# Everything Counts in Large Amounts



## Patrick Bateman (Sep 11, 2006)

Listening to Gary Summer's Mercedes yesterday convinced me to throw in the towel on my current project and try something different. That car really made me re-evaluate some of my opinions on two channel stereo, and what works and what doesn't work.

For nearly a decade, I've had a gnawing suspicion that direct radiators are reaching a level of sophistication that they can compete with horns. For instance, in the 90s you basically had to run horns to get gobs and gobs of dynamics. It's not that direct radiators *aren't* dynamic, it's just that horns were *more* dynamic.

Listening to Gary's car I noticed that his imaging was even more 'pinpoint' than what I can do with waveguides. And there were two aspects that his car just KILLED mine on:

1) stage width
2) smoothness

Based on that, I decided to rip out my waveguides and try something different.

Four years ago, an obscure PHD thesis by a student in Florida got me to try putting my tweeters in the center of the dash. That worked shockingly well; way better than I would have expected. It wasn't *perfect*, but it was good, and it was *different*. (http://www.diymobileaudio.com/forum...ion/72891-anyone-tried-using-one-tweeter.html)

So last night, after I got back from the MECA show in Riverside I ripped out my waveguides, chopped 'em up, and turned them into an ambiopole:


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## Patrick Bateman (Sep 11, 2006)

Back in 2010, most of what I knew about ambio was based on reading papers. Now that I've built and listened to a few, I have a better grasp on how/why it works. Basically our perception of high frequencies is determined by frequency response. It's not determined by where the tweeter is located. It's not determined by how wide your tweeters are, or how deep they are. *It's just frequency response.* In a car, this creates a problem: both tweeters must match 100% to preserve imaging cues.

Listening to Gary's car, it was clear that this is a car that's been very, very, very very carefully tuned so that the high frequencies match. This creates that 'pinpoint' imaging that's so elusive in a car. Heck, it's hard to make a car sound like the stage is in the center, but getting real definition all across the stage is maddeningly difficult.

So that's the first part of ambio: getting those high frequencies to match 100%. Doesn't matter that the tweeters are right in front of you. As long as they match, the high frequencies will extend past the boundaries of the speaker.

As we go lower in frequency, imaging gets trickier. Our perception of low frequencies is determined by phase.

_Here's an example of how speaker locations can screw up low frequency imaging cues:_

Let's say you have your midbass in your car door. The left speaker is 4' away. The right speaker is 6' away. Let's say you're listening to some vocals, and the vocals are centered at 1125hz, right in the midrange. 1125hz is 1' long. This means that the phase of your right speaker 'lags' the left by *two full wavelengths.* That's a LOT! We can perceive differences of a fraction of a wavelength. So two full wavelengths of difference will skew things in a HUGE way to one side of the car.

This is why most winning cars these days use digital delay to 'sync up' the low frequencies. *But note that this only works in one spot.*

This is another one of those things I had to rethink after listening to Gary's car. I've generally been opposed to 'one seat' cars, as I had concerns that the reflected energy would be phasey or unnatural. (Since we're only fixing the phase in one spot, the reflected energy is potentially worse than a car *without* DSP.)

*But I didn't hear any real issues with the 'space' in Gary's car, so I guess the drawbacks of DSP are possibly overblown.*

It seems pretty odd that you could put two speakers in *front* of you, and hear sounds to the left and to the right. But this actually works, give it a try sometime. IMHO, the low frequencies of an Ambio set up are tricky to get right. *This is because we want to prevent the sound from the left from 'bleeding' into the right.* No joke, I had an ambio setup at home for a while that literally put a wall up between the two speakers. Since I work in front of a computer all day, at home, this gave me a chance to figure out what works and what doesn't work in ambio. The barrier method works pretty good... but isn't too practical in a car.

So in a car, we use a processor to do what the barrier does. This is 'crosstalk cancellation', and there's been quite a bit written about it on this forum and on others.

In my next post, I'll write up some reasons why I think there's hope for crosstalk cancellation after all...


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## Hanatsu (Nov 9, 2010)

Interesting topic... keep it going. Let's see if we can draw any conclusions, I love experimenting


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## Patrick Bateman (Sep 11, 2006)

Thanks!

In post 2 I said I'd describe why I think there's hope for crosstalk cancellation. So here goes:









When I first tried Ambio, I had the speakers in the center of the dash. *At the time, this was the most practical location in my Accord.* My '05 Accord had a very tall instrument pod, which basically made it impossible to put two speakers in front of me. (I could probably squeeze a couple of 2" drivers, but that's about it.[/b]

Last night I was screwing around with various locations, *and discovered that Ambio *really* works best if the speakers are *absolutely* equidistant to your ears.* The effect is pretty crazy; it's almost like focusing a lens. You get the speakers equidistant and everything just snaps into focus. It's quite a trip.

Now that I understand Ambio better, this makes sense. The processed signal is delayed by about 68 micro seconds. (A microsecond is one millionth of a second!!!)

This is a really important point here, because 99.99% of the world hasn't heard ambio, and it's really easy to get unacceptable results if you set it up wrong:

*Our delay is measured in microseconds, so lining up the two speakers *perfectly* makes an audible difference.* This doesn't mean you have to listen with your head in a vise, but in my '10 project, the speakers weren't even *close* to equidistant, because they were in the center of the car.

TLDR: Put the speakers right in front of you. Make sure they're in phase.

On a side note, I think there's a way to do ambio with the speakers in the center of the dash. *maybe*. If I'm right, it might be possible to have two full range speakers in the center of the dash, but create a soundstage that appears to be in front of you. I'll get into that later...



Here's some listening notes from various locations over the last day:
1) With the speakers in the center of the dash, the stage was kinda big, with good focus. The sound seemed to extend almost to the corners of the dash. Focus and intelligibility was excellent, better than stereo.

2) Putting the speakers at eye level, right in front of me was a revelation. You know that thing at the eye doctors, where they try a bunch of lenses and one lens snaps everything into focus? That's what it was like with the speakers right in front of me. In this location, voices were right in front of me, and ambiance wrapped around me in an 180 degree arc.

For the first time in 42 years, I could *clearly* hear different depths in the recording. This was quite astonishing; I've heard a handful of speakers that have pinpoint imaging left to right, but depth has always been elusive. I've heard Danley talk about getting the crossover dialed in on his Synergies, and how the depth of the sound is one thing that happens when you get the xover right. So this may be a 'synergistic' thing that's happening here', with the Ambio and the Synergy horns. (This is the first time I've done Ambio with Synergy Horns; the previous experiments were with full range drivers and with my Gedlee Summas.)

One thing that was troubling about this is that my home setup, with the Summas, didn't do this. It was *wide*, definitely, but not startling the way the Synergy horns were in my car. Is this due to the (relatively) flat phase of the Synergies? Maybe.

So keep in mind, if you try this yourself, the effect may not be as pronounced if you're using speakers that don't have flat phase. Interestingly, Princeton is using Geddes speakers for their own lab, so maybe they've come up with a 'fix' for the phase response? 

If anyone wants to try Ambio, consider using a full range sealed speaker, or a two-way with 1st order xovers. Flat phase seems to be important. (And this is only logical; 4th order xovers introduce a significant phase shift, which will counteract the effect of Ambiophonic processing. If you're clever, you could counteract that effect with DSP, and perhaps Princeton is doing that. But if you don't have DSP, stick with phase-coherent speakers for this project.)

3) Now that I know that the speakers need to be equidistant, I tried doing that on the dash. Basically two waveguides, but tilted towards me to 'correct' the distance. This definitely sounded better than firing forward, but the soundstage didn't 'pop' into focus the way that it did with the waveguides in front of me.

4) Under the dash didn't have the crazy huge soundstage that I heard up on the dash. But that's where I'm going to put the waveguides, because there's just no room on the dash for two waveguides. Also, I think that under the dash has real potential, possibly more than ON the dash. The reason is because we can absorb early reflections. In the pics from Princeton, you'll notice that the back wall and the side walls are heavily treated. In a car, we should be able to mimic that effect by covering the surfaces close to the waveguide with wool or felt. On the dash we can't do that, because of the window!


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## BigRed (Aug 12, 2007)

Keep in mind Gary's car has absorption that is extremely helpful in achieving his results


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## teldzc1 (Oct 9, 2009)

Thanks Patrick, this sounds really interesting. How low can you cross the tweetes?

Sent from my SAMSUNG-SM-N900A using Tapatalk


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## Patrick Bateman (Sep 11, 2006)

teldzc1 said:


> Thanks Patrick, this sounds really interesting. How low can you cross the tweetes?
> 
> Sent from my SAMSUNG-SM-N900A using Tapatalk


I'm crossing my tweeters over at 10khz or so.
Compression drivers have a response that looks like this on a constant directivity horn:










Basically their innate response on a CD waveguide is a 6db/octave lowpass that starts around 2khz. So when you combine the natural lowpass response, with a 6dB/octave electrical highpass, *you get flat response.*

Acoustically, the crossover is about 1500hz, but electrically, it's about 10khz. At 1500hz the compression driver is attenuated by about 18dB, which knocks it's output down from about 109dB to 91dB.


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## Hanatsu (Nov 9, 2010)

Patrick Bateman said:


> Thanks!
> 
> In post 2 I said I'd describe why I think there's hope for crosstalk cancellation. So here goes:
> 
> ...


Haha, gotta love that statement together with picture above xD


----- ----- -----


Here's some thoughts of mine (this might be complete BS though):

*I've tried lots of different placements and different locations, types of speakers, waveguides to some extent as well in the quest for optimal focus. Focus is one of the most important things for me, I want "laser focus" when playing a nice recording to be pleased with a system. For several years I've messed with this, I currently have two systems, completely different in two different cars and I clearly hear the staging difference between the two even though I've set it them up using the same technique/methods while setting up the system. Both cars have a similar amount of deadening (i.e pretty damn much). Both systems use speakers crossed in their optimal power response region.

-System 1: Small midranges in sail panels and tweeters on-axis from pillars in an anti diffraction design. Small distance between listener and speakers.

-System 2: Large midranges facing windshield in dash, tweeters in sails mounted as wide as possible, slightly off-axis. Slightly larger distance between speakers and listener and slightly smaller PLD. 

System 1 got an amazing focus, really. Among the best I've heard in any system, better than my home audio setup. It got great width, got a 13/15 points in EMMA last year, great height but lacks depth. The sound got a "headphone" type of character, it's a bit in your face. No matter what I did, I couldn't get rid of that headphone feel while having that focus. 

System 2 got good focus, not as good as System 1 (not finished with this system yet though) but it got nothing of that headphone-in-your-face sound, it also have less width but just as good height as S1... Since I'm in the middle of building this setup I tried lots of crazy stuff, one of the things was to place a tweeter in the middle of the dash and it was like I was sitting in the S1 car all over again. I was asking myself WHY it increased the focus that much by just placing a tweeter in the center of the dash. 

*Here's my theory:*

_It's because of *two* things (mainly). Number 1 being frequency response, rather the power response to be exact. Number 2 is an extension of N1; the reflections involved in creating the FR you're hearing at listening position._ 

OK. 'As we all know', we localize sound more and more based on intensity differences as the frequency goes up. For a 1-seater it's kinda easy, we simply need a DSP capable of L/R individual equalization. When the perceived FR intensity is the same from both channels we get that "mono-laser-imaging-feel" in the center (T/A must of course be set as well, but skip that for now). But here's the thing... *I've never archived that laser imaging based on measurements alone USING THE STANDARD METHODS. *

The ones that are familiar with my posts know that I'm a 'measurement guy'. I believe everything can be described through measurements. So why the h*** couldn't get this right? I first thought my method of measuring was flawed but after lots of experimenting I found out that the issue was caused two different things. First off, my method was indeed flawed for higher frequencies but that was only part of the problem. The other issue was that the perceived level was different depending on how far the driver was mounted from you. 90dB from the near speaker sounded quieter than 90dB from the far speaker and the difference got worse as frequency went up. I found out that this was highly related to the power response of the driver and the PLD vs the listener. The closer the driver was to a point source the less the volume difference between L and R, I observed this using widebanders in their beaming range. Also using the driver closest to you off-axis made the difference less prominent. 

I think this is due reflections. The more reflections the more diffused and "prominent" the source sounds, the far driver have a larger path to your ears and therefore will the sound be able to reflect off panels and stuff in a larger degree before the sound reaches you (you could say there's a larger amount of "phantom sources" from the far side). I thought this was only an HRTF thing at first, but I think it's more than that. Here's a view of my FR target in "System1":



and this is off axis dispersion of my tweeter:



Notice how much the far side response (right side) drops off above 5kHz? This driver act more like that widebander in its beaming range. To confirm my theory, I experimented with this driver:



This driver got an amazing power response. It doesn't drop of significantly even above 10kHz. I found that using these two drivers the right side suddenly sounded bright. Had to turn the level down an additional 3-4dB to attain that proper center above 5-6 kHz because this driver was "igniting" the phantom sources more. I know that my thoughts are a bit controversial but I've found that I can repeat the measurements in different setups based on the driver's power response. The better power response, the more attenuation on the far side. A widebander almost require no attenuation at all if they are mounted on-axis. 

So what has all of this to do with the single center tweeter? I think it staged so well because the power response was "igniting" a more uniform pattern of phantom sources both left and right side, a more uniform "mess" if you want. What I want to highlight is that it's not so much what type of direction control you use or if you "spreading the chaos" around but instead how even the L/R perceived power response is. In other words, focus can to a large degree to EQed in, it simply requires different tuning to sound right. I'm not saying that install has nothing to do with it, all of my rant above is made under the assumption that you already have a proper install. I should perhaps mention that I ALWAYS mount tweeters in ear height, no experience with systems that have them mounted in any other ways. 

For you who's interested how I measure I can tell you that I use RoomEQ for acoustic measurements, I use 8 sweeps on each driver. For the driver side (assuming left here) speaker I do 5 measurements around the left ear and 3 around the right and for the passenger side (assuming right here) speaker I do 2 measurements around left ear and 6 measurements around right ear. Found that this is generally a good averaging technique.


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## Hanatsu (Nov 9, 2010)

I also should mention that I've used bandpassed correlated noise to "backengineer" that FR target response. Using this method has been the basis of all my assumptions.


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## ccapil (Jun 1, 2013)

Interesting thread. Love reading your posts Patrick.


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## Patrick Bateman (Sep 11, 2006)

This thing is insanely sensitive to spacing!
I cleaned up the ambiopole, and had it mounted in my car.
When listening to some tracks I'd already listened to, *the soundstage width seemed worse this evening than it did this morning.*
This made no sense; the performance should have improved, not gone downhill.

Then I noticed that I'd mounted it off-center by about *three quarters of an inch(!!!)*









Moved my head to the right, and *poof*, the focus was back.


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## thehatedguy (May 4, 2007)

Also Gary's car is a discrete 5.1 system with a real center and rear speakers.

So which was better, his car or the Magic Bus?


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## JoshHefnerX (Jun 13, 2008)

I'd have to say it must have been one hell of a listen to have changed your mind on things fundamentally.

Josh


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## Patrick Bateman (Sep 11, 2006)

JoshHefnerX said:


> I'd have to say it must have been one hell of a listen to have changed your mind on things fundamentally.
> 
> Josh


Here's some background on this:

Back in 2009 I really wanted to attack the soundstaging problem, and I wrote a thread called 'creating the perfect soundstage.*'

There were a few key things to that project:
1) The drivers were crossfired. The reasons why this is a good idea are detailed in a paper at gedlee.com (cited in the '09 thread.)
2) The horns were on the dash, not under the dash

So we have three pillars for this soundstage at this point : drivers on dash, pushed way, way into the corners, and crossfired.

Here's the next big part of it, and I'm sorry but all of you guys running Hybrid and Fountek miss this next piece:

*You gotta have some serious output. Dynamics. It's essential for a believable car stereo.*

One of the stranger aspects of that project was that I used some cheap Tangband computer speakers for midranges. Littly tiny 2" jobs, basically equivalent to what you'd find in a set of cheap Logitech computer speakers. I used these drivers for a very specific reason: To make this setup work, the waveguide had to be pushed way, way back against the windshield. I wanted a 100% seamless transition from waveguide to windshield. When you do this, *it's like the cabin just disappears.* Basically there's nowhere for sound to diffract, or go backwards. Even a tiny gap - even five centimeters - will blow the whole illusion.









The cheap Tangband computer speakers were a big part of this. Due to Hoffman's Iron Law, if I was going to use 2" speakers, I had to find the speaker with the lightest cone and the biggest motor that I possibly could. An array of four of the Tangband speakers has an efficiency of 92dB and a power handling of 32 watts. Once you horn load the array, your efficiency is around 100dB for the array. *So my midrange array could do 110dB on just ten watts.* This is really critical; *I am bored to death with cars that image great but can't even hit 100dB without distorting.* For instance, the ubiquitous Fountek FR88 will do 96dB with fifteen watts. And that's it's power limit! Just 15 watts.

Sixteen dB probably doesn't "sound" like a huge difference. But it means that my array of cheap computer speakers doesn't even need one watt to hit SPLs where the Fountek is on the verge of melting down.

I don't mean to sound like a complete lunatic, but there really aren't many midrange drivers that can pull off this trick.

Here's a pic of Gary's interior:










You can get a good look at the front stage in this Morel video here: https://www.youtube.com/watch?v=AyheMIGeH6c










^^ Here's a comparison of the front stage from my '05 Accord versus Gary's Mercedes

Gary's car confirmed for me something that I'd suspected for a few years: that you can get horn-level dynamics with direct radiators. *Basically he's pushed the midrange so far into the corner, it's getting truly horn loaded by the windshield.* To make this work, you *really* have to push those drivers back. A gap of even five centimeters won't work; ideally the cone of the woofer would meet the glass and the dash. The driver has to be waaaay back for this to work.

The other part of the 'secret sauce' is that midrange. Remember how I noted that I could hit 100dB with one watt? And this was specifically because I used drivers with a very light cone, and a massive neodymium motor.









Well guess what Gary's using? Yup, a Morel dome midrange, massive neo motor, huge voice coil. The efficiency on Gary's mid is a full 91dB. My mids were a little more sensitive, but Gary's mids have nearly four times as much power handling.

That Morel is a BEAST. Huge voicecoil, hexatech winding to increase power handling, and it's basically the perfect driver to jam into the corner of a windshield.









Dayton RS52 is an obvious alternative, but the stupid flange makes it hard to do the things that you can do with the Morel









I personally considered using the Dayton, even sawed it in half (the frame is plastic, a hack saw takes it apart like butter.




Ugh, I didn't mean to type up the world's longest post. Here is a summary:

1) When I did my 'ultimate soundstage' project in '09, I frequently wondered if one could do the same trick using direct radiators
2) Gary's car does the same trick, using direct radiators
3) The key to the design is that the drivers have to be pushed way way way back. *There must be a seamless transition from the edge of the radiator to the windshield.*
4) You can take your Fountek and your Hybrid speakers and listen to your Nora Jones SACD on it. But I like me some dubstep and I need dynamics. If you're like me, use a midrange with high output capability.


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## Patrick Bateman (Sep 11, 2006)

Here's some more data on that beautiful midrange.

1) spec sheet : http://www.morelhifi.com/wp-content/uploads/2011/10/morel_car-catalog-05-2013_web.pdf

2) a pic Gary uploaded of his stage on an Alpine forum :

















Here's an example of how a lot of people do it. When you have the midrange eight inches from the windshield, the midrange sound is going to wrap around, and it's going to hit the windshield half a millisecond behind the primary sound. And then it's going to come right back atcha. That extra energy can make the stage sound very big and spacious. Similar to listening to speakers at home in a 'live' room. But that extra energy also smears the imaging cues in the actual recording. So you end up with a soundstage that's big and diffuse, but every recording sounds the same, and you don't have that 'pinpoint' imaging that's possible with a system like Gary's.

Basically if you can push the driver all the way into the corner, the front half of the car almost seems to disappear. Because all of the cues that tell you that you're in a car are reflections. When you push the driver all the way into the corner, all the energy is going forward; there isn't even a fraction going to the back. The only exception to this rule are higher order modes, which is why a well designed waveguide can take the illusion a little bit further. Having said that, direct radiators frequently have superior CSD. (And ribbons are even better.)


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## Orion525iT (Mar 6, 2011)

My initial thoughts when you posted the picture of the Mercedes was focused on the design of the surround the and the dash mat. I wonder if he is using some absorbing materials? That way the high frequency stuff is absorbed to prevent the messy image typical of dash/a-pillar installs, while still lensing the midrange/upper midrange frequencies forward. 

I tried something similar in my bimmer, but using two small full rangers side by side in array without a tweeter. It sounded ok, but I think for my car, that the relatively steep angle of the windshield and the large cluster surround caused some issues. Might try the array again in my daily driver, just to see. The array should limit horizontal dispersion. I don't know if that would be good or bad, but using a 2 driver array should allow me to push the speakers even closer to the windshield and dash, while gaining cone area and sensitivity.


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## Patrick Bateman (Sep 11, 2006)

There's two ways to deal with reflections. You can absorb them, diffuse them, or both. The big problem is that the diffusers or absorbers need to be at least one quarter wavelength of the frequency to work.









Here's the diffusers from my living room. (Not the cat, the thing behind it.) My living room diffusers are 25cm deep and they work to 338hz.

Alcantra dash mats will have a subtle effect, but below 10khz their effect is basically nil.

One reason that I'm keeping my speakers below the dash is that you can really go crazy with diffusion and absorbtion. I noticed Linda Kobayashi's(sp?) Smart car had covered up the door with some type of felt.

btw Dunlavy patented this back in the 90s. He's already done all the research, just read his patent : Patent US4167985 - Speaker system - Google Patents


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## Patrick Bateman (Sep 11, 2006)

Out of curiosity, I read the Dunlavy patent. Dunlavy specifies polyurethane foam with a density of 1.3lbs per square foot.

Mainstays 1.5 Comfort Coil Mattress Pad - Walmart.com

^^ Wal Mart sells closed cell foam that's 1.2lbs per square foot. As I found out in my various experiments with horns, *all foam is not created equal*, so you really want to get the right type. I personally found that fiberglass insulation was by far the most absorptive, but putting fiberglass insulation in your car probably isn't healthy. (I believe there's some studies indicating it causes lung cancer.) But plain ol' closed cell foam should be fine. Dunlavy specs two inches of it.









Oddly enough, it sure seems like Dunlavy switched to wool felt at some point. These are Dunlavy SC-IVs









Looks like wool to me.

The use of two inches of damping material is not accidental. An eight inch sound wave is 1.7khz. You want your damping or diffusion to be at least one quarter wavelength. Therefore, *Dunlavy's two inches of wool or foam is effective from 1.7khz to 20khz.* That's why it surrounds the tweeter.


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## Patrick Bateman (Sep 11, 2006)

http://www.mscdirect.com/product/details/48544746?item=48544746

^^ Here's a source for the wool. $60 is enough to treat any car.

I'm thinking about lining the 'tunnel' under the dash. Basically soak up any early reflections. You really gotta go thick with this stuff; even a half inch of wool is only effective to 6750hz.

One 'wacky' idea I had, for the home, was to put this stuff in a frame and then stretch a cover over it. The reason that this works is that you can use one layer that's acoustically transparent, and then put the wool *underneath*.









For instance, at home I have a 100" rectangle painted on my wall. I use that as a TV; my projector is on the opposite wall. (Never mind the horn, it's the only picture of my living room I have handy.)

So you make a 100" frame that's about 1.5" deep. You fill up the entire frame with wool. So now you've just eliminated reflections on THIRTY ONE SQUARE FEET of your room. And the wool will work down to 2250hz. You then wrap the entire frame in a low weight fabric that's white. The key is that the sound can pass through the light weight fabric, but it can't pass through the felt. The sound can't "see" the fabric but it does "see" the felt, at least down to 2250hz. Voila! You now have a 100" home theater screen that doubles as an absorber. If you were totally nuts you could just cut a hole in the wall, but that's some Next Level ****


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## JoshHefnerX (Jun 13, 2008)

Patrick Bateman said:


> I don't mean to sound like a complete lunatic, but there really aren't many midrange drivers that can pull off this trick.


You're a good kind of lunatic, always enjoyed your posts. It's hard to tell in those photos are the drivers in the a-pillar aimed across the dash or somewhat into the cabin?

Josh


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## Butt Hz (Apr 25, 2014)

thehatedguy said:


> So which was better, his car or the Magic Bus?


That's what I would like to know


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## Patrick Bateman (Sep 11, 2006)

Butt Hz said:


> That's what I would like to know


Gary's Benz does all of the audiophile stuff very well.
Imaging, tonality, soundstaging.

But I'm a basshead and Jon's bus has the best bass I've ever heard in a vehicle, and maybe the best bass I've ever heard anywhere.

When I did that soundstaging project in 2009 I quickly realized that the things I really care about in audio are dynamics, articulation and bass. Soundstaging is a neat magic trick but 90% of the recordings are practically mono.

By the way, the dynamics in Gary's Benz were incredible. But the bass in the Magic Bus is unparalleled.


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## Bluenote (Aug 29, 2008)

Patrick Bateman said:


> Here's some more data on that beautiful midrange.
> 
> 1) spec sheet : http://www.morelhifi.com/wp-content/uploads/2011/10/morel_car-catalog-05-2013_web.pdf
> 
> ...


Patrick thanks for this post! I agree that Gary's Benz is astounding and possibly the best car I have heard (IME) & with my limited exposure to (3-4) comps total. 
I wondered if the same principle about pushing the mids into the corner would apply for a point-source > (Morel Hybrid Integra 402) http://www.morelhifi.com/wp-content/uploads/2012/04/Hybrid-intergra1.pdf)


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## Patrick Bateman (Sep 11, 2006)

Bluenote said:


> Patrick thanks for this post! I agree that Gary's Benz is astounding and possibly the best car I have heard (IME) & with my limited exposure to (3-4) comps total.
> I wondered if the same principle about pushing the mids into the corner would apply for a point-source > (Morel Hybrid Integra 402) http://www.morelhifi.com/wp-content/uploads/2012/04/Hybrid-intergra1.pdf)


Oh definitely, but it creates a new set of problems. As I see it, here are a few options:

1) two way stage on dash
pros: good imaging, good articulation, if the drivers and the crossovers are correct you can get *close* to point source behavior

2) coax on dash
Same pros as #1, but it's more difficult to push the driver back into a corner, because coaxes are generally larger than conventional units. There are some exceptions to the rule; the Kef drivers in particular are barely larger than conventional units. Coaxes always have better polars at the xover than conventional drivers. OTOH, this may not matter as much in a car, where we're optimizing the sound for a single point in space

3) Synergy horn on dash
Same pros as #2, but your output levels can get pretty redonkulous. Compression drivers have sensitivities close to 110dB. One big advantage of the Synergy for me is that you can put the midranges ahead of the tweeter instead of behind it; this makes it easier to fit everything. When I listened to Gary's car back to back with my car, my Synergies had a 'hardness' to the sound that I'd attribute to higher order modes. I'd like to spend some time with a mic and an EQ and see if I can take some of that 'edge' off.


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## Bluenote (Aug 29, 2008)

Thanks Patrick! my first comp was in Sacramento 3 years ago, I heard Gary's car then and he heard mine. I had CDM88 / Piccolo tweeter off axis in the a-pillar and be recommended exactly what your suggesting...to put them deep in the far corners of the dash. It's funny how I am being revisited by this...I decided for the 402 because I felt the CDM88's were too thin (sound wise) and couldn't be crossed low enough...I will see what these point source can do but will definitely keep these placement cues in mind.


