

Vifa OX20SC00-04 3/4" Fabric Dome Tweeter 

Dayton Audio ND20FA-6 3/4" Neodymium Dome Tweeter

Dayton ND20FB-4 Rear-Mount 3/4" Neodymium Dome Tweeter


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## derickveliz

This is how mine started with a pair of HAT L1v2... *My idea was to use the tweeters shape in junction with the sphere...*


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## 000zero

derickveliz said:


> This is how mine started with a pair of HAT L1v2... *My idea was to use the tweeters shape in junction with the sphere...*


I have these tweeters coming to me in the mail and your setup looks awesome. How did you make those enclosures?


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## Bayboy

Perfect example IMO Zero!!!


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## 000zero

Bayboy said:


> Perfect example IMO Zero!!!


Not sure if you think that was my setup, but I actually quoted derickveliz in that response. Don't want to steal anyones thunder..


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## derickveliz

000zero said:


> I have these tweeters coming to me in the mail and your setup looks awesome. How did you make those enclosures?


*Thanks, go to m*y BUILD and check thread # 8

.


----------



## Bayboy

000zero said:


> Not sure if you think that was my setup, but I actually quoted derickveliz in that response. Don't want to steal anyones thunder..




Oh?!!! You're about to go to jail.... copyright infringement! :laugh: Nahhh but I know whose it is. It is an perfect example of how the tweeter should flow out to the edge. Only way I see it could be better if there was an built-in horn like on some of the Dayton Neo tweets I linked which it may be. Can't see beneath the grill, but still great craftsmanship.


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## Hiace200

I buy this tweeter stand which is made by aluminum in Guangzhou, China at about $30-USD.

I will try it tomorrow !


----------



## Patrick Bateman

In the classifieds section there was a user who was selling a set of Sunfire home theater speakers. I haven't followed the work of Bob Carver very closely, but was pleasantly surprised to find that he's espousing a lot of the things that I've learned from Geddes, along with a few tricks that I came up with on my own.

When I get a moment I'll post the interview; the things that Bob says have a lot of relevance to this thread.










In a nutshell, Bob is selling a speaker which uses a diffraction reducing enclosure, along with a ribbon tweeter to control directivity. Bob put the woofers on the side of the enclosure because he realized that the orientation of woofers is basically meaningless at certain frequencies, but *time alignment* is extremely important.

In other words, you can get better polar response with the woofers on the SIDE of the enclosure, even though it looks a bit silly. This is because it aligns the radiators (tweeter and woofer) very very close together.

Bob is also using an insanely small enclosure, because it increases power handling and improves imaging. This is something that I've been encouraging for some time. I hate WinISD and it irritates me to no end that people are building huge boxes because WinISD tells them to. IMHO it's best to use a small sealed enclosure for our midbasses because it increases power handling. Which is exactly what Bob is doing.

I tried to build something similar to this about a year and a half ago, but came close to chopping my thumb off in the process. These enclosure are very difficult to fabricate due to their insanely small size. If only I had a CNC router...


----------



## SSSnake

I hope the iterview is much better than the marketing literature. This quote from the literature made me want to vomit...



> By bouncing sound off the walls and floors this introduces the room itself as part of the instrument of sound.


I had always thought that Geddes and most others were trying to control directivity to REDUCE the effects of the room on the sound. If Carver is going the other direction with this design (which the marketing hype indicates) I am VERY surprised.

The other thing about the marketing hype that bugs me is this:



> Sunfire created the category of small-box, high power subwoofers more than a decade ago with the original True Subwoofer. This design relies on high-pressure, High Back-emf technology which provides very high bass output from a very small box. When migrating this subwoofer technology into the midrange and high frequencies on the Cinema Ribbons, we find the same advantages: high output, small size, high efficiency, and low voice-coil heating.


While I admire the design and understand the motiviation for a small box (primarily WAF) these designs are NOT high efficiency and they do NOT reduce voice-coil heating as compared to other designs. Hoffman's iron law doesn't get broken very often . 

Again all of this may be marketing hype but I have a lot of respect for Carver and had hoped his marketing would reflect the science behind his concepts. Neither of the quoted sections seem to...


----------



## Patrick Bateman

SSSnake said:


> I hope the iterview is much better than the marketing literature. This quote from the literature made me want to vomit...
> 
> 
> 
> I had always thought that Geddes and most others were trying to control directivity to REDUCE the effects of the room on the sound. If Carver is going the other direction with this design (which the marketing hype indicates) I am VERY surprised.
> 
> The other thing about the marketing hype that bugs me is this:
> 
> 
> 
> While I admire the design and understand the motiviation for a small box (primarily WAF) these designs are NOT high efficiency and they do NOT reduce voice-coil heating as compared to other designs. Hoffman's iron law doesn't get broken very often .
> 
> Again all of this may be marketing hype but I have a lot of respect for Carver and had hoped his marketing would reflect the science behind his concepts. Neither of the quoted sections seem to...



I agree that Carver includes a healthy dose of hyperbole in his pitch. But he didn't say that the small box increases *efficiency*. He said that it increases power handling and reduces voice coil heat. This is true.

A very very small box controls excursion. I have some B&C eights in a box thats barely big enough to contain the frame, and the power handling is mind boggling, because excursion is so tightly controlled. Small boxes are the hot ticket for huge midbass power handling IMHO

The voice coil heat argument is a bit trickier. When you think about it, a very small box is prone to overheating, because there's so little air in the box. But the key is that *it's not ported.* At the tuning frequency of a ported enclosure, the impedance drops to it's lowest point, which means that the amplifier is absolutely dumping power into the woofer.

I think this is another reason that very small sealed enclosures can tackle such abusive amounts of power, particularly if the resonant frequency is in the passband. Here's an example of this:









Picture the typical car audio setup, with a set of 170mm woofers in the door. They have a resonant frequency of 40hz, and they are crossed over at 80hz. *The resonant frequency of the woofer is below the passband.* Due to this, the woofer has an impedance of four ohms at 80hz, and our amplifier is dumping two hundred watts into the woofer, creating voice coil heat.









Compare this to the Carver setup. The free air resonance of the woofer is 60hz. *Because it's in a very small box, the resonance is moved up to 95hz.* Because the resonance is in the passband, the impedance is just eight ohms at 120hz, *and our amplifer is dumping half the power into the woofer*.

Hopefully that makes sense. In a nutshell, the sealed box controls excursion, and pushing the resonance of the woofer up reduces the amount of power that is getting dumped into the woofer at the low end of it's passband.


*_My pics of the impedance are only for illustration. I didn't do any sims, I just posted the pics to show how the woofer's resonance moves up and down in the passband depending on the resonance, and how crossing over below the resonant frequency can increase your power handling if the excursion is kept under control._


----------



## Patrick Bateman

XtremeRevolution said:


> Its Hoffman's Iron LAW, not Hoffman's Iron theory.
> 
> With regard to increasing power handling, its also a load of ********. Yes you increase power handling due to controlling cone excursion, but you consequently reduce output at a greater rate than you increase power handling, which is counterproductive.


The efficiency will suck, but amplifiers are cheap. So we have a two step process for massive output from a small woofer:

Step 1: Put the woofer in a very very very very very small box. Taken to the extreme, you literally seal off the basket of the woofer. This is what I do in my Unity horns.
Step 2: Now that you have excursion controlled by the box, you have to deal with heat. This requires two things. First, the biggest voice coil you can fit onto the woofer. Second, the sealed box pushes up the impedance of the woofer at the low end of the passband, and that can reduce the amount of power going to the woofer by half or more. (IE, it doubles your output at the low end, right where we need it.)
























The woofer on the left is a 400GTI, which fits this design criteria nicely. Big ol' voice coil, lots of venting, and a small cone. That is a neodymium motor too! The biggest one I've ever seen on a midrange.


----------



## Patrick Bateman

XtremeRevolution said:


> *GOOD* amplifiers are not cheap. ****ty power is cheap. Class D automotive is cheap. Good, distortion-free power with excellent dynamics is not cheap.
> 
> As your power requirements go up, so does your distortion. You severely limit your sound quality with a small cabinet.


I'm not saying that distortion is completely irrelevant, but it's pretty easy to fix with a big voice coil and a small box.

Distortion goes up with *excursion*. Because of this, a 6.5" woofer in a car door, flopping around wildly because the door leaks like a sieve, can be outperformed by a 4" woofer with high power handling in a very very small box. The box controls excursion, and that's why it sounds cleaner.

*The key is keeping excursion under control.*



XtremeRevolution said:


> I understand this is the best you can do for car audio, but don't make it sound like its a great thing when its really only the best thing you can do with your requirements. When your requirement is small and compact, you do the best you can, but that's a requirement that should be stretched as much as possible.


Diffraction is a pretty big deal. That's why people in this thread are getting such excellent results with spheres.

*I believe that reducing diffraction is more important that reducing distortion.*

Small enclosures offer some big advantages in terms of diffraction. That's why the Carver design is exciting. Check out the reviews - people are raving about these. I think that has a lot to do with diffraction.


----------



## DS-21

XtremeRevolution said:


> "Controlling directivity" is synonymous to destroying your off axis listening.


Quite the opposite, in fact. Controlling directivity, perhaps counterintuitively, can be used to expand the "sweet spot" into a "sweet _zone._ 



XtremeRevolution said:


> Proper home theater and music listening speakers are designed as such that they can be heard without any changes at any listening angle.


So you're saying it's omni or nothing?

And sadly most speakers are designed with big flare-ups of energy in the midrange, due to the directivity mismatch between a midwoofer and a flush-mounted dome tweeter at the crossover frequency. They can lock in in a small spot, but everywhere else...ewww.



XtremeRevolution said:


> Tweeters are especially crucial to this effect due to the wavelengths of the frequencies they produce, hence the use of waveguides.


Um, waveguides control directivity...



XtremeRevolution said:


> *GOOD* amplifiers are not cheap. ****ty power is cheap. Class D automotive is cheap. Good, distortion-free power with excellent dynamics is not cheap.


Yes it is. And plenty of those "class D automotive" amps provide your "good, distortion-free power with excellent dynamics,."




XtremeRevolution said:


> With regard to 6.5" door drivers "flopping around," this is not something you would ever experience in home audio with the exception of an open baffle design.


Depending on levels required and highpass frequency, that's not true.



I design my speakers and the placement of the tweeters using the following baffle diffraction simulator. Feel free to play around with it some and you'll see not only a predicted baffle response, but also a suggested crossover network to flatten the response. 



XtremeRevolution said:


> "Controlling directivity" is synonymous to destroying your off axis listening.


Quite the opposite, in fact. Controlling directivity, perhaps counterintuitively, can be used to expand the "sweet spot" into a "sweet _zone._ 



XtremeRevolution said:


> Proper home theater and music listening speakers are designed as such that they can be heard without any changes at any listening angle.


So you're saying it's omni or nothing?

And sadly most speakers are designed with big flare-ups of energy in the midrange, due to the directivity mismatch between a midwoofer and a flush-mounted dome tweeter at the crossover frequency. They can lock in in a small spot, but everywhere else...ewww.



XtremeRevolution said:


> Tweeters are especially crucial to this effect due to the wavelengths of the frequencies they produce, hence the use of waveguides.


Um, waveguides control directivity...



XtremeRevolution said:


> *GOOD* amplifiers are not cheap. ****ty power is cheap. Class D automotive is cheap. Good, distortion-free power with excellent dynamics is not cheap.


Yes it is. And plenty of those "class D automotive" amps provide your "good, distortion-free power with excellent dynamics,."




XtremeRevolution said:


> See my current project for an example:
> Statements_Monitor


I recently heard the adult-sized version of that speaker. For what it is, it's fine. But trust me, compared to the stuff PB uses daily (GedLee Summas)...well, it's barely a toy. I would go so far as to say that the gap between the little Carver things and Statements is minute compared to the gap between Statements and big controlled directivity mains.


----------



## Patrick Bateman

XtremeRevolution said:


> Perhaps I misrepresented the word directivity. What I meant to say was I had heard very directional speakers. Given the way you chose to use the word, it is obvious that waveguides serve a purpose, but I'd rather say they enhance directivity. Regardless, its irrelevant.
> 
> Commonly available class D amps are inferior in regard to sq to class A and class AB amps. Class d architecture has been around for years but only recently has it started to reach fidelity levels that can be used in home theater. Don't you think there's a reason stereo car amps are not designed on a class D architecture? Also consider the testing methods used to test class AB amps cannot validly test class D amps. More on that if you're interested. Again, this was a side point, and is insignificant in comparison to the main points I made. How about you address those.
> 
> You telling me the little carver things are nearly the same as the statements tells me your completely full of **** and that you haven't heard the statements. The statements are a transmission line midrange design to eliminate midrange cabinet coloration and create a much wider sound stage using the rear opening reflection, with an extremely flat frequency response and amazing low frequency extension/impact. They rival line arrays 10x their cost in parts. Re-read hoffmans iron law till it sinks in. To also call them barely a toy is insulting at best. I know money doesn't buy performance but to spend $800+ on components alone and have you call them a toy is a real stretch. They also need to be used in the correct room size and with a capable amplifier.
> 
> Tell me real quick what speakers have you built or designed that gives you such an authority to trash talk the design of real engineers?
> 
> 
> Sent from my HTC Awesome using Tapatalk


----------



## DS-21

XtremeRevolution said:


> Perhaps I misrepresented the word directivity.


By "misrepresented" you mean "don't understand," I presume. 



XtremeRevolution said:


> Commonly available class D amps are inferior in regard to sq to class A and class AB amps.


As soon as I see idiot spew like that, I know I'm not dealing with someone who knows what s/he's talking about. Show me a _single_ controlled listening test that supports your idiot assertion!



XtremeRevolution said:


> You telling me the little carver things are nearly the same as the statements tells me your completely full of **** and that you haven't heard the statements.


It appears you read about as well as you think you can hear. I didn't write that. What I wrote is that the _difference_ between the Carver jewelboxes and Statements is _less than the difference_ between the Statements and GedLee Summas. Since you seem big on cost comparisons, for reference, just the driver complement in a single of Summas is more than the driver complement in a pair of Statements.



XtremeRevolution said:


> The statements are a transmission line midrange design to eliminate midrange cabinet coloration and create a much wider sound stage using the rear opening reflection, with an extremely flat frequency response and amazing low frequency extension/impact. They rival line arrays 10x their cost in parts.


Cockamamie midrange tunnel aside (if it has any effect, it is merely to slightly smear the midrange - again I've heard them and you appear not to have, given that you claim to be in the "project" process) it appears that you have consumed gallons of the Kool-Aid. Enjoy your project, but you'd be wise to avoid attacking people like PB who have forgotten more than you or I together have figured out. (And done more crazy/interesting projects than most of the rest of the audio internet community combined.) It's pretty clear from your posts that you don't understand what he's writing about, anyway. (Or what I'm writing about.)



XtremeRevolution said:


> Tell me real quick what speakers have you built or designed that gives you such an authority to trash talk the design of real engineers?


Well, I "designed" an ultra-low diffraction (>2" roundovers on the top and bottom, rounded front corners, and 2" roundovers on the sides wrapping around in a continuous curve to the back of the cabinet) sealed cabinet for my Tannoy System 12 DMT II's, and in my youth (before I learned that others do it better than I can) I probably designed and built a new pair of mains every 6-7 months.


----------



## bassfromspace

XtremeRevolution said:


> I expected as much from you. I'm not one to leave an argument but I have no desire to argue anything with someone who resorts to personal attacks to make a point and can't even stick to the topic at hand. I'm out of here. You apparently have all the knowledge and expertise to figure everything out. Class D automotive amps are better than class AB in every concievable way, my understanding of the word directivity determines my intelligence, and because I support hoffmans law, I must be an idiot by the same regard. Surely everyone is wrong and the only way to perfect baffle diffraction is to use a sphere. Man have we all been fooled.
> 
> I understand what he's writing about, and I also have enough understanding in speaker design to know what the flaws are. What threw me off was one of the earlier posts where he compared the baffle diffraction of a sphere to that of a squared centered baffle. No mention of filters, crossovers, or baffle placement.
> 
> Surely I'm the one drinking the coolaid. I'm clearly mistaken. Let's all replace all of our speakers with spheres on sticks that we have to mortgage our houses to buy, and try to squeeze some midbass out of thin air since they're clearly superior. Forget cabinet volume, its irrelevant. Every designer in the past 100 years is wrong. Forget efficiency, its pointless. Hell, let's just go down to 80db efficiency and push 1000w through them with automotive monoblocks instead. Yeah, my alpine mrp-m1000 would be great for powering a floorstanding speaker. Oh yeah, and the guys over at denon, yamaha, pioneer, onkyo, and everyone else who sells receivers of any kind are stupid. What are they thinking, class D is so much better. Silly idiots, they should know better. If we don't have excursion, we won't have to worry about distortion. Let's just make 6.5 comps with 5" voice coils and neo magnets to handle the power. Forget frequency response, who needs to hear 90-300hz anyway. Has a response chart of these speakers' design performance even been posted yet?
> 
> Sent from my HTC Awesome using Tapatalk


Stop while you're ahead.


----------



## DS-21

XtremeRevolution said:


> Class D automotive amps are better than class AB in every concievable way,


To be clear, nobody wrote that. What was written, and what is _true,_ is that nobody has ever shown that there is a sonic difference between a good class AB and good class D amp in a controlled listening evaluation. 



XtremeRevolution said:


> my understanding of the word directivity determines my intelligence,


Again, learn to read. Nobody has written what you claim they have. That said, your willingness to throw around technical-sounding words without understanding what they mean, followed by getting extremely defensive about it...those things together do allow reasonable people to draw some legitimate inferences about your ability to communicate in written English. Some, rightly or wrongly, consider that a reasonable proxy for intelligence.



XtremeRevolution said:


> and because I support hoffmans law,


Please point out where anyone said anything tending to negate HIL.

How about you define HIL, for that matter. I suspect you don't quite know what that term means (either).



XtremeRevolution said:


> Surely everyone is wrong


One should never discount that possibility entirely... 



XtremeRevolution said:


> and the only way to perfect baffle diffraction is to use a sphere.


Funny, considering you're replying to me. Where did I once mention a sphere? I take it geometry wasn't your best subject in middle school. 



XtremeRevolution said:


> Oh yeah, and the guys over at denon, yamaha, pioneer, onkyo, and everyone else who sells receivers of any kind are stupid. What are they thinking, class D is so much better. Silly idiots, they should know better.


Why don't you think before you write? It's kind of an important exercise, if one wishes to avoid looking like a fool.

Let's look at Pioneer's flagship receiver.
What kind of amplification does it use? HINT: ICEpower = Class D. 

I suspect within five years the others will follow suit as well. Especially if oil stays so high. The cost advantages of smaller, lighter amps (coupled with the utter lack of sonic penalty - note that I'm not saying one is _superior_, only that good implementations of either are _sonically indistinguishable from one another;_ that is not a subtle distinction) when dealing with container shiploads of the things is simply too compelling over the long term.



XtremeRevolution said:


> If we don't have excursion, we won't have to worry about distortion. Let's just make 6.5 comps with 5" voice coils and neo magnets to handle the power.


You're missing kind of an important piece in the whole puzzle. Actually several, but I'll let you go back through and figure it out, if you can.


----------



## s4turn

anyone tried these for enclosures?

NEW Pyle Motorcycle Complete Stereo AMP/Speaker System | eBay

Im sure theres cheaper and smaller versions


----------



## 94VG30DE

XtremeRevolution said:


> With regard to "Bob's" insanely small enclosure, I would LOVE to see a frequency response chart. Someone with such "revolutionary" designs must clearly have the data to back up his claims. By that regard, so should the OP. This thread is 1.5 years old yet I haven't yet seen a frequency response chart.


That's b/c the F/R plots of the compact midbass aren't in this thread, b/c this thread wasn't intended to cover that. Somewhere it got derailed. 

A lot of the discussion you are looking for can be found here: 
http://www.diymobileaudio.com/forum...anced/71993-unity-v-midbass-strikes-back.html 
and maybe here: 
http://www.diymobileaudio.com/forum...ed/69727-project-gnib-grand-national-box.html 
and maybe here: 
http://www.diymobileaudio.com/forum...08-midranges-midbasses-sub-optimum-boxes.html


----------



## Hiace200

Further report for post #374

I put the tweeter into the aluminum stand and placed it on the dash. 

The sound becomes smoother, no harsh even when I played music of chinese traditional musical instrument , and the music somelike melt in the air. Thanks Mr Bateman !


----------



## mathman

Patrick Bateman said:


> The efficiency will suck, but amplifiers are cheap. So we have a two step process for massive output from a small woofer:
> 
> Step 1: Put the woofer in a very very very very very small box. Taken to the extreme, you literally seal off the basket of the woofer. This is what I do in my Unity horns.
> Step 2: Now that you have excursion controlled by the box, you have to deal with heat. This requires two things. First, the biggest voice coil you can fit onto the woofer. Second, the sealed box pushes up the impedance of the woofer at the low end of the passband, and that can reduce the amount of power going to the woofer by half or more. (IE, it doubles your output at the low end, right where we need it.)


Is this better than just using a high-pass crossover? Wouldn't that reduce power and excursion? Or, are you doing this in part for packaging concerns? I feel like I'm missing something here.

BTW, thanks for your contributions. I'm about halfway through reading pretty much everything at your forum, and it's fantastic!


----------



## Patrick Bateman

s4turn said:


> anyone tried these for enclosures?
> 
> NEW Pyle Motorcycle Complete Stereo AMP/Speaker System | eBay
> 
> Im sure theres cheaper and smaller versions


I should get these for my bike 

I've been hit by one car too many, so I refuse to ride with headphones, and Parts Express sells a $20 battery powered amp that would work nicely with something like this.


----------



## Patrick Bateman

XtremeRevolution said:


> My replies are in red.
> How about you answer questions since you've proven incapable of addressing points I've made with any resemblance of decency.
> 
> 1. how do you produce midbass if your goal is to limit excursion, and how do you increase output while limiting excursion? After all, the whole idea here is to make a very small enclosure because of the notion of "a 6.5 comp flapping around in a door" is somehow bad. So say we take that 6.5 and stuff it in a .05 cubic foot pillar pod and we limit its excursion. How then do we get a usable frequency response from 90-200hz? Keep in mind, it was stated that excursion produces distortion, so keeping excursion down is of paramount importance.
> 
> 2. once you've explained the above, explain what the frequency response will look like without any equalization. I have yet to see a frequency response chart of
> 
> This post is also what I've been responding to:
> 
> 
> I claimed that even though you increase power handling in a smaller enclosure, you exponentially decrease your output. You can go as far as to make said driver a sealed back driver in a very small box (which if our point is to control excursion should have been thought of by more companies than Goldwood) and I am claiming that by doing so, you are causing massive problems in the 90hz-200hz range. You *REQUIRE* excursion for low frequency extension. By nature of every loudspeaker designed in the last 50 years, you cannot hit the lower registers without excursion. The above quoted post claims to defy Hoffman's law, that you can simply put the drivers in an extremely small enclosure and pump more power into them to get the same output. What the above poster doesn't realize is that you have now created an output ceiling, and for every decrease in enclosure size, you're reducing that ceiling. If we could all get all the bass extension we ever could out of a sub box that barely fits our subs, don't you think we'd all have done it by now? Just build massive subs with 10" voice coils to handle the heat and put them in insignificantly tiny boxes. You can stretch, but you cannot defy Hoffman's Iron Law.