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## Patrick Bateman (Sep 11, 2006)

Bluenote said:


> Thanks Patrick! my first comp was in Sacramento 3 years ago, I heard Gary's car then and he heard mine. I had CDM88 / Piccolo tweeter off axis in the a-pillar and be recommended exactly what your suggesting...to put them deep in the far corners of the dash. It's funny how I am being revisited by this...I decided for the 402 because I felt the CDM88's were too thin (sound wise) and couldn't be crossed low enough...I will see what these point source can do but will definitely keep these placement cues in mind.


As they say in software, 'that's not a defect that's a feature.'
Yes, the CDM88 won't play low.
But that's *good*. The light cone and high motor force raises efficiency.

If you can, do a back to back listening session in a car with a 3" like the Fountek FR88 (wide bandwidth, low sensitivity) and the CDM88 (less bandwidth, high sensitivity.)

I think you'll find the Fountek sounds 'polite' in comparison. I like dynamics and big SPL. YMMV


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## sqnut (Dec 24, 2009)

Patrick Bateman said:


> I like dynamics and big SPL. YMMV[/font]


I think dynamics are primarily in the response. A more sensitive driver will play louder at the same power, but I don't think louder means more dynamic. Dynamics in your sound is down to the overall response imo.


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## Bluenote (Aug 29, 2008)

Thanks! Much of what you post is way over my head but provides a great opportunity to learn. I will revisit this and hopefully post my findings with reference to this thread.


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## thehatedguy (May 4, 2007)

Was your speakers really "hard" sounding, or were the Morels just that much more laid back? Morels to me are pretty laid back speakers, more warm sounding to me than Dyn. Your speakers may have had less distortion than the Morels.

I know what you are describing though, I've always found horns to have that characteristic...I've always though it came from low distortion and lower dispersion.


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## thehatedguy (May 4, 2007)

IMO and IME I don't think what you are saying is true. I've never heard a lower sensitivity speaker have the dynamics of one what has higher sensitivity...no matter how much power you dump into them.



sqnut said:


> I think dynamics are primarily in the response. A more sensitive driver will play louder at the same power, but I don't think louder means more dynamic. Dynamics in your sound is down to the overall response imo.


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## Patrick Bateman (Sep 11, 2006)

sqnut said:


> I think dynamics are primarily in the response. A more sensitive driver will play louder at the same power, but I don't think louder means more dynamic. Dynamics in your sound is down to the overall response imo.


IMHO dynamics are mostly determined by output. IE, if you have two drivers and one is capable of more output, *it will sound more "dynamic."*

Here's an example:









The Fountek FR88 is arguably the most popular driver for mounting on the dash. It's small and it has wide bandwidth. People buy it because they think "hey I can have almost all of my sound come from one driver and that's a good thing right?"

The Fountek has a sensitivity of 84dB and power handling of 15 watts. That means that it's maximum output is 96dB. 









The Dayton RS52 has a sensitivity of 91dB and power handling of 60 watts. That means that it's maximum output is 110dB.

The SPL level of the road noise in your average car is in the low 70s. Let's call it 72. Let's say you're cruising down the road in your car, and you're listening to your music at a level that's 20dB louder than the road noise. That would be 92dB. *In this scenario the Fountek is FOUR DECIBELS away from it's SPL limit while the Dayton is EIGHTEEN.*

That's a HUGE difference. The Dayton won't play low, but it's dynamics are an order of magnitude greater than the Fountek.

And, again, I'm not a huge fan of high sensitivity drivers. I am personally using the Dayton ND91 in my own car, but I'm using a pile of them. (Currently four and I'd like to get four more in there.)


On a side note, I find it funny that I couldn't find a single picture online of someone using the RS52 on the dash, even though it's such a great candidate. Everyone gravitates towards the low-efficiency, high bandwidth drivers.


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## Patrick Bateman (Sep 11, 2006)

thehatedguy said:


> IMO and IME I don't think what you are saying is true. I've never heard a lower sensitivity speaker have the dynamics of one what has higher sensitivity...no matter how much power you dump into them.


ditto.


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## ErinH (Feb 14, 2007)

someone PM Gary and get him in here. 


I heard Gary's car a few years back at MECA Finals 2010. I didn't get a chance to really get in to the demo but from what I recall, it was very impressive. That said, the most impressive thing regarding Gary is Gary himself. I had no idea the accolades he has received (numerous Oscars and tons of high-profile jobs). And you wouldn't have gotten any of that from a conversation with him, which I had for about 20-30 minutes that day. 


I think the real basis for great sound is in the crossover, which of course relates to driver response, placement (proximity and aiming), and crossover. It's a trip to be able to sit in my own car and have the stage be so stable without any EQ on the mids or tweeters. A couple years/setups ago, that just wasn't possible. Gary's setup certainly does a good job of keeping the mid and tweeter close to each other; I'd really be curious to see how the hoods affect the response and dispersion.


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## teldzc1 (Oct 9, 2009)

Patrick Bateman said:


> 4) You can take your Fountek and your Hybrid speakers and listen to your Nora Jones SACD on it. But I like me some dubstep and I need dynamics. If you're like me, use a midrange with high output capability.


LOL! Best post I've read in a while!

Sent from my SAMSUNG-SM-N900A using Tapatalk


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## ErinH (Feb 14, 2007)

Patrick Bateman said:


> ditto.


I'd almost agree here, but I'd still have to factor in the crossover and power handling at a given bandpass.

Even with my modest sensitivity Scan 26w in my towers, with the bandpass set to 50-480hz, LR4 on both ends, it can take gobs of power and get STUPID loud. To the point that my wife was yelling at me from downstairs and I couldn't' even hear her. The thing about being distortion free (or at least so low that it's completely inaudible) is that it's downright dangerous. Distortion is always a good indicator of "hey, dude, you're going too high on the volume" but with the right mix of crossovers to limit excursion and HF breakup, you mitigate distortion and it's easy to get way ahead of yourself even with moderately spec'd sensitivity drivers.
http://www.diymobileaudio.com/forum/2096617-post214.html


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## Patrick Bateman (Sep 11, 2006)

Actually I don't think distortion is the issue. I think it's just sheer output, that's the trick to good dynamics.

For instance, I've measured speakers at various power levels, and noticed that as you reach a certain point, *additional power barely raises output level.*

I think Wayne Parham published the best example of this. He published some measurements where you could see that past a certain point, additional power made virtually no difference. (Eventually he literally burned up the driver.) 

So you could have a driver with very low distortion, like the Fountek, but if it's physically incapable of large SPL, it's dynamics will be limited.

And this doesn't mean that everyone should immediately go out and buy Morel or Dynaudio. There's definitely a 'sweet spot' between the two extremes. I noticed that even JBL uses relatively small voice coils on many of their midranges. But the reason they can get away with it is because the cone is light. So the driver doesn't *need* a hundred watts to get to 104dB. But drivers like the Fountek combine low power handling with low sensitivity, which limits their SPL severely.

TLDR: high sensitivity + high power handling = great
high sensitivity + low power handling = good
low sensitivity + high power handling = good
low sensitivity + low power handling = bad


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## Patrick Bateman (Sep 11, 2006)

bikinpunk said:


> Even with my modest sensitivity Scan 26w in my towers, with the bandpass set to 50-480hz, LR4 on both ends, it can take gobs of power and get STUPID loud. To the point that my wife was yelling at me from downstairs and I couldn't' even hear her.


The Geddes speakers are a hard sell, because they don't really sound different than a well designed speaker from Best Buy. (And that's not criticism; there are plenty of $500 speakers that perform well.) But one funny thing about them is that you find yourself shouting at people in the same room when they're playing. They're so effortless and the HOMs are so low, you can play them at 110dB and it sounds like 90dB.

Have you ever been in a stereo store, and some knucklehead cranks up the stereo to 11? And it's deafening everybody, and it's annoying right?

When you do that to the Geddes speakers, they don't even sound loud, it's like they go from 0 to 10 without a hint of compression, distortion, etc.

Remember how I mentioned that the Fountek maxes out at 96dB? The Gedlee Summa maxes out at ONE HUNDRED AND TWENTY SIX DECIBELS. Oof.

It's hard to describe. I've literally made myself hoarse from talking over them, and they didn't even "seem" loud.

That's part of the reason I use compression drivers nearly 100% of the time. When you're aiming to generate 110-120dB comfortably, the tweeter becomes the weakest link. This is also why the Danley Genesis horns are flying off the shelves. (Sixty four tweeters in their largest model.)


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## BigRed (Aug 12, 2007)

Treating and maximizing the environment is much more important than the drivers. What works in home doesn't transfer in a car


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## ErinH (Feb 14, 2007)

Patrick Bateman said:


> When you do that to the Geddes speakers, they don't even sound loud, it's like they go from 0 to 10 without a hint of compression, distortion, etc.


that's exactly what my speakers sound like. at 106dB full range, I didn't feel like they were loud enough. even though my wife was yelling to tell me to turn it down from 15 feet away. That's the kind of "distortion lets you know" instance I'm speaking of. When you lack that pre-cursor, you tend to want to keep pushing until you finally do hit that point. In my case, I run out of volume before then. And that's with 800w on the midbass and 500w on the tweeters. It's insane. But in a good way.


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## teldzc1 (Oct 9, 2009)

Patrick Bateman said:


> Dayton RS52 is an obvious alternative, but the stupid flange makes it hard to do the things that you can do with the Morel
> 
> 
> 
> ...



So the backside of the RS52 is just a large plastic chamber? Does removing it affect the response greatly?


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## ErinH (Feb 14, 2007)

Patrick Bateman said:


> Actually I don't think distortion is the issue. I think it's just sheer output, that's the trick to good dynamics.
> 
> For instance, I've measured speakers at various power levels, and noticed that as you reach a certain point, *additional power barely raises output level.*


that's power compression which is a form of distortion.


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## Patrick Bateman (Sep 11, 2006)

teldzc1 said:


> So the backside of the RS52 is just a large plastic chamber? Does removing it affect the response greatly?


If I'm not mistaken, all of these dome mids are virtually identical. You have a dome attached to a surround, and the voice coil is in a gap. The hole in the gap forms a chamber. You can enlarge that chamber to lower the FS.

You can shrink the chamber to virtually nothing, which raises the Q and the sensitivity, while raising the F3.

That's what Morel did with their dome midrange.

You can do the same thing with the Dayton.










Compression drivers work on the same principles. Here's a B&C DE25 opened up. You can see it's basically the same thing as the Morel and the Dayton, but flipped upside down.


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## Patrick Bateman (Sep 11, 2006)

bikinpunk said:


> that's exactly what my speakers sound like. at 106dB full range, I didn't feel like they were loud enough. even though my wife was yelling to tell me to turn it down from 15 feet away. That's the kind of "distortion lets you know" instance I'm speaking of. When you lack that pre-cursor, you tend to want to keep pushing until you finally do hit that point. In my case, I run out of volume before then. And that's with 800w on the midbass and 500w on the tweeters. It's insane. But in a good way.


Totally. The Geddes speakers are complete overkill. It's one of the reasons I'm building me some Synergies that are smaller. 126dB is a neat trick, but I'd be fine with 116dB.


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## MetricMuscle (Sep 16, 2013)

I swear this friggin' HiFi sport never ceases to amaze and aggravate me!



Patrick Bateman said:


> Here's some background on this:
> 
> Back in 2009 I really wanted to attack the soundstaging problem, and I wrote a thread called 'creating the perfect soundstage.*'
> 
> ...


So-

- You installed the four 2" TangBands in a waveguide with something on the same baffle next to the opening, a tweeter? 

- If possible, would I want to get frequency response down into upper midbass territory, like around 300Hz or so?



Patrick Bateman said:


> Gary's car confirmed for me something that I'd suspected for a few years: that you can get horn-level dynamics with direct radiators. *Basically he's pushed the midrange so far into the corner, it's getting truly horn loaded by the windshield.* To make this work, you *really* have to push those drivers back. A gap of even five centimeters won't work; ideally the cone of the woofer would meet the glass and the dash. The driver has to be waaaay back for this to work.
> 
> 1) When I did my 'ultimate soundstage' project in '09, I frequently wondered if one could do the same trick using direct radiators
> 2) Gary's car does the same trick, using direct radiators
> ...


So what about a horizontal line array of those four 2" TangBands? Or a horizontal MTM using a larger more efficient mid and tweeter? What mid do you like for this, Patrick, keeping in mind how important diameter is to allowing them to be pushed back into the windshield/dash corner?

This is a great spot as far as wasted space that is easily accessible and shouldn't block vision when driving etc. My defroster vent doesn't extend all the way over to the edge of the dash, leaves me about 6". Also really provides a solution for where to mount the rear spearkers on my rear deck.

I had kinda wondered about doing this when reading the On-axis vs Off-Axis thread and the indepth discussion on reflections. They aren't avoidable so we have to manage and or use them to our advantage.

Doesn't look like Gary totally trusts the glass above his enclosure, he has sorta shrouded them a few inches. Are his mounted Off-Axis? Do you still profess Off-Axis is better if designed for a one-seat, drivers side, arrangement?


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## Orion525iT (Mar 6, 2011)

Patrick Bateman said:


> And, again, I'm not a huge fan of high sensitivity drivers. I am personally using the Dayton ND91 in my own car, but I'm using a pile of them. (Currently four and I'd like to get four more in there.)


The ND91s are no doubt low sensitivity. I have eyeballed them many times, but got put off by the sensitivity. The one thing I tried to understand was if/how using multiples could increase sensitivity. Arrays are said to increase sensitivity, but what if the drivers are separated slightly? How would using smaller drivers relate to dynamics? I have read claims that using two drivers of the same cone area and vd as a larger driver are still less dynamic.


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## cajunner (Apr 13, 2007)

the psychoacoustics of sound, with fatigue and compression playing their part, means that getting loud without distortion is what allows you to listen longer.

some of the issue with finding the top of the playback scale, and then tapering back to what you consider a suitable listening level, is that you know there's a crest factor but you don't care, you heard what the speakers were capable of, and you don't want to listen at a lower level.


it's insidious, you get used to a volume level almost instantly. Let's put this into a scale.

You play your low-midrange into distortion, say, at 96 db.

Your tweeters can go to 105, no sweat.

your subs can push 120, easy.


you know about equivalent loudness levels, everyone's seen the chart by Fletcher and Munson.

but what you didn't figure on, is when the music happens, if it doesn't have a whole lot of low-midrange, you're gonna set the system above 96 db for your listening level, because we like the bass all the way to massage mode, and until the midrange starts to complain and you go "whoa, must have turned it up too much" because there wasn't any reference point of distortion when you first set your volume.

that's why it's important to try and get an equal response, you don't want a system that has a frequency range that distortion happens a full 10 db or more before the rest of the response.


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## Patrick Bateman (Sep 11, 2006)

Orion525iT said:


> The ND91s are no doubt low sensitivity. I have eyeballed them many times, but got put off by the sensitivity. The one thing I tried to understand was if/how using multiples could increase sensitivity. Arrays are said to increase sensitivity, but what if the drivers are separated slightly? How would using smaller drivers relate to dynamics? I have read claims that using two drivers of the same cone area and vd as a larger driver are still less dynamic.


When two drivers are within 1/4-1/3rd of a wavelength they will act like one.
For instance, if you have two 3" woofers with a center-to-center spacing of 3" they will behave like one driver to 1,125hz. (speed of sound = 13,500 inches per second.)

As you go from 1/4 wavelength to larger distances, things get complex. Even with a spacing of a full wavelength it can still work. But the problem at these distances is that it will work at certain angles and not at others. And on top of all that, it will depend on phase, so the crossover has an effect! IE, with a first order slope you'll have flat response on-axis, but with a second order butterworth you won't! (Maddening, huh?)


TLDR : keep two drivers within one quarter wavelength and they will act like one, up to a point. That point is determined using this equation:
(speed of sound / center-to-center spacing / 4)


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## sqnut (Dec 24, 2009)

Unless I'm reading this wrong, dynamics for me is the systems ability to to deliver the impact on a transient as it goes from -30db to -5db. If one speaker is 3db more efficient than the other then it will be 3db louder at -30 and 3db louder at -5. Some drivers sound more dynamic than others, sure. Scans are more dynamic than dyns. I'm just not sure its down to efficiency alone. Morels aren't high efficiency speakers and yet Patrick puts Garys car ahead of the magic bus on dynamics. 

Dynamics are in your midrange response ~ 500-1khz. The drivers that sound more dynamic are the ones that do mid range better imo.


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## Patrick Bateman (Sep 11, 2006)

MetricMuscle said:


> I swear this friggin' HiFi sport never ceases to amaze and aggravate me!
> 
> 
> 
> ...



If you'll let me get on my soapbox for a minute, I think one of the general reasons that people aren't happy with their stereos is that there tends to be an attitude of 'put the speakers where they'll fit, use high order xovers to prevent them from overlapping, then add digital delay to fix the pathlength problem.'

This will get you a type of sound that is clean and 'hifi', but it falls down at a lot of tests:
1) imaging suffers
2) articulation suffers

A proper mid-tweet array just basically sounds like one seamless driver, if done carefully. So it has all the advantages and disadvantages of a larger driver.









For instance, an array of two drivers that's about 8" tall will have a polar response that's fairly similar to an 8" driver.









Smaller drivers will have a wider sweet spot, at the expense of power handling.

If you get the drivers really REALLY close together, they really do behave like one. But that requires insanely tight spacing. With a 2khz crossover point a tweeter would need to be 4.25cm from the midrange, or less than 2"!

Since that isn't practical with anything but Synergy horns and coaxials, we generally crossover that's equal to one wavelength. Going back to the example of 2khz, that means a center-to-center spacing of 17cm or 6.7".









Ever notice that 75% of the speakers out there look like this? Well that's why. 6.7" center to center spacing plus a 2khz crossover works. Increase the driver to 8" and you're pushing the tweeter too hard, but you can reduce it to just about any size if you don't need the extension of a 6.7" woofer.


Horizontal arrays aren't seen too much, because they're off axis response is ****. But in a car that might be an advantage, because you won't be sending as much output into the window as you would with a vertical array.


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## garysummers (Oct 25, 2010)

View attachment Benz.pdf


The mid and tweeter were aimed as shown, on axis. Height at ear level.


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## BigRed (Aug 12, 2007)

Mark Eldridge had been utilizing a horizontal array for a while for the reasons you have described


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## Patrick Bateman (Sep 11, 2006)

I'll probably head up to T.H.E. show at the end of the month. The system described in this thread is about 90% finished. I have a mic set up downstairs and I need to do some tuning, but I likely won't make any big changes before the end of the month.

If anyone wants to hear it, or just talk shop, send me a PM

Tickets are $15

The Home Entertainment Show Newport 2013 Attendee Pre-Registration


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## rton20s (Feb 14, 2011)

I'm tracking along, to some degree.  And I understand wanting to keep your mid and your tweeter close together. It seems that this has migrated from using some type of horn directly in front of you (anywhere from ear level to below the dash) to using the shape of the windshield/dash/a-pillars to have somewhat of a horn affect with traditional mids and tweeters. 

That being said, does any of this translate to the likely most widely used 2-way combinations our there? Mid down low (door or kick) and tweeter up higher? Separation is obviously going to be an issue (phase, crossover, etc.), but do you see any advantages to "corner loading" just a tweeter? (Compared to a traditional A-Pillar or sail panel mount.) And if so, what criteria should said tweeter need to meet to qualify as a good candidate for a corner loaded installation? Would the "pods" created for such a tweeter installation benefit from some sort of CCF or wool surround as mentioned earlier?


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## Patrick Bateman (Sep 11, 2006)

rton20s said:


> I'm tracking along, to some degree.  And I understand wanting to keep your mid and your tweeter close together. It seems that this has migrated from using some type of horn directly in front of you (anywhere from ear level to below the dash) to using the shape of the windshield/dash/a-pillars to have somewhat of a horn affect with traditional mids and tweeters.


When you get the drivers to touch the windshield, you get full-on, no holds barred horn loading. You still get horn loading as you move away from the windshield, but the energy reflected backwards gets reflected, and that reflected energy gets mixed in with the initial wavefront and rolls off your highs. Basically you can get horn loading on the mids as long as you can get the cone within about 2" of the windshield. With the tweeter it's a lot more complex because the wavelengths are so short.



rton20s said:


> That being said, does any of this translate to the likely most widely used 2-way combinations our there? Mid down low (door or kick) and tweeter up higher? Separation is obviously going to be an issue (phase, crossover, etc.), but do you see any advantages to "corner loading" just a tweeter? (Compared to a traditional A-Pillar or sail panel mount.) And if so, what criteria should said tweeter need to meet to qualify as a good candidate for a corner loaded installation? Would the "pods" created for such a tweeter installation benefit from some sort of CCF or wool surround as mentioned earlier?


I really think Gary's solution is a great recipe.
I went to bed about midnite on Saturday, woke up at four in the morning and pondered his design, realized there's no real way to improve on it, then decided I'd do something different. Walked down to the garage, sawed my waveguides into pieces, and glued them back together.

I mean, how do you improve on that stage?
Are there tweeters more efficient than the Morel? Sure, but you'll have to use a compression driver, and that requires a proper waveguide. Gary's system seemed to have plenty of dynamics, so I'm not sure if a compression driver would improve things. (Polars might be better.)

I'm not aware of a 3" midrange that will go louder than that Morel. And it's plenty smooth.

Another neat thing about the whole setup is that it's fairly easy to get 90% of the way there with competing drivers. ATC, Dynaudio, Tangband, and Dayton all make drivers like this.

But I'm also very keen on doing weird stuff in my projects, so simply doing a low cost clone of a very good front stage doesn't appeal to me too much. Hence, I went ambio.

Ordered a processor from Ambio4you on Sunday. In the meantime I'm doing the processing with my iPad.


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## thehatedguy (May 4, 2007)

ATC domes are HUGE. Badassed, but HUGE...like a massive 6.5 huge. I would love some, but the price and size say otherwise.

So I'm going to try the coax route with the Tannoy 8s.


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## rton20s (Feb 14, 2011)

Patrick, I think you initially caught the part where I was asking about a simple 2-way front stage then went away from it.  If you aren't running a 3-way front stage, or even a 2-way with a mid on the dash, is there any reason to try and corner load a tweeter? 

So, I understand that with a tweeter alone it would have to essentially be right on the glass (or very close to it). But is there really any reason to do this compared to a traditional pillar or sail panel install? Are you only reducing the delayed reflections, or is there something more to it?


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## Patrick Bateman (Sep 11, 2006)

rton20s said:


> Patrick, I think you initially caught the part where I was asking about a simple 2-way front stage then went away from it.  If you aren't running a 3-way front stage, or even a 2-way with a mid on the dash, is there any reason to try and corner load a tweeter?
> 
> So, I understand that with a tweeter alone it would have to essentially be right on the glass (or very close to it). But is there really any reason to do this compared to a traditional pillar or sail panel install? Are you only reducing the delayed reflections, or is there something more to it?


Actually it's the midrange that gets horn loaded.
The loading on the tweeter is complex, because it's not possible to get it all the way into the corner without a waveguide.










Waveguide sizes get truly ridiculous at low frequency, but at high frequency, they're tiny. For instance, if you cross a 3" midrange to a 1" tweeter at 4500hz, *you only need a 3" waveguide for the tweeter.*

On the other hand, if you cross a 3" midrange over to a 8" woofer at 400hz, *you need a thirty four inch waveguide*   

See where I'm going with this? The windshield is both horn loading the midrange and also acting as a waveguide. But, again, the trick only works if you get it all the way into the corner. If you're even three or four inches from the windshield the sound radiated backwards will get reflected and delayed in time. This creates a pleasant sense of 'space', and a lot of people are probably 100% happy with it. But the *only* way to get that pinpoint accuracy is to eliminate that radiation to the back. That means getting the driver all the way into the corner* or eliminating the back wave.

Second options sounds FABULOUS by the way, but nobody read my threads about cardioids 



* if I didn't make it clear, all small drivers are basically omnidirectional for most of their bandwidth. The energy radiates to the sides and to the back is a real problem. Check out Linkwitzlab.com to see why.


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## Bluenote (Aug 29, 2008)

Double post...


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## Bluenote (Aug 29, 2008)

Patrick this is really good info! One more scenario...let's say you have mids and tweets positioned in the far corners of the dash, but you are running a center channel facing up towards the windshield...this has been the suggested position for those with MS8 L7 and perhaps other Surround configs. Would the center defeat the effect of horn loading the L/R mids / tweets?


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## Orion525iT (Mar 6, 2011)

Patrick Bateman said:


> ... or eliminating the back wave.
> 
> Second options sounds FABULOUS by the way, but nobody read my threads about cardioids


I guess I am nobody, because I have been thinking about cardioids for the last month or so. Pretty sure it was one of your threads (or at least your input) that sent me that direction. Hmm... 

http://www.diymobileaudio.com/forum...on/105984-u-frame-semi-cardioid-bass-car.html


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## Patrick Bateman (Sep 11, 2006)

Orion525iT said:


> I guess I am nobody, because I have been thinking about cardioids for the last month or so. Pretty sure it was one of your threads (or at least your input) that sent me that direction. Hmm...
> 
> http://www.diymobileaudio.com/forum...on/105984-u-frame-semi-cardioid-bass-car.html


replied!

The cardioids sound really good.


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## Patrick Bateman (Sep 11, 2006)

Bluenote said:


> Patrick this is really good info! One more scenario...let's say you have mids and tweets positioned in the far corners of the dash, but you are running a center channel facing up towards the windshield...this has been the suggested position for those with MS8 L7 and perhaps other Surround configs. Would the center defeat the effect of horn loading the L/R mids / tweets?


IMHO the only reason to run a center channel is if you want a car that sounds good from both seats. If you're resigned to having a 'one seat' car, stereo will get you a wider image. Whenever you have two sound sources, then add one in the center, the width of the stage is going to get 'pulled' towards the center. This is just physics. So a center channel is perfectly valid if you have a wide room or you want to listen off axis. But if you have a narrow room and you're only listening from one seat, stereo is the way to go IMHO. (My stereo Mazda 6 has a way wider stage than my Logic7 Genesis.)

Now I'll sit here and wait for Andy to school me


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## rton20s (Feb 14, 2011)

Patrick Bateman said:


> Now I'll sit here and wait for Andy to school me


I think Andy has been so busy lately that all he has time to do is pop in, drop one liners, and split.


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## Bluenote (Aug 29, 2008)

Patrick Bateman said:


> IMHO the only reason to run a center channel is if you want a car that sounds good from both seats. If you're resigned to having a 'one seat' car, stereo will get you a wider image. Whenever you have two sound sources, then add one in the center, the width of the stage is going to get 'pulled' towards the center. This is just physics. So a center channel is perfectly valid if you have a wide room or you want to listen off axis. But if you have a narrow room and you're only listening from one seat, stereo is the way to go IMHO. (My stereo Mazda 6 has a way wider stage than my Logic7 Genesis.)
> 
> Now I'll sit here and wait for Andy to school me


Patrick thanks for the feedback. This has been a good discussion and even it's better that the focus of the discussion began with observations about a very cool set-up i.e, Gary's Benz.


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## MetricMuscle (Sep 16, 2013)

If I understand correctly, the benefits of this type of installation are-

- Waveguide created by windshield and dash create a gain in response.
- The waveguide better handles reflections and uses them for increased SPL.
- Does a better job of raising the mid and tweeter up to ear level than A-pillar or sail locations.