This discussion is a bit off-topic - the main reason I posted the Carver solution is that Carver addressed one of the problems with the spherical tweeters. Which is that they don't play low. By putting the tweeter on one face, and the woofer on the other, you get a full range solution.

As far as Hoffman's Iron Law goes, I've admitted that the efficiency of the Carver solution will be atrocious. I wouldn't be surprised if it's in the low 80s. *The thing is, efficiency is completely overrated.* I have seven hundred watts for each channel. Power is cheap.


















I haven't heard the Sunfire speakers. I *have* heard the Gallo speakers, and the dimunitive speakers from Sony. The Gallos sound shockingly good, particularly since they use a Tang Band woofer that costs ten bucks. The Sony speakers sound "thin", but they image like crazy.

*And that's what I'm getting at in this thread.*

This thread isn't about deliver chest thumping bass. This thread is about imaging, and speakers that sound smooth as silk. The Gallos in particular fit that bill. Is there distortion? You betcha. Is it offensive? No, I don't think it is. It took me a few years to wrap my brain around the idea that distortion isn't the worst thing in the world. Diffraction is a bigger problem than distortion IMHO.

















*Not to get off-topic, but I think that car audio has been stuck in the nineties for far too long.* Look at all these threads where people obsess over amplifiers that haven't been in production for twenty years. C'mon people, it's 2011. Look around - small speakers are the norm today. You don't have to run 6.5" woofers up front, there are small woofers that can do the job better. Look at how speakers have evolved in the last twenty years! Your home speakers are getting smaller every single year - why are your car speakers still hyoooge? Efficiency and size are linked (Hoffman's Law), but power is cheap. That's why home speakers are so tiny now.



XtremeRevolution said:


> This above is something neither you nor the OP has addressed. You will be fine right down to about 500hz, maybe even down to 250 or if you're lucky, even 200, but go down from there to 90hz and you will start having serious problems trying to reproduce linear sound. THIS is why people use WinISD to create massive enclosures for their subs and speakers; because even if you don't need very low frequency extension, you *still* need to be able to play the frequencies your sub cannot, and that will still require you to hit at least 100hz. Many people who build large enclosures to get low frequency extension don't plan on running a sub. Take the speakers I built for my father in law for his birthday based on the Dayton ND105. Very high excursion, and .55 net cubic feet per floor standing speaker that is tuned to 38hz and produces an F3 of 39hz and can play musically down to 32hz. You take that exact same cabinet, shrink it to .2 cubic feet (or smaller if you can accomodate the drivers), make it sealed, pump a lot of power into those drivers, and tell me where the hell my low end extension is going to be.


The problem with WinISD is that it encourages people to treat car audio as if we're working in an anechoic chamber. Cabin gain is very real.

For instance, Sundown Audio has been able to generate something like 140dB with a single eight. 140db!!!!!! Plug those numbers into WinISD and it will tell you that the woofer is good for 110dB.

Cabin gain gives us a TON of headroom. Besides making it trivially easy to make bass below 160hz, the car's cabin also reduces excursion, which is how the SPL guys are able to keep their woofers from exploding. (well, MOST of the time.)



XtremeRevolution said:


> My claim is that if you put your 6.5 comps in pillar pods and reduce your volume to insignificantly low levels in an effort to control excursion, you will have a non-linear response that will drop off sharply the moment you need to reproduce frequencies that require any level of reasonable excursion. At that point, what would have been a 2-way system now becomes a 3-way system because you still need another driver to produce lower frequencies. You otherwise have a gigantic frequency gap between the sub's higher limits and the 6.5 driver's lower limits, and no reasonable amount of equalization will fix it.
> 
> Furthermore, you have absolutely no need for a small enclosure "to increase power handling" if you're crossed high enough to where you're not producing any excursion anyway. Why not limit excursion with a higher frequency point instead? Its essentially the exact same thing.
> 
> To produce low midbass frequencies, you need either cone area or excursion. You can only fit so large of a speaker in a pillar pod, and you're limiting excursion, so therefore, you will sacrifice low midbass response.
> 
> With regard to "Bob's" insanely small enclosure, I would LOVE to see a frequency response chart. Someone with such "revolutionary" designs must clearly have the data to back up his claims. By that regard, so should the OP. This thread is 1.5 years old yet I haven't yet seen a frequency response chart.


Now you're just trolling, you KNOW that spheres have flatter response than rectangular enclosures. You've used The Edge, you know that flat faced enclosures suffer from peaks and dips in the frequency response.

Roundovers and spheres don't just make the speaker SOUND smoother, they MEASURE smoother too.


----------



## Genxx

*I have attempted to run a set of 6.5 comps off of my monoblock just for ****s and giggles and I didn't like what I heard.*

WTF^^^^

99% of all mono blocks are designed for sub duty and designed with a narrow band width for this use. As smart as you claim to be you should know this. Gee wonder why it sounded like crap.

There are many manufactures that were known for class A/B amps know swithcing to full range class D in the last 3-5 years in car audio, if you have not noticed.


----------



## el_chupo_

Genxx said:


> *I have attempted to run a set of 6.5 comps off of my monoblock just for ****s and giggles and I didn't like what I heard.*
> 
> WTF^^^^
> 
> 99% of all mono blocks are designed for sub duty and designed with a narrow band width for this use. As smart as you claim to be you should know this. Gee wonder why it sounded like crap.
> 
> There are many manufactures that were known for class A/B amps know swithcing to full range class D in the last 3-5 years in car audio, if you have not noticed.


From the owners manual of the MRP-M1000 amp:
Frequency Response (200Hz/ -3dB) ....... 20 - 200 Hz


This is why it sucked.

Anywho, interesting discussion...


----------



## 94VG30DE

XtremeRevolution said:


> I do know this. The problem is that there aren't very many Class D amps out there for stereo use in cars. Most class D amps are designed for sub duty. I pointed this out to state the obvious. They are not exactly readily available.


We seem to be reaching some consensus here on a few items, but I am not sure why you still seem to think full range Class D is sparse in mobile audio. Off the top of my head, JL, Infinity, Arc, Sony, Kenwood, and Alpine all make full-range class D. These are not small companies with limited distribution.


----------



## t3sn4f2

XtremeRevolution said:


> *GOOD* amplifiers are not cheap. ****ty power is cheap.



View attachment 20062


----------



## Genxx

It actually easier to name the Car Audio companies that don't have full range class D then it is to name all the one's that do.


----------



## Patrick Bateman

mathman said:


> Is this better than just using a high-pass crossover? Wouldn't that reduce power and excursion? Or, are you doing this in part for packaging concerns? I feel like I'm missing something here.
> 
> BTW, thanks for your contributions. I'm about halfway through reading pretty much everything at your forum, and it's fantastic!


Without a doubt, the main reason that I am a fan of very small sealed enclosures is that it gives you the flexibility to put speakers in weird locations. When I got started in audio in the 90s a 5" woofer was considered "small."

Nowadays you can belt out 110dB with a pair of 3" woofers. That was just impossible back then.

To illustrate how LOUD a small enclosure can get, I've posted some sims in my forum for you guys:

Audio Psychosis • View topic - Ultra Small Midranges










This enclosure is the exact same width as a compact disc, and a pair will do 110dB.

Best of all, small enclosures allow you to create a really strong image in a car. It is very very difficult to create a good image when you're using large woofers with a tweeter that's nowhere close to the woofer.


----------



## Patrick Bateman

XtremeRevolution said:


> Those were the FR charts I wanted to see. You've confirmed my suspicions but impressed me at the same time. I would definitely say you'd need a midbass to play these well, along with a sub. A 4 way system it would appear (if you include the sub as being one). More complexity for better imaging and smoothness. I presume this is all run with active crossovers?


Now *thats* a controversial question!

Here's why -

Most people in car audio have a setup that looks like this:

tweeter covering three and a half octaves, from 2khz to 20khz
midbass covering four and a half octaves from 80hz to 2khz
subwoofer covering two octaves from 20hz to 80hz

With these ultra-small midranges, I'd be looking at something like this:

tweeter covering two octaves from five to 20khz (By using a very high xover point, we move the transition to an octave where it's difficult to detect. (Because we don't hear well at high frequencies.) Reducing the bandwidth of the tweeter also allows us to use very high efficiency options, such as ribbons. A high xover point increases power handling and reduces distortion too.
midrange covering five octave from 160hz to 5khz (this is very important - by covering such a wide range we're hearing most of our imaging cues from one set of drivers. It's almost like a full range system. The idea is to eliminate that godawful xover transition in the midrange.)
subwoofer covering two octaves 40hz to 160hz
ULF subwoofer covering three octaves from 10hz to 80hz (optional)

I would say that this is a very unorthodox set of xover points. Particularly the idea of running your subs up to 160hz.

The reason that the subs are overlapped is because we have a catch-22 here. If we cross over at 160hz, we're going to need to locate our subs carefully so that the imaging doesn't go to hell. *But if we want to get to 20hz, we're going to need a big woofer with lots of displacement.* So it's a catch-22.

Overlapping the subs solves the "catch-22." A pair of small subs gives you the flexibility to locate the upper subs where they won't ruin your image. And the ultra-low-frequency sub raises our output from 40 to 80hz, and forms a low end that reaches to 10hz.

Note that this setup won't work at home; the ULF depends on cabin gain. At 20hz we're getting about 24dB for free, from cabin gain.


----------



## DS-21

XtremeRevolution said:


> So tell me right quick why in both automotive and home environments, most stereo amplifiers in the past 30 years have Class A or Class AB and not Class D,


Past _three decades,_ huh? May as well ask me why most stereo amplifiers sold 50 years ago have been tube and not solid state....

Technology moves on. What may not have been viable in 1985 for reasons of chip development, cost, scale of production, etc., is very much viable in 2011. 



XtremeRevolution said:


> and why the bulk of the market sells Class D amplifiers as monoblocks for powering subwoofers. You've been implying that there's clearly no reason for that.


You really shouldn't be trying to read into words when you can't properly interpret the plain meaning of the words in front of you to start with!

But if you want a reason, here's one: the industry is very conservative. Here's an old thread you may find interesting. Affordable Full-Range Class-D (Switching) Amps - CARSOUND.COM Forum

Read that thread, and note that Harman now has full-range Class D amps in both the Infinity and JBL lines. I don't necessarily expect you to be able to infer why I'm asking you to make that note...



XtremeRevolution said:


> Now, do keep in mind I'm also in the process of building my own Class D amp for stereo use, after having fiddled with a cheap Tripath amp for a while, so I'm not discounting the use of class D in all occasions, but I have attempted to run a set of 6.5 comps off of my monoblock just for ****s and giggles and I didn't like what I heard.


So, as others have written, you think class D amps are bad because...you didn't like what you heard when you ran a set of mains speakers off of a subwoofer monoblock? 

Wow, just wow. 

I bet a Class AB amp with a steep filter at 200Hz would sound like **** driving those speakers, t



XtremeRevolution said:


> Nobody had written that [your understanding of the word directivity determines my intelligence,]
> ? Sure could have fooled me.


Not "could have." Did. Let's be precise with our language, OK? Though precision would compel one to say that nobody fooled you, except yourself and your puzzling inability to digest the text in front of you in a manner consistent with the standard conventions of the English language.

That said, why are you so willing to throw around terms in a combative way (see, e.g., directivity; see also HIL) when you make it clear in your commentary that you don't understand them?



XtremeRevolution said:


> I don't know what the acronym stands for.


Wow, really? Let's rehash the exchange:

"XtremeRevolution:" and because I support hoffmans law,
"DS-21": Please point out where anyone said anything tending to negate HIL.
"XtremeRevolution:" I don't know what the acronym stands for. 

Now, if you had dinged me for that clumsy "tending to negate" instead of a more clear "contrary to" or something like that, I would understand. But I'm sorry, it's not unreasonable to expect someone to figure out how to expand an unfamiliar acronym by just _looking at the context._


Why don't you think before you write? It's kind of an important exercise, if one wishes to avoid looking like a fool.



XtremeRevolution said:


> You really think I'm that much of an idiot? It is their flagship receiver.


Again, let's limit the scope of the inquiry to the actual words used, OK? 

XR: Oh yeah, and the guys over at denon, yamaha, pioneer, onkyo, and everyone else who sells receivers of any kind are stupid. What are they thinking, class D is so much better. Silly idiots, they should know better.
DS: Let's look at Pioneer's flagship receiver.
XR: See supra.

A reasonable person can certain infer that a company does not think a technology is inferior if they use it on their flagship product, no?

And while I didn't dig deeper at the time, it appears that they offer other receivers with Class D amps as well. And in the past they've offered very cheap ones. I know because years ago I bought one of them.



XtremeRevolution said:


> Considering Class D amplification should cheaper, you should question why it didn't start in the low end.


Well, ignoring your baseless assertion "should be cheaper," the fact of the matter is, it has been in the low end for some time. In fall of 2005, I bought a Panasonic receiver with all of the surround-decoding codecs at the time and a novel ampilfier technology that combines DAC and amp by converting directly from PCM stream to PWM. Tests at the time showed it to have about 80W/ch into 8Ω, I think with 5 of the 7 channels driven though it could have been all 7. (It was >2 channels driven.) It cost me well under $300 new on amazon at the time.

(Why baseless? These things require new parts, often have IP licensing involved, and so on. So _over the long term_ they may end up considerably cheaper, in the short term that does not by any means have to be the case.)



XtremeRevolution said:


> I also specifically stated, commonly available class D amps.


Odd scope shift on your part, because if one can show something is in stock at Crutchfield or Vann's or Amazon it can reasonably be considered "commonly available." This receiver clearly meets that test.



XtremeRevolution said:


> Pioneer's flagship receiver that costs someone both their arms and legs is not a commonly available Class D. How's about we take a $350 class AB receiver and find a Class D receiver to compare it with. After all, the claim was power is very cheap. $2,200 for a receiver is not cheap unless you're made of money, which I'm not.


Let's just say you're obviously not aware of current trends in 120V amplification, just as you are not aware of current trends in 12V amplification. While admittedly they are standalone amps rather than AVR's, Crown, Peavey, Behringer, Crest, and many others offer scads of dirt-cheap power today. For example, a third-party test of Peavey's IPR-1600, which costs just $300, showed it to make 280W/ch into 8Ω and 550W/ch into 4Ω. Peavey IPR-1600 Amplifier Test Results :: ABELtronics. 

Can anyone reasonably say that $0.55/W into 8Ω, or $0.30/W into 4Ω, isn't "cheap?"



XtremeRevolution said:


> Yes, you can get an assembled amp Class D board from a number of websites (sure being one of them) that will deliver in excess of 100W RMS for dirt cheap, but once again, that's not a commonly available amp.


If you are going to attempt written communication, it helps to be clear with your word choice. "Commonly available" is a term with a defined meaning. "Commonly" means: as a rule; frequently; usually. "Available" means "obtainable or accessible and ready for use or service." 

Thus, anything regularly stocked by a major national or regional vender (Amazon, Parts Express, etc.) and made available by them for purchase can be reasonably be labeled "commonly available."

*WORDS MEAN THINGS.*



XtremeRevolution said:


> I also know that properly designed Class D amps have extremely high fidelity. Tripath proved that it is possible and that it rivals the sound of tube amps, but that wasn't up until a few years ago. These aren't yet mainstream.


Tripath chip amps were in Apple iMacs seven years ago! How much more effing "mainstream" do you want?

And you seem unduly smitten with audiophool idiot-ese, such as "rivals the sound of tube amps" or "sounds as good as something n times the price." Those are phrases that mean nothing.



XtremeRevolution said:


> 1. how do you produce midbass if your goal is to limit excursion, and how do you increase output while limiting excursion?


Multiple drivers.



XtremeRevolution said:


> 2. once you've explained the above, explain what the frequency response will look like without any equalization.


Who cares? We have sophisticated, pocket-sized EQ at our fingertips. This is 2011, not 1985.



XtremeRevolution said:


> You *REQUIRE* excursion for low frequency extension.


No, you don't. You can get LF extension with EQ. 

But if you want LF extension at meaningful SPL, you need _volume displacement,_ not excursion. Volume displacement can be achieved with longer throw, or with greater radiating area, or any combination thereof. One can achieve greater radiating area with big drivers, or multiple small ones. In most cars, I would wager that fitting multiple smaller drivers is stealthier, easier, and (because you also get the benefit of "room mode" randomization) better-sounding.

That doesn't necessarily hold for cars like my daily driver, which is a small convertible. In such a car, one needs as many big drivers as will fit.



XtremeRevolution said:


> The above quoted post claims to defy Hoffman's law, that you can simply put the drivers in an extremely small enclosure and pump more power into them to get the same output.


Actually, all you're showing here is that you don't understand HIL. To paraphrase: HIL is the following: you can only have two of the following three things: small cabinet volume, LF extension, and efficiency. 

A tradeoff of small volume + LF extension + inefficiency mitigated by application of massive power falls entirely within HIL. 



XtremeRevolution said:


> If we could all get all the bass extension we ever could out of a sub box that barely fits our subs,


We can. Some people do. Heat management just becomes more important at that point.



XtremeRevolution said:


> you *still* need to be able to play the frequencies your sub cannot, and that will still require you to hit at least 100hz.


Then get a sub that can play higher. There's no reason to limit subwoofer highpass frequencies so. Localization in a car is mostly caused by rattles, and the only way not to excite them is to tame them. That's why even cars with subs at your feet can exhibit "bass in the back."

It's trivial today to find a subwoofer driver with an 18" cone, ~20mm xmax, AND inductance low enough to play up to 700-800Hz. (Aura makes a bunch of 'em.) At home, I run 150Hz (admittedly, with mains also run full-range, and the subwoofer drivers are all clean to around 1kHz) and there's no localization issues. Maybe there would be with a corner sub, but not with a well-implemented multisub system and, again, the mains also playing the bass. Overlapping is your friend.



XtremeRevolution said:


> I shudder at the thought of Sony and Kenwood amps, but especially Sony. I run Kenwood amps in my car and that's only because I didn't know any better when I bought them and I haven't gotten around to replacing them. I run two kac-7203 class AB two channel amps.


Kenwood's class D amps are the real deal: high power, compact, and clean. Here is an independent third party test of the 4-channel: Kenwood Excelon XR-4S Reference Fit Amp Review - Amplifier Reviews - Car Audio and Electronics


----------



## DS-21

XtremeRevolution said:


> There was a big discussion on this on techtalk.PE and a general consensus was that power on reserve in a larger amplifier than is needed is often a good thing as it has the capability of playing with a much better dynamic range and avoids the risk of clipping and/or distortion at higher volumes as a result of dynamic peaks.


Hmm, I wonder who wrote that "general consensus." IIRC, the phrasing went something along the lines of, 

"The reason bigger amps often sound better is that they have more headroom to avoid clipping on peaks. There's no point delving into minutiae when that simple and obvious statement explains so much of the observed variance in controlled conditions. (The rest is generally noise floor.)"



XtremeRevolution said:


> Here's a nice article that some people may enjoy reading as well:
> Why Class D Amplifiers May Test Well But Often Sound Terrible


Since you were willing to accept my take on why higher power is generally better, you should also read my thoughts on that vacuous, pointless article and take them to heart.


----------



## ChrisB

DS-21 said:


> Since you were willing to accept my take on why higher power is generally better, you should also read my thoughts on that vacuous, pointless article and take them to heart.


Not to mention, that article was written in 2005. A lot has changed since then regarding the technology associated with full range class d amplifiers. I'd be willing to bet that Xtreme couldn't pass your amplifier challenge, or mine for that matter.

Also, why is there so much bickering about amplifier topology in an "improve your soundstage" thread? Amplifier topology has NOTHING to do with the soundstage.


----------



## bloobb

i dont know if anyone else had a harshness issue from tweets in their face on their dash? my solutuon; i took my styrofoam balls and faced the tweeters directly into corner of the glass and dashboard, facing 180 degrees off axis.

better then seeing titties for the first time. amazing smoothness and imaging to my ears. no more harshness off "s" sounds from vocals either.


----------



## Hiace200

ChrisB said:


> ............Also, why is there so much bickering about amplifier topology in an "improve your soundstage" thread? Amplifier topology has NOTHING to do with the soundstage.


A Clown apppeared !


----------



## 000zero

bloobb said:


> i dont know if anyone else had a harshness issue from tweets in their face on their dash? my solutuon; i took my styrofoam balls and faced the tweeters directly into corner of the glass and dashboard, facing 180 degrees off axis.
> 
> better then seeing titties for the first time. amazing smoothness and imaging to my ears. no more harshness off "s" sounds from vocals either.


What kind of tweeters do you have?


----------



## bloobb

000zero said:


> What kind of tweeters do you have?


jl c5-650 component set tweets. 1" soft dome silk. ill run a quick rta as I havent finalized the install. (read, electrical tape holding the balls in place lol). they sit in a 95 integra which has an awefully slanted windshield also. I suspect i killed early reflections and diffraction.

and p.s. this tweeter in balls thing was a freakin awesome idea and this is the first time i've ever had decent imaging separating my tweets from the woofer more then 8". thanks patrick bateman


----------



## keep_hope_alive

bikinpunk said:


> I still have yet to really understand the purpose of this. The biggest advantage I'm seeing here is that most people are now using them on axis.
> So, that alone - going from off-axis to on-axis - would likely be a huge improvement.
> Who has gone from on-axis w/o sphere mount to sphere mount, same firing angle?
> 
> To me, the issue is that the flange itself dictates the baffle step/diffraction fo when not mounted to a baffle which is typically how you could think of most car audio installs being on the dash), matching the same diameter sphere to the flange diameter doesn't seem to be beneficial to me.
> 
> I'd like to see measurements on this. Heck, if someone can take the time to send me a tweeter with and without the sphere (and maybe of different size spheres) I'll be happy to measure the response so we can get a clear understanding of how the sphere size vs tweeter/midrange flange size affects response. For diffraction to be minimized you'll have to at least use a sphere larger than the flange size of the driver used. Otherwise you're at the mercy of the driver's flange.
> If I'm wrong on this, please let me know. I'm just not seeing how there's any true gain with a sphere the same size of the tweeter/mid flange and I'm banking that the noticeable gain in response is mostly due to those who had tweeters firing across the dash, now firing on axis (and thus reducing comb filtering issues).
> 
> I dunno... my random $.02.


What you are asking for is in the LDC. I totally agree with you that it is not a fair comparison when the location and aiming changes. The LDC does baffle comparisons just as you or I would.


----------



## ErinH

Don't recall seeing it. Will have to check again. Thanks for the heads up.


----------



## keep_hope_alive

bikinpunk said:


> Don't recall seeing it. Will have to check again. Thanks for the heads up.


In The 7th Edition you will find exactly what you want. Granted, the "up to" 8th order diffraction is simulated, but he references actual tests done as well with both tweeters and full range drivers.


----------



## Wesayso

*3D Printing to make balls *



Wesayso said:


> The prints are in... Model changed a bit to create a smooth transition to my door panel, the model in an STL file:





















More here...


----------



## t3sn4f2

bloobb said:


> i dont know if anyone else had a harshness issue from tweets in their face on their dash? my solutuon; i took my styrofoam balls and faced the tweeters directly into corner of the glass and dashboard, facing 180 degrees off axis.
> 
> better then seeing titties for the first time. amazing smoothness and imaging to my ears. no more harshness off "s" sounds from vocals either.


I suggest looking for other solutions for that single problem, that don't compromises other performance aspects.


----------



## Bayboy

bloobb said:


> i dont know if anyone else had a harshness issue from tweets in their face on their dash? my solutuon; i took my styrofoam balls and faced the tweeters directly into corner of the glass and dashboard, facing 180 degrees off axis.
> 
> better then seeing titties for the first time. amazing smoothness and imaging to my ears. no more harshness off "s" sounds from vocals either.



Did you try them back on axis with the spheres before going off axis? If so, how much difference? Did the spheres necessitate going off axis or did all the techniques applied (sphere, placement)? Any processing used or changed after the reinstall?


----------



## bloobb

Bayboy said:


> Did you try them back on axis with the spheres before going off axis? If so, how much difference? Did the spheres necessitate going off axis or did all the techniques applied (sphere, placement)? Any processing used or changed after the reinstall?


tl:dr unless bored lol. observations ensue

I sat in the car last night and turned the rta on for some ball turning fun. my dsp was set to pass through. The off axis response had nothing to do with the balls. The balls simply made the tweets more transparent all around. I never did like them on the dash, however this balll concept smoothed my dislikes. I think when the tweets are facing me and tucked into the corner it was bouncing stuff off my windshield bad. 

yea frankly I dont recommend this after some testing, unless you have a mic and rta. I managed to hit a sweet spot in my windshield that keeps the rta flat and causes a slight 3db rolloff after 16k. if you have a mic and rta it's worth a shot if all else failed. again, my suspicion is I lined up the early reflections and the balls helped muffle diffractions.

but, when they are on axis, I get a massive 8 db peak at 15k. no eq'ing or TA I can do w my equipment smoothed it. turning the balls until it leveled out worked. which was literally 180 degrees turned. ( I dont have a signal processor outside of my excelon x995). However, every other placement of the balls caused other less then heathly peaks and dips. 

After i determined the ball tweeters sound better faced away from me. (and by better i mean perfect, at least to my ears) I had to eq a 5db dip out of 9k and I had to eq out a 5-8db peak around 1.9k. the soundstage is lovely and wider then before. I wish someone with more experience then me could hear it and grade it.


----------



## Bayboy

Kind of perplexed here... you say 180 off axis, you mean you literally fired the tweets into the corner of the pillar/windshield sort of like one does with subs facing rear?!


----------



## Patrick Bateman

bloobb said:


> tl:dr unless bored lol. observations ensue
> 
> I sat in the car last night and turned the rta on for some ball turning fun. my dsp was set to pass through. The off axis response had nothing to do with the balls. The balls simply made the tweets more transparent all around. I never did like them on the dash, however this balll concept smoothed my dislikes. I think when the tweets are facing me and tucked into the corner it was bouncing stuff off my windshield bad.
> 
> yea frankly I dont recommend this after some testing, unless you have a mic and rta. I managed to hit a sweet spot in my windshield that keeps the rta flat and causes a slight 3db rolloff after 16k. if you have a mic and rta it's worth a shot if all else failed. again, my suspicion is I lined up the early reflections and the balls helped muffle diffractions.
> 
> but, when they are on axis, I get a massive 8 db peak at 15k. no eq'ing or TA I can do w my equipment smoothed it. turning the balls until it leveled out worked. which was literally 180 degrees turned. ( I dont have a signal processor outside of my excelon x995). However, every other placement of the balls caused other less then heathly peaks and dips.
> 
> After i determined the ball tweeters sound better faced away from me. (and by better i mean perfect, at least to my ears) I had to eq a 5db dip out of 9k and I had to eq out a 5-8db peak around 1.9k. the soundstage is lovely and wider then before. I wish someone with more experience then me could hear it and grade it.


Could you post a pic?

15khz is an ultra short wavelength; so there's gotta be something VERY close to the tweeter that's creating that peak.

Whatever it is, it's likely a multiple of 0.225". (peaks and dips are generally caused by geometry, and 0.225" is the length of 15khz divided by four.)

Another possibility is that the peak is indicative of a tweeter that needs a phase plug.










That's why this plastic phase plug is here - without it you'd get a peak due to the sound off the edge of the tweeter summing with sound radiating from the center.


----------



## Vancomycin

Tremendous read/thread!
Thank you Patrick and all.

I'm a science guy and I am having trouble grasping it all, but what I can comprehend has had me reading about this interesting topic for hours today.

Can't wait to play with some of these ideas. Have a teardrop shaped hummingbird feeder....and those Hertz tweeters pictured...


----------



## Wesayso

Vancomycin said:


> Tremendous read/thread!
> Thank you Patrick and all.
> 
> I'm a science guy and I am having trouble grasping it all, but what I can comprehend has had me reading about this interesting topic for hours today.
> 
> Can't wait to play with some of these ideas. Have a teardrop shaped hummingbird feeder....and those Hertz tweeters pictured...


Be sure to share your pictures and results


----------



## bloobb

Patrick Bateman said:


> Could you post a pic?
> 
> 
> That's why this plastic phase plug is here - without it you'd get a peak due to the sound off the edge of the tweeter summing with sound radiating from the center.


mid page 17 has a picture from the outside looking in. a phase plug is a good idea, but i'm not sure i could fabricate one. i got the the rta very flat by just adjusting the balls left and right some independently. and still firing tweeter into the corner of the windshield/dash. sounds fantastic


----------



## vmi77

Patrick Bateman said:


> That's why this plastic phase plug is here - without it you'd get a peak due to the sound off the edge of the tweeter summing with sound radiating from the center.


Phase plugs on tweeters are generally used to prevent the droop in response below the breakup that is due to the phase delta between center and rim. It's a destructive interference that causes a droop, blocking the center removes part of the signal causing the droop. It's purpose is not to eliminate the peaks, though it may have this secondary result.

Here's an example of a hard-domed midrange unit that has similar properties to a tweeter. The RS-52 comes without a phase shield. You can see how the response changes with a couple of different phase shields tested. Yellow is the response without a shield.










This is probably a better example, I forgot that I had it. The yellow graph is the RS28 with the stock phase shield removed.










Dave


----------



## asawendo

Update pictures (for your info this is not a daily use car) just to fulfill my curiousity about spheres  as explained in this wonderful thread. Thank You all.

Before

















[/IMG]








[/IMG]

After




























Picture of Midbass










Picture of Subwoofer










Best Regards

Wendo


----------



## 000zero

That's an awesome job Wendo, what did you make the enclosures out of?


----------



## asawendo

000zero said:


> That's an awesome job Wendo, what did you make the enclosures out of?


I am using MDF and particle board 

Thank you Bro

Best Regards

Wendo


----------



## DS-21

asawendo said:


> Update pictures (for your info this is not a daily use car) just to fulfill my curiousity about spheres  as explained in this wonderful thread. Thank You all.


Is that little yellow driver the Davis Acoustics cone tweeter?

And if so, how do you get PE to get a pair to you without having them destroyed in shipping? I tried a few times, and they never arrived in functional condition...


----------



## 000zero

asawendo said:


> I am using MDF and particle board
> 
> Thank you Bro
> 
> Best Regards
> 
> Wendo


MDF, nice. How did you make a sphere out mdf? Layers and sanding?


----------



## asawendo

000zero said:


> MDF, nice. How did you make a sphere out mdf? Layers and sanding?


Yeah layering and sanding in order to have smoothest spheres i could have. And finally paint it with special coating

You should try it Bro.

Best regards

Wendo


----------



## asawendo

DS-21 said:


> Is that little yellow driver the Davis Acoustics cone tweeter?
> 
> And if so, how do you get PE to get a pair to you without having them destroyed in shipping? I tried a few times, and they never arrived in functional condition...


It's Monacor SPH30X (germany)

Very strong neodymium magnet just move away from screwdriver or bolts Bro 

Best regards

Wendo


----------



## asawendo

I think they have similarity with davis acoustic kevlar driver but i can not confirm that.


----------



## rexxxlo

asawendo said:


> Update pictures (for your info this is not a daily use car) just to fulfill my curiousity about spheres  as explained in this wonderful thread. Thank You all.
> 
> Before
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> [/IMG]
> 
> 
> 
> 
> 
> 
> 
> 
> [/IMG]
> 
> After
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Picture of Midbass
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Picture of Subwoofer
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Best Regards
> 
> Wendo


i know its off topic but thr subwoofer is very unique can you show some more pics? are those ports ontop?


----------



## 94VG30DE

vmi77 said:


> Phase plugs on tweeters are generally used to prevent the droop in response below the breakup that is due to the phase delta between center and rim. It's a destructive interference that causes a droop, blocking the center removes part of the signal causing the droop. It's purpose is not to eliminate the peaks, though it may have this secondary result.
> 
> Here's an example of a hard-domed midrange unit that has similar properties to a tweeter. The RS-52 comes without a phase shield. You can see how the response changes with a couple of different phase shields tested. Yellow is the response without a shield.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> This is probably a better example, I forgot that I had it. The yellow graph is the RS28 with the stock phase shield removed.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Dave


Great first post Dave. Welcome to the forum


----------



## hottcakes

why are people trying to send this to the dumb question forum?


----------



## subwoofery

hottcakes said:


> why are people trying to send this to the dumb question forum?


Because they are way over that... They heard about diffraction 20 years ago and it's a concept way too easy for them to understand  

Kelvin


----------



## asawendo

rexxxlo said:


> i know its off topic but thr subwoofer is very unique can you show some more pics? are those ports ontop?


Yeah its custom vortex ported enclosure using 10 inch B&W Composite Kevlar Subwoofer.

Here is some more pics:



















Best regards

Wendo


----------



## dcm220

I've never heard of vortex ports. That's pretty badass.


----------



## Lorin

Is that a spiral port on the top of the sub? If so (or if not), than what purpose does it serve?

also curious as to possibly "blocking" the waves on the way out. It may sound somewhat rudimentary (and it has been years ago), but I recall adding some foam weatherstripping in a circle around the edge of a tweeter in my home monitor. The idea (wasnt mine by the way) was that the foam surround on the outside edge would keep the "stray" music away from reflective objects (corners, walls, ceiling) and allow the sound to be directed toward the user (assuming all speakers arranged to do so). Was rumoured to have a similar effect as the cusions, etc., that are ocassionally found in home installs, just more local to the speaker. I put some on only the tweeters in my monitors and it did seem to help somewhat (could be that it was pure psychological though). Still running the same monitors to this day. Keep in mind, no technical experimentation to back this up, merely suggestion read somewhere at the time and my "percieved" impression that it improved the sound. Either way, the cost was minimal at best. does this make any sense?


----------



## littlejuanito

I found these website that sells wooden spheres. I may just give these a try, as I would much rather have my mid and tweeters on these.

Wholesale Wood Balls & Wooden Ball


----------



## asawendo

I am using spiral vortex port to accomodate large and long port in order to have very low tuned bass Bro.

Speaking about the spheres itself I've got best result when crossfired them and it is very easy to do that because they have swivelling base.

Best regards

Wendo


----------



## Bayboy

I think I see how the spiral ports work... Pretty neat! How did you calculate and build that?


----------



## asawendo

Bayboy said:


> I think I see how the spiral ports work... Pretty neat! How did you calculate and build that?


LMS and Bassbox Pro and my own custom application 

I try to avoid muddiness/group delay, one note bass also port noise as far as I can  

I also using thick mdf and special mix glue in order to make sure it doesn't rattle when the bass kickin'

The result is ultra low and deep bass that feel in my body rather than heard. 

Best Regards

Wendo


----------



## The Baron Groog

What's the box tuned to?


----------



## asawendo

The Baron Groog said:


> What's the box tuned to?


The Box tuned to 20 Hz Bro.


----------



## Dremgragen

Best 19 pages I've read on a forum in my life.

I wanted to do kickpod install in my new car instead of door location and was wondering how to vent my mid without cutting through the carpet and floor/frame (brand new car, don't want to cut the carpet or do anything else major until it's paid off). 

After reading this thread I think I will just try a small sealed enclosure for my mid as Patrick was suggesting and see how it sounds. I can always try to make larger or smaller to taste, right?  

One thing; using the formula with my midbass/midrange 6.5" speaker in mind.... 13500/1000Hz/3.14 = diameter of 4.3. a 4.3" diameter ball isn't going to house a 6.5" speaker. Did I do something wrong there? Should I find a ~7" ball and just house the mid in it with a rounded back or should I look for something larger like a 8-10" and go for a hemispherical baffle that is cut to shape to rest in the corner of the floor? 

2500Hz crossover point for my 1.3" tweeter... 13500/2500/3.14 = 1.7, but I think it will rest better in something larger like a 2.5" - 3" ball, smoother edge between the tweeter and enclosure, installed in kick pod location next to mid. (crossover point for my components is recommended 2.5kHz).

Thanks Patrick and everyone else who has contributed. Completely new and interesting concept for me, but now it makes so much sense when I recall the various times I've seen teardrop and egg-shaped enclosures.


----------



## subwoofery

Dremgragen said:


> Best 19 pages I've read on a forum in my life.
> 
> I wanted to do kickpod install in my new car instead of door location and was wondering how to vent my mid without cutting through the carpet and floor/frame (brand new car, don't want to cut the carpet or do anything else major until it's paid off).
> 
> After reading this thread I think I will just try a small sealed enclosure for my mid as Patrick was suggesting and see how it sounds. I can always try to make larger or smaller to taste, right?
> 
> One thing; using the formula with my midbass/midrange 6.5" speaker in mind.... 13500/1000Hz/3.14 = diameter of 4.3. a 4.3" diameter ball isn't going to house a 6.5" speaker. Did I do something wrong there? Should I find a ~7" ball and just house the mid in it with a rounded back or should I look for something larger like a 8-10" and go for a hemispherical baffle that is cut to shape to rest in the corner of the floor?
> 
> 2500Hz crossover point for my 1.3" tweeter... 13500/2500/3.14 = 1.7, but I think it will rest better in something larger like a 2.5" - 3" ball, smoother edge between the tweeter and enclosure, installed in kick pod location next to mid. (crossover point for my components is recommended 2.5kHz).
> 
> Thanks Patrick and everyone else who has contributed. Completely new and interesting concept for me, but now it makes so much sense when I recall the various times I've seen teardrop and egg-shaped enclosures.


I'm not saying spheres are unecessary for mids but they are better suited (size wise) to tweeters. Patrick actually doesn't understand why everyone is using it on mids up on the dash... 

Use the concept for tweeters, done!

Kelvin


----------



## Dremgragen

Right, I understand that; and I understand that it is the spherical baffle (not the enclosure) that is the goal for this dispersion technique, but theoretically it should do the same for my mid for 1kHz and up if I can swing it. 

I was disappointed that I had to go with an automatic transmission for my new car to get the options I wanted, but now that I want to make kick pods I'm loving not having the clutch pedal there. I have tons of room for mid installation - a semi-hemisphere should fit fine in theory - and match the tweeter.


----------



## cyberdraven

Patrick, sorry for this noob question.

Just to resurrect your post that says you need to cross your tweets high enough, say 5K above and the mids to play more than 5 octaves from 160Hz to 5K while the sub will do the lows 160Hz. (i'll skip the 2 sub section as ill dwell on the mid to tweets integration).

Interestingly, a thread from scott buwalda had the same views saying we its not advisable to cross tweets below 4K. Same theory, i suppose to have a single driver playing at those critical points (1K-4k).

Now, how do you dwell with these truth's of life:
1. Normal mids had an FR of 50-3KHz. Im using the seas RW165 and graph shows dip beyond 3.5.
2. An interesting thread of yours also talks about beaming and a 6.5" mids beams at 2.7KHz. Isnt we need to play speakers below the beaming point? or this is the magic "ring" trick of the doctor comes into play?
3. Will it be advisable to play the mids more than 5 octaves? I was made to believe the ideal is to play it 3 and a half.
4. If you opt to have a single sub, can you still attain SQ and have underlap in crossover, say 120Hz? This is shouldnt ask but rather to experiment on my own, but i'll be glad to hear your thoughts.

Thanks and kodus for an interesting thread!


----------



## 000zero

subwoofery said:


> I'm not saying spheres are unecessary for mids but they are better suited (size wise) to tweeters. Patrick actually doesn't understand why everyone is using it on mids up on the dash...
> 
> Use the concept for tweeters, done!
> 
> Kelvin


My understanding is that the spheres reduce diffraction and disperses the sound waves evenly in all directions, which improves imaging. Also, since the human voice is handled by the mid range driver then you would get better imaging for voices. Wouldn't that be a pretty significant improvement? Or am I not understanding this correctly?


----------



## subwoofery

000zero said:


> My understanding is that the spheres reduce diffraction and disperses the sound waves evenly in all directions, which improves imaging. Also, since the human voice is handled by the mid range driver then you would get better imaging for voices. Wouldn't that be a pretty significant improvement? Or am I not understanding this correctly?


Yes you understood correctly... But it all depends on how low you want to minimize diffraction. 

A 500hz soundwave is 27" long. Mids installed in doors will have reflection and phase problems (bouncing off the center console) unless you angle the driver. Angling the driver might actually create diffraction of the door. 
In order to minimize diffraction down to 500Hz, you actually need a sphere that is 4.29" in diameter. A small 3" mid might benefit from it but even then, wavelength are too long and localization shouldn't be a problem - a 4" mid, not so much. 
For my mids, I would actually worry about placement, angling and reflections more than diffraction. 

People putting mids and tweets up on the dash, most of the time, have closer object (windshield, dash, side windows) - which yields phase problems much much higher in frequencies where phase problems are harder to localize. 

That's my opinion, correct me if I'm wrong... 

Kelvin


----------



## 000zero

subwoofery said:


> Yes you understood correctly... But it all depends on how low you want to minimize diffraction.
> 
> A 500hz soundwave is 27" long. Mids installed in doors will have reflection and phase problems (bouncing off the center console) unless you angle the driver. Angling the driver might actually create diffraction of the door.
> In order to minimize diffraction down to 500Hz, you actually need a sphere that is 4.29" in diameter. A small 3" mid might benefit from it but even then, wavelength are too long and localization shouldn't be a problem - a 4" mid, not so much.
> For my mids, I would actually worry about placement, angling and reflections more than diffraction.
> 
> People putting mids and tweets up on the dash, most of the time, have closer object (windshield, dash, side windows) - which yields phase problems much much higher in frequencies where phase problems are harder to localize.
> 
> That's my opinion, correct me if I'm wrong...
> 
> Kelvin


I'm not to worried about diffraction at 500 Hz, mainly I was only thinking about 1 kHz and up since that is where most of the imaging cues come from. I had coaxial's down in my doors and they didn't image very well, also I felt like the sound was coming from my feet as opposed to in front of me.

I just bought some Focal 100v Slim mids for $60 on CL and I put them in 6" Styrofoam spheres and placed them on the dash to test them out. So far I like what I hear but I don't have my tweeters installed yet, so I will wait to make the final judgement. I eventually want to get the HAT L3 to match my L1V2, the end goal is to have the mid in half a sphere coming out of the a-pillar with the tweeter in a full sphere right above it. Right now I'm just figuring the angle and distance I want to place the speakers at. I think that will be a good compromise for diffraction of the mid's while still considering reflections.


----------



## Vancomycin

How would I design a sphered interface please for Morel MDT-22tweeters with this sort of design...?

ht....tps://www.madisound.com/store/product_info.php?products_id=566

Fs 650 Hz and crossed at 1800Hz (2.77X), powerful full sound

Thanks


----------



## 000zero

Vancomycin said:


> How would I design a sphered interface please for Morel MDT-22tweeters with this sort of design...?
> 
> ht....tps://www.madisound.com/store/product_info.php?products_id=566
> 
> Fs 650 Hz and crossed at 1800Hz (2.77X), powerful full sound
> 
> Thanks


You would have to make the radius of the face (where your tweeter will be mounted) a little bit longer then the diagonal length of the tweeter. Then to make the tweeter mount flush you would have to router a lip the shape of the tweeter face plate.


----------



## Vancomycin

Thanks very much.
Sounds about right....you've applied the often elusive powers of common sense...


----------



## subwoofery

Vancomycin said:


> How would I design a sphered interface please for Morel MDT-22tweeters with this sort of design...?
> 
> ht....tps://www.madisound.com/store/product_info.php?products_id=566
> 
> Fs 650 Hz and crossed at 1800Hz (2.77X), powerful full sound
> 
> Thanks


Taking 900Hz as the number for my calculation (half your Xover freq), it seems like you need a ball of at least 2.39" in diameter... 

Kelvin


----------



## Vancomycin

subwoofery said:


> Taking 900Hz as the number for my calculation (half your Xover freq), it seems like you need a ball of at least 2.39" in diameter...
> 
> Kelvin


Thanks very much Kelvin. I have always appreciated the posting contribution of "subwoofery" on this great forum.

Very considerate of you to correct to my preferred ambient temperature of 20 Celsius or, for you, 293 Kelvin 

Is that 2.39 inches diametre or radius please?