Important aspects to make this a success-

- Speaker baffle must extend from windshield to dash, no gaps for backwave to wrap around and create bad ill-timed reflections or cancellation.

This mostly works for the midrange so, what frequency range, 300 to 3KHz?


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## JoshHefnerX (Jun 13, 2008)

In order to get this waveguide/horn effect does the angle to the windshield matter, as long as it's touching the glass?

Josh


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## Patrick Bateman (Sep 11, 2006)

MetricMuscle said:


> If I understand correctly, the benefits of this type of installation are-
> 
> - Waveguide created by windshield and dash create a gain in response.
> - The waveguide better handles reflections and uses them for increased SPL.
> ...


That's a great summary. Waveguides and horns are complex beasts, but fundamentally all they do is take the energy that would normally radiate to the sides and to the back and they 'focus' that energy forward.

I would argue that even a flat speaker baffle is a waveguide. It's simply a waveguide that has 180 degrees of coverage.

As far as stage height goes, that's mostly going to be determined by where the sound is the loudest. For instance, if your midrange is at eye level, it's probably going to *sound* like it's at eye level. But there's some weird exceptions to this rule. For instance, if you're listening really far off axis, like 90 degrees, the reflection off of the other side may be louder than what you hear at your seat!

When I was messing around with dipoles and cardioids that was one of the strange things I noticed, that you could point a speaker away from you, at a hard reflective surface (you know, like a passenger window  ) *and the reflection is so strong it's virtually like putting a speaker there.* Particularly with cardioids, which are directional, you could create the illusion that the sound was radiating from a point where it wasn't.


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## Patrick Bateman (Sep 11, 2006)

JoshHefnerX said:


> In order to get this waveguide/horn effect does the angle to the windshield matter, as long as it's touching the glass?
> 
> Josh


The windshield is basically acting like a waveguide here.
If I'm not mistaken, the ideal shape for a waveguide throat is flat.
This might sound like splitting hairs, but it's not; if the shape of the wavefront at the throat isn't perfect then everything goes to hell. 

















Next time you're at Guitar Center, take a look at the prosound speakers. Look at the tweeters. You'll notice that they're not spherical like a Dynaudio dome, they're flattened out into a parabolic shape. There's a reason for that; it makes the waveguide work better. The pics above show a Dynaudio tweeter versus a tweeter ripped out of a Genelec prosound monitor.








*
The ideal shape is flat, but flat shapes get expensive.

* from review here : http://www.diymobileaudio.com/forum...-band-w4-1757sb-flat-cone-mid-full-range.html


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## Patrick Bateman (Sep 11, 2006)

Looks like Genelec is using a Vifa part. They modified it by using a different face plate, but it's basically a $30 Vifa tweeter:

D19AD-05/06 - Vifa ¾ inch dome tweeter aluminum diaphragm ferrofluid - Europe Audio









Here's what it looks like on a conventional speaker









Genelec in it's natural element

When you put a 1" source onto a waveguide, your high frequencies start to fall off. This is because there's a pathlength difference from the front of the dome and the edge of the dome. Again, a fraction of a centimeter doesn't seem like it would be a big deal, but at 20khz, it actually is! At 20khz your margin of error is 0.16875" (1/4 WL at 20khz.)

So Genelec cleverly opted for a 3/4" Vifa part that minimizes that error by virtue of it's small size, combined with the fact that the dome is flatter than your typical dome tweeter.


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## ErinH (Feb 14, 2007)

I believe you're right about the drivers. If you search eBay you can find piece parts and I'm pretty sure I recall seeing Vifa drivers used. Seems like one model uses a 8" Vifa woofer.


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## Patrick Bateman (Sep 11, 2006)

Wow, I just had an epiphany:

My car is now set up with an ambiophonic stage. And I really like it; the soundstage is pinpoint and the center is better than any I've heard.

At Saturday's MECA event, *I noticed that just about everyone had a wider stage than I do.*

IMHO, this extra width is caused by reflections off of the side glass. For instance, when your tweeters are up high, sound from the right tweeter is reflected off of the left window. According to Toole, sounds delayed by ten milliseconds or more add a pleasant sense of ambience.

My system has a hard time recreating that, because the area of the car below about chest level has a lot of stuff that diffuses sound waves. (The driver, the complex curves on the door and the dash, the seats, the carpet, etc.)



But it just occurred to me that the entire point of the thesis that inspired the 'one tweeter thread' was to have the tweeters seperated from everything else.

So here's what I'm picturing:

An ambiopole down low, under the dash, covering 300hz -10khz, and then two tweeters up high. The high tweeters don't just raise the stage, they add ambience via reflections off of the side windows.

They would cover just one or two octaves. 5khz - 20khz.


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## sqnut (Dec 24, 2009)

Reflections from the side windows is creating cross talk at both your ears which limits your width. Roll the windows down and the width should go up. IMHO width cues are in the upper mid bass and lower mid range and then in your highs. In my limited experience maximizing PLD between the two mid bass and your tweets, helps with width. 

Height cues are ~1.0 khz and up. Having some amount of 2khz and everything higher at dash level or higher is great for height. 

Waiting to be told I'm wrong on all counts


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## ErinH (Feb 14, 2007)

Patrick Bateman said:


> My car is now set up with an ambiophonic stage. And I really like it; the soundstage is pinpoint and the center is better than any I've heard.


I had the *complete *opposite result. The soundstage changed dramatically with music but I never felt like it improved things in any regard. Didn't take me long to scrap that idea.


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## Patrick Bateman (Sep 11, 2006)

bikinpunk said:


> I had the *complete *opposite result. The soundstage changed dramatically with music but I never felt like it improved things in any regard. Didn't take me long to scrap that idea.


IMHO, the 'trick' with ambio is similar to most processing:

You have to use the minimum humanly possible.

I've tried ambio using a physical barrier (a big board, from the speakers right up to my face, at home). And I've tried ambio using processing. (Foobar2000 plugin, at home.)

Neither was particularly satisfying. The version using software had some tracks with a huge soundstage, but other tracks it made them sound worse due to timbral changes. The version using a physical barrier and no software was more successful, but it lacked the width of the software version. (With a physical barrier there are no timber changes.) The center image is really solid with both, which I like a lot. Music is mostly mono really.

But a *combination* of both methods, which is what I'm doing in my car right now, seems to be really solid. By using waveguides on everything above 300hz I'm mimicking the effect of a physical barrier, and then I'm using a *little* bit of processing on top of that.


















Jason Melo used a variation on this for his. Basically a fraction of the speakers are receiving a processed signal, while the majority aren't.

One idea I had, to mimick this effect with two speakers, would be to process my entire music library like this:

1) First we take a stereo song and convert it to ambio
2) Then we merge that ambio song with the stereo song

So we get a song that's 50% stereo, 50% ambio. Theoretically, it seems that the dials in the ambio app should be capable of doing this, but even at their subtlest settings the effect seems to be quite pronounced. Considering that the iPad app doesn't even work on my iPad, I'm guessing that there's some bugs in the code. (I have a processor from the miniDSP guys on the way from Hong Kong, and I'm using the iPhone app on my iPad. Why the iPhone app works and the iPad app doesn't work is anyone's guess! You get what you pay for.)


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## Patrick Bateman (Sep 11, 2006)

sqnut said:


> Reflections from the side windows is creating cross talk at both your ears which limits your width. Roll the windows down and the width should go up. IMHO width cues are in the upper mid bass and lower mid range and then in your highs. In my limited experience maximizing PLD between the two mid bass and your tweets, helps with width.
> 
> Height cues are ~1.0 khz and up. Having some amount of 2khz and everything higher at dash level or higher is great for height.
> 
> Waiting to be told I'm wrong on all counts


Based on what I understand from Haas, *most of our imaging cues are formed in the first 0.62 milliseconds. That's 21cm or 8.37".*
My ex-gf had a car that imaged really nice from the drivers seat, and crappy from the passengers seat. My theory was that they applied a little bit of delay in the head unit. Since the speaker on the left is generally *at least* eight inches closer than the one of the right, it really screams "hey this is the first signal so the soundstage is going to get panned HARD to the left." I have a center channel in my Genesis, and you can flip it on and off. It's really a trip to hear how hard the stage shifts when you turn off the center. But even with the center turned on, the soundstage is still a ways to the left, due to the left speaker *still* being closer than the center.

There's an interesting discussion of the situation here: Audio Asylum Thread Printer


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## sqnut (Dec 24, 2009)

In a room we are dealing with three different types of sound. Direct, early reflections and late reflections. In a car its only direct and early reflections, late reflections are virtually non existent. All our 'location' cues are from the direct sound. Early reflections amplify the direct sound above ~800hz and make the imaging a bit fuzzier. Late reflections give you room cues, how big is the space you're listening in, ambiance etc. That is how I understand it.

In a room as you increase the distance between the speakers the stage gets wider which is why I spoke about increasing PLD between drivers. Eventually you'll hit the point where the side walls prevent you from moving the speakers further apart. So width is based on distance between speakers and ultimately the width of the room.

However Polk made the SDA line of home speakers, where each speaker had one midrange that carried the others channels info from ~ 300-5khz iirc but in reverse phase and attenuated 12-15db. Man those SDA's gave a 25 foot width in a room 15 feet wide. Just amazing. I have always wanted to try this in a car. If we could get this to work in a car the issue of width would be solved forever. Although probably the early reflections in a car would kill this effect.

Getting a strong centre in a car is down to timing and L/R eq. Without the dsp and you in the drivers seat, yes the stage will pan hard towards the nearest driver, left in your case and right in mine.


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## garysummers (Oct 25, 2010)

Patrick, I found the opposite to be true in my car. If you noticed when you were in the car that I had placed felt on the B-pillar and also on the driver side window. see photo









I found that by eliminating the reflections off the hard plastic pieces in the B-pillar and out about 3.5" inches onto the glass that the image focus and clarity improved. I first saw this by just putting my arm up and blocking the glass for the width of my arm. The difference in the actual RTA response with and without was almost negligible but to my ear without the acoustic treatment the image smeared in the area shown in the photo in the frequency range shown.
I would have masked more of the glass but that may have affected driving visibility.
I did not see it really affecting the stage width!









I believe by eliminating those close reflections the image becomes more stable!

Your thoughts?


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## cajunner (Apr 13, 2007)

Patrick Bateman said:


> Based on what I understand from Haas, *most of our imaging cues are formed in the first 0.62 milliseconds. That's 21cm or 8.37".*
> My ex-gf had a car that imaged really nice from the drivers seat, and crappy from the passengers seat. My theory was that they applied a little bit of delay in the head unit. Since the speaker on the left is generally *at least* eight inches closer than the one of the right, it really screams "hey this is the first signal so the soundstage is going to get panned HARD to the left." I have a center channel in my Genesis, and you can flip it on and off. It's really a trip to hear how hard the stage shifts when you turn off the center. But even with the center turned on, the soundstage is still a ways to the left, due to the left speaker *still* being closer than the center.
> 
> There's an interesting discussion of the situation here: Audio Asylum Thread Printer


and that's the key to everything!


Haas, is where it's at.

in a car, you can't escape Haas, with direct radiation but reflections will clear the bar, you're basically in a cocoon where you think you're safe, but everything in the reflective zone is fair game as first reflections to the ear cross the 10 foot marker...


so working with the first reflection, a-la batwings on a-pillar/dash pods, is an effective solution when you think it wouldn't really matter.

horns work simply due to their amount of direct radiation is so much greater than an omni-baffle load, it pushes the imaging into tighter focus because all the side reflections, all the long "past Haas" effects, are down in level.

that's why it can seem like horns are "in your face" so much, too. I bet a system with ambient located drivers, coupled with the under-dash car audio horns, using separate processing would be the bomb since you could tailor the amount of "room" you want, while never giving up that clarity of first arrival times.


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## sqnut (Dec 24, 2009)

Hi Gary,

With your background I know your car would sound incredible. The setup looks amazing and I'm sure a lot of TLC and tuning went into it. I'm curious though if you have tried it w/o the centre channel i.e. only L/R. How does that sound vs running the centre?


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## garysummers (Oct 25, 2010)

When playing stereo recordings I never use the center channel. Only "Pure Stereo"

I only use the center channel when playing discreet 5.1 program, ie. Dolby Digital, DTS, and DVD-Audio discs.


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## kustomkaraudio (Jun 20, 2009)

sqnut said:


> Hi Gary,
> 
> With your background I know your car would sound incredible. The setup looks amazing and I'm sure a lot of TLC and tuning went into it. I'm curious though if you have tried it w/o the centre channel i.e. only L/R. How does that sound vs running the centre?


I will chime in for this one.

The center channel is only on when 5.1 media is being played, as well as the rear fill.

Only the left and right front speakers and subwoofer are on during 2 channel play back.


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## sqnut (Dec 24, 2009)

garysummers said:


> When playing stereo recordings I never use the center channel. Only "Pure Stereo"
> 
> I only use the center channel when playing discreet 5.1 program, ie. Dolby Digital, DTS, and DVD-Audio discs.


:thumbsup: makes perfect sense now.


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## garysummers (Oct 25, 2010)

As I have stated in other posts and I know there are some that will disagree but the up-mix systems available today for car audio greatly alter the timbre and the image/stage while attempting to derive the center and rear information. A trade off some are happy with, as for me I would prefer to keep the recording in it's original format and hear it as the original artist intended.


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## sqnut (Dec 24, 2009)

kustomkaraudio said:


> I will chime in for this one.
> 
> The center channel is only on when 5.1 media is being played, as well as the rear fill.
> 
> Only the left and right front speakers and subwoofer are on during 2 channel play back.


with 10-12 output channels what is being used for processing?


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## garysummers (Oct 25, 2010)

Not sure what you mean.

The processors are two Alpine PXA-H990's

View attachment Final System NEWV5nologo.pdf


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## sqnut (Dec 24, 2009)

garysummers said:


> As I have stated in other posts and I know there are some that will disagree but the up-mix systems available today for car audio greatly alter the timbre and the image/stage while attempting to derive the center and rear information. A trade off some are happy with, as for me I would prefer to keep the recording in it's original format and hear it as the original artist intended.


I agree 100% If it doesn't sound right, any side benefit is immaterial to me.


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## Patrick Bateman (Sep 11, 2006)

garysummers said:


> When playing stereo recordings I never use the center channel. Only "Pure Stereo"
> 
> I only use the center channel when playing discreet 5.1 program, ie. Dolby Digital, DTS, and DVD-Audio discs.


Any thoughts on rear fill with stereo?

Since you already have full range drivers with dedicated amps and processing, I figured you'd tried it.

In my five channel car I only have two modes, two channel or five channel. I can't do four channel.


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## sqnut (Dec 24, 2009)

garysummers said:


> Not sure what you mean.
> 
> The processors are two Alpine PXA-H990's
> 
> View attachment 53348


Thanks, that is some system. How close is the sound to that in your studio?


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## garysummers (Oct 25, 2010)

If you are properly extracting the correct amount of the L minus R from the front channels, applying the appropriate delay time and properly set levels it can have a dramatic effect on the stage width and overall sonic dimension.
In a previous install I did back in the 90's in a 1991 Volvo 780 Bertone, I used the Audio Control ESP3 to derive L-R and it was quite affective in adding a extra dimension to the sound stage. I did however leave the front left and right intact and added to it in the rears the extracted L-R.


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## garysummers (Oct 25, 2010)

How close is the sound to that in your studio?

Don't own a studio. Motion Picture mixing studios cost millions to build and maintain. I let others do that and just use it.


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## ErinH (Feb 14, 2007)

Patrick Bateman said:


> IMHO, the 'trick' with ambio is similar to most processing:
> 
> You have to use the minimum humanly possible.




How's a single 2" aura whisper per side for minimal? That's what I started with. Tried a couple other methods, too. None worked. The stage would expand and contract with a lot of variation per recording but it was never focused by any stretch. Maybe in a home, but certainly not with the typical car setup. I'm speaking from practical experience from a period when I WANTED something different to work badly. I even tried a phased array LCR setup. Though, ultimately standard 2-channel is where I wound back up. 

The problem I found with ambio was due to PLDs and while I fully believe you can do a great job with DSP wrt PLDs, TA totally screws up ambio (because it's already screwing phase). I think it might bear more fruit if you had two separate setups in the same car. IOW, a left and right equidistant from each listener. Which would mean placing the right speaker at/near the center of the car to complete the equilateral triangle for the driver. And for the passenger you'd do the same. And you wouldn't have both playing at the same time because you'd practically have summed mono. 

Cliffs: I don't know how you managed to get ambio to work but it sure didn't for me. And it wasn't for a lack of actually trying it in my car


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## Patrick Bateman (Sep 11, 2006)

sqnut said:


> In a room we are dealing with three different types of sound. Direct, early reflections and late reflections. In a car its only direct and early reflections, late reflections are virtually non existent. All our 'location' cues are from the direct sound. Early reflections amplify the direct sound above ~800hz and make the imaging a bit fuzzier. Late reflections give you room cues, how big is the space you're listening in, ambiance etc. That is how I understand it.
> 
> In a room as you increase the distance between the speakers the stage gets wider which is why I spoke about increasing PLD between drivers. Eventually you'll hit the point where the side walls prevent you from moving the speakers further apart. So width is based on distance between speakers and ultimately the width of the room.
> 
> ...


We can do this in the car *right now* and it's free if you have an iPhone or iPad : Software

Get it from the App Store, just posting the link because Stephan also has some other cool stuff that's relevant here, like DSP bass cancellation that might offer some of the goodness of Whitledge's Magic Bus. Basically using DSP to soak up bass resonances, instead of the helmholtz absorbers Jon uses.


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## ErinH (Feb 14, 2007)

Patrick Bateman said:


> ...
> like DSP bass cancellation that might offer some of the goodness of Whitledge's Magic Bus. Basically using DSP to soak up bass resonances, instead of the helmholtz absorbers Jon uses.



Try telling Jon they're the same thing. 
(FWIW, I have been trying to stress the importance of a good parametric EQ for the same reasons)


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## cajunner (Apr 13, 2007)

garysummers said:


> If you are properly extracting the correct amount of the L minus R from the front channels, applying the appropriate delay time and properly set levels it can have a dramatic effect on the stage width and overall sonic dimension.
> In a previous install I did back in the 90's in a 1991 Volvo 780 Bertone, I used the Audio Control ESP3 to derive L-R and it was quite affective in adding a extra dimension to the sound stage. I did however leave the front left and right intact and added to it in the rears the extracted L-R.


so what lycan proposed with l-r, attenuated and delayed rear fill, was already successful and being utilized decades before DIYMA got wind of it?

is that like a black box thing that went mainstream, but... since manufacturers have to make a profit, they licensed PL-2 and put that in their processors, taking the place of the un-badged version?

and can someone develop exactly what is needed, without calling it Circle Surround, or SRS, or whatever?


then sell it, without infringing on any "Tate-Fosgate" type patent issues?


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## Patrick Bateman (Sep 11, 2006)

bikinpunk said:


> How's a single 2" aura whisper per side for minimal? That's what I started with. Tried a couple other methods, too. None worked. The stage would expand and contract with a lot of variation per recording but it was never focused by any stretch. Maybe in a home, but certainly not with the typical car setup. I'm speaking from practical experience from a period when I WANTED something different to work badly. I even tried a phased array LCR setup. Though, ultimately standard 2-channel is where I wound back up.
> 
> The problem I found with ambio was due to PLDs and while I fully believe you can do a great job with DSP wrt PLDs, TA totally screws up ambio (because it's already screwing phase). I think it might bear more fruit if you had two separate setups in the same car. IOW, a left and right equidistant from each listener. Which would mean placing the right speaker at/near the center of the car to complete the equilateral triangle for the driver. And for the passenger you'd do the same. And you wouldn't have both playing at the same time because you'd practically have summed mono.
> 
> Cliffs: I don't know how you managed to get ambio to work but it sure didn't for me. And it wasn't for a lack of actually trying it in my car


Where were the drivers? Here was my experience in the car:

1) With two drivers on the center of the dash I had a nice center image in the center of the dash, but width was all over the map. Some recordings were very wide, 80% of them sounded mono. I ditched it quickly.

2) Putting the drivers RIGHT IN FRONT OF ME made all the difference in the world. I can't stress how important it is to have them equidistant to your ears. It literally 'pops' into focus and then the car seems to disappear. I've always preferred my center to be at the center of the car too, so this is a new thing for me.


I have a 'hunch' that it might be possible to put the ambiopole in the center of the car. To make it work, you'd have to physically move the drivers to time align it.









This is Darin Hawbakers car. (We both have Mazda6s.)

For the life of me, I couldn't figure out how he got ambio to work in the center of the dash. Then it occurred to me that you could delay the left channel and that might do the trick. And when I say delay, I'm talking fractions of an inch. I sat in the car and tried to measure it with a tape measure, then realized that it has to be so exact, it's probably better to get in the ball park and then tweak it by ear. Even an inch of movement seems to alter the illusion. Total 'head in a vise' soundstage.


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## garysummers (Oct 25, 2010)

FYI

This is the monitor system in the mixing stage I am currently working.

Main Screen channels: L.C,R

5742

Subwoofers for the .1 channel and I believe there are three of them!

4642A

With about 5,000 watts per channel all active 
The room can mix formats from mono to ATMOS and everything in between!


Try to get your car to sound like that!!!


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## KP (Nov 13, 2005)

Horn loading midranges on top of the dash like this?


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## MetricMuscle (Sep 16, 2013)

It just occurred to me that an up firing dash speaker could also be considered a waveguide loaded horn style if pushed to the corner of the dash and windshield. This might be my only option as the windshield / dash relationship in both of my cars isn't conducive to an upright vertical baffle installation of a driver with any real size.


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## Patrick Bateman (Sep 11, 2006)

garysummers said:


> FYI
> 
> This is the monitor system in the mixing stage I am currently working.
> 
> ...



















That waveguide looks familiar 

Parts Express sells a Pyle knockoff of the JBL progressive transition waveguide. Very good performance, about as good as I've measured. There's a couple of QSCs that might perform a *little* bit better, but it's very very close.










Here's the frequency response with a $125 JBL 2408H-1. Top curve is on-axis; bottom curve is 45 degrees off axis. It actually performs a little b8it better off axis than on, which is a bit unusual for horns.


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## seafish (Aug 1, 2012)

garysummers said:


> If you are properly extracting the correct amount of the L minus R from the front channels, applying the appropriate delay time and properly set levels it can have a dramatic effect on the stage width and overall sonic dimension.
> In a previous install I did back in the 90's in a 1991 Volvo 780 Bertone, I used the Audio Control ESP3 to derive L-R and it was quite affective in adding a extra dimension to the sound stage. I did however leave the front left and right intact and added to it in the rears the extracted L-R.



I have a AC 90/11 (basically an ESP3 with a built-in amp for the center channel, that I wll be installing in my truck soon. 

Can you tell (or even draw??) for me how you fed the derived L-R signal into the REAR channels? Or did I misunderstand what you did with the ESP3??


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## garysummers (Oct 25, 2010)

Do you think it is designed that way on purpose? This is the room that the system is in.

View attachment stage1.pdf


It has the most uniform response across the room as I have ever heard.
Very smooth and real good Dialogue intelligibility. 
Man can it go loud, without distortion.


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## garysummers (Oct 25, 2010)

You feed Left and Right into the unit. Outputs are Left, Right, Center, Rear.
You can turn the center control to extract L+R from Left an Right.
Turn the rear control to extract L-R from Left and Right.
I would defeat the center control or use very little of it to the center channel in the dash. Just enough to center your stage.
Send the L_R signal to your rear speakers. Yes it is mono but just "Y" it to the amplifiers for your rear speakers. Adjust for the best width and space. If you can apply delay to the rear channels that will help as well. A bit of de-correlation can help as well.


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## Patrick Bateman (Sep 11, 2006)

I have some exciting news: *It looks like you CAN put the ambio speakers in the center of the dash.* DSP delay does indeed work here.

As noted earlier in the thread, I've tried ambio set ups with the speakers right in front of me, and with the speakers on the center of the dash. With the speakers right in front of me *the soundstage was dramatically wider *and* had a solid center image.* Get everything centered and the boundaries of the car almost seem to disappear. It is very very cool. The best sound was right up on the dash, but it's not practical to put the speakers there, due to the instrument cluster. So I put the ambio speakers under the dash, and the stage was lower and narrower due to that.

When I put the speakers in the center of the dash, there was a strong center image, but width suffered.










After looking at Darin Hawbaker's setup, it dawned on me that DSP delay might give us the best of both worlds. Ambio is very picky about timing; the processing depends on delay, so if the timing is off by even a fraction of a millisecond, the effect doesn't work well.

So I measured *exactly* what the pathlength was, popped it in to my MiniDSP, and lo and behold, I have a soundstage that's almost a hundred and eighty degrees now.


If anyone wants to give this a try at home, put a couple of sealed full range speakers up on the center of the dash. Then get the ambio app for your iPad or iPhone. And delay the LEFT speaker by 0.12 milliseconds. (IE, both speakers face forward, like Durwood's pic, but the closer speaker is delayed by 0.12 milliseconds so that it's in sync with the further speaker.)

Also, I tried enabling and disabling the delay, and noticed that it changes the center and width of the soundstage. So you can probably 'dial it in' using delay.


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## subterFUSE (Sep 21, 2009)

Great thread. Learning so much. Sub'd.


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## ErinH (Feb 14, 2007)

KP said:


> Horn loading midranges on top of the dash like this?


indeed. 

or John's Murano here:
http://www.diymobileaudio.com/forum...-06-nissan-murano-meca-modex-sq2-bound-8.html

Then there's Matt's truck, which doesn't have the tweeters tucked, but more aimed in a waveguide manner:
http://www.diymobileaudio.com/forum...ll-gallery/29688-matt-rs-chevrolet-truck.html

There are more installs that attempt to use the windshield as a waveguide than I can count. I can think of about 10 people I know personally who are doing or have done this. Numerous stock systems have the drivers placed here as well.

The real problem is getting the 'guide' smoothed out, like you (Kirk) have done. Most have no smooth transition to the glass or dash - especially the ones that have the drivers below the dash - which essentially is the same setup a sail panel tweeter setup has; one major boundary 'guiding' the sound (if only it really were that easy). 

The one drawback I've noticed in every setup with the drivers buried up at the glass like this is reduced width. The width stops at the pillars. That just seems to be the tradeoff. That's actually why John moved his tweeters to the sails, from his initial dual aura whisper setup.


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## ErinH (Feb 14, 2007)

Patrick Bateman said:


> Total 'head in a vise' soundstage.




which is the kicker to me, so let me get semi-OT here for a second...
Why chase all these 'fancy' methods of quasi-stereo when *simple 2-channel stereo WITH A FOCUS ON SOUND POWER AND INSTALLATION can net you such a great response.* Instead of spending a billion hours on the RTA, spend a few hours on setting up crossovers, T/A, and levels and you're 80% there. The rest should be simple tonality adjustments or smearing fixes (if your install is such that the smearing is bad enough). I've been trying to hammer this stuff home for the past year or so and I can't tell you the number of people who have told me how little EQ or variation they had in respect to head movement with their system by simply focusing on these things. There are many, many great threads here discussing how to do these basic things which have helped a lot of people including myself. 





*Again, I've tried all sorts of stuff in my car as recently as early last year, from 5.1 via the h800 to phase arrays with (2) 8-channel DSPs running LCR with an MTM setup layed on its side to rear-fill (both dolby pl2 via the rfq5000 as well as simple differential) to ambio and even summed mono center tweeter only. I did all of that and STILL wound right back up at simple 2-channel. *I focused on sound power; matching the dispersion patterns between the mid and tweeter and I netted the best results. With minimal EQ (currently running NO EQ above 300hz; only EQ'ing modal issues). 



We (the car audio community) can keep spinning our wheels on "unconventional" stereo but the fact of the matter is that we won't be doing ourselves service until we understand some basics of frequency response and then basics of DSP (ie; crossovers, time, and levels) and how to apply that. Some people, such as myself, have a hard time taking words and putting them to use so I suggest attending a meet or comp and *listen *to cars. There's a lot of people who think they have it all figured out and you realize quickly they don't. And from the internet, it's not always easy to know who to believe and who not to believe. When you hear one that sounds good, ask the owner if they would give you some pointers. That's the best way to learn. Maybe they can even help you out. I've heard _numerous _cars that were jacked up and all it took was a simple polarity swap and/or some time alignment to get things sounding completely better. And, yet, it's those same people who come here, read these really cool threads and go attempt whatever it is, then come back wondering why their system doesn't sound as good as they think it should. 



*I'm not targeting anyone with the above response. Nor am I knocking the ideas... Especially since I've tried a lot of them myself and learned a lot from the practice. I'm just making the general point that it doesn't have to be complex to sound good. *You/we/me/my just have to understand how to get the basics down first and then, possibly, these other, less conventional methods will do something more for you (and make no mistake, you WILL have to deal with a tradeoff somehow). 



- Erin


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## MetricMuscle (Sep 16, 2013)

bikinpunk said:


> Why chase all these 'fancy' methods of quasi-stereo when *simple 2-channel stereo WITH A FOCUS ON SOUND POWER AND INSTALLATION can net you such a great response.*


LOL! You do remember who started this thread. There are already too many folks content with doing it the easy straight forward way, folks who don't wake up at 4 in the morning unable to allow the now perceived inferior waveguides in their basement to live unaltered one more minute.

A man can be an artist.
Patrick's art is HiFi.
He's about to paint his Masterpiece.

Audi looks to be experimenting with this type of placement.
Prolly gonna need some processing control.
Maybe Gary can try this next.


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## newfinish (Sep 2, 2013)

love this thread!
made me think about an old article from tom nousaine about rear fill if any of you have seen it? I'm posting it for fun...
I'm planning to install in my car again and all these ideas got me thinking keep it up!


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## ErinH (Feb 14, 2007)

MetricMuscle said:


> LOL! You do remember who started this thread. There are already too many folks content with doing it the easy straight forward way, folks who don't wake up at 4 in the morning unable to allow the now perceived inferior waveguides in their basement to live unaltered one more minute.
> 
> A man can be an artist.
> Patrick's art is HiFi.
> He's about to paint his Masterpiece.


Well, heck, I'm sure a few guys in this thread would consider their efforts an attempt at a masterpiece as well. I know I haven't spent years rebuilding, measuring and testing all to achieve a crappy system... at least not on purpose. 

What I'm saying is that there isn't really anything new here. Ambio has been tried. Cardoid has been tried. "Dash as a waveguide" has been tried and used by many on this forum, as Kirk mentioned earlier. The ideas are really cool and fun to persue, for sure! It's just trying to apply different approaches to the car audio environment. Which is GREAT. I've played around with a lot of it myself. * My point is simply that the basics need to be understood before springboarding off in to the abyss. If you don't really have a solid grasp on fundamental aspects of audio, then you'll find yourself in a big mess of trouble.* I'm pretty sure others have tried to make this same point but it seems to have gotten lost in the shuffle as this thread has meandered from topic to topic. Not that I mind that... it suits my ADD tendencies very well.


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## Patrick Bateman (Sep 11, 2006)

MetricMuscle said:


> LOL! You do remember who started this thread. There are already too many folks content with doing it the easy straight forward way, folks who don't wake up at 4 in the morning unable to allow the now perceived inferior waveguides in their basement to live unaltered one more minute.
> 
> A man can be an artist.
> Patrick's art is HiFi.
> ...


Whoah, let's not get carried away now 

I'm not 'painting a masterpiece', I'm that crazy neighbor down the street that's building a boat out of matchsticks in his back yard. There's definitely an argument for doing things the normal way!

"_Addiction is characterised by inability to consistently abstain, impairment in behavioural control, craving, diminished recognition of significant problems with one’s behaviours and interpersonal relationships, and a dysfunctional emotional response. Like other chronic diseases, addiction often involves cycles of relapse and remission. Without treatment or engagement in recovery activities, addiction is progressive and can result in disability or premature death._"


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## ErinH (Feb 14, 2007)

To bring this back more toward the discussion, check the links I gave above with some of the build threads regarding "windshield as a waveguide'. There's some really good pictures and ideas there. There's really great discussion sprinkled throughout this site as well. I can't find a specific link ATM though I know there's been plenty of discussion on the topic. As I said earlier, the real problem I found with that type of setup has been with regards to width, which seemingly stops right at the pillars. I'm not really a fan of that type setup, though I won't say it can't be made to sound good. I think that's a good method for installing a speaker when you want/need stealth. But, optimally, I couldn't really recommend it. There's a lot to fight, namely with regards to EQ. I've had better luck bringing the drivers closer to me and shooting for more of a direct firing type install than one that has to fight dash contours. But, every car is different. The huge instrument cluster in my car may not be as bad in your car.

The issue with typical setups like this, though, are they don't have symmetrical dashes. And when the dash/horn is your waveguide, well, that creates a problem. Furthermore, the transition of the driver to the waveguide is key. So, when it's not smooth and doesn't contour to the waveguide (in this case, the dash/windshield), there's additional problems. * Kirk's setup, a few posts up, has fairly smooth entry from his midrange/tweeters to the dash/windshield. Look at how his mids are aimed and how they extend with the windshield. *I have heard Kirk's car. Numerous times. Kirk knows what he's doing... one of the best sounding cars of all time using stock type locations (albeit the latest version modifies the dash for this waveguide type setup). The thing Kirk has over most people is he knows what he's listening for and knows through trial and error what he's doing. Or so I presume. either that, or he's just darn lucky.  You'll also see Kirk has the mid and tweeter very close to each other. This is a very important thing to keep in mind as it keeps lobing to a minimum and he's able to cross the drivers over at a reasonable frequency.


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## Patrick Bateman (Sep 11, 2006)

bikinpunk said:


> which is the kicker to me, so let me get semi-OT here for a second...
> Why chase all these 'fancy' methods of quasi-stereo when *simple 2-channel stereo WITH A FOCUS ON SOUND POWER AND INSTALLATION can net you such a great response.* Instead of spending a billion hours on the RTA, spend a few hours on setting up crossovers, T/A, and levels and you're 80% there. The rest should be simple tonality adjustments or smearing fixes (if your install is such that the smearing is bad enough). I've been trying to hammer this stuff home for the past year or so and I can't tell you the number of people who have told me how little EQ or variation they had in respect to head movement with their system by simply focusing on these things. There are many, many great threads here discussing how to do these basic things which have helped a lot of people including myself.
> 
> 
> ...


_Here's an analogy: Fifteen years ago, the clock speeds of computer processors were going higher and higher and higher. IBM, Intel and AMD were all locked in a race. For six months one manufacturer was on top, then a different one would take the crown. This literally went back and forth for about a decade. Then a little lab at Intel, in Israel not Oregon iirc, they took an old Intel processor and tweaked it for something besides speed. *They tweaked it for POWER.* And this was a complete game-changer. Up until that point, everyone had been obsessed with clock speed, but this tiny team showed that sometimes it's better to go a little bit slower but have much less power and much less heat. Intel ended up abandoning their architecture entirely. If anyone had the last of the 'old school', the Pentium 4, they may recall how ridiculous it was. The processor could go nearly 4ghz, but it was loud, expensive, and would practically catch on fire if the fan failed. It was the apex of development at the time, but it was also highly impractical._

Why ambio? Because I listened to Gary's car and said to myself "I don't think I can do better than this." For instance, when I heard Harry Kimura's car in the 90s, the dynamics were like nothing I'd heard before. But after messing around with horns under the dash, I realized you could improve things by putting them ON the dash. So that's an example of how you might improve Harry's car. But Gary's car? What's there to change?

Also, ambio and cars are a match made in heaven. The drawback with ambio is that it only sounds great from one spot, and from the other locations, it sounds phasey and weird. Up until a week ago I thought that meant that the ambio speakers had to be right in front of you, ideally at eye level. That's not so hot for a car; you have the instrument pod there.

But pondering Durwood's car gave the solution, DELAY. And it works! I have the ambio speakers where a center channel goes, the vocals are coming from the center, but the soundstage is dramatically wider than what I was getting in the corners.

Did I post the video yet?

https://www.youtube.com/watch?v=hlBuNXrNvoI&list=UUSJEKRUxzKjLcA2FAXdJsmg

It sounds all phasey and weird, but that's because there's one mic. Ambio depends on the Haas effect, so it's hard to get a 'feel' for the soundstage unless you're there. It's also brighter than I'd like, as the speakers were under my dash five days ago and it's still EQ'd for that.

Also, I'm going on my honeymoon in five hours, I should probably pack. And, you know, stop screwing around in the garage  (I really should talk to a psychologist ;P )


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## MetricMuscle (Sep 16, 2013)

I do believe Patrick was after more dynamics which include more output which a waveguide or horn can help with. He started this thread after hearing Gary's car and wanted to improve on his own in Stage Width and Smoothness. This lead to other ways to go about waveguide/horn loading in a car which brought us to using the waveguides that already exist in a car, the windshield and/or the back glass instead of installing an actual waveguide on or under the dash. 

So why do dash mounted mids or coaxials get boo hoo'd so much, especially in the On-Axis vs Off-Axis thread? I realize not all dash speakers are pushed all the way forward to where the dash meets the windshield. If they are not, does this create the same issue as having a gap in the baffle of a vertically mounted driver using the windshield/dash as a waveguide?
Is the angle of the dash to the windshield important?
Is the length or depth of the dash important?
Neither of my cars have deep dashes and both have average windshield angle, not straight up nor really laid down.
A co-worker recently purchased a 2000 Camaro. Deep dash and laid back windshield.









Some mini vans have crazy deep dashes, SUV's too.


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## ErinH (Feb 14, 2007)

Patrick Bateman said:


> Why ambio? Because I listened to Gary's car and said to myself "I don't think I can do better than this." For instance, when I heard Harry Kimura's car in the 90s, the dynamics were like nothing I'd heard before. But after messing around with horns under the dash, I realized you could improve things by putting them ON the dash. So that's an example of how you might improve Harry's car. But Gary's car? What's there to change?
> 
> Also, ambio and cars are a match made in heaven. The drawback with ambio is that it only sounds great from one spot, and from the other locations, it sounds phasey and weird. Up until a week ago I thought that meant that the ambio speakers had to be right in front of you, ideally at eye level. That's not so hot for a car; you have the instrument pod there.
> 
> ...



I know you like the ambio setup you're playing with, but man... we just have had two entirely different experiences. Though, I did say this earlier, so what you're saying is what I was thinking would be the only way to get it to work, it seems:


bikinpunk said:


> The problem I found with ambio was due to PLDs and while I fully believe you can do a great job with DSP wrt PLDs, TA totally screws up ambio (because it's already screwing phase). I think it might bear more fruit if you had two separate setups in the same car. IOW, a left and right equidistant from each listener. Which would mean placing the right speaker at/near the center of the car to complete the equilateral triangle for the driver. And for the passenger you'd do the same. And you wouldn't have both playing at the same time because you'd practically have summed mono.



Still, I just didn't like it. I never got focus like I wanted to. The phase stuff ambio does just killed it for me. 


Back to Gary's car, what's the one thing you see that it has in common with Jon's? (hint: lobing)

I'm telling you, man, *I really think a great system can be boiled down to simple polar response*. Sure, you won't get the same polar vertically as horizontally, but if you can keep a smooth response free of holes at the crossover using drivers within the passband they aren't breaking up (ie; mid going above beaming and showing modal issues) or distorting (ie; tweeter crossed too low) then what you hear is essentially the same thing that is reflected. And this ties in to the early reflection theory/argument some make. I've had nothing but great success with this***.

***great success is measured by the less EQ I have to use to get good response at the seat. I'm not saying you can't have great response at a seat with the right EQ. I am saying with the right install and crossover points, you won't have to have near the EQ you did before and you won't be chasing your tail fixing a problem that can't be fixed, either.


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## ErinH (Feb 14, 2007)

Oh, BTW, enjoy your honeymoon, man!


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## ErinH (Feb 14, 2007)

going back to what I said previously...

***great success is measured by the less EQ I have to use to get good response at the seat. I'm not saying you can't have great response at a seat with the right EQ. I am saying with the right install and crossover points, you won't have to have near the EQ you did before and you won't be chasing your tail fixing a problem that can't be fixed, either. 

I'll expand on that. This is just one guy's opinion:
Left/right EQ matching is practically a necessity in a car due to the asymmetric environment, but I've found with the right crossover setup, you can really minimize that which will get rid of the 'head in a vice' issue. 

The less you have to clamp your head down, the more everything about the soundstage seems to improve. Focus may not be quite as dead on as it could be (though, that said, my focus has improved) but what you really seem to get is a great presentation in regards to space. The key things I love about a great car is they all: have great sense of space (depth, width, height... 3D feel to them). Now, impact is a big deal to me (and if you've heard my car you know I may place that over some other things with the current setup) and so is tonality. Tonality always seems to be a bit different from car to car BUT in only rare instances is it _so _different from another that it's not enjoyable. Some do tonality better, subjectively at least, but overall, most don't have any glaring issues. At least not cars from the main people I know. 

The things that then separates systems typically are: impact and space. Dynamics is what it is. If it's there, awesome. If it isn't, well, poop. I want to have fun in a system. I'm not saying bone crushing bass. But, what I want is to 'feel' that snare get smacked, or to have the kickdrum have some heft, and at the same time be able to hear the skin of the snare. But SPACE.... S-P-A-C-E.... well, when I get in a car and it has a great sense of space, it's just plain awesome. It removes the 'car' from the equation. There's a handful of cars that have done that. And that's something I've strived for ever since hearing Eldridge's NASCAR. I just love hearing a system with width that changes with recording, vocalists that aren't always fixed at the same location but move with the recording as they should, and layering that allows you to tell that a cymbal is behind the singer. I gush over that stuff. As you can tell.


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## garysummers (Oct 25, 2010)

Real quick thought!

Erin, I agree with a lot of what you are saying about basics because that's what I know. Phase, Time, Timbre, Level, get them right and your going to start getting the result you want.

*BUT, we need people like Patrick!!*

When He was in my car listening (I have given hundreds of demos over the years), I could see that his brain was working a million miles an hour, thinking, calculating, postulating, all in the matter of a 3 minute song. He thinks in a different space than I do and I like that. Outside the box as it is said. He makes me think!! Half of his post are over my head and I have to re-read them carefully, but occasionally something will click and there is knowledge.

He reminds me of my years working with Tom Holman (THX) at Lucasfilm.
Who by the way, taught me a lot.

I know you feel the same way! Just had to put it out there.

And Patrick, please enjoy that honeymoon!


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## Patrick Bateman (Sep 11, 2006)

bikinpunk said:


> going back to what I said previously...
> 
> ***great success is measured by the less EQ I have to use to get good response at the seat. I'm not saying you can't have great response at a seat with the right EQ. I am saying with the right install and crossover points, you won't have to have near the EQ you did before and you won't be chasing your tail fixing a problem that can't be fixed, either.
> 
> ...


The Synergy horns in my car do a couple of things that regular speakers do not. First, the phase is flat in a five octave span from 700hz to 13.5khz. *This is no boast, I believe I posted the measurements.* The only other type of speakers that can do this trick are full range speakers. I also posted a measurement of a $100 set of computer speakers from Cambridge Sound Works (Henry Kloss, inventor of the acoustic suspension enclosure.) Henry's speakers also had flat phase. But my Synergy horns will get hella loud; they're good for about 110dB. Try doing *that* with a computer speaker.

For the sake of argument, lets say you have a two way loudspeaker with a 4th order Linkwitz Riley xover at 2khz. The LR xover introduces 360 degrees of phase rotation at the crossover point. The phase varies over a bandwidth of about an octave. *This means that from about 1500hz to 3khz the phase response of the system is all over the map, and reaches a maximum of 360 degrees of rotation.* 360 degrees of phase at 2khz is equivalent to one wavelength. One wavelength is 6.75" long. Sound travels 13.5" in one millisecond. *The ambio processing inserts 0.071 millisecond of delay.* This means that the phase rotation of the crossover absolutely swamps the all-pass delay of the ambio processing: the crossover adds 0.5 millisecond of delay, or seven times as much as ambiophonics does.

^^^ I hope that last paragraph made sense, because I'm beginning to believe that Ambio probably isn't even worthwhile unless the phase is correct. My Gedlee Summa speakers use something like a 4th order highpass on the compression driver. When I used ambio processing on the Summas, I was also kinda 'meh' on the effect. *I ended up using a physical barrier with the Summas because I didn't like the sound of the ambio processing on the Summas.*

Phase is a pain in the ass to understand, and IMHO, a lot of the ambio guys are gravitating towards phase coherent speakers via trial and error. You see a lot of them using Jamboxes (full range, one speaker), electrostatics (one driver covers almost all the bandwidth) and line arrays. (an array of drivers covers almost all of the bandwidth.)

Synergy horns may very well be the ultimate speaker for Ambiophonics. Ambio lowers dynamics, but Synergy horns have dynamics to burn. Ambio depends on delay, but most speakers are not time-coherent. A reflective environment like a car adds early reflections. These early reflections happen at about the same intervals that crosstalk does. Waveguides cut down on those early reflections.

_Reflections arriving between .62 and 20 milliseconds will have virtually no effect on the apparent direction of the source as long as they sound like the original signal, but if not they will shift the apparent direction of the source in the direction of the reflection. Helmut Haas, "The Influence of a Single Echo on the Audibility of Speech," JAES March 1972._
Basically the waveguides are eliminating early reflections. The reflections are still there, but they're all getting focused into the first arrival. So now our brain thinks "ok, the sound is coming from the center of the dash." But then the ambio processing comes in and does it's crosstalk cancellation. With the wrong crossover, it sounds like a phasey mess. But with a phase coherent speaker that's very directional, the car disappears. This is because of the precedence effect, our brain filters out the later information.

Basically I'm not saying that you DIDN'T get crap results with ambio. I'm saying I may be getting unusually good results with Ambio because Synergy horns are practically perfect for the application.


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## Patrick Bateman (Sep 11, 2006)

garysummers said:


> Real quick thought!
> 
> Erin, I agree with a lot of what you are saying about basics because that's what I know. Phase, Time, Timbre, Level, get them right and your going to start getting the result you want.
> 
> ...


Oddly enough, Lucasfilms was a real inspiration for me. I don't want to get too far off topic, but I don't think the series would have been successful if it wasn't for ILM.








I remember watching these videos as a teenager, of sound engineers plucking guide wires on telephone poles and using those sounds for the movie, and just thinking *this is completely nuts!* I was an art major in college, and was doing 3D computer animation long before it was mainstream. (Had a Commodore Amiga.) *But the main reason I never pursued 3D animation as a career was that I figured no one would ever exceed what the Lucas guys were doing with models.* (All of this was in the 80s.)

Nowadays I'm a software guy, but I've heard that online gaming is pushing the boundaries of what is possible. And a lot of those challenges were first tackled by the Lucas guys way back when they were doing games on the C64.


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## Patrick Bateman (Sep 11, 2006)

Ha! You worked with that guy:

Ben Burtt on the sound of ‘Raiders,’ ‘ET’ and Spielberg’s inspiration | Hero Complex – movies, comics, pop culture – Los Angeles Times


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## garysummers (Oct 25, 2010)

Ben Burtt hired me in July 1979 to work on The Empire Strikes Back.


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## sqnut (Dec 24, 2009)

garysummers said:


> Do you think it is designed that way on purpose? This is the room that the system is in.
> 
> View attachment 53354
> 
> ...


Nice office and you get to watch the movie for free


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## ErinH (Feb 14, 2007)

garysummers said:


> When He was in my car listening (I have given hundreds of demos over the years), I could see that his brain was working a million miles an hour, thinking, calculating, postulating, all in the matter of a 3 minute song. He thinks in a different space than I do and I like that. Outside the box as it is said. He makes me think!! Half of his post are over my head and I have to re-read them carefully, but occasionally something will click and there is knowledge.


Let me analyze this statement and provide you an alternative:
Maybe it wasn't that his brain was trying to racket up new ways of doing things or schemes. Maybe he was just so impressed by what he heard, the result was completely opposite of what you think. Maybe he was just so overwhelmed that his brain just stopped and he was in pure awe! 

How's that for an alternative? LOL. 






garysummers said:


> I know you feel the same way! Just had to put it out there.


I totally get that. and as I said, I appreciate the discussion. I've tried a lot of unconventional things as well thanks to various discussion here that spurned the desire to go and learn more. No need to reiterate my intended point as I've done it a couple times already. Just saying the discussion is not unwelcomed. When I found Galzon's (father of ambiophonics) works a couple years ago, I thought I had hit a goldmine. Only to realize this stuff was done in the 70's. And Hafler circuits have been around since before I was born as well. I realize I'm a relative young guy in this hobby, but it doesn't mean I am not as passionate about furthering knowledge in it as well. A lot of these home audio type ideas are VERY interesting and cool as heck... especially the old stuff. Unfortunately, a lot of this stuff just doesn't pan out the way we hope but if nothing else, the process of trial and error is where you learn and are then able to apply that to other areas that you may not have considered at first. And that's what I dig about these conversations. 


here's a REALLY great link on Galzon's works. Tons of stuff represented here. Great discussion on 3-channel stereo (interesting fact: stereo was initially both 3 and 2-channel but 2-channel ultimately won out namely due to practicality). 
Gerzon Archive


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## beef316 (Dec 12, 2006)

This is a very cool thread on many levels. Thanks all.

Sent from my SCH-I535 using Tapatalk


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## ansuser (Dec 18, 2011)

Cool thread.
I've done some experimentation at home using cheap active computer speakers trying to emulate what can be done in the car.
Here are my observations:
1. RACE algorithm works pretty well if you have listening point somewhere between speakers. Best results were obtained with 20 degrees angle between speakers at the listening point. 
2. It is absolutely necessary to upsample signal before ambio processing. For 44.1 kHz sampling rate signal can be delayed with 22.6 microseconds step. At the same time, 5 microseconds adjustment in RACE algorithm makes significant audible difference.
3. Moving listening point outside speakers range (that is left speaker is actually on the right from listening point and right speaker is even further on the right) without time delay totally ruins the ambio effect. Putting time delay AFTER ambio processing makes things better but nowhere close to what can be experienced in central listening position.
4. Stage width with ambio is comparable with what I get in the car with MS8 processing (logic7 enabled), but with less early reflection artefacts.

P.S. I used foobar and foo_dsp_ambio plugin


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## thehatedguy (May 4, 2007)

Still not getting the horn loading aspect of putting your speakers near the glass...haven't seen too many horns that had mouths larger than the speakers that were being loaded by them. Or too many horns that had 3 sides and nothing but baffle for the 4th.

Run an impedance curve of the speakers, if you are really truly horn loading them, you will have 3 peaks in the curve.


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## MetricMuscle (Sep 16, 2013)

So maybe it's less of a horn and more of a waveguide. 
Direct sound and reflected sound compete and have different arrival times. 
Reflections are inconsistent and thusly bad.
Reflections cannot be eliminated in a car environment, only managed.
Direct sound can be turned into reflected sound.
Do away with direct sound, turn it all into more consistent reflected sound.
Reflections managed.

I've read some of the Ambio links and threads.
Did I miss somewhere, does it rely on reflection from the sides to give the wide stage width? Managing reflections more consistently.


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## seafish (Aug 1, 2012)

garysummers said:


> You feed Left and Right into the unit. Outputs are Left, Right, Center, Rear.
> You can turn the center control to extract L+R from Left an Right.
> Turn the rear control to extract L-R from Left and Right.
> I would defeat the center control or use very little of it to the center channel in the dash. Just enough to center your stage.
> Send the L_R signal to your rear speakers. Yes it is mono but just "Y" it to the amplifiers for your rear speakers. Adjust for the best width and space. If you can apply delay to the rear channels that will help as well. A bit of de-correlation can help as well.


Gary, THANKS for taking the time to explain...defintiely gonna try it when I hook up the AC90/11 and I'll report back what I think on another thread.


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## Darth SQ (Sep 17, 2010)

Subscribed.
This forum never ceases to amaze me. 


Bret
PPI-ART COLLECTOR


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## sqnut (Dec 24, 2009)

bikinpunk said:


> I think the real basis for great sound is in the crossover, which of course relates to driver response, placement (proximity and aiming), and crossover. It's a trip to be able to sit in my own car and have the stage be so stable without any EQ on the mids or tweeters.





bikinpunk said:


> I can't tell you the number of people who have told me how little EQ or variation they had in respect to head movement with their system by simply focusing on these things.
> 
> I netted the best results. With minimal EQ (currently running NO EQ above 300hz; only EQ'ing modal issues).
> 
> ...





bikinpunk said:


> ***great success is measured by the less EQ I have to use to get good response at the seat. I'm not saying you can't have great response at a seat with the right EQ. I am saying with the right install and crossover points, you won't have to have near the EQ you did before and you won't be chasing your tail fixing a problem that can't be fixed, either.


I'm with you on doing the basics right. But you lost me by repeatedly mentioning minimal or no eq. A quick look at Andy's charts of response at speaker level and ear level in a car and there is no way that the ear level mess can be sorted out by just crossover, slopes or speaker placement. 

Imho proper and extensive eq (you will use at least 60-70% of the bands per driver). is one of the keys to achieving all the attributes you've mentioned. Dynamics, space, tonality, timbre. The max eq requirement is an octave above and below each xover points. Yes response around the xover point is critical, that's why you have to use the eq. 

To my mind the eq is one of the central themes for a car that has all the attributes you've mentioned. Dynamics, space, tonality and timbre. Of these space is the only attribute that requires L/R and hence imaging. The other three attributes can be dialed in via the eq without pinpoint imaging. 

Yes setting TA and xover to ensure the drivers remain in their comfort zone is important. But once done, it's done and you have what you have. To tweak this sound for the key attributes, you have to use the eq. The problem is that using the eq is like learning a new language. For some one like Gary using the eq is intuitive cause he does it all day. 

So if the sound is slightly harsh, bright and brittle, you would look to cut at one or more of the following 16khz, 8khz, 1.6 and 2.5khz and so on. Now you've solved bright and brittle issue but the sound is dull. So you raise 1khz for a more dynamic sound but now the lower end has thinned out. So you're playing in 100-200 zone and so on. Eventually it all falls in place. It is painfully frustrating and slow. You're constantly correcting for both the problem as well as maintaining the overall balance. Using the eq to cut the peaks you see on your RTA is only a small part of the story.

The key to using an eq is to figure out the effect of each frequency on the overall sound and how certain frequencies work together. Then try and pick one defect at a time and figure out the frequency where you will start. In most cases one issue will require a sequence of of 2-3 corrections across different ranges, to correct the issue and maintain overall balance. 

This is all by ear. You can't learn the eq language if 80% of your mind space is focused on how it measures. You must measure to set TA, you must measure for L/R balance (if you wish). But once this is done, 100% of the focus should be on how it sounds. *If it sounds right and you can verify that it sounds right* (I am not talking about sounds right to my ears), then it doesn't matter how it measures. The eq is not the be all end all thing, I agree there's a lot more to good sound, but it is certainly a central theme for good sound.