For Anthony, water exists as a liquid at this temperature  (j/k)


----------



## subwoofery

Vancomycin said:


> Thanks very much Kelvin. I have always appreciated the posting contribution of "subwoofery" on this great forum.
> 
> Very considerate of you to correct to my preferred ambient temperature of 20 Celsius or, for you, 293 Kelvin
> 
> Is that 2.39 inches diametre or radius please?
> 
> For Anthony, water exists as a liquid at this temperature  (j/k)


No worries mate... 

Heh... I thought I was much more friendly and not so cold  
If I'm not mistaken, it's minus 273°C 

2.39" in diameter. 

Kelvin


----------



## Vancomycin

Very friendly and appreciated.

WhenI take the speed of sound 343.2 m/s and divide by 900Hz and divide by 2 and then by pi...I get 6.0691cm (or 2.39 inches), and I assume that is the radius (as we divided by 2 above).....? 

You knowledgable guys on this forum have taught this noob quite a bit, so now I officially know next to nothing and am exponentially that much more dangerous....!


----------



## Vancomycin

I believe that's what our esteemed comrade Patrick did...


"Now the practical part, how to build it.

Let's say we wanted to diffuse sound down to 100hz. The speed of sound is 13500in/second. So to diffuse sound down to 100hz, we'd need a spherical enclosure that's 42.98" in diameter. Here's the equation:

required sphere radius = 13500 / lowest frequency / 2 / pi
required sphere radius = 13500 / 100 / 2 / 3.14159

Hmmm that's not gonna work is it? 

Psychoacoustic studies have shown that matching frequency response above 1khz is more important than *below* 1khz.

Based on that we could reduce our sphere from almost four feet to a little over four inches. At that size, it starts to get practical to do this in the car.

My local craft store sells some clear plastic spheres, I have no idea what they're for, but they work for spherical enclosures. They're 8cm in diameter and they're less than a buck. An 8cm sphere will control diffraction down to 1365hz."


----------



## subwoofery

_"8cm sphere will control diffraction down to 1365hz" _
Yup that threw me off too. But reading on the following posts, I believe it's the diameter. 

Kelvin


----------



## stealthninja

Very informative , yet still I am far too inferior to fully comprehend. But I am VERY thankful for the very detailed effort in teaching the dumb and blind.

So I might just be a little dumber than most of the posters in this thread, So is there a way I can pay some one to create some of these enclosures for my tweets and mids? And better yet tell me the optimal location for the placement of the mid and tweet. If you tell me how to measure what you need measured, I will be very happy to see some results, and pay you for them. The car I am reffering to the install is a 08 chevy cobalt sedan , if that helps any.


----------



## 000zero

stealthninja said:


> Very informative , yet still I am far too inferior to fully comprehend. But I am VERY thankful for the very detailed effort in teaching the dumb and blind.
> 
> So I might just be a little dumber than most of the posters in this thread, So is there a way I can pay some one to create some of these enclosures for my tweets and mids? And better yet tell me the optimal location for the placement of the mid and tweet. If you tell me how to measure what you need measured, I will be very happy to see some results, and pay you for them. The car I am reffering to the install is a 08 chevy cobalt sedan , if that helps any.


The 'optimal' place to put your speakers will differ from car to car, and even from person to person. The best thing you can do is go to an arts and crafts store and buy some styrofoam spheres of different sizes. Its pretty easy cut out a hole for your speaker, I did it with a kitchen knife and a spoon. It doesnt have to be perfect just needs to hold the speaker securely. Then get some double sided tape and start placing at various spots in your car.

Once you figure out the position and size of the spheres yourself (it is DI*Y*MA) then maybe you can get someone to fabricate you some nice finished enclosures.


----------



## asawendo

000zero said:


> The 'optimal' place to put your speakers will differ from car to car, and even from person to person. The best thing you can do is go to an arts and crafts store and buy some styrofoam spheres of different sizes. Its pretty easy cut out a hole for your speaker, I did it with a kitchen knife and a spoon. It doesnt have to be perfect just needs to hold the speaker securely. Then get some double sided tape and start placing at various spots in your car.
> 
> Once you figure out the position and size of the spheres yourself (it is DI*Y*MA) then maybe you can get someone to fabricate you some nice finished enclosures.


Well said Bro....


----------



## 000zero

asawendo said:


> Well said Bro....


Thanks. So far I have gone through half a roll of double sided tape trying to find the right placement . Still looking......


----------



## MDubYa

subwoofery said:


> _"8cm sphere will control diffraction down to 1365hz" _
> Yup that threw me off too. But reading on the following posts, I believe it's the diameter.
> 
> Kelvin


Threw me off too then my buddy figured it out...
13500/1365/2/3.14 = 1.574 (inches) 

1.574 is the radius. So the diameter is actually 3.15inches... Which converted to cm is 8.

Hope that helps


----------



## asawendo

000zero said:


> Thanks. So far I have gone through half a roll of double sided tape trying to find the right placement . Still looking......


Goodluck Bro...


----------



## masswork

asawendo said:


> Update pictures (for your info this is not a daily use car) just to fulfill my curiousity about spheres  as explained in this wonderful thread. Thank You all.


Just had a chance yesterday to listen to those rounded enclosure.
And yes, it really sounds good!

The shape, the color, and the size is just about right... reminds me to something 

So, this improvement really works.
Although the cost for making one like above is surely more than $2


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## asawendo

masswork said:


> Just had a chance yesterday to listen to those rounded enclosure.
> And yes, it really sounds good!
> 
> The shape, the color, and the size is just about right... reminds me to something
> 
> So, this improvement really works.
> Although the cost for making one like above is surely more than $2


Hello Masswork, yeah it is definitely more than $2  but the result worth it every penny. :drummer:

Smooth and natural sound and great imaging 

Thanks for reffering me this amazing threads from PB.

Best Regards

Wendo


----------



## ikari2_2000

Learned something new


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## keep_hope_alive

I had about $4 invested per sphere for mine, not including paint. I liked the ones I did for my friend so much, I am doing a pair for myself!


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## asawendo

keep_hope_alive said:


> I had about $4 invested per sphere for mine, not including paint. I liked the ones I did for my friend so much, I am doing a pair for myself!


He he he that's great Bro! 

I think I wil try with several full range driver to see the result.


----------



## douggiestyle

Here's another option for those who don't want to build from scratch

* Lenovo Speaker M220 (for each speaker):
o Approximate length: 90 mm (3.5 in)
o Approximate width: 90 mm (3.5 in)
o Approximate height: 93 mm (3.6 in)
o Approximate weight: 0.5 kg (1.1 lb)

Lenovo Support - Lenovo Speaker M0520 - Overview

$13 shipped red or black
Red Lenovo Multimedia Stereo USB Speakers


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## Bayboy

Those Lenovos are pretty nice! Wonder what kind of internal room do they have. Contemplating how to do these RS75-4 but the flange is a bit wide for their cone size for something like that probably. Would still have to glass a baffle for them I'd imagine....

Sent from my SCH-I500 using Tapatalk


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## Bayboy

Being lazy and cheap I decided to give this a try utilizing mini Glad bowls (cups rather) I had sitting in the cupboard that I use to take salad dressing to work. Cut up some quick rings to bring the RS75-4 flush with the cup's lip. Added duct seal with copper BB's to help damp the bowls. Covered with an old tank top I use for work and then CA glued. Still have some sanding, add some filler perhaps, then priming before I can say it's done, but I think I will give a audition before I go all the way.

Not the best in a round over, but at least it's an attempt to fit them on my suv's shallow dash finally...

I did play with one hooked up to a home receiver. Played some tracks I normally listen to and I have to say I was generally impressed with the tonality and output. It went low enough in the midrange with enough impact that I see no problem having it mate up with a dedicated midbass. I would probably cross over around 300-400hz @ 24db to start with once in the car. As for it's upper end, fairly detailed, but until on the dash I will reserve comments. Cups were also partially filled with poly.


----------



## Babs

Don't look now, well yeah you might want to look now.. A certain center channel of the spherical-enclosure type that's probably blown by one of the two spherical manufacturers is about to end auction. I'm thinking scrapping it for the two round enclosures would be good fodder for some diy wide-banders. Don't know if linking the auction here is kosher or not, so you'll have to hunt'r down. Easy enough.


----------



## Bayboy

If you were going to scoop them up I'm quite sure you have by now. What were they?

Sent from my SCH-I500 using Tapatalk


----------



## Babs

It was one of those MTM gallo acoustics center channels that kept popping the amp circuit according to the ad.. Went for like $50+shipping. Would have been a cool item to tear apart for parts for those spheres.. No, I'm not gonna try it just yet as I want to give the vifa d26+pioneer x-overs+TB mids a try as a thrown together front-stage.

There are some orb audio jobs out there now I think with some age that might be a good deal also though. Funny just finding a suitable item for an enclosure seems to be the challenge. 

Tennis anyone? hmmm.. A tennis ball with some finish work on the outside and a hole cuttout for tweet or wide-band. LOL!! That's funny enough to try. It's be easy to work with I guess. Sand off the fuzzies first I suppose and drop in a flush mount.


----------



## Bayboy

Yeah finding or fabricating a suitable enclosure can be a pain especially if using a wideband driver. It may be overkill, but I built the tupperware bowl like I would a normal enclosure... reinforced, damped, and sealed. True it's just a 2" driver, still you want to get the maximum performance within it's range.

The hardest part is room for a roundover. Easier for small tweeters since a small sphere is easy to accommodate. Not so easy for small drivers when you have limited dash space.

Sent from my SCH-I500 using Tapatalk


----------



## Patrick Bateman

Bayboy said:


> Yeah finding or fabricating a suitable enclosure can be a pain especially if using a wideband driver.


I am going to throw some iMac speakers up on eBay this week which are good candidates. They're in a spherical enclosure, and use JBL drivers which have a very wide range. They're quite similar to the TangBand whispers that Madisound sells for about $30 a pair. I expect that I'll get about five bucks for each woofer on eBay.

But the real great thing about the iMac drivers is that they don't require any fabrication. They're already mounted in sturdy spheres. They're even ported.


----------



## The Baron Groog

Patrick Bateman said:


> I am going to throw some iMac speakers up on eBay this week which are good candidates. They're in a spherical enclosure, and use JBL drivers which have a very wide range. They're quite similar to the TangBand whispers that Madisound sells for about $30 a pair. I expect that I'll get about five bucks for each woofer on eBay.
> 
> But the real great thing about the iMac drivers is that they don't require any fabrication. They're already mounted in sturdy spheres. They're even ported.


Funnily enough i was looking at the waterfall graphs for these the other day, respond much better if you mod them:

DIY2000


----------



## Bayboy

You know Patrick..... I am wanting to try some whispers pretty bad for the size and performance, but I can't get past trying to aesthetically match drivers (all Dayton RS). I think I need professional help with this matching affixation. 


Whoops.... spoke too soon!!! Putting the RS75-4 on the dash now and wow has it made a difference over the way the RS180-4 and Dayton silk dome interacted! The little glad bowls seem to work very good. I can run them almost all the way down to 200hz @ 24db with minimum excursion, but 300-400hz seems to blend better as far as stage height. The main difference is the amount of clean midbass the RS180's are able to put out without the extra strain of midrange breakup. Haven't dialed it in yet as I was just playing with one side, but big difference at this point. Treble output isn't too bad.... clean but not overly bright like the graph states. May put in the ND20FA's later to give extra sheen once I configure a passive between the two, but right now the little 2" is decent enough. Very clean & detailed in the midrange IMO. I will put the RTA on them along with a re-eq maybe later. Right now enjoying some nuances that I have been struggling to hear. 


Advantages from the minor round over.... eh, I'm not sure as I never had them in the truck playing before so I can't really add to that aspect. Sorry...


----------



## argetni

does this really work?


----------



## Bayboy

argetni said:


> does this really work?



What are you referring too? Spherical enclosures? If so, diffraction is real, there is no doubt about that. Home audio manufacturers have been dealing with it for years. I can attest to that. Now as far as any construction that you've seen on here..... some ideal, others less than ideal (mines).... However it is something that you will have to hear to see the difference yourself.


----------



## derickveliz

To me the spheres work on the tweeters, for the Mids it was just cometics.

I'm redoing my front end, the Mids are going to the a-pillars off-axis and tweeters remain in spheres...


----------



## keep_hope_alive

i enjoy the spheres I did in the Scion tC with Hertz ML28 tweeters so much, i'm doing a set for my own car using my Oz-25 tweeters which are currently off-axis on the a-pillars. i have a separate set of a-pillars so i can switch back and forth if necessary (or while the spheres are curing/drying). 

the sound stage width is greatly widened and it's just amazing how you can't locate a tweeter that is staring you in the face. diffraction is very real, as is the resulting phase-interference/comb-filtering that ensues.


----------



## HondAudio

I went and looked at some wood spheres at Michael's and JoAnn over the weekend. The ones at Michaels were $1.49 each, but would require that they be run across a table saw to make the flat mounting area larger. The ones at JoAnn were $3.49, but already had a mounting surface large enough for my tweeters. If I can figure out how to make a jig to hold them so the flat surface faces up and perfectly flat, I think a Forstner bit will make the tweeter cutout for me.


----------



## Bayboy

HondAudio said:


> I went and looked at some wood spheres at Michael's and JoAnn over the weekend. The ones at Michaels were $1.49 each, but would require that they be run across a table saw to make the flat mounting area larger. The ones at JoAnn were $3.49, but already had a mounting surface large enough for my tweeters. If I can figure out how to make a jig to hold them so the flat surface faces up and perfectly flat, I think a Forstner bit will make the tweeter cutout for me.




Why the choice of wood spheres if you don't mind my asking? Easier towards a finished product I take it? If it's a small format tweet, the small plastic 2 piece spheres seem fairly simple after doing the glad bowl trick.


----------



## HondAudio

Bayboy said:


> Why the choice of wood spheres if you don't mind my asking? Easier towards a finished product I take it? If it's a small format tweet, the small plastic 2 piece spheres seem fairly simple after doing the glad bowl trick.


I guess I missed where to find the plastic spheres. The wood spheres in question were 2.5" in diameter, for comparison.

Where do I find those plastic ones?


----------



## Bayboy

Actually in the same stores you were in... I found some at hobby lobby, basically same as Michael's. Wasn't a R/C hobby store like I thought it would be but there was some pretty neat stuff in there if you have a little imagination.


----------



## inkdigger

Very cool, learn something new everyday!


----------



## Bayboy

HondAudio said:


> I guess I missed where to find the plastic spheres. The wood spheres in question were 2.5" in diameter, for comparison.
> 
> Where do I find those plastic ones?



Just a question was all, though a wooden sphere would seem a bit better if you have a way to shape it efficiently. The natural mass would seem a like plus if the tweeter is open back (vented pole). Either way get creative & productive.


----------



## asawendo

argetni said:


> does this really work?


Simple answer : YES!

Comprehensive answer : it depend on the quality of installation, and the quality of setting.


----------



## HondAudio

I'll pick up a couple of the wood spheres and take some photos. They might be too big for where I want to install them... that would leave me with using the surface/angled mount for my Bostons, shy of starting on A-pillars. Right now I'm trying to finish the new baffle for my sub, get the enclosure/amp rack put together, and start on the midbass baffles.


----------



## Patrick Bateman

RAAL from Serbia demo'd an interesting speaker at the RMAF this year, and it looks like it would be a good alternative to the spherical tweeters we're discussing here.

First, the audio pr0n:









The speaker is that aluminum thing that looks like a lamp. The designer is there in the picture, flew in from Serbia









A stereo set up

















Close up of the speaker









Anyone remember the Radio Shack Optimus Pro LX5 from the nineties? This thing was kind of a big deal. If you remember it's Linaeum tweeter, you'll see a strong family resemblance to the RAAL speaker above.

On a side note, looks like the designer (Paul Paddoc) lives a few miles from me. Odd. Must be something in the water here in Oregon. (The dude that wrote the LDSG lives a few miles away too.)

A DIY Ribbon Speaker of a different Kind - diyAudio


----------



## thehatedguy

I remember when RS was clearing out the Linaeum tweeters...they went CHEAP. I never heard any...wondered if they were any good.


----------



## Patrick Bateman

IMHO, it's hard to get real ambience in the car because the speakers are flush with the 'walls'. (AKA, the doors or a-pillar.)

This would be like listening to your home speakers on a bookshelf. The tonality is fine but there's barely a soundstage, and the ambience sucks. Pulls the speakers away from the wall and everything improves.

The whole idea with this spherical tweeter thread was to improve that. *I personally don't think that spherical midranges are as important as spherical tweeters.* I see a lot of people doing the spherical mids here, and if you're going to do one or the other, do the spherical tweeters. This is just basic physics - high frequencies are very short, and you don't need a big sphere to do the job. *To get a significant improvement at 500hz you need a really big sphere!*

I'd love to hear this JL Audio GTI - this is a well-done implementation:



















Here's the really cool thing about the cylindrical tweeter. This kinda makes my head hurt, but I believe *you could size the cylinder to lower the xover point*. Here's how this works. When you put that tweeter in a figure eight, the sound will 'wrap around' and augment the low end. I believe the frequency at which it will occurr is when *the diameter of the cylinder is equal to a multiple of one half wavelength.* For instance, if you are using a 4" cylinder, you'd see an increase of efficiency at 537hz, 1074hz, 2148hz, etc...


















Dan Neubeck from HTGuide built one of these - and you can see the increase in efficiency quite easily. Note the ten dB bump in efficiency at 1000hz?

If I'm not mistaken, this should also focus the energy in the frontal and rear lobe, which is A Very Good Thing for car audio, where the last thing we want is reflections off the left and the right. Because reflections to the side are what ruins stage width.


----------



## Patrick Bateman

Here's the on and off-axis response of Dan's satellites, with the woofers included. So we have a total of four woofers and one tweeter. The curves are zero, fifteen, thirty, and fourty five degrees off axis.

The first thing I notice is that there's some serious horn loading here - that little tweeter is getting some real gain in the cylinder. The polar response shows that the cylinders are changing the directivity too.

It's not truly "omnipolar" but I think that's actually a good thing. Ideally I want a lobe going forward and a lobe going backward, and nothing going to the sides. We see in the graphs that the speaker's response is quite smooth in a window of plus or minuse thirty degrees. That's quite good, and a heck of a lot better than you'd ever get from a conventional dome.

Another option that some might consider is a dipole. I *do* like dipoles, but keep in mind that Dan's figure-eight speaker will have INCREDIBLE power handling because the drivers don't unload. He's getting some crazy efficiency and output from this satellite.

More info here:

HTGuide Forum - Raal Omni Discussion


----------



## asawendo

Hei I remember the Linaeum! Also I remember when I heard them for the first time. Very smooth tweeter.


----------



## ReticulatingPigeonElf

^whoa, do they launch fireworks too?


----------



## cvjoint

Superb thread! It seems that I can implement a lot of these ideas in my own car. Time to smooth out the edges. Glad I found it before I mounted my line array permanently.


----------



## Patrick Bateman

I've been working too much lately, and haven't had much time for audio projects unfortunately. I've listed some spherical speakers that I bought up a few years ago. The whole reason I bought them was to experiment with some of the ideas that I've discussed in this thread. The speakers are similar to the Aurasound Whispers that Jason is (was?) using. The nice thing about the ones that I am selling is that they don't need an enclosure - it's basically included.

Here's a pic:









I hope it's ok i list this auction here - it is very specific to this thread, as these are spherical full range speakers. Five bucks each!

Spherical iMac Speakers, less than five bucks each DELIVERED | eBay


----------



## SSSnake

Doesn't the thick rim around the speakers themselves kind of violate the whole non-diffraction goal?


----------



## asawendo

SSSnake said:


> Doesn't the thick rim around the speakers themselves kind of violate the whole non-diffraction goal?


Yeah I have the same question, maybe PB could further explained to us?! Thx


----------



## Patrick Bateman

SSSnake said:


> Doesn't the thick rim around the speakers themselves kind of violate the whole non-diffraction goal?


It's likely there to prevent them from being damaged. If concerned, file it down. The diffraction from the ridge would be dependent on frequency, and since the rim is only a quarter of an inch, would likely occur above 14khz or so. (IE, probably wouldn't be audible.)

Having said that, I *do* agree that a ridge so close to the cone is a bad idea, and I would likely file them down for any serious design. I bought a big box of these because they are so unique. JBL wound up selling larger ones a few years later, but I prefer the small ones because they play much higher, and reducing diffraction is more important at high frequency than at low.


----------



## nitropilot

So mount the pods on the dash like in the JBL GTI pic you posted above? To the sail panel? Where do you think the best location would be? 
I wonder how good they can sound for such a small speaker. What high pass freq do you think they can handle? 1khz?


----------



## Patrick Bateman

nitropilot said:


> So mount the pods on the dash like in the JBL GTI pic you posted above? To the sail panel? Where do you think the best location would be?
> I wonder how good they can sound for such a small speaker. What high pass freq do you think they can handle? 1khz?


I wouldn't be surprised if you could go two octaves lower than that - all the way down to 250hz. The JBLs are really similar to the Aurasound Whispers sold by Madisound, and those drivers can go all the way down to 150 or 200hz.

The JBLs have an edge over the Auras because they're ported, which controls excursion on the low end.

As for location, I'd probably experiment with all the usual locations, and I'd pull the away from the edges of the car to increase ambience in the soundstage.


----------



## Winno

Wow, what a read.

My understanding from all of this (and from prior experience in home _and_ car audio) is that:

1. Avoidance of sharp edges through mounting the driver into a larger diametre sphere will assist in avoiding edge defraction. The pic below of keep_hope_alive's effort is the best execution of this principle in this whole thread - no edges because the driver is flush and the sphere gradually 'rounds away' from the driver edge.
Most people here in this thread mounting their drivers into spheres are still left with some form of small radius edge around the driver flange which, although edge defraction is minimised to a degree, it's still present as shown by the red lines in the second pic/diagram below. Regrettably, because of the size of my 3" mid, I'll be forced to end up with a similar result (I still need to be able to see out of my windscreen after all!) as I can go as big as a 5" diametre ball.

2. Mounting that driver/sphere as far away from glass, pillars, door trims, etc as realistically possible will also assist in avoiding disruptive and more immediate boundary defraction/reflections.

3. Because of physics (sphere size vs frequencies dealt with) the benefit is realised more with tweeters. Some here are mounting mids into spheres and being told that this, to a degree, will have a negligible effect, again because the spheres are too small for the lower frequencies coming from that driver.

*My point and question* comes about because my front stage will consist of a two way set up using wide band Audible Physics XR3M 3" cone drivers (point source ftw!) on the A-pillars and 5.25" Seas S16RNSL midbasses in the doors. I will have no tweeters as such!