In a car the overall response is the key. You need a ton of eq to get the right response. If we could measure all the vehicles accepted as great sounding, Garys Merc, Jons Bus, any finished product from KP, MattR etc, chances are there would be a high degree of correlation between the responses curves in these cars. I would also bet a significant sum on the fact that each vehicle achieves its response in part by extensive use of the eq where a lot of the tuning has been done by ear.


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## garysummers (Oct 25, 2010)

From my experience over the last 2.5 years building and tuning my car, I would roughly list the order of priority in achieving a proper tune.

1. Phase correct
2. Time correct

The two are almost equal in rank but I gave phase the top spot.

3) Level matched
4) Equalization

From my experience with my car until I got 1,2,3 correct , I was just "chasing my tail" trying to apply a correct EQ curve to the system.
How you get there has been discussed in many threads here in the past and will continue to be in the future.

JMHO


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## sqnut (Dec 24, 2009)

garysummers said:


> From my experience over the last 2.5 years building and tuning my car, I would roughly list the order of priority in achieving a proper tune.
> 
> 1. Phase correct
> 2. Time correct
> ...


Timing is the first thing I address. Phase to me in the context of a car is about managing the response around the xover points. I would certainly set timing, xovers and levels before I hit the eq. My post was more about using eq vs no or limited eq. 

OT Our ears are sensitive to both phase/timing and response. Some folks are left handed and some are right handed, likewise some are more sensitive to phase/timing issues while others are more sensitive to response. That could be one of the reasons why some people prefer Dynaudio and Vanderstien while others may prefer Wilsons.


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## ErinH (Feb 14, 2007)

garysummers said:


> From my experience over the last 2.5 years building and tuning my car, I would roughly list the order of priority in achieving a proper tune.
> 
> 
> 
> ...



Badabing!

You captured the essence of my posts that I believe SQnut overlooked. I'm not saying EQ isn't necessary to some degree. What I am saying is exactly what you said... Heck,
I think I even used the same "chasing your tail" analogy.


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## invecs (Jul 30, 2005)

Using eq also affects phase so it is really better to use little of it. Or try fixing the response first with the crossover or install.


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## Hanatsu (Nov 9, 2010)

You can minimize the amount of EQ you need by being creative with the crossovers, yes. Still using L/R EQ is an integral part of any good sounding system, it's absolutely necessary in all systems. If the FR is all over the map, you will never get a proper stage. I have never even once heard a system that sounded good without using EQ. 

Putting the things that's important in a numbered list is kinda meaningless imo. You need to get every aspect right. There's a lot of talk about "phase" here and I'd like to empathize that 'absolute phase' is not audible. It only matters when there's several drivers involved overlapping eachother to some degree. Make sure that polarity is the same in the entire system, EQ the stopband to proper 24dB/oct acoustic slopes and time align the drivers to match and the net phase shift should be 0deg where the HP and LP filters meet if you're using L-R filters. Don't understand why everyone keeps making such a fuss about phase really. If you EQing in a minimum phase area, you can EQ as much as you want, both relative phase and amplitude will be fixed as you EQ left and right sides to the same response.


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## Hanatsu (Nov 9, 2010)

invecs said:


> Using eq also affects phase so it is really better to use little of it. Or try fixing the response first with the crossover or install.


Using crossovers affect phase as well. The thing is that EQ might affect phase IN A GOOD WAY. The environment screws the transfer function and we use EQ to compensate. As long as you EQ in a minimum phase area you will improve both phase and amplitude. 

How exactly will you fix the response issues of a car by "install"?

...and you will not fix the L/R FR with crossovers, period.


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## ErinH (Feb 14, 2007)

Ugh. You guys are really missing my point and jumping straight toward the notion that I'm implying EQ is evil. 

I'm saying:
Crossovers, placement and use of drivers that perform well in an executed passband is crucial. Then TA and levels are DSP tools that help the system. Using these things and exhausting the tune with these FIRST will help ensure you have as good a system as possible pre-EQ. 

Otherwise, what it seems most people do is set crossovers willy-nilly and then start trying to use EQ to fix everything. The result is enormous amounts of EQ that don't really help the root of the problem and you ultimately wind up going in circles with the EQ. 

Easiest example:
You have a mid that breaks up badly above 4khz yet you put a crossover at 8khz because someone on the net said to do so with a different setup. So now you're cutting on the EQ to fix a driver problem that would be best fixed with a lower LPF.


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## Hanatsu (Nov 9, 2010)

bikinpunk said:


> Ugh. You guys are really missing my point and jumping straight toward the notion that I'm implying EQ is evil.
> 
> I'm saying:
> Crossovers, placement and use of drivers that *perform well in an executed passband is crucial*. Then TA and levels are DSP tools that help the system. Using these things and exhausting the tune with these FIRST will help ensure you have as good a system as possible pre-EQ.
> ...


Of course! I fully agree with that.

I measure speakers on a baffle outside the car to make sure I cross the drivers inside a passband where the power response is good. I know how important it is.


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## Hanatsu (Nov 9, 2010)

I have 2 different SQ oriented builds. They stage and sound different. My main build required lot of more EQ than the other one. Both systems are properly designed and installed but the better pre-EQ FR in one of the builds is probably due massive acoustic crosstalk. Even if the FR looks good "out of the box" the focus ain't anywhere close to the other system that utilize pretty much EQ.

I've said it before. You can't judge the execution of an install by the EQ amount that you need to apply. I hear people all the time bragging about how little EQ they needed. It's plain silly imo.


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## MetricMuscle (Sep 16, 2013)

What do phase issues affect other than timing? 
Or is it that phase issue have a varying effect on timing depending on frequency around the crossover point?


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## Darth SQ (Sep 17, 2010)

Patrick Bateman said:


> _Here's an analogy: Fifteen years ago, the clock speeds of computer processors were going higher and higher and higher. IBM, Intel and AMD were all locked in a race. For six months one manufacturer was on top, then a different one would take the crown. This literally went back and forth for about a decade. Then a little lab at Intel, in Israel not Oregon iirc, they took an old Intel processor and tweaked it for something besides speed. *They tweaked it for POWER.* And this was a complete game-changer. Up until that point, everyone had been obsessed with clock speed, but this tiny team showed that sometimes it's better to go a little bit slower but have much less power and much less heat. Intel ended up abandoning their architecture entirely. If anyone had the last of the 'old school', the Pentium 4, they may recall how ridiculous it was. The processor could go nearly 4ghz, but it was loud, expensive, and would practically catch on fire if the fan failed. It was the apex of development at the time, but it was also highly impractical._
> 
> Why ambio? Because I listened to Gary's car and said to myself "I don't think I can do better than this." For instance, when I heard Harry Kimura's car in the 90s, the dynamics were like nothing I'd heard before. But after messing around with horns under the dash, I realized you could improve things by putting them ON the dash. So that's an example of how you might improve Harry's car. But Gary's car? What's there to change?
> 
> ...




Now if Patrick responds to this thread during his honeymoon (say the within the next three days), we will know just how crazy neighbor down the street he really is. 
Addiction is a *****. 


Bret
PPI-ART COLLECTOR


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## Bluenote (Aug 29, 2008)

^LMAO!!!


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## garysummers (Oct 25, 2010)

I was not implying that EQ was not important but that you must get the system phase and time correct first. After that you can EQ all you want.


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## sqnut (Dec 24, 2009)

MetricMuscle said:


> What do phase issues affect other than timing?
> Or is it that phase issue have a varying effect on timing depending on frequency around the crossover point?


In a car the first step is to fix the timing from drivers that are at different distances. In a car fixing phase is nothing more than fixing the response around the xover point [edit] while keeping LP/HP on the same order for a start[edit]. I aim for an octave above and below the xover point. Phase affects response and playing with response around the xover point affects phase. *In a car* get the timing right and fix the response around the xover point so that you have a smooth response transition from from set of drivers to the next. In real world terms that is all you need to do. 

The forum already has way too many posts and threads about esoteric hair splitting on phase in a car.


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## sqnut (Dec 24, 2009)

garysummers said:


> I was not implying that EQ was not important but that you must get the system phase and time correct first. After that you can EQ all you want.


I totally agree. Thanks for putting it in a nut shell .


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## MetricMuscle (Sep 16, 2013)

bikinpunk said:


> Well, heck, I'm sure a few guys in this thread would consider their efforts an attempt at a masterpiece as well.





Patrick Bateman said:


> Whoah, let's not get carried away now
> 
> I'm not 'painting a masterpiece'


I guess none of y'all play the movie quote game at work either. 



sqnut said:


> In a car the first step is to fix the timing from drivers that are at different distances. In a car phase is nothing more than fixing the response around the xover point. *I aim for an octave above and below the xover point. *Phase affects response and playing with response around the xover point affects phase. *In a car* get the timing right and fix the response around the xover point so that you have a smooth response transition from from set of drivers to the next. In real world terms that is all you need to do.
> 
> The forum already has way too many posts and threads about esoteric hair splitting on phase in a car.


Thanks for the info, I'll just take a moment to re-read it a few times, mull it over and get a better grasp of it all.


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## sqnut (Dec 24, 2009)

bikinpunk said:


> Ugh. You guys are really missing my point and jumping straight toward the notion that I'm implying EQ is evil.
> 
> I'm saying:
> Crossovers, placement and use of drivers that perform well in an executed passband is crucial. Then TA and levels are DSP tools that help the system. Using these things and exhausting the tune with these FIRST will help ensure you have as good a system as possible pre-EQ.
> ...


I agree, fix everything else before you hit the eq.


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## Patrick Bateman (Sep 11, 2006)

PPI-ART COLLECTOR said:


> Now if Patrick responds to this thread during his honeymoon (say the within the next three days), we will know just how crazy neighbor down the street he really is.
> Addiction is a *****.
> 
> 
> ...


What, you think they don't have wifi in Copenhagen?  I got a full 90 minutes before my flight leaves for Italy!


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## MetricMuscle (Sep 16, 2013)

Patrick Bateman said:


> What, you think they don't have wifi in Copenhagen?  I got a full 90 minutes before my flight leaves for Italy!


LOL!

Now, if he tracks down a Home Depot and builds a new pair of waveguides on the balcony of his suite then, well, I wouldn't be completely surprised.


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## Patrick Bateman (Sep 11, 2006)

thehatedguy said:


> Still not getting the horn loading aspect of putting your speakers near the glass...haven't seen too many horns that had mouths larger than the speakers that were being loaded by them. Or too many horns that had 3 sides and nothing but baffle for the 4th.
> 
> Run an impedance curve of the speakers, if you are really truly horn loading them, you will have 3 peaks in the curve.


Not true.

"real" horn loading happens when the diameter of the duct is smaller than the wavelength.
For instance, if you have a 3" midrange like Gary's and it's playing 2khz, *then the duct must be 7" or less to provide horn loading.* (Because 2khz is 7" long.)

At low frequencies these sizes get ridiculous; to "truly" horn load a wavelength of 40hz would require a horn that's 28 feet wide!

That's why most of the devices that we call "horns" are actually quarter wave resonators. You reduce the horn mouth to a much smaller size, and then there's a standing wave that happens in the *length* of the horn. For instance, a seven foot LONG horn will resonate at 40hz.

And the reason that you see the multiple impedance troughs is that they correspond to the quarter wavelength resonances. And they're harmonic; you'll see troughs at 40hz, 80hz, 120hz, etc.

Long story short: yes, a windshield definitely horn loads a midrange. And the impedance curve of a "true" horn doesn't have to have multiple dips; in fact multiple dips indicate that the mouth is too small! Not that it's the end of the world; for instance tapped horns have multiple dips and they sound fine.


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## Patrick Bateman (Sep 11, 2006)

ansuser said:


> Cool thread.
> I've done some experimentation at home using cheap active computer speakers trying to emulate what can be done in the car.
> Here are my observations:
> 1. RACE algorithm works pretty well if you have listening point somewhere between speakers. Best results were obtained with 20 degrees angle between speakers at the listening point.
> ...


Very cool. I'd never considered that the sample rate of the file would affect the granularity of the ambiophonic processing.


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## Darth SQ (Sep 17, 2010)

Patrick Bateman said:


> What, you think they don't have wifi in Copenhagen?  I got a full 90 minutes before my flight leaves for Italy!


OMG!
Go be with your new wife for Christ's sake! 
This thread will be here when you get back......I promise. 
And stay out of the car audio stores lol.


Bret
PPI-ART COLLECTOR


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## invecs (Jul 30, 2005)

You can fix left and right response with xovers if you use shallow slopes. But to me, i don't equalize the left to sound like the right...because you are going to screw the response again if you do some frequency steering to get a good focused image.

Some people are lazy tuning and just use steep slopes and the beaming frequency of a driver as xover points and use eq to contour response. That would be ok too...if you get your target response and if you like the sound. To some people tuning finishes there specially those who rely on measurements. Using shallow slopes makes the sound more interesting...it changes phase and timbre of the sound depending on frequency overlap/underlap.

Changing speaker angles changes the degree of intensity on the upper range of a driver which could play a factor in xover frequency and slope selection.

I don't limit myself to using steep slopes and speaker beaming frequency as xover points. I love to experiment. I guess we just tune differently.


To each his own.






Hanatsu said:


> Using crossovers affect phase as well. The thing is that EQ might affect phase IN A GOOD WAY. The environment screws the transfer function and we use EQ to compensate. As long as you EQ in a minimum phase area you will improve both phase and amplitude.
> 
> How exactly will you fix the response issues of a car by "install"?
> 
> ...and you will not fix the L/R FR with crossovers, period.


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## sqnut (Dec 24, 2009)

invecs said:


> You can fix left and right response with xovers if you use shallow slopes. But to me, i don't equalize the left to sound like the right...because you are going to screw the response again if you do some frequency steering to get a good focused image.


Shallow slopes don't work in a car, period. In a car it's all about response. A car is an extremely hostile environment for listening to music. The response at speaker level is very different from that at your ear. Shallow slopes increase the pass band that each driver is playing and now the ear level mess is further compounded. Shallow slopes might work in a car if you had 1/6 oct eq per driver. 

Shallow slopes do not cure L/R issues to any meaningful extent. If you're using shallow slopes to cure L/R in any car/install you're going to have significant to a ton of smearing. Your slope is a linear algorithm, there's nothing linear about the L/R difference or combined response peaks and dips. A fixed algorithm won't fix it. 



invecs said:


> Some people are lazy tuning and just use steep slopes and the beaming frequency of a driver as xover points and use eq to contour response.


Excuse me, but I think its lazy to use shallow slopes and think response issues are solved. If you don't take the eq head on, you're swimming in the kiddie pool


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## invecs (Jul 30, 2005)

Did i say that I don't use an eq? I do. I just prefer to use a little of it in correcting response at the xover region. Beyond this, we are left with the use of eq.


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## garysummers (Oct 25, 2010)

"i don't equalize the left to sound like the right...because you are going to screw the response again if you do some frequency steering to get a good focused image"

I would politely beg to differ on this! Timbre matching between left and right is essential to creating a properly balanced and accurate soundstage.


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## invecs (Jul 30, 2005)

garysummers said:


> "i don't equalize the left to sound like the right...because you are going to screw the response again if you do some frequency steering to get a good focused image"
> 
> I would politely beg to differ on this! Timbre matching between left and right is essential to creating a properly balanced and accurate soundstage.


How would you do it in a car if you also take into account the frequencies affected by hrtf? If you use eq to frequency steer, it wouldn't be possible to sound the same for both. To me it's about what to compromise.


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## garysummers (Oct 25, 2010)

I am not using EQ to "Frequency Steer", actually I don't know what that means.
I am using equalization to match the frequency response of the Left and Right channels. The closer you get them to match at the listening position the more accurate and balanced your soundstage will be. When I do a response tuning, the first thing I do when I remove the testing mics from the car is to play a test CD I have with pink noise bursts that alternate left to right in 3 second intervals. The sound of the pink noise bursts should sound the same out of each channel. Will it be perfect? No!! But the closer you get it the better. Then I play a track with mono pink noise and it should image dead center without any significant timbre shift. If these two things occur in your car you are tuning frequency response the right way provided your target curve is accurate.


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## invecs (Jul 30, 2005)

Do you rely totally on t/a to correct imaging? What i meant by frequency steering is you adjust the level of some midrange and high frequencies of the right side speaker to center the image.


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## Hanatsu (Nov 9, 2010)

Ugh. Swallow slopes... you get heavy amounts of combing, that's why it sounds different. 

Tapaaatalk!!


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## garysummers (Oct 25, 2010)

"you adjust the level of some midrange and high frequencies of the right side speaker to center the image."

When you place a calibrated mic at the listening position and adjust each 1/3 octave band to align with your target curve and this is done for both left and right, you have no need to adjust "to center the image". You have already done that by adjusting the systems response to match channel to channel.

I will add this as well.

If you do as described above and your image does not center up, your issues will not be solved by equalization. I would look at timing and phase problems. It is not difficult to make your systems frequency response match a certain target curve on a computer screen, but the test is in the listening to determine if you have truly matched the response to the human ear channel to channel.


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## Darth SQ (Sep 17, 2010)

garysummers said:


> "you adjust the level of some midrange and high frequencies of the right side speaker to center the image."
> 
> When you place a calibrated mic at the listening position and adjust each 1/3 octave band to align with your target curve and this is done for both left and right, you have no need to adjust "to center the image". You have already done that by adjusting the systems response to match channel to channel.


Great info Gary. 
Thank you. 


Bret
PPI-ART COLLECTOR


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## captainscarlett (Mar 15, 2011)

Sorry if these have already been posted, thought these might be handy. 

I'll go back to reading page 2.


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## thehatedguy (May 4, 2007)

There is no throat so it can't load.

You see three peaks and two valleys with horns because your horn is tuned to one frequency which is the null between one set of peaks, and and the driver has a resonance which is the null between the other another peak and the middle peak.

It doesn't peak, null, peak, null, peak, null, etc. Not any good horn.

No, it definitely does not horn load the speaker. At best you might get some waveguide effect...but not horn loading and acoustical gain from it.



Patrick Bateman said:


> Not true.
> 
> "real" horn loading happens when the diameter of the duct is smaller than the wavelength.
> For instance, if you have a 3" midrange like Gary's and it's playing 2khz, *then the duct must be 7" or less to provide horn loading.* (Because 2khz is 7" long.)
> ...


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## BigRed (Aug 12, 2007)

Just got done with a good listening session at Gary's. You should compete again . Thanks for the time my friend


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## garysummers (Oct 25, 2010)

I would Jim but I would be in your class and after what I heard in your truck today and knowing your going to put the point source in there, I think NOT!


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## strakele (Mar 2, 2009)

Erin - beyond setting crossovers to keep drivers playing within their usable bandwidth and maybe tweaking the actual point and slope a bit from side to side to get the acoustic roll off point/slope to match as much as possible, what else can you possibly do with them to aid in tuning? And why is it any more beneficial to do this with crossovers vs EQ? And why bother level matching prior to EQ? Doesn't it make sense to set crossovers, EQ each driver relatively flat, then level match each pair together, then time align each pair, then time align the system?

Gary - you mentioned the most important thing being a phase correct system. I agree. Could you explain a bit how you go about accomplishing this?

Thanks guys


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## cajunner (Apr 13, 2007)

funny thing about electronic manipulation of the signal, no matter how much you click a slider on the DSP software you're never so invested that you can't click it back.

people scared to equalize their system, or overlap/underlap, work new slopes, rotate phase relationships, add and subtract time delays, add compression, use a tone control, etc. is just mind boggling.

I have actually read several different posters, do one thing in the digital domain, yet stall out without experimenting with some/all of the other things, on the basis that they are unsure how it will affect their "phase response" and I can't figure it. I see all the different permutations that can be put in place, then removed, and how will you know, if you don't try?

I think some people have residual fears from childhood experiences where a parent said, "don't touch that EQ! It has been set to correct the response!" and now as an adult people don't want to do much more than a smiley face curve.

don't be afraid of your equipment, they wouldn't put the features in, if they didn't want them to be used.


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## Darth SQ (Sep 17, 2010)

cajunner said:


> funny thing about electronic manipulation of the signal, no matter how much you click a slider on the DSP software you're never so invested that you can't click it back.
> 
> people scared to equalize their system, or overlap/underlap, work new slopes, rotate phase relationships, add and subtract time delays, add compression, use a tone control, etc. is just mind boggling.
> 
> ...


Mine look more like two check marks. 


Bret
PPI-ART COLLECTOR


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## sqnut (Dec 24, 2009)

strakele said:


> Erin - beyond setting crossovers to keep drivers playing within their usable bandwidth and maybe tweaking the actual point and slope a bit from side to side to get the acoustic roll off point/slope to match as much as possible, what else can you possibly do with them to aid in tuning? And why is it any more beneficial to do this with crossovers vs EQ? And why bother level matching prior to EQ? Doesn't it make sense to set crossovers, EQ each driver relatively flat, then level match each pair together, then time align each pair, then time align the system?
> 
> Gary - you mentioned the most important thing being a phase correct system. I agree. Could you explain a bit how you go about accomplishing this?
> 
> Thanks guys


Think of a waveform that covers 20-20khz. Ideally we would like the entire spectrum to be reproduced by one driver, as a true point source. Since this isn't possible, we need to break up the waveform. We can do this one of two ways. Let's assume that the waveform is being reproduced by three separate drivers. 

The first way gradually breaks up the waveform into different parts but does so very gradually across the spectrum. This ensures that any given frequency is being played audibly by at least two drivers. Shallow slopes help keep the waveform true to its original shape. This is phase coherence. The focus here is in keeping the shape of the waveform consistent. Speakers like Vandys and Dyn's are designed on this philosophy. In a home setup since the speakers/drivers are equidistant timing is not an issue. To quote Patrick, 500hz is being played both both by your mid bass and your mid range. 

The second approach is to breakup the waveform into three distinct parts on the back of steep slopes and use timing to assemble these three parts into the original waveform at your ear. Again, in a home environment since the drivers are equidistant, the three parts will be timed right and will assemble at your ear to form one waveform. Speaker companies like Wilson and Scan follow this path. The phase coherent folks feel that the integrity of the original waveform is compromised by this process. 

Two things to keep in mind. First the two environments ( home and car) are very different and second our hearing is based on the ability to pick differences in phase/timing, response and pitch. Let's look at these one thing at a time in the context of a car.

The two biggest differences between your room and the car are the fact that drivers are not equidistant in a car and there more early reflections and lesser direct sound in a car. So timing is critical, followed by response. The early reflections are adding a ton of combing and shallower slopes accentuate this problem. Over 7 years of tweaking with the bit10 with shallow slopes I always felt that 31 bands per driver were too little to get the right response. I.E. right tonality, timbre, imaging etc.

The two schools are basically based on what we are more sensitive to. Some of us are left handed and some are right handed. Similarly some are more sensitive to phase timing issues and some to response. So the phase sensitive crowd will always prefer shallower slopes to keep the integrity of the waveform. But in a car that means a ton more of comb filtering, hence more eq power needed. A better solution, considering that we don't have a processor that will do 1/6 oct eq, is to use the second approach and use timing to reassemble the wave form at your ear with eq around the crossover point to tackle response so that you assemble the original waveform from the three parts. In a car this works best. IMHO

Arun


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## sqnut (Dec 24, 2009)

Just my opinion but in a room, the phase coherent speakers like Vandy's and Dys image better but that imaging is at a pinpoint location. However without exception the phase coherent speakers are almost always darker, particularly in the midrange.

Speakers based on timing and steep slopes always sound more open and lifelike, but at the cost of sharpness of image. YMMV, but in a car the benefit of phase coherence with shallow slopes 6-12db/oct is far outweighed by the response crapping which is tough to cure. As a benchmark 24db/oct on all drivers with eq work around the xover points seems to work best, again ymmv.


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## Hanatsu (Nov 9, 2010)

sqnut said:


> Just my opinion but in a room, the phase coherent speakers like Vandy's and Dys image better but that imaging is at a pinpoint location. However without exception the phase coherent speakers are almost always darker, particularly in the midrange.
> 
> Speakers based on timing and steep slopes always sound more open and lifelike, but at the cost of sharpness of image. YMMV, but in a car the benefit of phase coherence with shallow slopes 6-12db/oct is far outweighed by the response crapping which is tough to cure. As a benchmark 24db/oct on all drivers with eq work around the xover points seems to work best, again ymmv.


^^

Dunno how this thread lead to talking about slopes again lol... But as you pointed out, in this aspect home audio and car audio are completely different. Using acoustic shallow slopes in the car won't make the imaging, focus and tonality better in any way IME, it makes it worse. The comb created by overlapping a wide range of frequencies over two drivers is a major issue and cannot even be fixed with EQ. It will sound different, but not for the better unfortunately. I still think that using acoustic 4th order Linkwitz-Riley is the best option in the majority of situations. Absolute phase is inaudible, you CAN get amazing imaging even if you use 48dB slopes. It's only a minor issue, cross the drivers inside their maximum power response region and use steep slopes so you're not going outside the omni-directional range in the lowpass stopband. Contrary to what some other people tend to think, I think the phase discussion is over-complicated and silly in a way. You will never get "phase coherency" inside a car, just look at the acoustic phase response in a car at seated position. It will be all over the map and it still sounds good if you get the crossovers, EQ and T/A right.

I've used some fancy FIR filters, phase EQ and crap to get the phase response "flat". I gave that up since I realized that it wasn't audible at all. Phase only matters when you put it in relation to another source with another phase response.


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## MetricMuscle (Sep 16, 2013)

Are steeper slopes more important for drivers which are physically farther away from each other than drivers which are closer?
So is 24dB the preferred slope in a car?


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## Patrick Bateman (Sep 11, 2006)

sqnut said:


> Shallow slopes don't work in a car, period. In a car it's all about response. A car is an extremely hostile environment for listening to music. The response at speaker level is very different from that at your ear. Shallow slopes increase the pass band that each driver is playing and now the ear level mess is further compounded. Shallow slopes might work in a car if you had 1/6 oct eq per driver.
> 
> Shallow slopes do not cure L/R issues to any meaningful extent. If you're using shallow slopes to cure L/R in any car/install you're going to have significant to a ton of smearing. Your slope is a linear algorithm, there's nothing linear about the L/R difference or combined response peaks and dips. A fixed algorithm won't fix it.
> 
> ...


What a silly statement. Of course shallow slopes work. I've been using them for years, and so has Dynaudio.

Speakers with high order slopes cannot be phase coherent. The only exception to this rule is if you're using something like RePhase, but that's some Next Level ****, and I'm pretty sure no one has tried doing RePhase in a car.


Based on what I'm hearing in my car, Ambio works better with phase coherent speakers, and that means I'll be using first order slopes. As usual.

BTW, it's a heck of a lot easier for me to use first order filters because I have efficiency to burn. A compression driver and a waveguide allow me to do things you can't do with a dome tweeter.


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## Patrick Bateman (Sep 11, 2006)

thehatedguy said:


> There is no throat so it can't load.
> 
> You see three peaks and two valleys with horns because your horn is tuned to one frequency which is the null between one set of peaks, and and the driver has a resonance which is the null between the other another peak and the middle peak.
> 
> It doesn't peak, null, peak, null, peak, null, etc. Not any good horn.


Undersized horns DO peak-null-peak-null-peak-null. You can see it in the impedance plot and in the CSD plot. The nulls correspond to the length of the horn. There is a null at one quarter wavelength, 1/2 WL, 3/4WL, etc.

