The AP's will be highpassed from about 250Hz (yet to be finalised at this stage) and run all the way up to 20Khz. They'll be mounted within 15 degrees of axis to preserve their top end response. For internal volume and lower octave production they'll need to vent into the A-pillar, which in turn will vent down through the top of the dash. So far, it's looking like a 5" diametre sphere is the go for this driver.

The Seas' will be flush mounted with the door skin in the doors.

Again, it's been said that mids in spheres is a wasted effort to a degree, but what about those wide band mids that'll be producing all treble up to 20Khz?

Thanks for your help, and a massive credit to those who've contributed here in this thread.

Steve,
Brisbane, Australia


----------



## Winno

I also have another quick question.

What would be the expected result of mounting a driver in a very very shallow and barely concaved horn/waveguide that has a largish radius round off to a sphere or cone at the rear? 

Would it assist by limiting and controlling the baffle defraction and stopping the sound from hitting surrounding surfaces sooner?
What would be the expected draw backs, generally speaking?

Perhaps a much larger sphere would be required for a 3" driver to allow for the guide and then the round off?

Cheers again.


----------



## Patrick Bateman

Winno said:


> Wow, what a read.
> 
> My understanding from all of this (and from prior experience in home _and_ car audio) is that:
> 
> 1. Avoidance of sharp edges through mounting the driver into a larger diametre sphere will assist in avoiding edge defraction. The pic below of keep_hope_alive's effort is the best execution of this principle in this whole thread - no edges because the driver is flush and the sphere gradually 'rounds away' from the driver edge.
> Most people here in this thread mounting their drivers into spheres are still left with some form of small radius edge around the driver flange which, although edge defraction is minimised to a degree, it's still present as shown by the red lines in the second pic/diagram below. Regrettably, because of the size of my 3" mid, I'll be forced to end up with a similar result (I still need to be able to see out of my windscreen after all!) as I can go as big as a 5" diametre ball.
> 
> 2. Mounting that driver/sphere as far away from glass, pillars, door trims, etc as realistically possible will also assist in avoiding disruptive and more immediate boundary defraction/reflections.
> 
> 3. Because of physics (sphere size vs frequencies dealt with) the benefit is realised more with tweeters. Some here are mounting mids into spheres and being told that this, to a degree, will have a negligible effect, again because the spheres are too small for the lower frequencies coming from that driver.
> 
> *My point and question* comes about because my front stage will consist of a two way set up using wide band Audible Physics XR3M 3" cone drivers (point source ftw!) on the A-pillars and 5.25" Seas S16RNSL midbasses in the doors. I will have no tweeters as such!
> 
> The AP's will be highpassed from about 250Hz (yet to be finalised at this stage) and run all the way up to 20Khz. They'll be mounted within 15 degrees of axis to preserve their top end response. For internal volume and lower octave production they'll need to vent into the A-pillar, which in turn will vent down through the top of the dash. So far, it's looking like a 5" diametre sphere is the go for this driver.
> 
> The Seas' will be flush mounted with the door skin in the doors.
> 
> Again, it's been said that mids in spheres is a wasted effort to a degree, but what about those wide band mids that'll be producing all treble up to 20Khz?
> 
> Thanks for your help, and a massive credit to those who've contributed here in this thread.
> 
> Steve,
> Brisbane, Australia


Running midranges in spheres is pointless simply because the wavelengths are so long. For instance, if you have a 3" midrange in a sphere and it's lowpassed at 1350hz, then the shortest wavelength that it's reproducing is 10" long. So the 3" sphere will do a little to reduce diffraction, but not a whole lot. (This ignores output above the xover point; admittedly you should factor that in.)

On the other hand, if you do it with a tweeter, the shortest wavelength reproduced is 0.675" long! So you get some serious bang for the buck with a tweeter sphere. *Almost anything you do to eliminate diffraction near the tweeter will make a difference, because it doesn't take much.*









Also, you mentioned that you're listening to your full ranges on-axis to maximize the top end. Keep in mind this isn't necessary if you have EQ. It's perfectly valid to cross fire them and tip-up the top end to compensate for the rolloff that occurs due to their directivity.

In fact, I'd argue that contributes to a wider soundstage.

It doesn't really impact your power handling because excursion isn't a problem at high frequency, and there isn't a ton of energy in the top two octaves unless you're in the habit of listening to dog whistles.

The graph above shows the response of a Peerless 3" on and off-axis. You'll note that it's basically flat on-axis, but output drops quickly off axis above 10khz. *You can listen to these off axis, by tipping up the top octave.* Only catch is that the off-axis response needs to be well-behaved, but this driver fits the bill.

Play around with it in the car, because a lot of the magic depends on the implementation.


----------



## Winno

Thanks for the reply. 

As I said on my post, I already understand that a 5" to 6" sphere will be of no benefit to mid frequencies. 

My question was about whether a sphere of this size would benefit the higher frequencies normally the domain of dedicated tweeters, that a wide band mid is able to produce in my case. 

My thinking is that it would benefit however, I'm just seeking confirmation from the experienced and knowledgable here. 

Cheers


----------



## Patrick Bateman

Winno said:


> Thanks for the reply.
> 
> As I said on my post, I already understand that a 5" to 6" sphere will be of no benefit to mid frequencies.
> 
> My question was about whether a sphere of this size would benefit the higher frequencies normally the domain of dedicated tweeters, that a wide band mid is able to produce in my case.
> 
> My thinking is that it would benefit however, I'm just seeking confirmation from the experienced and knowledgable here.
> 
> Cheers


Yes, a spherical enclosure reduces diffraction for a full range driver, as long as the driver is capable of playing to a frequency where the wavelengths are small enough.

IE, no real benefit in doing it if you have them low passed at 1350hz, but if you have them running full range, or even lowpassed at 2700 or 5400hz, you're going to hear a difference.

I guess I'd break up the candidates into three brackets:

Bracket one - great candidates for spherical enclosures are drivers with wide directivity that play to a very high frequency. Tweeters are an example of this. The smaller the better.

Bracket two - good candidates for spherical enclosures are drivers with wide directivity that play to a moderately high frequency, or drivers with narrow directivity that play to a very high frequency. Examples of this are 2" and 3" woofers.

Bracket three - poor candidates for spherical enclosures are drivers with wide directivity that play to a low frequency, or drivers with narrow directivity that play to a moderately high frequency. Examples of this are 5" and 6" woofers, or 3" and 4" woofers that are lowpassed below their upper limits. There are plenty of 3" and 4" woofers that can hit 10khz, so if you're using one without a lowpass, it's a good candidate, if you ARE using a lowpass, it's suitability for a sphere will be reduced as the crossover point gets lower and lower.


----------



## ErinH

Two things about this thread that I have concerns with: 
1. Dickason has done research on diffraction and his summary of it when I spoke with him yesterday was that the impact of diffraction was nebulous. So much so, he essentially said there's no reason to worry about it because it just isn't audible. 
My guess is that its due simply to the high Q of these peaks/dips. It takes fairly fine smoothing to see the differences spoken of which such disparity. Toole's research shows these are inaudible. 
2. For the sphere to do any good it needs to be larger than the flange of the driver and the driver needs to be flush mounted in that sphere. Otherwise you still have diffraction off the flange itself (if after reading the testing mentioned above, you find it matters at all).


----------



## ErinH

I'm not trying to bring down the mood of this thread. Just wondering how beneficial it truly is. 
That said, using a sphere from hobby lobby is easier than fiberglassing a baffle to my pillars.


----------



## Patrick Bateman

bikinpunk said:


> Two things about this thread that I have concerns with:
> 1. Dickason has done research on diffraction and his summary of it when I spoke with him yesterday was that the impact of diffraction was nebulous. So much so, he essentially said there's no reason to worry about it because it just isn't audible.
> My guess is that its due simply to the high Q of these peaks/dips. It takes fairly fine smoothing to see the differences spoken of which such disparity. Toole's research shows these are inaudible.
> 2. For the sphere to do any good it needs to be larger than the flange of the driver and the driver needs to be flush mounted in that sphere. Otherwise you still have diffraction off the flange itself (if after reading the testing mentioned above, you find it matters at all).


I just pulled up Dickason's profile on LinkedIn, and a couple of things struck me. First, audio is a very VERY small world. I've obsessively studied Geddes and Danley, and if you look on LinkedIn, Geddes has about two degrees of separation from Dickason in the world of audio. On LinkedIn, here's the profiles listed on Dickason's page:








Vance Dickason (self-employed)







Floyd Toole (self-employed)







Sean Olive (Harman)
Wolfgang Klippel (s/e)
Ken Kantor (formerly of NHT, Tymphany)
Tom Holman (University of SoCal)







Earl Geddes (s/e)

So this is a very small pool of experts, and none of them agree on diffraction, as far as I know.

So you bring up a good point, something which should have come up in the first page or two really!

Is combating diffraction a worthy goal?

I am inclined to say "yes." Twenty years ago, when I first started screwing around with audio, I had the same mindset that most beginners do. My goal was to reduce harmonic distortion by using high quality drivers, and I invested a lot of money in expensive amplifiers and crossover parts.

Twenty years later, I've practically done a 180. *Everything I've learned tells me that timing problems are more important than amplitude problems.*

So I would argue that the reason that guys like Linkwitz and Dickason discount the diffraction problem is that Linkwitz and Dickason are focused on amplitude problems. (IE, frequency response.)

And I would argue that the Geddes and Danley designs *attack problems in the time domain*, each in their own way. Geddes is a proponent of preserving the acoustic wavefront via low-diffraction cabinets and waveguides. Danley's designs are engineered so that they preserve acoustic phase across the bandwidth of the loudspeaker.

And as any good engineer knows, engineering is all about compromises. The Geddes and Danley designs do not have the best amplitude response on axis, in fact it's fairly ragged. *But the key to their designs, IMHO, is that they get the time domain right.* And I think that's humongously important.

Here's a real world example of what I mean. Have you ever clapped your hands in a small room? And have you noticed that there's an echo? *In a small room, that echo will occur less than ONE HUNDREDTH of a second after you clap your hands.* And yet the echo is very easily audible isn't it?

If you grok what I'm saying there, you'll start to understand why I think the time domain is so important. Our ears are very VERY sensitive to timing problems. You can tell when a sound is 'off' by a HUNDREDTH of a second, perhaps much less.

Conversely, it's VERY HARD to measure. Go ahead and try to figure out how to measure this stuff. It's not easy.

On the other hand, there are iPhone apps for a buck that can measure frequency response.

And THAT is why the audio world is obsessed over amplitude problems, but drops the ball when it comes to time domain problems. Problems in the time domain are devilishly difficult to analyze and quantify, while problems in the amplitude domain are trivially easy to analyze.


----------



## Patrick Bateman

Oh, in reference to my previous post, I think that ALL time domain problems are insidious. It's not just diffraction. Here's a few more examples of time domain problems:

- I think the reason that people are averse to the sound of bandpass boxes and vented boxes but like sealed boxes is because sealed boxes generally have better group delay
- I think the reason that people try horns in the car but get sick of them and go back to direct radiators is because undersized horns have terrible group delay, and that's a high price to pay for dynamics
- I think the reason that people like the sound of full range drivers, everything from $50 boom boxes to $800 Lowthers is because full range drivers are incredibly well behaved in the time domain. In fact, the only way to get better behavior in the time domain is to approximate a full range driver with an array
- I think the reason that hundreds of people on this forum have been looking for audio nirvana for decades, and yet they can't find it, is because expensive low distortion components do NOTHING to address the time domain problem, and in fact they can exacerbate it. That's why very cheap and inexpensive loudspeakers are often MORE satisfying that megabuck low-distortion speakers
- I think the reason that many people prefer vinyl over CDs is because some CD players suffer from high jitter, which is a time domain problem
- I think the reason that many people think MP3s sound weird is not because of the compression, but because the original source was poorly 'ripped', and the track has lots of jitter. *I believe that compressed audio can sound indistinguishable from the original if it's very carefully ripped, and compressed at a high bitrate.*

I'll probably lose all my credibility on this forum with this post


----------



## cvjoint

I think they are all right, the issue I take is that of emphasis. One researcher here brings attention to one aspect of sound reproduction but in doing so they find it necessary to downplay the other aspects that are relevant. My understanding of it all is that they are all important, but in trying to see which one you should give more relative importance you face the ongoing wrath of head researchers trying to bring their idea at the forefront while downplaying the rest. 

Geedes for examples uses massive pro audio drivers. No **** his design is not bound by high amplitude distortion, he effectively took care of it by using oversized drivers. If you look at Linkwitz work on decay it seems that hard cones and small cones seem to have better decay than large paper cones like the pro audio ones he uses. If he's such a big time domain buff why use a big paper cone? My guess is that he's trying to sell his beliefs about the ideal polar pattern at the expense of everything else that matters. I suppose that's just a way of getting your foot in the door with an idea. He's not the only one guilty of this but others as well, emphasis is often tied to their personal research, it is a form of bias. 

At the end of the day all maters and it's up to you to go through all their work and assign weights as best as you can. They won't do it for you. 

As far as diffraction goes I think it's a second order issue. Once I pick and mount all my drivers I can look and see if I can round off some edges. Without Patrick's thread I wouldn't have know about it so there is a lot of added benefit here despite it not being a primary concern.


----------



## asawendo

Patrick Bateman said:


> Oh, in reference to my previous post, I think that ALL time domain problems are insidious. It's not just diffraction. Here's a few more examples of time domain problems:
> 
> - I think the reason that people are averse to the sound of bandpass boxes and vented boxes but like sealed boxes is because sealed boxes generally have better group delay
> - I think the reason that people try horns in the car but get sick of them and go back to direct radiators is because undersized horns have terrible group delay, and that's a high price to pay for dynamics
> - I think the reason that people like the sound of full range drivers, everything from $50 boom boxes to $800 Lowthers is because full range drivers are incredibly well behaved in the time domain. In fact, the only way to get better behavior in the time domain is to approximate a full range driver with an array
> - I think the reason that hundreds of people on this forum have been looking for audio nirvana for decades, and yet they can't find it, is because expensive low distortion components do NOTHING to address the time domain problem, and in fact they can
> exacerbate it. That's why very cheap and inexpensive loudspeakers are often MORE satisfying that megabuck low-distortion speakers
> - I think the reason that many people prefer vinyl over CDs is because some CD players suffer from high jitter, which is a time domain problem
> - I think the reason that many people think MP3s sound weird is not because of the compression, but because the original source was poorly 'ripped', and the track has lots of jitter. *I believe that compressed audio can sound indistinguishable from the
> original if it's very carefully ripped, and compressed at a high bitrate.*
> 
> I'll probably lose all my credibility on this forum with this post


No. You don't!

Maybe I could add something

Imagine if a bass player/pianist/guitar in a group band played a delayed note than the other players. Let say 1 second late. I'm certain it will ruin the music. 

So timing is important for me both in music production and music reproduction (audio system). CMIIW


----------



## Winno

Thank you again for helping me decide what to do.

As my drivers will be high passed from 250Hz, I understand that the work I will do in mounting them into spheres will be of at least some use because at least some section of the pass band (the higher end of that band) will benefit.

The fact that they're wide band drivers also helps address other the many issues I have experienced in the past with separate drivers (including the time and phase issues spoken of in this thread above).

Wish me luck, and thanks again.

Steve


----------



## Wesayso

In a car it couldn't hurt to get as many of these factors right as you can. I have a small car and before i started I had a hard time figuring out where to put my tweeters. I had read posts about avoiding as many first reflexions as possible but also read the tweeter in door could be a bad position. Yet I chose this position because there were not a whole lot of other positions to place my tweeters without running into other problems and it was the right place to avoid as much first reflections as possible. Right from the start imaging was very good. The tweeters just dissapeared. No smear in high frequencies and that's the reason I believed a round over could help even further. Now I never hear where the tweeters are mounted even when I look at them. The sound is smoother and of coarse time alignment helps to get the music sound good but the main part is the absense of difraction and very early reflection helps the speakers dissapear in my opinion.








I've noticed there are very small differences in good sound and great sound. Time alignment was the biggest key to get the right groove in the music. You know, you forget all your priorities and the music just takes over. Not that dificult to understand as that makes the difference between a good singer and a great one. Timing is everything.
So if it's possible to limit as much of these problems as you can I am sure you will be rewarded. I've noticed this in my car and came to the conclusion to build an array like Roger Russells IDS-25 for my home to get rid of the time domain difficulties between drivers. 
I am certain that if you get the timing right the groove is in the music and makes you worry less about the other remaining problems. But why not try and solve as many as you are able to in your particular situation in your car/home etc?


----------



## Wesayso

I could not forget what I read about a project of a dutch guy named Tony Gee. One of the best imaging speakers he built was this one:
http://www.humblehomemadehifi.com/download/Humble%20Homemade%20Hifi_Mezzo%20Galactica_copy.pdf
A low difraction speaker that seems to draw you into the music, just read his Listening impressions and measurements.


----------



## cvjoint

that's really cool. I wonder how this design would look like for a rectangular planar.


----------



## Wesayso

O>--------<O ?


----------



## douggiestyle

Patrick Bateman said:


> I've been working too much lately, and haven't had much time for audio projects unfortunately. I've listed some spherical speakers that I bought up a few years ago. The whole reason I bought them was to experiment with some of the ideas that I've discussed in this thread. The speakers are similar to the Aurasound Whispers that Jason is (was?) using. The nice thing about the ones that I am selling is that they don't need an enclosure - it's basically included.
> 
> Here's a pic:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Patrick Bateman said:
> 
> 
> 
> I wouldn't be surprised if you could go two octaves lower than that - all the way down to 250hz. The JBLs are really similar to the Aurasound Whispers sold by Madisound, and those drivers can go all the way down to 150 or 200hz.
> 
> The JBLs have an edge over the Auras because they're ported, which controls excursion on the low end.
> 
> 
> 
> Bought a case of these JBL iMac speakers off eBay to play with. I only managed to get one side in tonight but managed to get some listening impressions in before calling it a night. I had the JBL crossed at 1k, 1.2k, 1.6k, 2k, and 2.5k. Efficiency will be an issue when crossed low, and they sound a bit harsh/spitty at 1k. (Plus as Patrick said, there isn't much benefit when crossed that low anyway). Crossing at 1.5k has promise, and I'm excited to try them there.
> 
> After playing with just the one JBL installed on the passenger side, I A/Bed them against my existing DLS Nobelliums (DLS on driver side). I know this isn't the best way to compare them, but I'm limited on experience, time, and resources.
> 
> Very rough thoughts: DLS sounded smoother whereas the JBL has a colder, sterile sound. I thought there was a substantial increase in "airiness" coming from the JBL, but I'm not ready to make any sort of definitely statement yet.
> 
> It'll be very interesting to see first hand the trade offs between timing and amplitude once I get the other speaker in.
Click to expand...


----------



## gokiburi

bikinpunk said:


> I'm not trying to bring down the mood of this thread. Just wondering how beneficial it truly is.


I certainly don't have golden ears, and I was skeptical, but I could tell a difference in before/after and A/B listening tests. Yeah, yeah, I know, psychacoustics.


----------



## Sarthos

Okay, I gotta admit some things in this thread are kinda confusing me. Namely, why does it make a difference how the back of the thing is shaped? Sphere vs teardrop? I see the issue with the flat surfaces, but not really the sphere vs. teardrop vs etc shape.

I just did the tweeter pods that use PVC endcaps. How exactly does this differ in a result? I smoothed the front surface so the tweeter and the PVC mate up smoothly, will changing the cylinder shape to a sphere really make a difference though? Also, would it help extra for people to wrap these spheres in foam or a similar substance to further reduce reflections?

And why exactly does the diameter of the sphere make a difference?


----------



## subwoofery

Sarthos said:


> Okay, I gotta admit some things in this thread are kinda confusing me. Namely, why does it make a difference how the back of the thing is shaped? Sphere vs teardrop? I see the issue with the flat surfaces, but not really the sphere vs. teardrop vs etc shape.
> 
> I just did the tweeter pods that use PVC endcaps. How exactly does this differ in a result? I smoothed the front surface so the tweeter and the PVC mate up smoothly, will changing the cylinder shape to a sphere really make a difference though? Also, would it help extra for people to wrap these spheres in foam or a similar substance to further reduce reflections?
> 
> *And why exactly does the diameter of the sphere make a difference?*


Answer on the first page. 

Kelvin


----------



## The Baron Groog

If you read back to post 35 there are diagrams representing the baffle step diffraction from drivers mounted into different shaped baffles-that will show you the difference between mounting options.

Post 2 details why the diameter of the sphere makes a difference


----------



## xMplar

just have to say i have a kind of audio guru / mentor guy here in oz who talks abo0ut alot of the things you guys are talking about in here hs 30-40 years background is in home audio and im trying to learn from him and use it in car audio the spreical 3 quarter egg tweeter or ide i have used in my SPL car which everyone said was stupid but it ended up making the sound bareable to listen to then a few other mods for diffration and a few other bits and bbs that are very commen in home audiophiles and what the doof doof crowd call oldtimers and whalls a 150db car that will play all types of music not just bass and would play it well 

now were upping the anti were making it a more tradtional SPLer by putting in 4 x 15s but stickeing to the same build principles cylindrical internals extrenls roundovers and positioning of things that will not only help the quality of the sound made but the amount of sound made it worked for a 150db car so why not more??

now were adding sound absorbtion and waveguide etc aswell as the sperical eggs and a bucnh more tricks ill staret a build log as soon as i know it all works well when i get the first listen in about a week anyway but i also wanted to say this is one of the best reads in an audio forum especially car audio 

i have seen for sum time well done to you patrick great topic ohh and is that your car by the way as i have one identicle well identicle in that its a e34 5 series bmw thats it tho im still working on that car Essquees are hard to extract from a car while still making it look good to other ppl and yourself


----------



## xMplar

here is sum of the pods i have used in my SPLer car and will most likly use simalar in my essquees car the tweeter sits almost perfect so the round over is almost perfect nt quite but almost i bought these fron a matew who found a place in maylasia who mkaes them out of full on fibreglass in like a 1" 2" 3" 
4" 5" 6" 7" 8" 9" 10" and so on you get the point 

they are called podlets and in bigger versions call bass bombs trhere is also some other types in difernt shapes
and the have a roundin lip so you can actually screw into the lip if needed or glue to it whatever takes you fancey

Ren
xMplar


----------



## gokiburi

Looks pretty cool. 

Consider working in some punctuation now and then.


----------



## Sarthos

Well I read an equation for how the diameter matters, it's the question of why the diameter matters? As opposed to small diameter with lots of open air around the thing? Having the equation in front of me and knowing why the equation works are two different things


----------



## douggiestyle

bikinpunk said:


> I'm not trying to bring down the mood of this thread. Just wondering how beneficial it truly is.
> That said, using a sphere from hobby lobby is easier than fiberglassing a baffle to my pillars.