The first two nulls are the strongest because the wavelength only has one path. For instance, let's say you have a 40hz horn. It's seven feet long. (Because 40hz is 28' long.) At the tuning frequency of 40hz there's only one path : down the horn. (Because the wavelength is HUGE - it's 28' long.)

At the 1/2WL frequency the same is true, as the wavelength is 14' long.

But as we get higher in frequency, the wavelengths are shorter, and then the sound has multiple paths down the horn. (due to the short wavelength.)

TLDR : Yes, undersized horns definitely DO peak-null-peak-null-peak-null in the impedance plot. This is normal for quarter wave resonators.



thehatedguy said:


> No, it definitely does not horn load the speaker. At best you might get some waveguide effect...but not horn loading and acoustical gain from it.


All horns are not waveguides, but all waveguides are horns. You don't need a throat in a horn to get horn loading; the horn loading is caused by the length and volume of the horn itself, not by the throat. What the throat is there for is to change the compression ratio, which can smooth the response. The throat chamber acts as a physical high pass filter, the throat chamber basically does the same thing that an inductor does : it rolls off the highs.

By juggling the compression ratio at the throat and the volume of the throat chamber, you can change the response of the horn.

But that doesn't mean that a horn with a 1:1 compression ratio isn't a horn. For instance, Dr Bruce Edgar used a 1:1 compression ratio on his midrange horn IIRC. That used a Dynaudio midrange, not all that different than the Morel midrange that Gary is using.


I actually re-read Edgar's article on midrange horns on the plane, have had to read his papers about ten times now. Takes a while for it all to "sink in"


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## Patrick Bateman (Sep 11, 2006)

Here's a quick summary of where the project is at:

1) I took the horns I had under the dash of my car, detailed in the thread at diyaudio named 'Edge of No Control', and turned them into an ambiopole (Home Page)
2) I liked the sound, but there's a couple of drawbacks. First, way too big to have on the top of my dash. Second, it requires DSP delay to image properly.

So...

In the next few weeks I'll do the following:
1) Make a new horn that's smaller
2) Swap out my AudioControl EQ for a miniDSP so that I can do digital delay
3) Add a MiniAmbio processor so that I don't have to do the ambiophonic processing with my iPad


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## Patrick Bateman (Sep 11, 2006)

I liked the sound of the Morel mids in Gary's car. I'd never considered using a dome midrange in my car, but I now see there are some nice advantages:

1) Dome midranges have re-donk-u-lous voice coils, which means massive power handling. The Dayton RS52 has a 2" voice coil. To put that in perspective, *that's as big as most subwoofer voice coils.* Sure, there *are* some subs with 3" and 4" voice coils, but that's not the norm. And a 2" voice coil on a 2" driver is just plain nuts. The big ol' voice coil raises power handling dramatically, reduces power compression, and probably distortion too. The big voice coil on the Dayton is probably one of the reasons that few people have anything bad to say about that driver.









In order to model the driver properly, *we have to cut it in half.* This is because Dayton doesn't publish a full set of T/S parameters on it. I did the dirty work, and here's what it's "real" parameters are. The VAS figure may be off by 10-20%, but Dayton doesn't even publish it, so this is better than nothing.









Here's the predicted response of the Dayton RS52 using my T/S measurements. Note that Hornresp tends to predict a high frequency rolloff that's much lower than what happens in the real world, because Hornresp treats diaphragms as if they're perfect radiators. In the real world, the high frequency rolloff is typically an octave or two higher than predicted, depending on how the diaphragm is damped.

















^^ Here's a couple of published measurements of the RS52 from other speaker builders. I went with a sensitivity between the two published designs, or about 92dB. If my guess is correct, then the moving mass of the RS52 is about 0.76 grams. That sounds about right, as the Peerless 830970, a driver with a similar size, has an MMS of 1.4g. (The 830970 is higher because it has a suspension and a spider. The suspension and spider of the 830970 lowers it's sensitivity and it's FS.)

Here's some more reading on the RS52, from someone else that sliced theirs in half too: http://www.htguide.com/forum/showthread.php?20024-RS52-tests-and-tweaks


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## Patrick Bateman (Sep 11, 2006)

We should be able to use Hornresp to simulate the response of the Dayton when you corner load it. Similar to how the Morel is corner loaded here in Gary's car.









Here's the dimensions of the corner. This is a fairly simplistic model; in the real world it will be a bit different because of the slope of the windshield, slope of the dash, etc. But modeling a corner gets us a lot closer to how the midrange will behave than if we use a flat baffle as our model. (And all loudspeaker spec sheets are measured on a flat baffle.)

TLDR : modeling a corner isn't a perfect sim, but it's a heck of a lot closer to reality than loudspeaker spec sheets









Here's a comparison of the response on a flat baffle, and in a corner. I see the following:
1) sticking it in a corner raises our output level by about 6dB
2) We lose that "boost" by 2khz. *The reason that this happens is because of the large throat.* If the throat was infinitely small, the boost would go all the way to infinity. As you can imagine, this becomes a bit of a juggling act. If you're trying to run the driver to 20khz you'll need a small throat, but if you're using a crossover at 1khz you won't need a small throat. The question of "small throat vs big throat" will really depend on your crossover point.










Here are the hornresp specs for that corner, if you want to sim this at home.

Also, hornresp has an option for corner loading a driver - it's in the box labeled "Ang". *I don't use that option as it assumes that the corner loading is infinite. And in our case, it isn't.

*


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## Patrick Bateman (Sep 11, 2006)

One big difference between the Dayton RS52 and the Morel midrange dome is that the Dayton has a lower FS. That probably means a lower sensitivity too. (low FS and low sensitivity go hand-in-hand.)

*I wanted to 'bump up' the efficiency by reducing the back chamber.* A side benefit is that it makes the package much smaller too.


















Here's a couple measurements showing how far we can increase the sensitivity.

In the first graph I've nearly doubled the 'stock' FS by reducing the back chamber to virtually nothing. The volume of the second chamber is the same, but I stuffed it with fiberglass.

The fiberglass gives us the high FS we need for high sensitivity, but also lowers the 'Q' which flattens the frequency response.

In my sims, the reduction of the back chamber raises output by close to 5dB, but at the expense of output below 500hz. Basically it's lower limit is about 500hz.


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## Patrick Bateman (Sep 11, 2006)

I drove up to T.H.E. Show yesterday, from San Diego, and it gave me a chance to figure out what I want to do with the system next.

As noted about a week, it IS possible to use DSP to delay the speakers, so that you can place them in the center of the dash.

But after listening for about 4-6 hours, I decided that it sounds best closer to the driver.

Basically the soundstage has more depth and more width if it's more 'centered' with the listener.

Due to that, I have to build some waveguides.










^^ Here are the plans for the waveguide. It's quite simple to put together. Basically get some 1/5" or 1/4" MDF or plywood, and cut out the two shapes at the top of the page. The dimensions are in the plan. The entire thing could be put together in less than thirty minutes. It will be easiest with a miter saw; follow the angles posted to get everything to fit, and you'll end up with a four sided pyramid that is also a waveguide.

The waveguide is assembled in three pieces. First the throat, then the body of the horn, and then the mouth.

Instructions for making the throat piece are here: How to Reduce Diffraction on Your Conical Horn - diyAudio


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## calebkhill (Jan 12, 2013)

garysummers said:


> I am not using EQ to "Frequency Steer", actually I don't know what that means.
> I am using equalization to match the frequency response of the Left and Right channels. The closer you get them to match at the listening position the more accurate and balanced your soundstage will be. When I do a response tuning, the first thing I do when I remove the testing mics from the car is to play a test CD I have with pink noise bursts that alternate left to right in 3 second intervals. The sound of the pink noise bursts should sound the same out of each channel. Will it be perfect? No!! But the closer you get it the better. Then I play a track with mono pink noise and it should image dead center without any significant timbre shift. If these two things occur in your car you are tuning frequency response the right way provided your target curve is accurate.


Where can we get these tracks?


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## Patrick Bateman (Sep 11, 2006)

calebkhill said:


> Where can we get these tracks?


The Ultimate White Noise Generator | Hearing Calibrated


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## garysummers (Oct 25, 2010)

You could download from the site Patrick has suggested. Then edit it in something like Audacity. Create your own time interval for bursts. Make sure you do not degrade the quality of the file.


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## Rs roms (Jul 12, 2012)

garysummers said:


> You could download from the site Patrick has suggested. Then edit it in something like Audacity. Create your own time interval for bursts. Make sure you do not degrade the quality of the file.


Just a quick question garry, the length and angles of flanges on the pillars are calculated or just approximate to deal with the early reflections.


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## calebkhill (Jan 12, 2013)

garysummers said:


> You could download from the site Patrick has suggested. Then edit it in something like Audacity. Create your own time interval for bursts. Make sure you do not degrade the quality of the file.


Can audacity alternate between L/R channels


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## ansuser (Dec 18, 2011)

Patrick Bateman said:


> Here's a quick summary of where the project is at:
> 
> 1) I took the horns I had under the dash of my car, detailed in the thread at diyaudio named 'Edge of No Control', and turned them into an ambiopole (Home Page)
> 2) I liked the sound, but there's a couple of drawbacks. First, way too big to have on the top of my dash. Second, it requires DSP delay to image properly.
> ...


Patrick,

your ambiophonics idea took my attention and I spent some time reading stuff and made several simulation using advanced FEA software.

The problem modeled was 2D circular space (this shape is the only possible with non-reflective boudaries) 2 meters in diameter. There are 2 speakers in the top half and 2 listening positions: in the bottom half on the center line and in "driver's position", i.e. 40 cantimeters on the left. 
Distance between ears is 20 cm, distance between speakers is 50 cm, distance from central listening position is 1.3 meters.
Originally, single frequency sine signal is fed only into right channel

Here are relative SPL plots of what you get in 3 freqs(100 Hz, 500 Hz, 3000 Hz). At the left lower quarter you can see 2 white points - these are ears locations for driver's position. You can also notice ripples at the 3000 Hz plot - it is caused by computational grid resolution limits


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## ansuser (Dec 18, 2011)

Next step was ambiopho R.A.C.E. algorythm implementation and input signal modification so that only right ear can hear the signal from right speaker.
I must say I went to extreme here and used 1000 recursions with 1% of signal attenuation.

Here are SPL plots for central listening position.

You can clearly see null at the left ear location while right ear position has some significante SPL levels. That means, RACE works.
You may also notice that distance between lobes become shorter with frequency growth. I've estimated 3000 Hz as a limit to have good crasstalk reduction with head size somewhat greater than a pinpoint :laugh:


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## ansuser (Dec 18, 2011)

After thar I adapted RACE algorythm to optimize it to off-center listening position.

It is absolutely clear that you can not just delay one channel to get stuf working. You need to use asymmetrical (i.e. different for left and right channel) time delays for ambio recursions.
Here are SPL plots for off-center position.

One can notice that low-frequency crosstalk can not be efficiently removed.


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## ansuser (Dec 18, 2011)

I've put together results at different frequencies and made cross talk vs. frequency plot. Also I estimated power required for spaekers to apply signal to remove crosstalk, and I must say it is something! +18db at 100 Hz!!!

It is obviouse that off-center position can be used to some extents (with modified R.A.C.E. algorythm), but low-freq range crosstalk can not be removed as good as for center position.


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## ansuser (Dec 18, 2011)

And last one note:
applying 50% reflection at boundary transforms everything in ugly way:

Hope it helps.
I think, ambio is better suited for more controlled space than a car


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## garysummers (Oct 25, 2010)

Rs roms said:


> Just a quick question garry, the length and angles of flanges on the pillars are calculated or just approximate to deal with the early reflections.


I would like to say there was a lot of science that went into the design. But that was not the case! Just used my ears! Then Scott made them look good!


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## durwood (Mar 7, 2007)

ansuser said:


> Hope it helps.
> I think, ambio is better suited for more controlled space than a car


I agree a controlled space would be better, but I disagree ambio is not suited for a car. Consider proper stereo reproduction requires speakers be placed at specific azimuth angles +/-30deg and also must be placed away from boundaries as well. Ambio placement at least allows you to place them far away from side walls.  No doubt reflections are going to cause problems but stereo layout also suffers from this.

Another point, the off center errors are much smaller for ambio vs stereo in theory.
http://www.transaural.com/cbpublications/documents/modifieddipole.pdf




ansuser said:


> I've put together results at different frequencies and made cross talk vs. frequency plot. Also I estimated power required for spaekers to apply signal to remove crosstalk, and I must say it is something! +18db at 100 Hz!!!
> 
> It is obviouse that off-center position can be used to some extents (with modified R.A.C.E. algorythm), but low-freq range crosstalk can not be removed as good as for center position.


Agreed. I don't use crosstalk cancelation for midbass. I think the optimal source distribution model that improves on ambio and works better for off-center seating situations is the way to go and I think some german cars implemented a form of this based on speaker placement (VW, BMW, Mercedes). The RACE model and the electro-music plugin both leave the bass frequencies alone IIRC.



ansuser said:


> After thar I adapted RACE algorythm to optimize it to off-center listening position.
> 
> It is absolutely clear that you can not just delay one channel to get stuf working. You need to use asymmetrical (i.e. different for left and right channel) time delays for ambio recursions.
> Here are SPL plots for off-center position.
> ...


Cool, I would be interested to know if you optimized it for your simulations or if you have some software you use to actually listen this way. I proposed a similar solution using VST plugins strung together, but it sure would be nice to have an ambio panner plugin. I lack the skill to program myself, and could not justify to pay some VST programmers for something I wanted to use, not for resale.

electro-music.com :: View topic - Ambiophonic Time Correct Panning




ansuser said:


> Next step was ambiopho R.A.C.E. algorythm implementation and input signal modification so that only right ear can hear the signal from right speaker.
> I must say I went to extreme here and used 1000 recursions with 1% of signal attenuation.
> 
> Here are SPL plots for central listening position.
> ...


I think RACE is cool, but if you strive for perfection I think it only makes the sweet spot really small no? The general opinion seemed to be you can comprimse a bit and keep the listening spot larger or go to the other extreme and make the sweet spot small. I have a fantasy where the ideas of ambisonics could be combined with ambiophonics to allow you adjust the sweet spot merely by adjusting a single knob. How cool would that be. Similar to zooming in and out on a map. That was one of the concepts of ambisonics that was really different.


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## ansuser (Dec 18, 2011)

durwood said:


> Cool, I would be interested to know if you optimized it for your simulations or if you have some software you use to actually listen this way. I proposed a similar solution using VST plugins strung together, but it sure would be nice to have an ambio panner plugin. I lack the skill to program myself, and could not justify to pay some VST programmers for something I wanted to use, not for resale.
> 
> electro-music.com :: View topic - Ambiophonic Time Correct Panning
> 
> ...


I'm not a programmer as well. I've just calculated cross talk delays independly for left and right sides based on actual ears and speakers location. Since it was single freq analysis, it is resulted in simple phase shifts that are different for left and right channel

My understanding of ambiophincs, there is no sweet spot. There are lobes, and you can compromise channel separation by widening the null part of the lobe.


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## Patrick Bateman (Sep 11, 2006)

There's a good chance I'll only be using the processing over 2-3 octaves. Here's why:

1) the whole intent of the processing is crosstalk cancellation. But by using waveguides, *I can physically reduce crosstalk.* For instance, it's trivially easy to reduce the off-axis intensity of a driver by six dB using a waveguide. Getting higher amounts of rejection requires a dipole or a long narrow waveguide, but 6dB is a piece of cake.
2) the main problem with waveguides is SIZE; a 500hz waveguide is 27" in diameter! Luckily, we have a 'built in' waveguide called a windshield, so we can get pretty good pattern control if we engineer it right.
3) Once we establish that, it turn out that we really need crosstalk cancellation over the span of about two octaves: 350hz-1400hz. Taken to the extreme, I might be able to whittle that down to once octave : 350hz-700hz.

The new waveguides are drying in the garage as we speak.


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## Patrick Bateman (Sep 11, 2006)

Durwood - what are you doing your processing with?

I was using the PC and iPad apps.

The MiniAmbio is a quantum leap past them. The MiniAmbio is so clean, I had a hard time convincing myself it was even running. I literally had to remove it from the chain a couple times to convince myself that I hadn't accidentally set it to 'bypass.' It's processing is very VERY subtle.

Not sure if this is due to processing power, an improved algorithm, electronics, or something else.

The device appears to be a total flop; according to my receipt, I am the proud owner of MiniAmbio #122.


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## ansuser (Dec 18, 2011)

Patrick Bateman said:


> The device appears to be a total flop; according to my receipt, I am the proud owner of MiniAmbio #122.


That's beacuse another AD/DA transform in a signal chain considered like herecy in audiophiles' cirlcle :laugh:

BTW, according to modeling I've done, RACE processing DOES change signal phase in the listening point.


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## durwood (Mar 7, 2007)

Patrick Bateman said:


> Durwood - what are you doing your processing with?




PC m-audio delta410 + VST's. Currently I am using the ambio.one VST (before that I was using the electro-music one), although I have collected them all, at least what I have come across over the years. It seems very subtle as well using the bypass button.

Weldroid! [ambient, idm, hardcore, electronic, audio, mp3, music]: Ambiophonics Processor VST: ambio.one




> The MiniAmbio is a quantum leap past them. The MiniAmbio is so clean, I had a hard time convincing myself it was even running. I literally had to remove it from the chain a couple times to convince myself that I hadn't accidentally set it to 'bypass.' It's processing is very VERY subtle.
> 
> Not sure if this is due to processing power, an improved algorithm, electronics, or something else.


I don't know how you can define "clean". That is some kind of subjective jargon. All the plugins I have used all have a different algorithm. I can wire them all up in my PC and switch back and forth and not get the same result twice. Plus, they all have various adjustments and some of the names give to the adjustments are very odd. I take it for the artform it is, someone's interpretation on how it "should" work.



> The device appears to be a total flop; according to my receipt, I am the proud owner of MiniAmbio #122.


This stuff will always be speciality (maybe you remember the Carver Sonic Hologram?), stereo is too entrenched for people who want simple ways to play one space over the top of a completely different space. You expect a paradigm shift? Forget it, that ship has sailed long ago. People that do try this try it for 30 secs, when they have given stereo/panned mono years and years of patience. It's funny to watch Andy try to promote L7 for years and the majority of people are still using it in 2 channel config (should have given them more channels Andy  )


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## cajunner (Apr 13, 2007)

garysummers said:


> I would like to say there was a lot of science that went into the design. But that was not the case! Just used my ears! Then Scott made them look good!


if initial calculations demanded the hoods look like a sideways vagina, with the speaker in the "pink" that would have been uh... err... interesting.

maybe that would be the next iteration, huh?

upper labial fold, reducing frequencies from 1300-2900 hz, larger majora reductions in the range of 3K to 9Khz, diffraction...

the bush in the inside corner, deals with Higher Order Modes.



HOM, HOM, HOM...


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## Darth SQ (Sep 17, 2010)

cajunner said:


> if initial calculations demanded the hoods look like a sideways vagina, with the speaker in the "pink" that would have been uh... err... interesting.
> 
> maybe that would be the next iteration, huh?
> 
> ...




:inout:
You really need to get out more.......


Bret
PPI-ART COLLECTOR


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## Patrick Bateman (Sep 11, 2006)

garysummers said:


> I would like to say there was a lot of science that went into the design. But that was not the case! Just used my ears! Then Scott made them look good!


Oddly enough, you can get really good results from just eyeballing it. Basically a smooth transition from cone to windshield goes a long way.









I read that the mold for some of the Danley horns was made by simply cutting a hole in a box, covering it in burlap, then pressing the woofer into the burlap.

Waveguide ala Genelec, need help for building - diyAudio

_Hi guys

For what its worth, the every first one of these below was made using burlap to make the “waveguide”. Perhaps you can use spandex to do the same thing. Stretch the fabric across a framework, uniformly stretched a bit.
With something round, the size you need, press in the fabric to the depth you need and clamp in position. Get some thin epoxy resin from the hobby shop and brush on a few coats until the fabric is ridged enough to deal with. Fill in the rear area with “great stuff” or equivalent polyurethane expanding foam.
Be sure to drill a number of big holes on the back side to let the excess out as it expands. Figure it will take a couple trys until you get the hang of it but then it will be easy once you figure out what you need for your application.
Good luck

Tom Danley_


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## garysummers (Oct 25, 2010)

calebkhill said:


> Where can we get these tracks?


I have posted the pink noise tracks I spoke of in my dropbox.
The link is below.

https://www.dropbox.com/sh/nu27oosycsc79d6/AACTUGa8sD129YnLCbErA9exa


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## JoshHefnerX (Jun 13, 2008)

Patrick, is there a website that you know of that can give an overview to the basic diff between the different horn shapes and how they affect the sound (tractix, parabolic, ect)?

Josh


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## Patrick Bateman (Sep 11, 2006)

JoshHefnerX said:


> Patrick, is there a website that you know of that can give an overview to the basic diff between the different horn shapes and how they affect the sound (tractix, parabolic, ect)?
> 
> Josh


Check out the thread titled 'great waveguide list' at diyaudio.

I have a hard time getting excited about horns these days.








The JBL PT waveguide (http://www.parts-express.com/pyle-ph612-1-screw-on-constant-radiation-horn--292-2572) is ridiculously good. If it was $200 I might think twice about it, but at $14 it's really hard to recommend anything else. Gary noted earlier in the thread that his reference speakers, at work, are JBL. They use a larger version of this very same waveguide.

The waveguides from Autotech, diysoundgroup, and Pi Speakers look good too, but there's nothing under $50 that can compete with the JBL clones from Pyle. (IMHO.)


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## garysummers (Oct 25, 2010)

Patrick, would it be reasonable to cut the throat down on that horn and place a 4" point source driver in there. It would be in a sealed enclosure behind the horn. Such as the one here:

Xtant Technologies 4" Point Source Full Range Speakers Pair Macrom | eBay

Good idea or disaster?


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## Patrick Bateman (Sep 11, 2006)

garysummers said:


> Patrick, would it be reasonable to cut the throat down on that horn and place a 4" point source driver in there. It would be in a sealed enclosure behind the horn. Such as the one here:
> 
> Xtant Technologies 4" Point Source Full Range Speakers Pair Macrom | eBay
> 
> Good idea or disaster?












Diffraction off of the tweeter becomes an issue.


















Kef has been refinining this for a decade, and they've even reduced diffraction off of the surround









Tad does likewise; and it's not surprising, the designer of this speaker used to work for KEF!









Best Buy, of all places, used to sell a speaker for something like $150 that was clearly a knockoff of this.


Not saying the Macrom won't work; but the Kef will work better.


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## ErinH (Feb 14, 2007)

garysummers said:


> Patrick, would it be reasonable to cut the throat down on that horn and place a 4" point source driver in there. It would be in a sealed enclosure behind the horn. Such as the one here:
> 
> Xtant Technologies 4" Point Source Full Range Speakers Pair Macrom | eBay
> 
> Good idea or disaster?



What you'll have to pay attention to is the termination of the mid to the horn's throat. Additionally, you'll also want to match the directivity of both the mid/horn and tweeter. This is what makes or breaks a good concentric design. Otherwise, you may wind up with two different radiation patterns before and/or after the horn is accounted for which would really destroy the purpose of the concentric. 



FWIW, Gary, I actually have a pair of the Kef R-series concentrics in my car. I've got pictures/details in my build log (not to bog down this thread with OT):
http://www.diymobileaudio.com/forum...edan-v-my-full-disclosure-build-tune-log.html


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## calebkhill (Jan 12, 2013)

garysummers said:


> I have posted the pink noise tracks I spoke of in my dropbox.
> The link is below.
> 
> https://www.dropbox.com/sh/nu27oosycsc79d6/AACTUGa8sD129YnLCbErA9exa


..


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## Patrick Bateman (Sep 11, 2006)

First segment of waveguide, using the guide from post #1

















































My inspiration was this QSC waveguide, which measures beautifully


















wood filler helps a lot


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## Patrick Bateman (Sep 11, 2006)

Here's what it looks like in the car























































The waveguide is designed to use the windshield to extend the waveguide.
This allows me to liberally remove large chunks of the waveguide, while still maintaining directivity and loading. (Because it meets up with the windshield.)

It is very possible that I may end up removing 50 or even 75% of it.


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## rton20s (Feb 14, 2011)

Who needs to see while driving?


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## ErinH (Feb 14, 2007)

So, you're going to drive with that?...


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## rton20s (Feb 14, 2011)

Looks like someone needs to get in contact with a good plastics fabrication company to have this fabbed up with lexan/acrylic. Distortion would likely be an issue though. (Visible, not audible.)


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## Patrick Bateman (Sep 11, 2006)

bikinpunk said:


> So, you're going to drive with that?...











I drove around for about six hours on Saturday with THIS monster up on the dash. It was originally designed to go UNDER the dash, but I threw it up on the dash because it sounded better.

Surprisingly enough, it worked fine!

I am 6'3" tall, and if I adjust the seat my head actually touches the ceiling.

But I didn't need to do that. As absurd as these speakers look, my visibility is about as good as it would be if I was a foot shorter. This configuration probably isn't optimum for someone who's 5' tall, but for me, I can see fine. I am not looking AT the speakers, I'm looking OVER them. If anything, the speakers in the corners were more distracting, because you need to look into the corners to change lanes and the speakers can 'hide' things on the left when they're near the A Pillar.









One thing that helps is that the view in front of me is unobstructed, because the speakers are basically in the center of the dash. I tried putting the speakers on top of the instrument cluster, and that was definitely distracting.


One concern I *do* have is getting pulled over; so when I'm done I'll probably do something to the back side so that they're camouflaged into the interior.


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## Patrick Bateman (Sep 11, 2006)

rton20s said:


> Looks like someone needs to get in contact with a good plastics fabrication company to have this fabbed up with lexan/acrylic. Distortion would likely be an issue though. (Visible, not audible.)


If everything works alright I may add some glass to it.
Not fiberglass, but glass. (After all, fiberglass IS glass.)

Picture replacing part of the waveguide with a sheet of glass and you get the general idea. The walls are flat so it should be fairly easy to do.









I wouldn't be the first


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## thehatedguy (May 4, 2007)

Somehow I don't think CHiPs is going to let something like that go unnoticed...

I would check the DMV cause something tells me that isn't legal, and if it is, it shouldn't be.


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## thehatedguy (May 4, 2007)

I'll just stick with my Tannoys whenever I get my car back up and playing. Gary's probably heard some System 8 NFM2s sometime in his life...unless I can find some System 10 DMT2 for a good price.


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## Patrick Bateman (Sep 11, 2006)

thehatedguy said:


> Somehow I don't think CHiPs is going to let something like that go unnoticed...
> 
> I would check the DMV cause something tells me that isn't legal, and if it is, it shouldn't be.


illegal!

https://www.dmv.ca.gov/pubs/vctop/d12/vc26708.htm

Good thing I never drive. My car is a year old and I've managed to drive an average of 110 miles a week.


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## Darth SQ (Sep 17, 2010)

bikinpunk said:


> So, you're going to drive with that?...


Ambio................
It's not for everyone.




Bret
PPI-ART COLLECTOR


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## thehatedguy (May 4, 2007)

The other way to do ambio is with a physical divider between the two ears...let's see something like that pulled off in the car


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## Patrick Bateman (Sep 11, 2006)

thehatedguy said:


> The other way to do ambio is with a physical divider between the two ears...let's see something like that pulled off in the car












DON'T MAKE ME BUILD AN AMBIO HELMET

But seriously, yeah, this would work. A bicycle helmet with a sheet of plexiglass attached to eliminate crosstalk.