Erin, I've got two of the iMac speakers to spare for testing. I can send them to you if you're interested. Gives you a chance to see the diffraction difference for yourself.

It'd be interesting to see measurements as well, which brings back the spirit of the DIY community.

1. Very cheap - much cheaper than the Aura NS2 and decent used supply available online/craigslist
2. Pre-made enclosure 
3. Diffraction benefits (I can't confirm this yet)
4. Ability to play low (250k? I didn't like them at 1K but like them at 1.5k, though I didn't have much time with them)

For anyone else interested in these, the wire leads are very thin and short and makes crimping nearly impossible. I think the best thing to do is to solder on longer wire leads. Hoping to get a full review in the review section but that isn't likely until after the holidays.


----------



## Srt10venomous

very interesting, subscribed.


----------



## Patrick Bateman

John Krutke discovered that it's possible to purchase the midranges used by B&W in their speakers. Here's a pic:


















The spherical enclosure used by B&W is based on the principles described in this thread. The enclosure basically makes the speaker 'disappear.' Even a small discontinuity between the cone and the woofer would screw things up, which is why the surround on the speaker is practically non-existent.

More data on the woofer here:

HTGuide Forum - B&W FST mid


----------



## cvjoint

There are at least two discontinuities still, the tweeter housing on top and the large woofer on the bottom. 

In the linked thread it's said that they cross at 4khz, the directivity mismatch between the mid and tweeter would probably be very noticeable. The lack of suspension on the bottom also requires a rather high crossover point cutting into the meat of the midrange. That roundover design sure seems to compromise a lot on the other fronts. The mid is however built seemingly very well.


----------



## asawendo

Wow is it 5" midrange? Very beautiful teardrop spheres shape and exquisite craftmanship.

By the way Patrick do you know how much internal volume of that enclosure?

Best regards

Wendo


----------



## The Baron Groog

Patrick Bateman said:


> Even a small discontinuity between the cone and the woofer would screw things up, which is why the surround on the speaker is practically non-existent.




Did you ever have a close look at Pioneer's PRS mids? They used an alcantara style material for the surround to counter this. Lovely drivers if you've not listened to them, a side by side comparison to the DLS Iridium (twice the RRP) and 10 or 11 of us out of 12-13 prefered them (Dealers at the product launch)



asawendo said:


> Wow is it 5" midrange? Very beautiful teardrop spheres shape and exquisite craftmanship.


If they're the same as the drivers in the lower spec'd systems without the tear drops they're 6-7" (Alpine UK has these in one of their test rooms for a reference system-though their chief tech isn't a fan of the B+W metal dome tweeters)


----------



## b&camp

Earl Zausmer ran those mids in pods on his dash in the last iteration of his red BMW, with B&W 15s in the floor.


----------



## The Baron Groog

^I've seen someone on here planning on the same, forget who/where/when!


----------



## trumpet

bloobb said:


> i dont know if anyone else had a harshness issue from tweets in their face on their dash? my solutuon; i took my styrofoam balls and faced the tweeters directly into corner of the glass and dashboard, facing 180 degrees off axis.
> 
> better then seeing titties for the first time.


:laugh:

I took a look at a link someone shared in this thread to a crafts supply company. These ball knobs caught my eye: 2" Ball Knobs / Wooden Doll Heads

I'd have to drive 2 hours to the nearest Michaels so I'm more keen to buy online.


----------



## Zbebop

Have you installed the plastic bowls over your car speakers? 

I'm curious how it sounds in a typical car door. Would their be any potential damage to the speaker?


----------



## pocket5s

b&camp said:


> Earl Zausmer ran those mids in pods on his dash in the last iteration of his red BMW, with B&W 15s in the floor.


Was that the BMW that had them motorized so they came up out of the dash? Fom the mid 90's or so? If so I got to listen to that car at one of the finals. He seemed like a good guy, took the time to explain how it all worked and how they were positioned and all that. As I recall he had a laser pointer where he had you look in the rear view mirror so you could align your seating/posture so the laser was aligned right to your ear. 

For some reason I thought they were 13's in the kicks but that was a long time ago. I remember reading about the install and all the work that went into it.

BTW Mr. Bateman, I spent the better part of a few hours reading all your work on your horn experiments. Fascinating stuff...


----------



## trumpet

I took a walk through the small local hardware store after work. I had thought about using rubber toy balls for the tweeter spheres, and I picked up a pair of dog toy tennis balls. It looks like they'll be perfect for my flush mount cups once I cut a slice out for the 1-13/16" hole required. My Dash Designs dash mat will be arriving tomorrow, so if I get that put in I want to try moving my tweeters from the kick panels up onto the dash in the spheres.


----------



## Jamaican

hey!, im from jamaica....saw the forum and loved it..

ive always wondered where to put ma tweeters as im into loud sound....the bullet tweeters are way to big and refuse to cut ma door.....sooooo...i got some floats, the ones u use in the valve mechanism of ur toilet....and the small shaft to the back has the metal in it..perfect to mount using a nut and a washer.

my cam sux! will post better pics tomorrow


----------



## Jamaican

who wants to give me some ideas?.....im not sure what to stuff inside of it.

my plan is to use some primer on it after i sand it then spray paint it maybe matte black....

ill take a pic of my car tomorrow. my next issue is i dont kno how to hold the tweeter in place once its inside.....i was considering to use some brackets and bend them into the shape of the inside...but thats alot of stress


----------



## trumpet

Jamaican, we need to see pictures of the tweeters with the cups.

Here's what I did in 10 minutes with a knife and a sanding drum on a Dremel. I'm not sure if the diameter of the ball is large enough for the best effect of reducing diffraction. I might try again with a hole sized only for the tweeter. I think the friction fitment might be good enough for this to work without glue or other fasteners.

I'm stoked about what the pink will do for ess-que.


----------



## dietDrThunder

Grocery stores are all stocked up with Easter stuff now...at least down here in TN they are. I bought a bag of 36 plastic eggs for $5. As I was actually on a mission to find such stuff, I also bought a few styrofoam solid spheres in different sizes (cut/hollow out, cover w/ material?), and some larger eggs that would fit a 3 1/2" driver.

I'm going to take Wed. as a work-on-my-car day, so my plan is to move my tweets (HAT Imagine) from the OEM door spots to egg pods on the dash, among a few other things. I'll post up results if anyone is interested. Right now my imaging is absolute crap, so I admit I have high hopes for this approach.


----------



## dietDrThunder

trumpet said:


> Here's what I did in 10 minutes with a knife and a sanding drum on a Dremel. I'm not sure if the diameter of the ball is large enough for the best effect of reducing diffraction. I might try again with a hole sized only for the tweeter. I think the friction fitment might be good enough for this to work without glue or other fasteners.
> 
> I'm stoked about what the pink will do for ess-que.



Aww...I saw these exact toy tennis balls when I was out on my quest (see post above) and I passed, thinking that the eggs were a better bet. Now that I see/read your post, I think I was wrong about that. It did not occur to me that I might be able to affect a nice friction fit in the tennis ball and obviate the need for glue/silicone/whatever.

Nice!


----------



## dietDrThunder

Ok, so I tried a few different methods, including the tennis balls, and I settled on what you see below. The balls are EPS (expanded Poly styrene) that is stiff and firm. It's essentially the same stuff you'd find in a motorcycle helmet. I got these at Hobby Lobby for a few bucks.

They are very nice to work with, and sculpt easily with a dremel sanding drum. I was very happy with them, but I jacked up the finishing process so the end result doesn't look great. I am confident that the set that will replace them (next week probably) will look great. Some pics...


----------



## CrossFired

Does $2. per tweeter count?


----------



## subwoofery

CrossFired said:


> Does $2. per tweeter count?


Your tweeter cup doesn't help with diffraction... You need round overs on the sides for that (similar to the one a few pics above your post). 

Kelvin


----------



## CrossFired

I did not have diffraction in mind when I did that. These Pioneer tweeters sound harsh off axis, so I tried them at zero degrees and the harsh sound was gone.

They were on a surface mount before I glue them into the 45*/90* PVC elbows.

Diffraction comes from edges. The bezel of these tweeters are rounded, and there's little diffraction if any.

I do like the ball idea, I may try it, if I can find a 2.5" rubber/foam ball.






subwoofery said:


> Your tweeter cup doesn't help with diffraction... You need round overs on the sides for that (similar to the one a few pics above your post).
> 
> Kelvin


----------



## Patrick Bateman

WLDock said:


> Good read here folks!
> 
> I have wanted to do some type of spherical or egg shaped enclosure for awhile now. My thinking is....a spherical enclosure along with a mat might be about the best way to get a small mid on the dash.....as it has to be one of the toughest places in the car to put drivers....reflections everywhere. However, when you have a car with a wide and long dash it is worth a try to put speakers there as there are benefits to dash mounting as well.
> 
> I was looking at some of the Gallo and Orb sets to play with. However, I ended up picking up a set of the KEF KHT1000 "egg" speakers in the Picofote1 IPOD dock. Mated with a sub, these are some nice sounding small speakers. The enclosure and the Uni-Q driver do a nice job in these....even more so in the larger models.
> 
> I hope to do some type of sphere or egg shape enclosure for some 3" fullranges to be mounted on the dash...will see...



I wrote the following post about the Kef, over on diyaudio. Thought I'd repost it here, since it definitely fits the bill of a 'low diffrraction wide bandwidth' loudspeaker.

And, yes, I did buy ten of em 

I know there's a lot of people reading this thread that don't have the time to build a synergy horn, or the space that's required to get it to play down to 300hz. Here's an alternative you might consider:


















This is the satellite from a KEF KHT1005. Here's a list of reasons you might consider it in lieu of a Synergy horn:

1) after screwing around with Unity horns for over half a decade, I'm convinced that their fundamental goodness has little to do with their efficiency, and a LOT to do with the near-perfect transition from midrange to tweeter. *Basically a Unity/Synergy horn fools our brain into thinking it's one wide-bandwidth driver.*
2) Once you hear this done properly, conventional two-ways will never sound the same; I can't listen to a conventional two-way without *immediately* knowing that something is wrong. Literally the second I walk into a room.
3) The KEF UNI-Q isn't perfect, but it has a LOT of the Unity goodness. I think this is due to (you guessed it) the near-perfect transition from midrange to tweeter. This is especially notable on vocals and percussion.

































4) One way to determine if a loudspeaker has some of that Unity goodness is to look at the polar response. The graph above shows the polar response of two loudspeakers. The first is a conventional two-way (Focal Chorus 807V) and the second is a Kef UNI-Q (Q900).

Note how the transition from the Kef's midrange to tweeter is nearly perfect? To the microphone, it seems to be one driver. *There's a little 'wiggle' at 5khz where the midrange hands off to the tweeter.* But that 'wiggle' isn't as severe as the noticeable widening of directivity that occurs with the Focal two-way. (Note how the Focal directivity gets much broader at 4khz? That's because the tweeter is much smaller than the woofer, and so has wider directivity. In the Kef, the midrange cone acts like a waveguide for the tweeter, so the directivity change is verrrrrrrry slooooooow.


I couldn't find any directivity plots of the KHT1005 online, but I'm willing to bet it's comparable to the Q900 that was measured by Stereophile.









Here's a frequency response measurement of the KHT1005 satellite, from Home Theater magazine.


Last but not least, I think that one of the most important reasons that Synergy horns don't sound like regular speakers is that they're symmetrical. For instance, a regular two-way speaker is generally optimized for good horizontal directivity (if it's optimized at all.) *It's hard to get good vertical directivity from a two-way, due to the fact that the pathlength differences vary greatly depending on angle.* The Synergy horns don't have this problem; if you flip an SH-50 on it's side, the directivity is the same.

The same is true with a Kef UNI-Q, at least down to 300hz or so. (Synergy SH-50 is admittedly symmetrical down to a much lower frequency.)


If all of this has piqued your curiosity, the final icing on the cake is that the UNI-Q can be had for about $50 per satellite for the next 24 hours. *Newegg has them on their Black Friday flyer.* Even if you DIY, it's pretty easy to spend $50 per channel on a Synergy horn *crossover*, and that doesn't even factor in the cost of drivers, labor, failed experiments, and anti-depressants when your midranges don't work 

I'm putting my money where my mouth is, and buying ten 

Newegg.com - KEF KHT1005.2SE Home Audio Speaker System w/ White Satellite Speakers

promo code is EMCJJHF34 and it's good for 24 hours.

Happy Thanksgiving!"


----------



## invinsible

I tried sphere enclosure with Morel tweeters couple of years back. Here is another take on Sinfoni Midrange and tweeter in Sinfoni Demo Car made out of fiberglass. The mids sound much more open and airy.


----------



## co_leonard

Followed the basic "sphere" and "as few sharp edges as possible" and "radiused corners to avoid diffraction" in my A-Pillar build.














































Seems to have worked! Detailed and pinpoint soundstaging after RTA. 

More here: http://www.diymobileaudio.com/forum...sq-build-8th-gen-honda-civic-philippines.html


----------



## Datsubishi

Wow! That's quite a read. A lot of useful ideas Backed by some data and a lot of personal experiences. I am looking at changing things up in the near future and am very interested in trying this. What do I have to lose for $2 and some of my time? Some good looking and decently integrated installs as well. Thanks everybody.


----------



## Datsubishi

Does the issue arise from the sound waves coming directly off the diaphragm? Would a horn loaded tweeter/mid reduce this phenomenon or eliminate this issue all together?


----------



## co_leonard

Datsubishi said:


> Does the issue arise from the sound waves coming directly off the diaphragm?


I think (correct me if I'm wrong) as long as the diaphragm works like a pure piston (within its proper passband), this shouldn't be an issue.


----------



## Datsubishi

It looks like, from the picture on the first page, that the waves emitted from the dome reflect off any hard edge and even part way around the baffle. It has been said that the most important frequencies are 1khz plus so it's only really applicable to those bands. 

It looks like rounded baffles help, but an egg or sphere controls this almost completely. I read this whole article a while ago so it's not fresh in my head, but I don't remember reading anything specifically about a horn loaded speaker.


----------



## co_leonard

Datsubishi said:


> It looks like, from the picture on the first page, that the waves emitted from the dome reflect off any hard edge and even part way around the baffle. It has been said that the most important frequencies are 1khz plus so it's only really applicable to those bands.
> 
> It looks like rounded baffles help, but an egg or sphere controls this almost completely. I read this whole article a while ago so it's not fresh in my head, but I don't remember reading anything specifically about a horn loaded speaker.


I actually notice frequencies below 1kHz affecting the sound too. 

I have a test-CD with a recording of 5 instruments (played in this order):
- Voice
- Grand Piano note (sounds like C3)
- Acoustic Guitar strum
- Cymbal crash
- Triangle strike

There are 5 such tracks with those instruments.
- far left
- left center
- center
- right center
- far right

When heard through headphones or in a good (2-channel) home audio system, its easy to pinpoint the size (piano note sounds big compared to the triangle strike) and position of each instrument as the 5 tracks go from far left to left-center to center to right-center to far right.

Needless to say, it's a lot tougher to achieve this in a car.

I've heard one or two cars who's tuning focused on frequencies above 1khz. Like the piano note (fundamental is at around 130Hz) with harmonics that go up to around 2kHz. It sounded roughly in the correct position but the fundamental (midbass) was being pulled to the nearer speaker. 

But I digress. 

I don't think you have to worry about a horn-loaded speaker. Diffraction at the mouth is controlled by the curve of its throat. Like this:










Animated GIF taken from Wikipedia. 

The thing is, there are lots of types of horns out there. Tractrix, Multi-cell, Constant Directivity, Waveguides, etc... 

In the case of the USD Audio waveguide, I was told moving it a little bit at a time (left to right or by turning it to face the driver's seat) helps improve imaging and focus. 

Please correct me if I'm wrong.


----------



## Rob M

co_leonard said:


> I don't think you have to worry about a horn-loaded speaker. Diffraction at the mouth is controlled by the curve of its throat. Like this:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Animated GIF taken from Wikipedia.


That picture is misleading if you're considering diffraction (although it illustrates the impedance-matching properties of the horn quite well). There is indeed diffraction at the horn mouth discontinuity, and consequently a reflection that propagates back down the throat of the horn (where it's re-reflected).


----------



## Patrick Bateman

Has anyone considered doing cardioids up on the dash? A cardioid is basically a radiation pattern that's focused forward.









At CES I listened to the Gradient Helsinki, which uses cardioid radiation for it's midrange.

Obviously, the reason that cardioids would be nice for these spherical pods is because a cardioid would send most of the energy *forward* toward the driver, minimizing radiation towards the glass.

If any of you guys have been to a concert where it seemed like the bass 'dropped off' as you moved behind the stage, you were probably listening to a cardioid bass array. (They're becoming trendy in live sound; about six months back I went to a Bassnectar show where the bass easily dropped by half as you walked around the venue, and this was due to the cardioid radiation used by the subwoofer array.)

I'm just learning about cardioids, but here's some reading material:

Live Sound: Setting Up A Cardioid Subwoofer System: The Series - Pro Sound Web

_What applications is a cardioid subwoofer configuration appropriate for?

There are several situations where cardioid configurations can be useful.

For instance, when using conventional subwoofers with a wall behind them, the back wave will bounce back and cancellations will happen at the front (let’s not forget that subwoofers radiate in all directions).

In other words, the reflected wave from the back wall will arrive at a different time with respect to the direct wave, i.e., there will be a phase difference between them that will create destructive interference.

A cardioid configuration will radiate very little pressure backward, hence minimizing that effect._

DIY-dipole-1

2-way: Waveguide + Cardioid-like - diyAudio


----------



## Patrick Bateman

As noted in the last post, I was curious how a cardioid would work up on the dash.

I've never seen anyone do it.

Before 'making sawdust', I thought I'd run some sims. Here are the results (which are much better than I expected!)









First off, here is our woofer. The Dayton ND91. I picked this driver because it's about as large as you'd want to go up on the dash, before you start making the car 'undrivable.'









Here's the predicted response of the woofer.








I modeled the woofer in a PVC pipe that's 4" in diameter, and 4" deep. *Basically big enough to contain the woofer and no more.*









Here's the predicted polar map of the Dayton in that PVC pipe. *We see that's it's basically omnipolar below 3375hz.* (That's why the map transitions from orange to red at 3375hz, and it stays that way.)

We can do the math in our head - basically divide the speed of sound by the width of the PVC pipe:

13500 inches per second / 4" =
3375hz

So the pipe will constrain directivity until 3375, but after that, forget it. The sound simply wraps around.


----------



## Patrick Bateman

Now let's look at the same speaker, but in a cardioid enclosure.
Dimensions of the enclosure are *exactly the same as our sealed enclosure from the last post*. No difference at all, except I've opened up the back, to turn it into a cardioid.*









Here's the frequency response of the cardioid, versus an infinite baffle. Here we see that the bass is completely gone below 300hz, and there's a peak at 600hz.

Looking at the response, you might think "that looks like crap, why would I do that?"

The thing is - you can fix the response with EQ. But you can't use an EQ to change the directivity of your sealed box. *So basically we live with the lumpy frequency response of the cardioid, fix it with EQ, and gain some serious directivity.*









Here's the polar plot of the Dayton at 100hz. At this frequency, the radiation is basically dipole, due to the wavelengths being so long. (100hz is over eleven feet long.)









Here's the polar plot at 200hz. 200hz is about six feet long, so we're getting closer to the dimensions of our enclosure, and we're slooooowly transitioning from dipole to cardioid radiation. In the polar plot we see that radiation to the sides has been reduced by about eight decibels, and by about 2dB towards the back.









Here's the polar plot at 400hz. 400hz is about three feet long, so we're getting closer to cardioid. Response to the left and right is the same as the front, but radiation backwards is down by 3dB. (A reduction of three decibels is the same as reducing the watts going to the speaker by half.)









Here's the polar plot at 800hz. 800hz is about a foot and a half long, and now we're getting 'real' cardioid response. Response to the left and right is the same as the front, but radiation backwards is down by a full six decibels. (A reduction of six decibels is the same as reducing the watts going to the speaker by SEVENTY FIVE percent.)












If you're interested in experimenting with cardioids, you can get the software I used for free from here:

U & H Frame Woofer Worksheet

Once you mess around with it a bit, you'll notice a few things. First off, you need a fairly big pipe to get it to work at low frequency. BUT that's not a big problem for us in the car, because drivers up on the dash are generally small. Not too much of a need for cardioid radiation below 500hz or so.

You'll also notice that if you have EQ, you can 'dial it in' so that the response shape is flat. Basically add a bunch of EQ to the bottom end to flatten it out, then subtract some up high to do the same.

Last but not least, you'll want a driver with a LOT of excursion. And you'll want a highpass filter running, so you don't blow your drivers up.

questions / comments?


----------



## Hanatsu

Interesting. I'll try it out. Your ideas are creative as always 

I've become more and more interested in these things lately. Thanks again!

Sent from my Samsung Galaxy 3 via Tapatalk.


----------



## itsvel06

Cant wait to try this one out in my new install!!!!


----------



## andy cheah

xMplar said:


> here is sum of the pods i have used in my SPLer car and will most likly use simalar in my essquees car the tweeter sits almost perfect so the round over is almost perfect nt quite but almost i bought these fron a matew who found a place in maylasia who mkaes them out of full on fibreglass in like a 1" 2" 3"
> 4" 5" 6" 7" 8" 9" 10" and so on you get the point
> 
> they are called podlets and in bigger versions call bass bombs trhere is also some other types in difernt shapes
> and the have a roundin lip so you can actually screw into the lip if needed or glue to it whatever takes you fancey
> 
> Ren
> xMplar


Hi, mind telling me where in Malaysia you bought this. Tq


----------



## keep_hope_alive

Patrick Bateman said:


> questions / comments?


Thanks for continuing to share and provide excellent information.


----------



## bicycle_wreck

After looking at keep_hope_alive's posts, I decided to do something very similar for my CAL 20's this weekend.

My dad is also a car audio enthusiast, so he agreed to help me out and lend his machining skills. Just had to steal him away from my mom for an afternoon.

Results thus far:


----------



## IIGQ4U

Looking good!


----------



## bicycle_wreck

Thanks! Here they are as of this morning. Letting them harden for a couple of days before mounting them. Looks like I'll have to re-tap the lamp rod holes as the fill primer 'filled' up some of the threads. LOL.


----------



## Oscar

bicycle_wreck said:


> After looking at keep_hope_alive's posts, I decided to do something very similar for my CAL 20's this weekend.
> 
> My dad is also a car audio enthusiast, so he agreed to help me out and lend his machining skills. Just had to steal him away from my mom for an afternoon.
> 
> Results thus far:


sweet work right there


----------



## bicycle_wreck

Little follow up here. Still don't have the tweeters mounted in the pods.


----------



## keep_hope_alive

Nice work guys!

Sent from my DROID RAZR using Tapatalk 2


----------



## bicycle_wreck

Tweeters mounted. Haven't listened to them in the new pods yet as I'm still working on other aspects of the install.


































I will get some better pics today in the daylight. The flash on my phone is not all that great and makes everything look yellow.


----------



## WrenchGuy

hmmmm this may be the very reason why Im so astonished at the initial and somewhat crude (un-tuned) state of my pillar pods.

I did spheres for the whole diffraction issue but never put the thread worth of thought into it. They just sound so damn clean I was like wtf is peoples problem with this location...lol

When I pull the dashmat out from under them is when they error. Between the Spheres and dashmat it sounds very good so far.

I did the smooth foam trick and it works awesome.


----------



## maqupaqu

Patrick Bateman said:


> Has anyone considered doing cardioids up on the dash? A cardioid is basically a radiation pattern that's focused forward.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> At CES I listened to the Gradient Helsinki, which uses cardioid radiation for it's midrange...


Hi Patrick,

I have tried these with Tang Band W3-1364SA 3" Bamboo Cone Driver's. I made these enclosures for testing purpose from steel. Cylinder volume about 0,5l and there was 142 pieces 3mm holes. My friend tested these with proper testing equipment with different angles and the results were impressive. We tried with different wrapping materials and filling materials also. I have testing data somewhere in HD, but would not find those right now. 

Funny thing is that I'm from Helsinki  Got this idea about 3 years ago while watching Gradient Helsinki speakers. After this Finnish SQ competition team "DLS Revolution" tried cardioid radiation mid's but ended up to use basic sealed enclosures.


----------



## Finesa

Fantastic wooden globes there, I played with the same install today for about 3 hours before my car battery to go dead. Didn`t buikd the spheres, instead bought a pair of Canyon made computer speakers that had spherical enclosures and sounded horrible by all means, drilled them with a circular saw and got a pair of SB26STCN inside. I did then place them in my BMW 5-series and after some play using a mic and HOLM, the best location seemed the dash just above the center heating outlets, as shown in one of the first pics by Patrick. Indication was for no relfection ( one that matters ) down to 750Hz. When I moved them around, the second best place
turned out to be deep into the corner of the windshield, going up to 1.2Khz which is still perfectly acceptable for me. When I listen to them, I fell the soundstage move forward and its definitely not how it should sound, but measures well. Funny thing is that where I like them, about half an inch away of the windshield and not far away of my dials, measurements indicate reflections up to 3.4Khz with mic at my ears.
Tweeters are placed into D = 2.5" spherical enclosures and have short waveguides.
Have the battery recharging tonight and will try again Tuesday.


----------



## Babs

These aren't $2 by any means but whata ya think?

http://www.dakotadigital.com/index....t_id=254/category_id=622/mode=prod/prd254.htm










Looks like a SEAS Neo might fit ok. 

I'm grasping at straws as I'm realizing the stock spots in my 08 Civic Sedan just isn't going to cut it anymore.


----------



## Golden Ear

Looks cool, but how would you mount the tweet to it? I'm thinking you could drill and tap screw holes around the outside for set-screws.


----------



## Babs

Golden Ear said:


> Looks cool, but how would you mount the tweet to it? I'm thinking you could drill and tap screw holes around the outside for set-screws.



Maybe some kind of press fit?


----------



## Golden Ear

Babs said:


> Maybe some kind of press fit?


That would keep it real clean lookin huh? Nice


----------



## Patrick Bateman

Babs said:


> These aren't $2 by any means but whata ya think?
> 
> 2-1/16" Gauge Cups
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Looks like a SEAS Neo might fit ok.
> 
> I'm grasping at straws as I'm realizing the stock spots in my 08 Civic Sedan just isn't going to cut it anymore.


Spherical is better than cylindrical. Something the size of a tennis ball works pretty good.


----------



## seafish

Has anyone tried the old Apple/Harman Kardon pod speakers in a car audio install??


----------



## 94VG30DE

Yes. Searching the thread for iMac yields this. 

Among which are these posts: 
http://www.diymobileaudio.com/forum...mprove-your-soundstage-$2-22.html#post1471286
http://www.diymobileaudio.com/forum...mprove-your-soundstage-$2-21.html#post1469359
http://www.diymobileaudio.com/forum...mprove-your-soundstage-$2-19.html#post1345473
http://www.diymobileaudio.com/forum...mprove-your-soundstage-$2-19.html#post1345417
http://www.diymobileaudio.com/forum...61-improve-your-soundstage-$2.html#post822863 

But most importantly, some of the links I posted are from _the first page_ of the thread. It's not just lazy to skip reading the whole thread, but you will actually miss a ton of good content and discussion. Lot's of threads on this forum reference the diffraction discussions in this thread. Read up, it's great stuff to munch on.


----------



## seafish

94VG30DE said:


> Yes. Searching the thread for iMac yields this.
> 
> Among which are these posts:
> http://www.diymobileaudio.com/forum...mprove-your-soundstage-$2-22.html#post1471286
> http://www.diymobileaudio.com/forum...mprove-your-soundstage-$2-21.html#post1469359
> http://www.diymobileaudio.com/forum...mprove-your-soundstage-$2-19.html#post1345473
> http://www.diymobileaudio.com/forum...mprove-your-soundstage-$2-19.html#post1345417
> http://www.diymobileaudio.com/forum...61-improve-your-soundstage-$2.html#post822863
> 
> But most importantly, some of the links I posted are from _the first page_ of the thread. It's not just lazy to skip reading the whole thread, but you will actually miss a ton of good content and discussion. Lot's of threads on this forum reference the diffraction discussions in this thread. Read up, it's great stuff to munch on.


oooops...THANKS...I knew I had read somewhere on diyma about these cubes, just didn't realize that it was THIS thread!!!

I have 2 pairs of thos speakers...gonna play with them when I install my DRZ9255 and ESP3 center.


----------



## Finesa

Golden Ear said:


> Looks cool, but how would you mount the tweet to it? I'm thinking you could drill and tap screw holes around the outside for set-screws.


You can cut the tweeter flange using a circular saw then apply some high temp hot melt glue on the back of it and press it quickly into the enclosure. The hole for the cabling should be drilled already by this stage.

An update, I played for several days with Horn response and no matter how many tweaks I tried, I always came back to a design similar to the one by Sausalito Audio Labs. Its what they call an acoustic lens. There are several differences with the one I designed which is intended to act as a constant directivity beam focusing reflector. I tried to design it so it does not radiate 180 degrees as the original Sausalito design, but to focus the sound into a beam that would create a small sweet spot where the driver is. I find this a better approach as reflections are among the worst enemies I have encountered in the car environment. The old JBL lens that were used in theatres to focus sound on the rear rows looked to me like a better alternative but look horrible on a dashboard. The one I simulated has a much wider baffle to reduce back reflections to the windshield, the tweeter has a small vertical waveguide ( tweeter is mounted vertically ) and the reflector is larger with an equal height as compared to the internal tweeter cavity ( I believe the Sausalito design has a larger cavity and a smaller spike-shaped reflector ). This design, at least based on simulations with Horn response should concentrate the beam in the 1-4Khz specrum where at 5khz there is lobbing which would disappear at 6Khz and above. Not sure about how the Sausalito labs lens work but to me they look like they`re intended to control the directivity at a higher frequency.

I will post a pic of the reflectors later as I`ve left the engineering plastic rod with a guy to carve them out.


----------



## MAIDEN69

Decided to go the tweeter sphere route for my new 3-ways. Not sure if it will help any with the huge bezel of these tweeters. Or if a sphere would help a tweeter designed for huge off-axis performance. Still need to sand the face down a tad more to get the ball to sit perfect against the edge of the tweeter bezel.
I may have been better off going with a larger diameter ball but this was the best I could find at the local hobby store. Think these are 2.5". I may order some online in a 3"
See which ones look the best. 
I plan to start off with a stand off mount on the a-pillars and see how it looks and sounds.
If it just doesn't look good or doesn't much help the imaging, I will then create an eye socket into the a-pillars so they can be mounting into the pillar and be able to rotate like an eyeball. I like the sphere look so either option will give me the spherical look I'm after. But if the spheres off the pillar ends up sounding sweet enough, I will leave them as long as it looks good.
While these don't create a perfect sphere when the tweeter is mounted, this has to be better than mounting of a flat baffle.


----------



## Babs

That looks pretty cool! I bet they'll look great if you're flushing them up to that bevel line on the flange.

I've been pondering over such a thing myself for a set of NVX XSPTW tweets with a 2.9" (darn near 3") OD at the flange. 

How'd you make them? What are they? Wood balls?


----------



## MAIDEN69

Wooden spheres. Think for doll heads or something. I found them at my local Michaels craft store. Slim pickin's though. Only had two potential usable sizes. The other is smaller than this one so it wouldn't work.

I used a 1 3/4" hole saw. Then tried a 1.5" paddle bit to take out the remaining material. No go. I ended up having to drill it out and just keep chipping away at it. A pain without proper tools but not too bad. 
And if I had a mill to cut these out perfect, I would flush the bezels into the edge. No way I can do it by hand and end up with a perfect edge. This will have to do.


----------



## Patrick Bateman

MAIDEN69 said:


> Decided to go the tweeter sphere route for my new 3-ways. Not sure if it will help any with the huge bezel of these tweeters. Or if a sphere would help a tweeter designed for huge off-axis performance. Still need to sand the face down a tad more to get the ball to sit perfect against the edge of the tweeter bezel.
> I may have been better off going with a larger diameter ball but this was the best I could find at the local hobby store. Think these are 2.5". I may order some online in a 3"
> See which ones look the best.
> I plan to start off with a stand off mount on the a-pillars and see how it looks and sounds.
> If it just doesn't look good or doesn't much help the imaging, I will then create an eye socket into the a-pillars so they can be mounting into the pillar and be able to rotate like an eyeball. I like the sphere look so either option will give me the spherical look I'm after. But if the spheres off the pillar ends up sounding sweet enough, I will leave them as long as it looks good.
> While these don't create a perfect sphere when the tweeter is mounted, this has to be better than mounting of a flat baffle.


The donut shape on the front actually helps reduce diffraction. So the sphere just takes it a bit further.

With a width of 2.5" the sphere will reduce diffraction from about 5400khz down to the xover point.

Looks good!


----------



## Patrick Bateman

Finesa said:


> You can cut the tweeter flange using a circular saw then apply some high temp hot melt glue on the back of it and press it quickly into the enclosure. The hole for the cabling should be drilled already by this stage.
> 
> An update, I played for several days with Horn response and no matter how many tweaks I tried, I always came back to a design similar to the one by Sausalito Audio Labs. Its what they call an acoustic lens. There are several differences with the one I designed which is intended to act as a constant directivity beam focusing reflector. I tried to design it so it does not radiate 180 degrees as the original Sausalito design, but to focus the sound into a beam that would create a small sweet spot where the driver is. I find this a better approach as reflections are among the worst enemies I have encountered in the car environment. The old JBL lens that were used in theatres to focus sound on the rear rows looked to me like a better alternative but look horrible on a dashboard. The one I simulated has a much wider baffle to reduce back reflections to the windshield, the tweeter has a small vertical waveguide ( tweeter is mounted vertically ) and the reflector is larger with an equal height as compared to the internal tweeter cavity ( I believe the Sausalito design has a larger cavity and a smaller spike-shaped reflector ). This design, at least based on simulations with Horn response should concentrate the beam in the 1-4Khz specrum where at 5khz there is lobbing which would disappear at 6Khz and above. Not sure about how the Sausalito labs lens work but to me they look like they`re intended to control the directivity at a higher frequency.
> 
> I will post a pic of the reflectors later as I`ve left the engineering plastic rod with a guy to carve them out.












Check out my saw lenses over on Diyaudio. They work and they sound great. Glad to see more people checking them out!

The neat thing about the lenses, which a lot of people don't realize, is that they create a 'cardioid' pattern. So they're great for a dash, where you don't want sound radiating backwards. I didn't realize they were cardioid until I built and measured a few.


----------



## Orion525iT

Finesa said:


> I tried to design it so it does not radiate 180 degrees as the original Sausalito design, but to focus the sound into a beam that would create a small sweet spot where the driver is. I find this a better approach as reflections are among the worst enemies I have encountered in the car environment. The old JBL lens that were used in theatres to focus sound on the rear rows looked to me like a better alternative but look horrible on a dashboard. The one I simulated has a much wider baffle to reduce back reflections to the windshield, the tweeter has a small vertical waveguide ( tweeter is mounted vertically ) and the reflector is larger with an equal height as compared to the internal tweeter cavity.


Your not the only one. Can you post the sims? My idea was to use a SAW lens but shape the output more forward, but...



Patrick Bateman said:


> Check out my saw lenses over on Diyaudio. They work and they sound great. Glad to see more people checking them out!
> 
> The neat thing about the lenses, which a lot of people don't realize, is that they create a 'cardioid' pattern. So they're great for a dash, where you don't want sound radiating backwards. I didn't realize they were cardioid until I built and measured a few.


I have been fascinated by cardioid, but I could not find a reasonable way to use them in vehicle. So this is interesting, especially because I had hypothesized that if cardioid was not practical, that the SAW lens might be the next best thing for my goals. The key would be to figure out how that pattern is generated based on the geometry of the lens, and then tweak from there based on location and desired coverage. I would have thought the cardioid radiation pattern was generated by the way the sound wraps around the lens, but your picture does not seem to pay much attention to that aspect.


----------



## Patrick Bateman

Orion525iT said:


> Your not the only one. Can you post the sims? My idea was to use a SAW lens but shape the output more forward, but...
> 
> 
> 
> I have been fascinated by cardioid, but I could not find a reasonable way to use them in vehicle. So this is interesting, especially because I had hypothesized that if cardioid was not practical, that the SAW lens might be the next best thing for my goals. The key would be to figure out how that pattern is generated based on the geometry of the lens, and then tweak from there based on location and desired coverage. I would have thought the cardioid radiation pattern was generated by the way the sound wraps around the lens, but your picture does not seem to pay much attention to that aspect.












The cardioid radiation is basically due to the spherical enclosure that the tweeters mounted in. If it was flat and wide like a conventional loudspeaker, the sound would radiate forward only. Because it's curved, a fraction of the sound goes *backwards.* Not 100%; just a fraction. Hence, cardioid.

Something similar likely happens with the spheres discussed in this thread. But I started this thread mostly as a good; the spheres sounded good but I never did any polar measurements.


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## dileepsv

very nice!


----------



## Babs

MAIDEN69 said:


> Wooden spheres. Think for doll heads or something. I found them at my local Michaels craft store. Slim pickin's though. Only had two potential usable sizes. The other is smaller than this one so it wouldn't work.
> 
> I used a 1 3/4" hole saw. Then tried a 1.5" paddle bit to take out the remaining material. No go. I ended up having to drill it out and just keep chipping away at it. A pain without proper tools but not too bad.
> And if I had a mill to cut these out perfect, I would flush the bezels into the edge. No way I can do it by hand and end up with a perfect edge. This will have to do.


Nice! I know where I'm going this afternoon. 
For milling out the innards, and for possibly helping you flush the flange in, a dremel can be a great tool. Trick is the flushing in is delicate work. Easily screwed up by a hand tool as opposed to something like a table-top router or lathe. 

If I were doing that, I'd have the ball solidly viced down, and using a hand brace to very slowly and gently whittle out wood inside a penciled in circle... OR here's an idea.. Ball mounted to a hole in a piece of MDF from below, perfectly flat so you could put a router or a dremel with router face to it, and route out your flushed in space to a nice plane within the frame circle.

Fun DIY stuff though for folks that want to go a different route than glassing in a pillar. 

I had thought even of combining the two methods though (glassing to a pillar or molding part, and a sphere). Having a rounded over 'hemisphere' of sorts as a more shaped tweeter ring then cloth, CA glue, bondo shaping, etc, smoothing in a rounded over shape and blending into the pillar.


----------



## MAIDEN69

To mill it out would be the proper way I would think. When you buy these, they come with a flat spot on them that has a pre-drilled hole. Obviously you use the hole as your guide for the paddle bit or hole saw. Problem is, the ball actually has a 1/2" or so hole in it and is filled with maybe wood putty and then gets the little pilot hole. So when you start boring into it, the putty/filler crap busts apart and you lose your guide. That's why I couldn't use the paddle bit. Had the balls been solid, I think it would have worked fine. 
I could have first used a paddle bit the size of the outer tweeter bezel to create a rabbited edge for the tweeter to flush into the ball. Then the hole saw for the tweeter body. Then a smaller paddle to remove the center material. 
Another option for me now would be for me to just tape off the tweeter and use some body filler to mold the ball edge around the tweeter bezel creating the flush mount. I may end up doing this as my plan is to paint them anyway.


----------



## MAIDEN69

Quick plasti dip on one of the spheres to see how they look.
Looking at them, I wish I could countersink the bezel into the ball!!! Think I need bigger balls. lol


----------



## MAIDEN69

Patrick, would I benefit by using a bit larger diameter sphere? This one was 2 3/8"
What about a 2.75" or 3" sphere?


----------



## Babs

I think for looks at least it looks fabulous. I'd roll with it and see how they sound.

You could cheat and do a layer of glass and/or filler around them.


----------



## MAIDEN69

Babs said:


> I think for looks at least it looks fabulous. I'd roll with it and see how they sound.
> 
> You could cheat and do a layer of glass and/or filler around them.


Believe me, thought about that and may still do it. But I finished the second one this morning and fine tuned the seating of them into the ball some more and got it looking even better. They blend into the ball better now so I may just leave them.

Now to the mids...


----------



## lewiseyers

Patrick Bateman said:


> In part one I described why reflections are a BAD thing, some options for controlling them, and how this will improve your soundstage.
> 
> Now the practical part, how to build it.
> 
> Let's say we wanted to diffuse sound down to 100hz. The speed of sound is 13500in/second. So to diffuse sound down to 100hz, we'd need a spherical enclosure that's 42.98" in diameter. Here's the equation:
> 
> required sphere radius = 13500 / lowest frequency / 2 / pi
> required sphere radius = 13500 / 100 / 2 / 3.14159
> 
> Hmmm that's not gonna work is it?
> 
> Psychoacoustic studies have shown that matching frequency response above 1khz is more important than *below* 1khz.
> 
> Based on that we could reduce our sphere from almost four feet to a little over four inches. At that size, it starts to get practical to do this in the car.
> 
> My local craft store sells some clear plastic spheres, I have no idea what they're for, but they work for spherical enclosures. They're 8cm in diameter and they're less than a buck. An 8cm sphere will control diffraction down to 1365hz.
> 
> Here's a picture of a vifa ring radiator in one of these 99 cent spheres:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> So there's the math above, and they're readily available at craft stores. In the pic I'm using half a sphere. You'd want to take the entire sphere and cut it down to a point where it blends seamlessing with the diaphragm. The way that B&W does it is just about ideal:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> The teardrop shape is better than a sphere; it flattens out the frequency response and reduces diffraction. My local craft store has egg shapes, but they're not big enough for this application. YMMV




What about a half tennis ball being rubber surely this will act like sound deadening so you only get the sound of the speaker,.

im proberbly well wrong though!!


----------



## MAIDEN69

Someone already did some with tennis balls. It's either in this thread or this one.
Tweeter Spheres - pics and examples

Edit, the tennis balls are in this thread. Look at posts #60 & #540 in this thread. I would tell you the pages they are on but that would depend on your settings for how many posts per page so yours may be different than mine.


----------



## Finesa

Ok, was busy in the last weeks and haven`t done much even If I had the lens ready. I completed the install today and they`re in my car loaded with SB26STCN tweeters. Problem is, as I set on the head unit, my battery died so will post measurements tomorrow.

This is what I came up with so far ( see attached photos ). The first shows the passenger side lens installed where the second one shows the lens split in two before the final assembly.

They were actually quite easy to produce - I got some solid engineering POM plastic rod, did the curves using circles so the turner can carve it out and he did quite well. Those are larger than the B&O installed ones and have some differences which I simulated with Hornresponse - the tweeter has a short waveguide that modifies the radiation pattern in the vertical plane and the inner lens encompases the whole waveguide, I believe the initial Sausalito design asked for a tweeter of the same size as the inner lens where the B&O installs I have seen have a fraction of the dome blocked which I was afraid may lead to phase cancelations and create compression zones close to the soft dome just over the surround. This is not perfect as if I did the inner lens to tansform into the outer conical diffraction top in a circular manner, the top would be very large. This one is larger than the B&O designs too as I needed ot use a crossover point of 1.95Khz. Baffle is larger too to reduce window diffraction and allow me to place them further of it.

PS: To Patrick, I have seen your designs on diyaudio, I`m on there since 2006 but using my real name


----------



## Finesa

Ok, battery`s back on duty and today played some tracks. It sounded good and horrible at the same time. The placement of instruments and vocal were better than the spherical enclosures and moving my head up changed the tweeter dispersion a lot so the lens did their trick. 

Then came the problems - too much treble energy in the high midrange, on some moments it sounded like a Seas Magnesium cone brakeup and this was unexpected. I took my measurement rig out and the reason became evident ( see the photos ). The lens created a massive spike at 2.5Khz followed by a dip at 5.5Khz, both with great magnitude. At the same time treble above 10Khz was greatly reduced - I fed the tweter directly with no crossover/resistor and its power response was still weaker than the SB acoustics midwoofer ( mid rated at 90db/2.83V, tweeter at 92.5db/2.83V ). Something really bad was happening in this diffraction device. With two words, it sounds horrible. The old crossover that I used with the spherical enclosures is obsolete and I came up with a way to control that ragged response but this would require a higher crossover point and a 3rd order electrical filter. Another feature that made me curious is the rise in the 2nd and 3rd harmonics at 1Khz and 2.5Khz. Phase on the other hand exhibited much more linear shape than with the spheres before and may allow good phase tracking even with a good null.