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## MetricMuscle (Sep 16, 2013)

Patrick Bateman said:


> DON'T MAKE ME BUILD AN AMBIO HELMET
> 
> But seriously, yeah, this would work. A bicycle helmet with a sheet of plexiglass attached to eliminate crosstalk.


Safety first, It's a competitive world.


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## JoshHefnerX (Jun 13, 2008)

Maybe I missed it but it didn't say anything about anything transparent blocking the windshield. maybe another piece of glass would be ok??? Probably have to be careful about glare though

Josh


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## BigRed (Aug 12, 2007)

So all of us with pods on our dash are basically riding dirty


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## Patrick Bateman (Sep 11, 2006)

JoshHefnerX said:


> Maybe I missed it but it didn't say anything about anything transparent blocking the windshield. maybe another piece of glass would be ok??? Probably have to be careful about glare though
> 
> Josh











Chances are good it will end up looking a lot like this, but as an MTM, and flipped on it's side.

A dipole this small will rolloff at something like 1khz, but you just use brute force to bring the SPL back up. Is it efficient? No. But that's why you need a lot of displacement for the midrange and a high xover point.









Here's John's crossover points; note that the midrange is crossed over at a frequency close to where most of us are crossing over our tweeters (1khz)


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## FG79 (Jun 30, 2008)

Patrick Bateman said:


> Gary's Benz does all of the audiophile stuff very well.
> Imaging, tonality, soundstaging.
> 
> But I'm a basshead and Jon's bus has the best bass I've ever heard in a vehicle, and maybe the best bass I've ever heard anywhere.
> ...


Thank you for articulating what I've been saying for years.....that the imaging stuff is cool but is not "emotional" or "magical". Too much energy placed on an extremely challenging application, and not enough on what's important and relatively easy to achieve. 

When you sit in a well set up home system with top notch imaging speakers (with a top notch recording), the effect is cool but not the end all be all. The speakers that excite me the most are the ones that have soul to them.

BTW, mono in itself is not a bad thing. A true mono recording has its benefits too, mainly a more focused, heavier sound. But that's another topic!


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## Patrick Bateman (Sep 11, 2006)

This is getting a little ridiculous, but I've opted to trash *another* set of waveguides.









I didn't have any issues driving with this up on the dash, but the idea of getting pulled over by the cops gave me the willies. This waveguide has wide horizontal and narrow vertical directivity. To be specific, 135 x 90.









There's another speaker with wide horizontal and narrow vertical directivity...










































By using one of the Sausalito Audio Works lenses, I can basically get rid of three of the horn sides. The lens is a waveguide really; the difference is that the top, left, and right is absent.


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## ErinH (Feb 14, 2007)

with the size of the horns you're trying out and actually considering using (judging by the recent posts), you could seriously just buy a good concentric drive unit and call it a day. there are numerous options for smaller 3-4" kef concentrics on eBay.


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## Patrick Bateman (Sep 11, 2006)

bikinpunk said:


> with the size of the horns you're trying out and actually considering using (judging by the recent posts), you could seriously just buy a good concentric drive unit and call it a day. there are numerous options for smaller 3-4" kef concentrics on eBay.


I've definitely considered it. I have five of the 3" Kef Concentrics, and two of the B&C 5" concentrics. Both of them sound good, but the Kef won't get very loud. The B&C will, but it won't fit.









Here's my B&C 5" concentric (5FCX44)









Here's the 5NDL38

If B&C would make a neo concentric, that would probably do the trick.


Then again, having the drivers separate has it's advantages. In this case, by putting all the drivers facing up it allows me to cram a lot of output into a small space. I tried having the drivers face forward, they wouldn't fit. I've got about 3" to play with.

You'd laugh if you saw the things I did to make everything fit. I've shaved down my compression driver with a Dremel, I'm using a 3" midrange that has a flange that's about 1/4".

It reminds me of a story I read about Sony. Their engineers presented a product to management. Management took their design, *and dunked it in a bucket of water.* When air bubbles floated to the surface, management told them to go back to the drawing board, and come up with a design that didn't do that.

Basically management wanted their engineers to utilize every last millimeter of space in the chassis, to keep everything as small as physically possible.


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## ErinH (Feb 14, 2007)

I think you're putting too much stock in the "won't get loud" aspect. My kefs have standard sensitivity (mid-to-upper 80's) and you don't want for more volume. At least IMHO (and I'm sure many can back me up on this who have heard my car in the past year). 

Besides, if it's down to a rather nebulous concern over "loud enough" vs compact, all in one solution that you know works and won't get you pulled over by the CHP, then I'd take that one. Again, I understand wanting to experiment for the sake of it, but if the sensitivity is your ONLY concern?... the above reflects my sentiments.


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## Patrick Bateman (Sep 11, 2006)

bikinpunk said:


> I think you're putting too much stock in the "won't get loud" aspect. My kefs have standard sensitivity (mid-to-upper 80's) and you don't want for more volume. At least IMHO (and I'm sure many can back me up on this who have heard my car in the past year).
> 
> Besides, if it's down to a rather nebulous concern over "loud enough" vs compact, all in one solution that you know works and won't get you pulled over by the CHP, then I'd take that one. Again, I understand wanting to experiment for the sake of it, but if the sensitivity is your ONLY concern?... the above reflects my sentiments.


But you have the 5" KEFs 

I think those will be loud enough; I really struggled to get two 3" woofers on the dash, because dual 3" is about the same displacement as one 5"

There's a place in Florida that used to sell the newer KEFs, with the tangerine phase plug and the 5" cone, but they stopped.



If anyone's following this thread, and they have some 5" KEFs, YES that would be a great solution.


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## Patrick Bateman (Sep 11, 2006)

Actually, from looking at your car, did you have to cut into the A Pillar?

I'm really averse to touching my car; I haven't cut a single wire or removed a single driver in my last three cars. All of my systems are 100% removable.


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## Orion525iT (Mar 6, 2011)

Patrick Bateman said:


> Actually, from looking at your car, did you have to cut into the A Pillar?
> 
> I'm really averse to touching my car; I haven't cut a single wire or removed a single driver in my last three cars. All of my systems are 100% removable.


Source some extra pillars from the scrap yard and don't worry about it. Most pillars are super easy to pop off. Things get tricky with pillar air bags I suppose, but still...

For my new daily driver, I pulled entire doors from the scrap yard to make construction of isolated door pods easier and to keep the original doors. Alas, my car is 16 years old at this point. Older cars have their advantage when it comes to this stuff.


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## Orion525iT (Mar 6, 2011)

If you want to stuff the drivers as tight as possible into the dash/glass junction, it would seem that a horizontal MMT arrangement would be the way to go. More cone area, more displacement, more sensitivity. You could roll one off earlier to avoid beaming, or add delay for directivity control. 

I have played around with this arrangement quite a bit, but in my car can never seem to get over the chaos of the early reflections, even with the dash removed! Sounds good for a bit, but fatigue enters early. But I never built pods like in Gary's car.


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## Patrick Bateman (Sep 11, 2006)

Orion525iT said:


> If you want to stuff the drivers as tight as possible into the dash/glass junction, it would seem that a horizontal MMT arrangement would be the way to go. More cone area, more displacement, more sensitivity. You could roll one off earlier to avoid beaming, or add delay for directivity control.
> 
> I have played around with this arrangement quite a bit, but in my car can never seem to get over the chaos of the early reflections, even with the dash removed! Sounds good for a bit, but fatigue enters early. But I never built pods like in Gary's car.


An MTM is tighter. The problem with an MMT is twofold:

1) the radiation pattern is asymmetrical
2) one midrange is significantly further from the tweeter than the other.

Both issues can be addressed; for instance an asymmetrical radiation pattern can work in one's favor. And the second problem can be dealt with by turning it into a three-way. But a two-way MTM is easier and simpler IMHO


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## subwoofery (Nov 9, 2008)

Patrick Bateman said:


> When two drivers are within 1/4-1/3rd of a wavelength they will act like one.
> For instance, if you have two 3" woofers with a center-to-center spacing of 3" they will behave like one driver to 1,125hz. (speed of sound = 13,500 inches per second.)
> 
> As you go from 1/4 wavelength to larger distances, things get complex. Even with a spacing of a full wavelength it can still work. But the problem at these distances is that it will work at certain angles and not at others. And on top of all that, it will depend on phase, so the crossover has an effect! IE, with a first order slope you'll have flat response on-axis, but with a second order butterworth you won't! (Maddening, huh?)
> ...


Sorry if someone asked it already but I'm still on page 7 - haven't read everything yet. 

I've always wanted to try the multiple midbass thing and have everything I need for that. 
What I'd like to know if can we still install drivers at various distance, longer than 1/4 of a wavelength and use T/A to mimic a closer center-to-center spacing? 

In my current car, I have the space to install 3 midbasses per side (front door, rear door and trunk baffle) and the processing for it too. 

In order to use them up to let's say 400Hz, it would require an install with a center-to-center spacing close to 8.4" which is not really feasible... 

Kelvin


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## Orion525iT (Mar 6, 2011)

subwoofery said:


> Sorry if someone asked it already but I'm still on page 7 - haven't read everything yet.
> 
> I've always wanted to try the multiple midbass thing and have everything I need for that.
> What I'd like to know if can we still install drivers at various distance, longer than 1/4 of a wavelength and use T/A to mimic a closer center-to-center spacing?
> ...


I have been stewing on this too, as I plan to use multiple midbass.

The question in my head is wether there is a difference between measured summing (behave as one driver summing that I think Patrick referenced) and physcoacoustic summing. In my mind, phase is at issue in both. But are other factors precedent?


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## thehatedguy (May 4, 2007)

I don't know if I would go up to 400.

But on paper the midbass array thread Lycan started would be where I would find some answers...it works on paper, but sometimes paper and reality don't mix really well.


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## thehatedguy (May 4, 2007)

I still think a nice 8 or 10" coax would solve nearly all of the problems you are trying to get around.


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## JoshHefnerX (Jun 13, 2008)

I've always been interested in some tannoy concentrics
but never had the opportunity. I have listened to some different Kef's over the years. Anyone say how they compare?

Josh


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## Patrick Bateman (Sep 11, 2006)

subwoofery said:


> Sorry if someone asked it already but I'm still on page 7 - haven't read everything yet.
> 
> I've always wanted to try the multiple midbass thing and have everything I need for that.
> What I'd like to know if can we still install drivers at various distance, longer than 1/4 of a wavelength and use T/A to mimic a closer center-to-center spacing?
> ...



IMHO, there are two ways to look at this question:

The first opinion is that we perceive the sound of a midbass based on it's location. The reason for this is phase; at low frequencies our perception of location is based on phase. *So even if you use DSP to get the speaker in phase, our perception of it's location is still tied to it's physical location.* This is why you can manipulate high frequencies to change the width of a soundstage, but you can't do the same thing at low frequency.

But there's another way of looking at it, which is to simply use enough sources that you simply can't perceive where the low frequencies are. I did that at home, had something like twelve subs at one point. When I did this the sound seemed to come from *everywhere*. It wasn't a question of the sub sounding like it was behind you, or to the left, or to the right. The sub sounded like it was *everywhere.*

With enough midbasses, I think you'd get the same effect, but the question is whether you WANT that.


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## Orion525iT (Mar 6, 2011)

Patrick Bateman said:


> IMHO, there are two ways to look at this question:
> 
> The first opinion is that we perceive the sound of a midbass based on it's location. The reason for this is phase; at low frequencies our perception of location is based on phase. *So even if you use DSP to get the speaker in phase, our perception of it's location is still tied to it's physical location.* This is why you can manipulate high frequencies to change the width of a soundstage, but you can't do the same thing at low frequency.
> 
> But there's another way of looking at it, which is to simply use enough sources that you simply can't perceive where the low frequencies are.


This might be better to add to the Midbass array thread, but we are here so...

ITD, phase, Midbass arrays, Opsodis, and Haas.

My overly hopped and lagered brain has been trying to reconcile all the above theories into something that can work together. What I settled on was to use 4 6.5 midbass drivers as opposed to multiple ND91's (or other small midbass dirvers) in multiple locations.

1)We perceive location of sound in midbass due to ITD. We all know this. 2)Multiple midbasses may help to spread the chaos in the mobile environment in the same way that multiple subs do in the home environment. 3)Stage width has a lot to due with midbass placement; enter Opsodis. But with multiple midbasses, we now have the issue of phase. 4)But isn't that were Haas comes into the equation and can be leveraged to tie everything together?

Say you mount a midbass at the typical location at the left front of the door or even the left kickpanel. Stage may suffer and narrow as a result because of less than optimal ITD. In that location the sound wave hits your left ear first but also reaches your right ear a small time later. Now consider a driver in the door at your hip. With this location, the ITD between your left and right ear is greater, and you get better stage width (Opsodis).

Now consider midbass drivers at the front of the door _and_ at the hip. Again, as Patrick pointed out, TA wont fix the phase discrepancies. The question in my mind is; Do you really need to fix the phase discrepancy? This is where we may be able to leverage Haas. As long as the wave front from the midbass mounted at the hip reaches your left ear first, Haas effect takes over, and you only need to make sure that the wave front from both midbasses reach your right ear at or very near the same time. Haas effect makes it so the dominate spatial cues are coming from the hip location and not the front location. As long as you time align the wave fronts of both *left* midbass locations to reach the *right* ear at the same time, then you ensure that the wavefront from the hip arrives at the left ear first, and your brain won't recognize the delay from the front midbass.

In the ideal situation you get some elements of spreading the chaos, and Opsodis. Measuring equipment would obviously help with this, but I am willing to bet you could adjust things by ear too.

With >4 midbasses, things get more difficult. At least until you reach the point where, as Patrick stated, the sound comes from *everywhere*.


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## sqnut (Dec 24, 2009)

subwoofery said:


> In order to use them up to let's say 400Hz, it would require an install with a center-to-center spacing close to 8.4" which is not really feasible...
> 
> Kelvin


It's actually not Centre to Centre but the distance between the parts of the cone playing the same frequency. 400 hz is 33" or 1/4 wavelength = 8.35", not really an issue.

Now if you're crossing a 3" mid with a 1" tweet at 3khz, 1/4 wavelength = 1.10". You're never going to get a C 2 C of 1". 3khz is on the outer edge of the tweeter cone and midway on the 3" cone. Then again this is only theory. Best way is to play with install and find out.


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## Patrick Bateman (Sep 11, 2006)

Orion525iT said:


> This might be better to add to the Midbass array thread, but we are here so...
> 
> ITD, phase, Midbass arrays, Opsodis, and Haas.
> 
> ...


WOW

I'd never considered the Haas effect with distributed midbasses.

In my car, I'd intended to use four midbasses per side. And I've been reluctant to 'pull the trigger' on four more. The reason is because the midbass enclosures are a freaken nightmare to build (lots of small parts, time consuming to build them all), and each enclosure doesn't generate a lot of SPL. Basically a bunch of them are mighty, but one of them doesn't generate a lot of SPL.

I've been tempted to replace the midbass array with an 8", but I've avoided doing it because the midbass array sounds good.



But now that you've pointed out the Haas effect, the lightbulb has gone off, that you could do *an assymmetrical midbass array.* Basically one or two small drivers in ideal locations, and then a mighty midbass in another location.











BTW, this is *exactly* how the Grand National was rumored to work. Richard Clark had a couple of monster midbasses in his car, with 4" voice coils 12" cones and they were ported. We're talking about a midbass that's capable of belting out 120dB, maybe 130dB. But rumor has it that there were 5" midbasses in the FRONT of the car. He never came right out and admitted it, but he dropped plenty of hints.


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## Patrick Bateman (Sep 11, 2006)

Here's some elaboration on the last point. The precedence effect says that the first arrival will dominate. If the second arrival comes a millisecond later (13.5") *it will not take precedence unless it's ten decibels louder.*









So you could have a small midbass, like a 5", in an optimum location. This SB Acoustics is a good example. It will fit into an enclosure that's small enough to hold in your hand, which makes it easier to place in the optimum enclosure. It's good for about 105dB.









Then we do something like Clark did, but a beast of a midbass in a non-optimum enclosure. This is a JBL 12" midbass, good for something like 125dB.

If both midbasses are running off the same amp, you'd probably want one midbass that's about 10dB more efficient than the other. Don't focus on the spec sheet, because those figures are quoted at 1khz, you'll have to actually sim the enclosure. The spec sheet will get you 'in the ballpark.' For instance, that SB Acoustics midbass is good for 88dB with 2.83V, while a B&C 8NDL51 is good for 94dB with the same voltage.









Sixteen ohm drivers might be worth a look. For instance, this CSS woofer is 16ohm. The reason you want a sixteen ohm driver is because The Beast Midbass is going to have much, much higher power handling. (Because it's A Beast!) I ran into this problem at the MECA show, I blew up one of my midranges because 2/3rds of the drivers in my system are beasts and my midranges are puny. So you gotta be careful about how much power you send to them, unless you enjoy blowing drivers up. With a 16ohm midrange you'll minimize the power going to The Optimum Midrange. Another option is to run a couple of drivers in series, with The Beast Midbass in parallel. Two four ohm mids in series, wired in parallel with a 4ohm will yield a load of 2.666ohm.


One thing that makes it a bit tricky/expensive is that The Beast Midbass needs to be further away than The Optimal Midbass. In my car, the rear quarter panels are actually closer to my ears than the optimal midbass locations are.

I *think* you may be able to use DSP to solve this. (Contrary to what I said yesterday.)

What we do is we DELAY The Beast Midbass so that it's sound arrives *after* The Optimal Midbass (even though The Beast Midbass is physically closer.) The only reason that we can get away with this kind of audio ****ery is because the wavelengths are so long. For instance, a 200hz soundwave is five milliseconds long. (200 cycles per second, 1000ms in a second) *So if we delay The Beast Midbass by a millisecond, we're not 'crashing' into the next wave.* From the math, you can see that as you get higher and higher in frequency this gets trickier; if you tried to do the same trick at 500hz you'd probably be limited to about four tenths of a millisecond, which is equivalent to just 5.4".




TLDR : The idea of using two midbasses in an array is kinda brilliant. It solves the maddening problem of building eight midbasses, then running ten miles of speaker cable, hiding them, etc. Just build one beastly midbass, a smaller midbass, and put the latter in the optimum location. DSP delay may come in handy if The Beast Midbass is closer than the optimum midbass.


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## Patrick Bateman (Sep 11, 2006)

Some random quotes on this subject:

_"It is simple to do a system that has MB's in the rear 400 to 500 hz and down with the front speakers running 400 to 500 hz and up.

The front MUST be set up correctly, ie. pathlenghts, on axis mounting, and proper time alignment between the MB and the front speakers."_ (*Eric Holdaway* (his shop was one of the most prominent SQ shops in the early 90s), eleven years ago, CARSOUND.COM Forum - View Single Post - how did the buick grand national get away with the midbass in the rear side panels? )

_"somehow i think you know the answer before you asked the question------but here goes-------put any speaker behind you that is reproducing frequencies above about 80 HZ at a level that creates correct spectral balance with the rest of a normally balanced system and it will sound like they are where they are------in the back!!!!!!------and there is no way around it except to move them to the front...........RC"_ *Richard Clark*, sound off legend of the 90s

If anyone doesn't know who Clark and Holdaway are, here's a quote from Sound Off Legend Gary Biggs: _"When asked why he competes with an older car, Biggs' logic resounds with quintessential audiophile logic. "Back in the late '80s when I was getting into car audio, The Speaker Works in California had this Buick Regal and they were unbeatable. Then when Richard Clark bought it, he was just as unbeatable. That's when I figured there must be something to having a Buick Regal because two different guys kicked so much butt. Since I couldn't afford a Grand National, I did the next best thing and just bought a regular Buick." 

"you cannot put midrange speakers behind you and not hear them as being there if the system has reasonably well balanced frequency response-------there's simply no way to do it-------at least i have never heard it done--------*don't know when you heard the car but when i got it it was pretty obvious the mids were in the rear---------thats why i added small "midrange steering speakers" in the buick that dominated the midrange at low to medium listening levels*...........RC_ (*Richard Clark*, RC others midbass placement question - CARSOUND.COM Forum)[/i]

_"I wouldn't rebuild the kicks to try different angles if the imaging ans staging problems are below 400 Hz. In this range, it's entirely arrival time dependent. Angle won't make any difference. "_ *Mark Eldridge*, http://www.audiogroupforum.com/csforum/showpost.php?p=170588&postcount=18

"_As far as getting your speakers "in phase"... Your best bet is to absolutely minimize the path length difference in the midbass and midrange frequency ranges (~100 to 2,000 Hz), as this is where our ears are very sensitive to arrival time differences. You will never be able to get the left and right channel signals in phase at your ears for all frequencies. The best you can do is minimize the problems, and hope that aural masking covers up any that you can not address._" *Mark Eldridge*, http://www.audiogroupforum.com/csforum/showpost.php?p=1014&postcount=8


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## Patrick Bateman (Sep 11, 2006)

Here's a 'trick' for finding advice from Sound Off Legends. A lot of the old school hung out at audiogroupforum. The problem is that their names come up a lot. If you do a search for 'Richard Clark' you'll get over a thousand responses.

So, instead of searching for them by NAME, search for them by CITY:

For instance, a search for "Eldridge" returns nine THOUSAND hits : https://www.google.com/search?q=site:audiogroupforum.com+Eldridge
But a search for Mark Eldridge's hometown of Bixby Oklahoma returns 779 hits:
https://www.google.com/search?q=site:audiogroupforum.com+bixby

A search for "Clark" returns TWENTY EIGHT THOUSAND hits, but a search for Richard Clark's hometown of Burlington North Carolina returns only the posts where Richard Clark is involved:
https://www.google.com/search?q=site:audiogroupforum.com+burlington

Here's links for some more folks:

Andy Wehmeyer : https://www.google.com/search?q=site:audiogroupforum.com+awehmeye

Jason Winslow aka thehatedguy : https://www.google.com/search?q=site:audiogroupforum.com+charlotte+winslow

Harry Kimura : https://www.google.com/search?q=site:audiogroupforum.com+2001+harry_kimura

majestik6 aka me aka ???? : https://www.google.com/search?q=site:audiogroupforum.com+redmond+majestik6


There's a bunch of people I missed here, so if anyone has any other names, ask away! This would actually be a good thing to 'sticky' because the words of wisdom from the Old School Guys will steer you in the right direction. IE, I'd rather spend fifteen minutes reading what Mark Eldridge has to say about a subject than spend an hour sifting through the opinions of a dozen of unknowns. Same thing with guys like Danley; if Danley said it, it's probably true.


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## Orion525iT (Mar 6, 2011)

Patrick Bateman said:


> TLDR : The idea of using two midbasses in an array is kinda brilliant. It solves the maddening problem of building eight midbasses, then running ten miles of speaker cable, hiding them, etc. Just build one beastly midbass, a smaller midbass, and put the latter in the optimum location. DSP delay may come in handy if The Beast Midbass is closer than the optimum midbass.


Exactly the issue that sent me looking for other options initially. I almost purchased a bunch of small midbasses, but I couldn't get around the idea of all those complicated enclosures, all the drivers, all the amp channels, and all the processing, ect. It was maddening just in concept, which in my experience, would 10x more maddening in practice.

If one wants to know, the idea was actually a confluence of multiple theories and threads. Months of little bits of ideas floating around. 1) I became increasingly convinced of the testimony of people here, that have far more experience than I, as to the benefits of running pro audio type drivers. Namely in regards to dynamics. Many seem to prefer dynamics over perfect stage. So I was constantly thinking about those things. 2) I have read the midbass array thread and Patrick's Opsodis thread multiple times and realized that they seemed to be great theories independently, but they had conflicting implementation. I in fact posted about this in one of the threads. 3) The back and forth between Patrick and Hanatsu regarding absolute phase and relative phase started me thinking about phase more, in general. 4) Finally, subwoofery asking about TA and midbass arrays. 5) Four beers into a six pack of Terrapin Rye Ale, and I thought I had an answer to my quandary. Mind you, I already had the drivers, I just didn't know exactly what I was going to do with them. I read about the GN multiple times, but to be honest (this is not meant as any level of irreverence) I didn't pay that much attention due to the mystique and lore. So the GN did not factor much, but I am sure it was in the mix.

The idea still needs to be tested though . Back to building my midbass enclosures.


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## Patrick Bateman (Sep 11, 2006)

I've got a pair of 8NDL51s here, I think I'll give it a go.

The original plan was either 8NDL51s *or* midbass array, never considered making them part of the array.

The B&Cs are absurdly loud; I once tested them outside of my house and I think the neighbors nearly called the cops they're so loud

So my concern was that they's so potent, there's no need to include the Daytons 'in the mix'. But I hadn't considered the Haas effect; and that the first arrival will dominate.

Great stuff! If I'd put the B&Cs in the optimum location the car would be much less comfortable. (in the kicks.)

I think I'll try putting them on the rear shelf. I've had them there in the past; in my 2001 Accord I used them on the rear deck. But I never had anything up front to 'steer' things that direction, like Richard Clark did.


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## Orion525iT (Mar 6, 2011)

Patrick Bateman said:


> One thing that makes it a bit tricky/expensive is that The Beast Midbass needs to be further away than The Optimal Midbass. In my car, the rear quarter panels are actually closer to my ears than the optimal midbass locations are.
> 
> I *think* you may be able to use DSP to solve this. (Contrary to what I said yesterday.)


This was my thought. For some reason I spent a good chunk of time thinking about your response, even if not exactly correct in all cases, and it kinda made things fall into place.


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## thehatedguy (May 4, 2007)

When I talked to Harry about the midbasses under the dash of the GN he said there were none. Eric went under there and poked all around and found nothing. He/they said RC was full of it. This coming directly from Harry after we judged a show together that day. So I don't know who to tell you who to believe...they guy that built the car or the guy who bought the car.

Mikey7182 is running a pair of 2204s in his S-10 in the rear and was at the G2G in San Diego. I think he plays them up to 2-250 or so.

The only thing about adding the B&Cs would be they would really or really have the potential to dominate the other midbasses in terms of output.


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## thehatedguy (May 4, 2007)

And Clark did out right say he had Bose 4s under the dash that were gated. He said those only played to a certain volume and after that the 2204s came in. They never to my knowledge were ever said to play at the same time...if they were ever there to begin with.


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## oca123 (Aug 16, 2010)

I stopped at "Pinpoint" - If this is a matter of counting ingress, daily calorie intake... just tell me what to eat and ye shall get what you want.


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## Patrick Bateman (Sep 11, 2006)

Patrick Bateman said:


> This is getting a little ridiculous, but I've opted to trash *another* set of waveguides.
> 
> 
> 
> ...




Here's a video I made of the SAW lens doing it's thing:

Sausalito Audio Works vs Synergy Horn video 1 - YouTube

I really like these things. Every one I've built has sounded good to me, which is a lot more than I can say for horns.


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## quietfly (Mar 23, 2011)

nice video...


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## Patrick Bateman (Sep 11, 2006)

quietfly said:


> nice video...


Thanks!

Sasualito Audio Works vs Synergy Horn Video 2 - YouTube

Here's another one

This one does a decent job of showing off the advantages of dipole radiation; the pitch of the bass harmonics is nicely defined.

One interesting thing about the videos is that it's really easy to hear a weird echo. It almost sounds like I'm running an echo on the inputs, like you do for voices at a karaoke bar.