Red line: 4th order LR crossover that looks promising
Blue: raw response, 6db smoothing


----------



## Patrick Bateman

Finesa said:


> Ok, battery`s back on duty and today played some tracks. It sounded good and horrible at the same time. The placement of instruments and vocal were better than the spherical enclosures and moving my head up changed the tweeter dispersion a lot so the lens did their trick.
> 
> Then came the problems - too much treble energy in the high midrange, on some moments it sounded like a Seas Magnesium cone brakeup and this was unexpected. I took my measurement rig out and the reason became evident ( see the photos ). The lens created a massive spike at 2.5Khz followed by a dip at 5.5Khz, both with great magnitude. At the same time treble above 10Khz was greatly reduced - I fed the tweter directly with no crossover/resistor and its power response was still weaker than the SB acoustics midwoofer ( mid rated at 90db/2.83V, tweeter at 92.5db/2.83V ). Something really bad was happening in this diffraction device. With two words, it sounds horrible. The old crossover that I used with the spherical enclosures is obsolete and I came up with a way to control that ragged response but this would require a higher crossover point and a 3rd order electrical filter. Another feature that made me curious is the rise in the 2nd and 3rd harmonics at 1Khz and 2.5Khz. Phase on the other hand exhibited much more linear shape than with the spheres before and may allow good phase tracking even with a good null.
> 
> Red line: 4th order LR crossover that looks promising
> Blue: raw response, 6db smoothing











Your lens looks too short to me. With a width of 1" the height should be about 2" iirc. Yours appears to be about 2" wide so the height would be close to 4" tall.

















Here's a pic and the polar response of mine









Here's the response of the lens with wool for damping

From here:
Soundbar Bateman Style - Page 5 - diyAudio


----------



## Finesa

I thought about using modeling clay to experiment with different lens types as its easier, any cons to it?


----------



## Patrick Bateman

Finesa said:


> I thought about using modeling clay to experiment with different lens types as its easier, any cons to it?


There's only one 'correct' shape.

Basically at high frequencies, even a small pathlength difference will create comb filtering.

So to get the sound to make this 'hard' 90 degree bend, there isn't a lot of room for error.

But these are shockingly easy to build really. 
I know you can get excellent results with a 3D printer, but even if you make them out of wood it's very simple to build these.










Here's the diagram for a 1" radiator. (Note that most tweeters that are advertised as being 1" are often bigger, so make sure that the radiator really and truly is 1", it makes a difference.)

You literally drill four holes in wood and you are done.

If you want to sand and fill it, it will extend the response a little bit.

There's a drill bit for sale on eBay that's about the right size, so if drilling four holes is too time consuming, the drill bit from eBay can do it in one pass 










Here's the results in the real world.

Let me know how it sounds if you build one! Note that you must have a microphone to build one of these, or at the very least get one of those free apps for your cel phone that's a real time analyzer.

The reason you *must* have a mic is that the lens 'spreads' out the high frequencies, and due to that, you have to apply EQ to make it flat on axis.

In other words, if you build one of these and the tweeter sounds like it's "dull", the reason is because you need to EQ it up. This is fundamental to the design; there's no way to avoid it.


----------



## 1Sik1500

Kind of an old thread but lots of great info here. Just wanted to share what i came across after seeing another member in this thread get some 3d printed mounts. These showed up on the site. looks to be for Seascan speakers? 

Seas tweeter dashboard mounting pod by Kkallioj on Shapeways


----------



## Babs

Wasn't exactly simple but sounds great I think. Crossed at 2434hz on axis. Was quite a fun project. Now trying passively to sell. Wanna try my hand at a full pillar 3-way. 


Sent from iPhone using Tapatalk


----------



## cajunner

I think that if people who went through the trouble of making their own pods from scratch and "seat of pants" theory, got their pods measured then scanned and put into a database, the next person could just pay for the rights to print, get the scans' digital files, and go to the nearest commercial 3-D printer shop for their own.

I know it would be cool to do a bunch and sell them for a profit, but the whole open source thing would jump if people got something for it.

I'd like a well-done mount for the Chevy p/up series, on-dash and using Sausalito lens with a well regarded driver that didn't break the bank. Pay 10 bucks for the laser scan files, and bring them to the local library where for a few cents a gram I can have them printed, in color and with UV stabilized plastics or ready to glue with leather cut-out dimensions for stitching patterns.

that would be awesome if I could spend 10 bucks on a design, 10 bucks on leather, 10 bucks on plastic, and end up with fully optimized dash pods that look like they belong in the vehicle using speakers costing less than 100 bucks the pair...


----------



## Patrick Bateman

cajunner said:


> I think that if people who went through the trouble of making their own pods from scratch and "seat of pants" theory, got their pods measured then scanned and put into a database, the next person could just pay for the rights to print, get the scans' digital files, and go to the nearest commercial 3-D printer shop for their own.
> 
> I know it would be cool to do a bunch and sell them for a profit, but the whole open source thing would jump if people got something for it.
> 
> I'd like a well-done mount for the Chevy p/up series, on-dash and using Sausalito lens with a well regarded driver that didn't break the bank. Pay 10 bucks for the laser scan files, and bring them to the local library where for a few cents a gram I can have them printed, in color and with UV stabilized plastics or ready to glue with leather cut-out dimensions for stitching patterns.
> 
> that would be awesome if I could spend 10 bucks on a design, 10 bucks on leather, 10 bucks on plastic, and end up with fully optimized dash pods that look like they belong in the vehicle using speakers costing less than 100 bucks the pair...


Works for me, I'll start a thread.


----------



## Patrick Bateman

Here's some JBL 400GTIs I threw into spheres.

I did one thing different this time arround, which is that I made the back of the enclosure a pyramid shape









The primary reason I did that is so you can push the sphere back farther towards the windshield. But it's also a tip of the hat to The KLF and Tom Danley. (Danley did the Art Bell show a few times, talking about the pyramids at Giza, and the Unity horn was inspired by them.)


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## Finesa

Lots of time has passed but I have done exactly nothing on the lens  It seems the lens needs to be quite tall as you suggest, almost twice the dome diameter. That makes it too large or requires a smaller dome as what B&O use in the new E-class. Problem is, the small dome requires the crossover to be pushed much higher and this doesn`t please my ears at all. During my experiments I found that the lower the crossover frequency, the better the soundstage. I had some SB26STCN at disposal which are among the hifi dome tweeters allowing the lowest crossover point I know of, pushing the crossover down to 1.9Khz was enough to fool the brain most happens in front. The woofers I use are SB15MFC which start to exhibit beaming at around 2.8Khz. It was a must to use a large dome, or even better - a fullrange but with these lens it is not possible due to lens size.
Placing the tweeter around has not led to significant reduction in reflections and the use of a properly sized waveguide doesn`t seem to be practical either. 

One thing I thought about was the possibility to place the tweeter in the pillar/windshield corner and use a focusing lens instead of the more traditional approaches. This seems feasible in a car and may not look that bad. Have you tried this so far and with what results? I am aiming at the type below which, I believe, was introduced by JBL in the 50s:

https://stereonomono.files.wordpress.com/2013/07/blogjbl4343e.jpg


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## Patrick Bateman

Finesa said:


> Lots of time has passed but I have done exactly nothing on the lens  It seems the lens needs to be quite tall as you suggest, almost twice the dome diameter. That makes it too large or requires a smaller dome as what B&O use in the new E-class. Problem is, the small dome requires the crossover to be pushed much higher and this doesn`t please my ears at all. During my experiments I found that the lower the crossover frequency, the better the soundstage. I had some SB26STCN at disposal which are among the hifi dome tweeters allowing the lowest crossover point I know of, pushing the crossover down to 1.9Khz was enough to fool the brain most happens in front. The woofers I use are SB15MFC which start to exhibit beaming at around 2.8Khz. It was a must to use a large dome, or even better - a fullrange but with these lens it is not possible due to lens size.
> Placing the tweeter around has not led to significant reduction in reflections and the use of a properly sized waveguide doesn`t seem to be practical either.
> 
> One thing I thought about was the possibility to place the tweeter in the pillar/windshield corner and use a focusing lens instead of the more traditional approaches. This seems feasible in a car and may not look that bad. Have you tried this so far and with what results? I am aiming at the type below which, I believe, was introduced by JBL in the 50s:
> 
> https://stereonomono.files.wordpress.com/2013/07/blogjbl4343e.jpg


As waveguide technology has evolved, you'll notice that just about everyone is selling waveguides that have ZERO sharp edges:









JBL


















B&O









Revel

etc...

You get the idea.

The reason that manufacturers are doing this is because they've figured out that sound waves aren't well behaved, they don't go exactly where they're supposed to go. When you have a loudspeaker with ZERO sharp edges, the enclosure seems to "disappear." It also sounds smoother.

All of this is measurable, but it's tricky to measure, because it's difficult to isolate the effect of diffraction and reflection which happens within a few thousdandths of a second.

But it's the reason this whole thread was started.









Anyways, this JBL design, from half a century ago, is based on the idea that sound will follow a strict path without any issue. Which it won't. 

If you look at phase plug design, you'll see that JBL has figured out that these concepts apply all of the way down to the surface of the tweeter dome; the new designs are way more "open" than the old designs.


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## NonSenCe

ohh.. dont post pictures of those finnish genelecs.. those are awesome and i want a pair. but cant afford em. 

ooh that aluminum case.. i remember stroking them with awe when he/they were presenting prototypes in some fair. 

-----
oh.. and because of this thread i bought Audax SP12 sphere speakers, antiques store had two of them for sale.

not sure what to do with them yet. will i keep them as is at home somewhere (speakers for the kitchen radio or something like that). will i keep them for "oldies/retro look" build i have planned in my old car. or i do i start fiddling with them, finding speakers to swap in them to see if one can improve them and see how they work.  

when i got them i just liked their retro vibe as is.


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## gijoe

Bringing this one back up. I'm sorry if this has been covered, but I haven't gotten through all 25 pages of this yet.

I bought some LPG tweeters with the flush mount kit, and picked up some 60mm plastic spheres from the craft store. The tweeters are a perfect fit for the hemisphere, they fit so perfectly that I don't think I can get a better fit by using a 3D printer to print new pods. 

The question I have though is regarding the advantage of a full/semi sphere compared to the hemisphere. If I were to use a larger sphere and cut off the face, I would eliminate the sharp edge, but I couldn't install a larger sphere closer to the windshield. The 60mm hemisphere will fit tighter into the corner of the dash. I also bought some larger spheres, and I intend to shave the faces off and compare the FR of the two, but theorically, how much better would a fuller sphere, that must be further from the glass and A-pillar be, than a smaller hemisphere that can fit slightly closer to the corner of the dash?

My proof of concept resulted in a subjective improvement to the stage width, this may or may not have anything to do with the sphere. They are new tweeters, in new locations, and the previous tweeters were not installed in an optimal way given their shape/dispersion patter (BG Neo 3's in A-pillars).


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## SkizeR

These tweeters are already sealed, no?

Sent from my SM-G920V using Tapatalk


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## Patrick Bateman

gijoe said:


> Bringing this one back up. I'm sorry if this has been covered, but I haven't gotten through all 25 pages of this yet.
> 
> I bought some LPG tweeters with the flush mount kit, and picked up some 60mm plastic spheres from the craft store. The tweeters are a perfect fit for the hemisphere, they fit so perfectly that I don't think I can get a better fit by using a 3D printer to print new pods.
> 
> The question I have though is regarding the advantage of a full/semi sphere compared to the hemisphere. If I were to use a larger sphere and cut off the face, I would eliminate the sharp edge, but I couldn't install a larger sphere closer to the windshield. The 60mm hemisphere will fit tighter into the corner of the dash. I also bought some larger spheres, and I intend to shave the faces off and compare the FR of the two, but theorically, how much better would a fuller sphere, that must be further from the glass and A-pillar be, than a smaller hemisphere that can fit slightly closer to the corner of the dash?
> 
> My proof of concept resulted in a subjective improvement to the stage width, this may or may not have anything to do with the sphere. They are new tweeters, in new locations, and the previous tweeters were not installed in an optimal way given their shape/dispersion patter (BG Neo 3's in A-pillars).


If you have the ability to measure impulse response, I would do the following:

1) move the tweeters *away* from the windshield
2) measure the impulse response of your tweeters and your midrange, and line up the wavefronts so that they arrive simultaneously

Basically the idea is to move the tweeter away from the windshield to cut down on the 'glare' you get from the sound going backwards and getting re-radiated. To do it effectively, you have to get the midrange and tweeter in-phase, or else the tweeters will sound "disconnected" from the rest of the speakers

If you go that route you might consider using a larger sphere, but TBH this is a subjective thing. The small improvement in directivity might not be worth the ugly cosmetics of having a big pod on the dash.


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## gijoe

SkizeR said:


> These tweeters are already sealed, no?
> 
> Sent from my SM-G920V using Tapatalk


Yes the tweeters are sealed.


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## gijoe

Patrick Bateman said:


> If you have the ability to measure impulse response, I would do the following:
> 
> 1) move the tweeters *away* from the windshield
> 2) measure the impulse response of your tweeters and your midrange, and line up the wavefronts so that they arrive simultaneously
> 
> Basically the idea is to move the tweeter away from the windshield to cut down on the 'glare' you get from the sound going backwards and getting re-radiated. To do it effectively, you have to get the midrange and tweeter in-phase, or else the tweeters will sound "disconnected" from the rest of the speakers
> 
> If you go that route you might consider using a larger sphere, but TBH this is a subjective thing. The small improvement in directivity might not be worth the ugly cosmetics of having a big pod on the dash.


Thanks, it's difficult to see in the photo, but my midrange is in the dash, just to the right of the tweeter (under the dashmat). I still need to set TA and make sure that the mid and tweeter are in phase, so I'll take some more measurements. One of the reasons for using such a small tweeter is to keep the dash obstructions to a minimum, so even if the response is slightly worse, the smaller sphere would be ideal, but it may turn out that a tiny hemisphere isn't improving anything. So far, I've only measured the tweeters with all other drivers muted, I'll run some tests with the midrange playing too. I'm curious to see if the tweeter is having a big impact on the FR of the mid, because the tweeter is slightly in front of the midrange.


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## Patrick Bateman

Nah, the midrange won't "see" the tweeter. You can really go crazy when it comes to putting things in front of a midrange, it has to be acoustically "large" for it to become a problem, and even then, it will only create a low pass on the mid.

For instance, if your midrange plays to 2000hz and you had a 7" cube right in front of the midrange, the cube would start to effect the midrange because the cube is as large as the sound that the midrange is playing. (2000hz is seven inches long.)

But if you reduced the cube to 3.5" it would be acoustically invisible; the wavelengths from the mid would simply go right around it.

And if you changed that cube to a sphere, then the problem is solved entirely because you're not going to get diffraction (because there ARE no edges!)

That's why the spheres work so well for tweeters. 2000hz is seven inches long, but 20,000 hertz is 0.7" long, so at the higher wavelengths diffraction starts to be a real issue.


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## gijoe

I figured the tweeters would be acoustically transparent, but figured I'd ask. 

It looks like I have a lot of measuring to do this week.


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## SkizeR

gijoe said:


> Yes the tweeters are sealed.


Then there can't possibly be a benefit from these sphere pods..?

Sent from my SM-G920V using Tapatalk


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## gijoe

SkizeR said:


> Then there can't possibly be a benefit from these sphere pods..?
> 
> Sent from my SM-G920V using Tapatalk


The pod is not intended to deal with the backwave of the speaker, so the pod isn't really an enclosure, it's a baffle. The idea is to deal with the front wave and smooth out the distortion caused by diffraction at the sharp edges of the baffle. The inside of the pod does nothing at all in this case. We're just creating a baffle.


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## SkizeR

ahhhhh


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## Patrick Bateman

I 3D printed an enclosure for my Tymphany TC9s, and I gotta say this is one of the best sounding speakers I've ever made. It is *stunning* how good this $15 driver sounds in this enclosure. I'd say it's noticeably better sounding than my old favorite cheap speaker, which was Kef's sub-satellite system.

I ran a quick measurement too, and it's basically flat from 200hz to 20khz(!)

My dumb computer crashed and I lost the measurement.

But to make a long story short, if anyone's interested in trying a spherical enclosure, check out the Tymphany TC9. Unbelievable value.


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## Patrick Bateman

A forum member expressed interesting in having that pod printed, so I uploaded it to Shapeways.

I have no idea why, but Shapeways is charging an insane price for this thing. It costs about fifty cents for me to print these on my 3D printer, but Shapeways is charging about $300(!)

www.shapeways.com/designer/patrickbateman

So, um, obviously this isn't a great value if you use Shapeways. If there's a competing service that's more affordable, I can upload there also.

By far the cheapest route is to print it yourself of course; if anyone wants the STL file lmk. (It's too big to attach to this post.)


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## mzmtg

*My attempt at spherical pods for my Honda Pilot:

I’m installing the ¾” soft dome tweeters from my JBL GTO609c component set. I’m fitting the tweeter directly, without using the flush-mount cup supplied by JBL. This keeps the overall diameter of the tweeter down to 1.25”

Anyway, I went with the wood balls with the flat side from hobby lobby:*
20170518_212515 by ben.garner, on Flickr

20170522_221602 by ben.garner, on Flickr

*Using a 1.25” forstner bit that I got at Lowe’s:*
1495546050995 by ben.garner, on Flickr

*I actually found it easier to get a cut on the round side of the ball instead of the flat side with the existing hole. The bit would just wander and jump all over in the soft wood:*
20170522_221638 by ben.garner, on Flickr

20170522_222239 by ben.garner, on Flickr

*I used lamp rod and locking nuts to secure the pod to the A-pillar:*
20170523_090426 by ben.garner, on Flickr

*First impressions are positive, but I need to make another set. I’m not happy with the finish I was able to achieve and I need to aim the tweeters more toward the center of the car. I’d like to use some kind of stain or matte varnish to make the wood grain of the pods look decent instead of painting or flocking them.*


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## Stormy

Nice article. 

Side-note: I totally had that copy of AS&S back in the day and remember that install.


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## Patrick Bateman

This is the sixth most popular thread of all time, and numerous people have reported noticeable improvements by following the recommendations.

This afternoon I was doing some measurements, and stumbled across what I think is the greatest example of why and how this 'tweak' works.

IE, _subjectively_, we've heard the improvement, but it's been difficult to point to concrete data and say "here is an objective example of this improvement."

A few days ago, I made a speaker. Then today, I added a roundover. When adding a roundover, the response of the loudspeaker changed. And not in a subtle way - _it changed dramatically._

I was scratching my head, thinking that I'd made some kind of mistake. Maybe my levels were wrong, or I'd moved the mic, or the speaker wasn't exactly where it was supposed to be.

But, no, everything was correct.

And I was seeing two dramatic changes in the speaker:

1) off axis, it was louder. And not by a little bit - by almost six dB above 10khz! That's like quadrupling the power going to your tweeter.

2) There was a dip in the upper midrange that was reduced by about half

3) Overall, the curves were smoother with a roundover

Looking at the data, I was really scratching my head. *How would adding a roundover make my tweeter LOUDER off axis?* It just didn't make sense.

And then it hit me...

When the sound is hitting the edge of the box, that acts like a miniature version of the original source. But it's delayed in time (due to the pathlength difference.) And due to the time delay, the diffraction will be out-phase at certain frequencies, which will cause destructive interference with the original signal. Hence, that's why the speaker WITHOUT the roundover wasn't as loud off axis.

My mind was thorougly blown. Subjectively, I've heard how a roundover tends to make the speaker "disappear." I've heard how a roundover makes the highs sweeter. With my ears, I've heard how a roundover makes the speaker less fatiguing.

But up until today, I've never seen it illustrated so starkly in the data. Because today I accidentally did a measurement with and WITHOUT the roundover, at the exact same SPL, of the exact same tweeter and waveguide.










Here's the data. Top measurement is without roundover. Bottom is with roundover. The grey window over the measurement is my target window, based on the research of Floyd Toole. It's JBL's house curve.


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## gijoe

This is really just eliminating baffle diffraction, isn't it?


Diffraction from baffle edges


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## Patrick Bateman

It's more complex than Linkwitz realized. It's not a question of "eliminating" diffraction, it's a question of understanding that the shape of the baffle impacts the polar response, particularly off axis.

I think he started to realize that in later designs, hence the strange shape of the baffles later. Nobody really knows what the ideal shape is, yet. JBL is working on it with COMSOL here : https://www.comsol.com/paper/download/583641/audio product development at samsung audio lab better and faster with simulation_presentation.pdf

And there was a dude in Canada who used boundary element modeling to evaluate the Linkwitz baffle. His page is no longer available, but I saved some of the data here : https://www.diyaudio.com/forums/multi-way/247717-free-bem-solver.html

TLDR : not sure if we can "eliminate" diffraction, but I'm _definitely_ sure that taking the shape of the baffle into consideration is hugely important. The differences are audible and measurable.


JBL is really far ahead of the curve on this one, what they're doing with COMSOL is nutty. They're using the kind of software you might use to design a jet to design baffles. It's kind of amazing. I've spent the last couple years learning ABEC, which is one of the most difficult things I've ever done, and that's coming from a guy who literally learns software for a living. ABEC is HARD. Even now, I feel like we've only scratched the surface. 

So it's neat to get such a massive improvement in performance from two dollars worth of PVC.


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## dgage

My guess is it is related to aerodynamics and the laminar flow of a smooth transition vs the turbulence and pressure drag of an immediate end to the boundary where the waves pass.


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## Ride154

Hi Guys,
From all the info from this thread I modeled and printed these pods.
I'm far from an expert but they work well and when drivin' all you see is the tweeter itself.
In my BMW E91 they point to the ceiling light in the center of the car.
Tweeters are the SB acoustics SB29RDNC-C000-4.
If anyone is interested I'm willing to share the models.
Modeled in Sketchup.
Greeting Menno


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## gijoe

That's a neat design, but the baffle still has a 90 degree edge on it, I'd be interested to see the measurements between those pods and ones with round edges.


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## F150Man

I am using PVC endcaps for my 3" JBL midranges in my JBL 3-way system. I put cottonballs in them and painted them matte black and they blend into the dash corners and sit right next to and directly below the A-pillar tweeters. They sound great but seem to amplify 500-2K hz but the DSP works well with them.


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## Patrick Bateman

Yeah I hate to say it, but a disc is the absolute worst possible shape.

Sphere is nearly the best, elliptical is better. See the work of Olson on diffraction at www.linkwitzlab.com


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## Ride154

There is a lot of info on that site, could you point me in the right direction?
Love the learn more.

This is my first build with a dsp, so sorry for the noob questions and please correct me if I'm wrong.
I thought that with a dsp you're trying to get a stereo image in the centre on the dash.
What will change with a better soundstage?

And is the plastic ring around the actual tweeter a problem, at an angle of 180 ?










Or is the angle between the side of the pod and the tweeter a problem?










Will my tweeter sound better when I add a rounded ring on top of it?









And which shape is preferred? you can see a section cut of the ring on the side








Thanks in advance. Menno


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