*The interesting thing is that this is completely inaudible in person.*

This is another one of those Haas Effect things. When you sit in a loud restaurant and you're talking to someone, you only perceive what they're saying, for the most part. But if you were to make a phone call from that restaurant, it would sound like ****, because we need a brain and two ears to do The Haas Effect. When you run the sound through a phone, it collapses it to mono, and all the location cues are gone.


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## Patrick Bateman (Sep 11, 2006)

One other weird thing about the dipole - it seems to sound more "dynamic."
I have no idea why this would be, but it is very noticeable.

I am also running it at an INSANELY loud power level. I know why this is; dipoles are not efficient, so you better bring one monster amp if you want to run a dipole. I ratcheted up the gains on my amp by about fifteen decibels.


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## Orion525iT (Mar 6, 2011)

Patrick Bateman said:


> There's another speaker with wide horizontal and narrow vertical directivity...


So is there any formula for these lenses? How do you determine the contours? Is any aspect of their dimensions linked to frequency response? 

Is the beolab using a dome?


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## Patrick Bateman (Sep 11, 2006)

Orion525iT said:


> So is there any formula for these lenses? How do you determine the contours? Is any aspect of their dimensions linked to frequency response?
> 
> Is the beolab using a dome?




























The Sausalito Audio Works lens aka Beolab lens is a fibonacci spiral. Basically a spiral that adheres to the golden ratio.


























It takes all of fifteen minutes to build one. You take some pieces of 1/4" MDF or plywood. You drill a hole in each one. The big hole is 7/8". The medium hole is 3/4". The small hole is 1/2". Then you glue your three pieces together. Then you saw it in half and place it in front of your dome tweeter or your compression driver.

That's all there is to it. It takes the wave and it reflects it 90 degrees.

Give it a try, I've never made one that sounded bad.

Use some wood putty to smooth things out. It's really really easy.


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## Patrick Bateman (Sep 11, 2006)

Oh - a few more comments:

1) The dimensions of the device I posted in my last comment are for a 1" radiator. Like a 1" compression driver or a 1" tweeter. Or a 3/4" tweeter.
2) Compression drivers work best, but domes don't work too bad.
3) If you want to do this with a larger driver, just multiply everything by the diameter. For instance, a 3" diaphragm would require you to multiply all those dimensions by three. The wood would be 3/4" thick instead of 1/4" thick, the first hole would be 21/8" thick, etc.


It only works over about an octave; you're not going to put a 5" driver in a lens and get output to 20khz. But you can put a 1" driver in a lens and get output to 20khz, no problem at all.


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## T3mpest (Dec 25, 2005)

Patrick Bateman said:


> Oh - a few more comments:
> 
> 1) The dimensions of the device I posted in my last comment are for a 1" radiator. Like a 1" compression driver or a 1" tweeter. Or a 3/4" tweeter.
> 2) Compression drivers work best, but domes don't work too bad.
> ...


Does that avoid the reflection off the glass by doing that? Wouldn't be hard to build something like that for a center channel using a compression driver.. What does it do to the horizontal coverage pattern? Is it the same as no waveguide at all?


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## Patrick Bateman (Sep 11, 2006)

T3mpest said:


> Does that avoid the reflection off the glass by doing that? Wouldn't be hard to build something like that for a center channel using a compression driver.. What does it do to the horizontal coverage pattern? Is it the same as no waveguide at all?












A one inch tweeter only gets direction in the very top octave.
From 10khz to 20khz.

So you can have a tweeter aimed straight up, and it will play to 10khz, no problem.









The lens in the beolab, it takes that very last octave, and it reflects it *forward*.

Of course, the tweeter is playing over three octaves, so how do we deal with the other two?










That's where the baffle comes into play. The baffle *behind* the tweeter restricts the radiation into the forward lobe, and the "hat" on top restricts the vertical radiation.

*Put all of this together, and you end up with a radiation pattern that's narrow vertically (to reduce reflections off of the floor and the ceiling) but horizontally WIDE (to improve the image and frequency response for listeners off-axis.)*

Basically there are three parts to the Beolab lens. The first part is that lens in the center, the parabola shaped thing. That works over one octave, and it reflects the high frequencies 90 degrees. The second part is the baffle behind the tweeter. It looks decorative, but it's not; without that baffle the sound from the tweeter would radiate backwards. *And we don't want that; it will create a reflection off of the windshield.* The last part of the puzzle is the "hat" on top; that's what restricts the vertical radiation. Actually the flat surface that the tweeter sits on plays a part too; it does the same thing as the hat, but for the sound that would normally get radiated towards the floor.









Here's a pic of mine in the car

I mentioned this before, but these things work really nicely. I build a lot of weird stuff, and 75% of it doesn't work, but this is one of those things that *does* work. Here's an example of this:

I build a lot of horns, and a lot of the time I get everything working, and then find I just don't like listening to them. 








This constant directivity horn from Pyle, cloned from a JBL design from the 80s, is a good example of what I mean. It measures nice, but *after an hour of listening I wanted nothing to do with it.*
But the beolab lenses? Every single one I've built has been a joy to listen to.


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## T3mpest (Dec 25, 2005)

In the pic you've referenced, with the celenium compression driver on the dash, I only see the parabola shaped part that reflects the wave. Is that other peice you have slanted downward in some of the other pics the "top"? Only other question is how big do the top and bottom baffle pieces in between need to be.. The compression driver needs about a 1inch hole does the width and depth of your top and bottom effect your coverage in terms of frequencies the waveguide will work for? Last major question, it's hard to tell from the pics a bit, how do you line up your holes? The fancy version is a very smooth parabola with no edges, is it also losing depth like you showed in your graphic cross section picture? It seems like making it out of wood would create all kinds of weird reflections since the parbola isnt' smooth across it's Z axis, as opposed to the other one. I guess some body filler and fiberglass you could maybe fix that? IDK how critical that is though. 

So essentially the parabola is there to control directivity where the tweeter would normally be beaming and force it's output back to the direction we want.. Then the other 2 pieces control it's response down low, I think it got this? Want to make sure I get this properly, as this looks VERY buildable, moreso than somethings you post and you say it works very well. I can see the advantages for sure, especially for my install.


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## Patrick Bateman (Sep 11, 2006)

T3mpest said:


> In the pic you've referenced, with the celenium compression driver on the dash, I only see the parabola shaped part that reflects the wave. Is that other peice you have slanted downward in some of the other pics the "top"? Only other question is how big do the top and bottom baffle pieces in between need to be.. The compression driver needs about a 1inch hole does the width and depth of your top and bottom effect your coverage in terms of frequencies the waveguide will work for? Last major question, it's hard to tell from the pics a bit, how do you line up your holes? The fancy version is a very smooth parabola with no edges, is it also losing depth like you showed in your graphic cross section picture? It seems like making it out of wood would create all kinds of weird reflections since the parbola isnt' smooth across it's Z axis, as opposed to the other one. I guess some body filler and fiberglass you could maybe fix that? IDK how critical that is though.
> 
> So essentially the parabola is there to control directivity where the tweeter would normally be beaming and force it's output back to the direction we want.. Then the other 2 pieces control it's response down low, I think it got this? Want to make sure I get this properly, as this looks VERY buildable, moreso than somethings you post and you say it works very well. I can see the advantages for sure, especially for my install.












Here's an illustration, showing the three parts in the B&O piece, and in my piece. Dimensions are the same. The B&O baffle is a little bit wider, maybe 1". The dimensions of the lens are identical. My device doesn't have a "hat", but it will once I'm finished.

Here's a closeup of the holes:









It's all smoothed out now; smooth sounds and measures better. Just a bit of wood putty to smooth it all out.


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## Regus (Feb 1, 2011)

Patrick, did you ever try the lenses in a OPSODIS configuration (centre of the dash)? This seems like a possible alternative to the other waveguides you employed when you were experimenting with this. My only concern would be that by using the lenses with their wide horizontal dispersion pattern, you could still get side window reflections which would be problematic.

In addition, I was wondering about adding some suitable midranges with 31° of separation ( as per the diagram in the OPSODIS paper) either side of the tweeters, mounted horizontally, with larger SAW lenses to redirect their output forwards instead of upwards. The main problem here would be the limit on height, although a lens for a 3" driver is only 2.25" high, which is less than the diameter of the driver mounted vertically would be.

This is something that could be made as a unit that is placed on top of the dash initially and then later redone with the speakers sunk into the dash if it proved successful, or discarded if it did not.


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## Patrick Bateman (Sep 11, 2006)

Regus said:


> Patrick, did you ever try the lenses in a OPSODIS configuration (centre of the dash)? This seems like a possible alternative to the other waveguides you employed when you were experimenting with this. My only concern would be that by using the lenses with their wide horizontal dispersion pattern, you could still get side window reflections which would be problematic.
> 
> In addition, I was wondering about adding some suitable midranges with 31° of separation ( as per the diagram in the OPSODIS paper) either side of the tweeters, mounted horizontally, with larger SAW lenses to redirect their output forwards instead of upwards. The main problem here would be the limit on height, although a lens for a 3" driver is only 2.25" high, which is less than the diameter of the driver mounted vertically would be.
> 
> This is something that could be made as a unit that is placed on top of the dash initially and then later redone with the speakers sunk into the dash if it proved successful, or discarded if it did not.


I am still doing ambio.
The midranges and tweeters are going to be in front of me, not in the center of the dash.

I was able to achieve a solid center image with the speakers in the center of the dash, Opsodis style, but I found that the width was much better with the speakers directly in front of me.

I think this is due to timing; the ambio processing works in the realm of MICROseconds, and due to that very tight resolution, a variance of even an inch has a significant impact on the effect.

Basically, *you want the speakers *exactly* equidistant.* You can't get away with a foot of offset, or even a few inches of offset, like you can with a stereo triangle.

so...

One speaker will go in the left corner, the other speaker is going in the center of the dash, and the soundstage is centered right in front of the driver.


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## Orion525iT (Mar 6, 2011)

T3mpest said:


> The fancy version is a very smooth parabola with no edges, is it also losing depth like you showed in your graphic cross section picture? It seems like making it out of wood would create all kinds of weird reflections since the parbola isnt' smooth across it's Z axis, as opposed to the other one. I guess some body filler and fiberglass you could maybe fix that? IDK how critical that is though.


Really cool and informative blog I ran across last night.

B&O Tech: Curves are Better than Corners « earfluff and eyecandy

I really want to try this, but I need something good down to 1000hz and hopefully up to 20,000 khz. Is 5+ octaves too much to ask?

Main reason is that I am stuck with needing 10 channels of processing if I do a mid + tweeter combo in my current design.

I know some of the larger compression drivers reach down to even 800hz, but is this a suitable application for the lens?


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## Patrick Bateman (Sep 11, 2006)

Orion525iT said:


> Really cool and informative blog I ran across last night.
> 
> B&O Tech: Curves are Better than Corners « earfluff and eyecandy
> 
> ...


Mine is good for 500hz, and it's a dipole

If you went with a sealed design you could get down to 100hz easy

1000hz is easy


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## Patrick Bateman (Sep 11, 2006)

Orion525iT said:


> Really cool and informative blog I ran across last night.
> 
> B&O Tech: Curves are Better than Corners « earfluff and eyecandy
> 
> ...


Great article btw!


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## Orion525iT (Mar 6, 2011)

Patrick Bateman said:


> Mine is good for 500hz, and it's a dipole
> 
> If you went with a sealed design you could get down to 100hz easy
> 
> 1000hz is easy


But your not just using a compression driver, correct? 

I just checked out some compression drivers at PE. It looks like even some of the 1" drivers can get down to 1300hz or so. This may be better than the 1.4 or larger drivers because the magnet structure is smaller, and they generally cost less. I can use my midbass up to 1500hz is needed, since they are 6.5"

Would something like this work? My midbass are only 94db sensitive at 8 ohms. Would a 16 ohm compression driver help with integration over an 8 ohm?

FaitalPRO HF10RK 1" Neodymium Compression Horn Driver 16 Ohm 2/3-Bolt

Pricey, but being able to eliminate two sets of drivers, two channels of amp and two channels of processing would would put me ahead of the game despite the cost of the compression driver.


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## Patrick Bateman (Sep 11, 2006)

Orion525iT said:


> But your not just using a compression driver, correct?
> 
> I just checked out some compression drivers at PE. It looks like even some of the 1" drivers can get down to 1300hz or so. This may be better than the 1.4 or larger drivers because the magnet structure is smaller, and they generally cost less. I can use my midbass up to 1500hz is needed, since they are 6.5"
> 
> ...


But it's so easy to cram a midrange onto it, why just put a tweeter up there?


























IE, the footprint of my whole unit is small enough to fit in my hand. Why use a big compression driver that's good for 900hz, when you can easily get down to 500 or even 100hz if you go with a two-way?


If that size is too big, I wouldn't go looking for compression drivers.
If that size is too big, I would use a neodymium dome and a midrange.









If you went that route, it would end up looking a lot like this.
Keep in mind, this speaker has two passive radiators, a woofer, a tweeter and an amplifier.









*So if you could skip the PRs and put the amp somewhere else, you could definitely get this thing down to the size of a baseball.* A big chunk of the insides is electronics.


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## Vestax (Aug 16, 2005)

I only clicked on this thread for the Depeche Mode reference.


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## JoshHefnerX (Jun 13, 2008)

In the videos the sounds was very intelligible even w/ that echo effect. On the bottom of those enclosures are those 4"s and are the holes there to reduce distortion? I may have missed it earlier if you went over that.

Josh


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## Orion525iT (Mar 6, 2011)

Patrick Bateman said:


> IE, the footprint of my whole unit is small enough to fit in my hand. Why use a big compression driver that's good for 900hz, when you can easily get down to 500 or even 100hz if you go with a two-way?
> 
> 
> If that size is too big, I wouldn't go looking for compression drivers.
> If that size is too big, I would use a neodymium dome and a midrange.


Again, I would really like to eliminate 2 channels worth of processing and amp. I can't run 10 channels of dsp with my 2x8 minidsp. ( I can but its not at all easy) So unless those are running passive...

Are they passive? In the video it looks like there is a cap on the tweeter. Are the mids allowed to roll off on their own? What tweeter are you using?


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## thehatedguy (May 4, 2007)

Celestion CDX1-1425


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## Orion525iT (Mar 6, 2011)

JoshHefnerX said:


> In the videos the sounds was very intelligible even w/ that echo effect. On the bottom of those enclosures are those 4"s and are the holes there to reduce distortion? I may have missed it earlier if you went over that.
> 
> Josh


Dayton Audio ND91-4 3-1/2" Aluminum Cone Full-Range Driver 4 Ohm


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## Patrick Bateman (Sep 11, 2006)

JoshHefnerX said:


> In the videos the sounds was very intelligible even w/ that echo effect. On the bottom of those enclosures are those 4"s and are the holes there to reduce distortion? I may have missed it earlier if you went over that.
> 
> Josh


The coupling chamber does a few things:

1) the biggest reason it's there is that it reduces the center-to-center spacing. This improves the frequency response, the polar response, etc etc
The reason that this works is that the sound doesn't radiate from the cone; it radiates from the port. So we've virtually moved the source of the sound about an inch closer to the tweeter.

2) Although the SOURCE of the sound is closer to the tweeter, the DISTANCE to the tweeter is still the same. IE, the port might be two inches from the tweeter, but the DISTANCE to the cone of the woofer is five inches. *That distance adds a delay.*
So, this is a way to put the woofers *ahead* of the tweeter, but still have the two sources radiate as if they're on top of each other.

3) the coupling chamber filters the midrange, which reduces distortion 









Emerald Physics uses the same configuration in their speakers, albeit with much larger drivers than I am using


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## Patrick Bateman (Sep 11, 2006)

If someone wanted to try a SAW LENS, and doesn't have the space for a compression driver, check out the SB Acoustics neodymium ring radiator. Here's why:

1) It's less than 3" in diameter and less than 1" deep. That's small enough that you can plop it right in front of the cone of a 5" woofer.
2) A coax would work too, but most of the coaxes that cost less than $200 have ****ty mylar tweeters
3) The ideal driver for a waveguide or a SAW lens has a flat diaphragm. The SB Acoustics tweeter isn't flat, but it's closer to flat than a dome is
4) All of the SB Acoustics drivers sound pretty good.
​


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## MetricMuscle (Sep 16, 2013)

Vestax said:


> I only clicked on this thread for the Depeche Mode reference.


Patrick has gone about explaining this concept pretty well.
The graphs on the wall tell the story of it all.


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## Patrick Bateman (Sep 11, 2006)

Just for the **** of it, bought a couple of these Vifa neodymium tweeters off of eBay. $20 each, free shipping, cheap enough not to worry if they don't work as planned


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## JoshHefnerX (Jun 13, 2008)

Interesting, hadn't really thought about moving the sound source and mechanical delay.

Josh


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## Orion525iT (Mar 6, 2011)

Patrick Bateman said:


> If someone wanted to try a SAW LENS, and doesn't have the space for a compression driver, check out the SB Acoustics neodymium ring radiator. Here's why:
> 
> 1) It's less than 3" in diameter and less than 1" deep. That's small enough that you can plop it right in front of the cone of a 5" woofer.
> 2) A coax would work too, but most of the coaxes that cost less than $200 have ****ty mylar tweeters
> ...


Just looking at those literally 5 minutes ago. I think they are a go for me. I have been looking for a good excuse to try some SB stuff.


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## thehatedguy (May 4, 2007)

Might want to check out if SB ever got the glue problems with those tweeters fixed...a lot of the dimples were becoming domes with the glue let go.


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## T3mpest (Dec 25, 2005)

Orion525iT said:


> Really cool and informative blog I ran across last night.
> 
> B&O Tech: Curves are Better than Corners « earfluff and eyecandy
> 
> ...


Nice, at first I was like, "yup I understands the basics of diffraction" however the second half showing this lense and diffractions effect of various shapes was great and gave me some ideas on the good, better, best way to do things.. Thanks. That's also a good question you had.. Patrick said you can scale this up for bigger drivers which would let it go a bit lower, maybe a 2inch compression driver could get that low.. 1inchers can make 1000hz at SPL's used in a car, but idk how low a waveguide like this will load to get it down that low. Might be best served with a coax if you want to keep it all looking "pretty" and still fitting in a design like this.


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## Patrick Bateman (Sep 11, 2006)

T3mpest said:


> Nice, at first I was like, "yup I understands the basics of diffraction" however the second half showing this lense and diffractions effect of various shapes was great and gave me some ideas on the good, better, best way to do things.. Thanks. That's also a good question you had.. Patrick said you can scale this up for bigger drivers which would let it go a bit lower, maybe a 2inch compression driver could get that low.. 1inchers can make 1000hz at SPL's used in a car, but idk how low a waveguide like this will load to get it down that low. Might be best served with a coax if you want to keep it all looking "pretty" and still fitting in a design like this.
















































See a trend here? The more B&O refines the design, the more it starts to look like a sphere.










B&W learned the same thing

for lulz:
"the mind is perpetual motion, it's symbol is the sphere" : https://www.youtube.com/watch?v=4pwdTGX5K6Y

^^ MBM was one of the bands that got me interested in car audio, about 20 years ago


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## T3mpest (Dec 25, 2005)

Patrick Bateman said:


> See a trend here? The more B&O refines the design, the more it starts to look like a sphere.
> 
> 
> 
> ...


That settles it, I'm going to make one of these for fun.. Don't have a huge amount of room. Probably going to use a spare compression driver I have laying around B&C DE10. I think I'll cut out a few circles using my router and circle jig and use that as by base.. That plus some body filler should get me a pretty similar look to the one I linked without TOO much work, I think. Probably build one for proof of concept and sound and perhaps a second one if I want to do it permanent. It needs to look good if it's going to be front and center on my dash lol. Do you think a 1inch compression driver by itself can get me down to 1k-1.5k? I can put some midbass/lower midrange drivers down in my center console area, deep in the dash, I have lots of room down there, just need keep the crossover low enough that it won't pull my sound to the floor. If I do one on each side of the center console, the acoustic center would be the center of the car, IDK if that works out well or not though.. 

The issue is, I only have enough room for about a 3inch driver on top the dash.. So a 3inch cone speaker OR a compression driver, not really both without doing quite a bit of modification. Since this would be a center channel trying it's best to keep up with a very effecient front stage (also pro audio/horns) that seems like the best compromise. It needs to play down into the midbass area, be loud and effecient lol. I've always wanted a high effeciency center channel and this seems to be a way to do it, allows me to get a real compression driver on my dash without too much modification..

A few cars come stock with these, well with the upgraded sound package, bet the replacement parts cost an arm and a leg though


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## Patrick Bateman (Sep 11, 2006)

T3mpest said:


> That settles it, I'm going to make one of these for fun.. Don't have a huge amount of room. Probably going to use a spare compression driver I have laying around B&C DE10. I think I'll cut out a few circles using my router and circle jig and use that as by base.. That plus some body filler should get me a pretty similar look to the one I linked without TOO much work, I think. Probably build one for proof of concept and sound and perhaps a second one if I want to do it permanent. It needs to look good if it's going to be front and center on my dash lol. Do you think a 1inch compression driver by itself can get me down to 1k-1.5k? I can put some midbass/lower midrange drivers down in my center console area, deep in the dash, I have lots of room down there, just need keep the crossover low enough that it won't pull my sound to the floor. If I do one on each side of the center console, the acoustic center would be the center of the car, IDK if that works out well or not though..
> 
> The issue is, I only have enough room for about a 3inch driver on top the dash.. So a 3inch cone speaker OR a compression driver, not really both without doing quite a bit of modification. Since this would be a center channel trying it's best to keep up with a very effecient front stage (also pro audio/horns) that seems like the best compromise. It needs to play down into the midbass area, be loud and effecient lol. I've always wanted a high effeciency center channel and this seems to be a way to do it, allows me to get a real compression driver on my dash without too much modification..
> 
> A few cars come stock with these, well with the upgraded sound package, bet the replacement parts cost an arm and a leg though


If you want, I can upload a diagram that includes the baffle in the back.

Do you have a Dremel? I found that it was essential to get everything to fit.

Basically I had to hack up the back side of the lens, to get it to fit on my dash. (My windshield has a steep slope.)


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## T3mpest (Dec 25, 2005)

Patrick Bateman said:


> If you want, I can upload a diagram that includes the baffle in the back.
> 
> Do you have a Dremel? I found that it was essential to get everything to fit.
> 
> Basically I had to hack up the back side of the lens, to get it to fit on my dash. (My windshield has a steep slope.)


I don't, but a buddy does, I'm sure I can borrow if I can't get it right with a router and sandpaper, dremel probably makes quick work of some of that detail stuff. If you have a guide for doing the backside, feel free to post it.


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## Patrick Bateman (Sep 11, 2006)

T3mpest said:


> I don't, but a buddy does, I'm sure I can borrow if I can't get it right with a router and sandpaper, dremel probably makes quick work of some of that detail stuff. If you have a guide for doing the backside, feel free to post it.


Sounds good.

I'll have a design that includes the baffle posted tonight.


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## Patrick Bateman (Sep 11, 2006)

I'm going to need another day to make that design, I have an early meeting at work tomorrow


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## T3mpest (Dec 25, 2005)

Patrick Bateman said:


> I'm going to need another day to make that design, I have an early meeting at work tomorrow


No rush.. Turns out the DE10's just dont' quite clear my dash opening, freaking magnet is too big.. I know I'll end up cutting out a bigger mounting hole eventually anyway, but didn't want to start that way lol. Looking into nicer and small compression drivers although I can still build one and just sit up on the dash for proof of concept lol. BMS 4552 is .25inch less wide, I'm going to mock up some circles and see what works.


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## RocketBoots (Apr 16, 2011)

BMW 750Li Bang & Olufsen Surround Sound System - | EuroCar News

I always thought this was all style, no substance. Maybe they were on to something...


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## ecbmxer (Dec 1, 2010)

You could probably use one of those 3D printing services to make some of these relatively cheaply. I recall some people having tweeter mounts, grill rings, etc printed. 

This is a cool concept.


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## T3mpest (Dec 25, 2005)

ecbmxer said:


> You could probably use one of those 3D printing services to make some of these relatively cheaply. I recall some people having tweeter mounts, grill rings, etc printed.
> 
> This is a cool concept.


Not a bad idea at all, just have to find a blueprint for one. I looked around online for a 3d parabola dimensional without too much luck.. Just in case there was another way to make one with completely smooth transitions, I found one or two promising links, that was it.


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## Patrick Bateman (Sep 11, 2006)

ecbmxer said:


> You could probably use one of those 3D printing services to make some of these relatively cheaply. I recall some people having tweeter mounts, grill rings, etc printed.
> 
> This is a cool concept.


3D printing would definitely be ideal, but you can get excellent results doing it by hand.

Here's why:









A horn shapes a wavefront over a wide bandwidth. For instance, a compression driver mated to a horn that's 13.5cm wide will control the wavefront for four and a half octaves. (1khz - 20khz.)









The bandwidth is the reason that these old Mantaray horns sound like ****. You have to eliminate diffraction along the entire length of the horn, from throat to mouth. Fail to do that, and the horn is unlistenable. Ever been at a night club and the PA makes your ears bleed? Yeah, that's the sound of diffraction.


























Here in 2014, we're only controlling the wavefront for the first fraction of a millisecond. We're talking about one quarter of a millisecond.

You can see the effect if you look at the frequency response of a narrow angle horn, like the Mantaray, and a wide angle waveguide, like the JBL EOS waveguides. The Mantaray has a series of dips and peaks and has in it's response. This is because the wave is constrained to a small space.

When you open it up, everything gets easier. (And sounds better - there are AES papers on this - wide angle waveguides sound better.)


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## T3mpest (Dec 25, 2005)

Another question patrick.. I know you said it's "best" to use a compression driver to get a flat wavefront as that simplifies the design. What about the "coaxial" compression drivers from BMS.. If I enlarge my center channel spot by removing the stock baffle, I have several inches of depth to work with and could probably get one of the 1.5 or 2inch exit compression drivers on one of these. I know from previous posts you can't optimize a lens like this for much more than an octave.. Since those CD's roll off earlier than others and franky I can't hear much past 14k anyways, I'd rather worry about the octave from 10k-5k than from 10k-20k. How big would a lense like that have to be? Would you expect something like that to work well? I wouldn't start with a driver like that by any means as they are PRICEY (even if I only needed one lol), just asking.


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## Patrick Bateman (Sep 11, 2006)

I'd use one of these before I'd use the BMS

I considered using a dome tweeter, like Gary Summers did, but the small size of the Neo8 is compelling.

The big problem with the Neo8 is that you have to figure out someway to get the two wavefronts in phase (if you care about phase, I do.)

In this scenario, the B&O lens is mounted towards the glass, and the NEO8 is mounted face up, immediately in front of the B&O.

My main gripe with the BMS, besides it's insane cost, is that the reviews are unremarkable. If you really want a wide bandwidth compression driver and you don't mind spending some money, get the compression driver from the JBL M2. They're easily found on eBay for about $400.


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## Patrick Bateman (Sep 11, 2006)

Oh, one other thing:

The requirement for a flat wavefront is common to all waveguides. (And the B&O lens is a waveguide, albeit a strange looking one.)

You can use a dome on a waveguide, JBL Mackie Behringer, they all do it. A compression driver just works better.

A circular ribbon would probably work very well too. I've put ribbons on waveguides and they work every bit as good as a compression driver, *as long as you don't mind replacing drivers all the time. (They're fragile.)*


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## Patrick Bateman (Sep 11, 2006)

I wonder if these would work? Again, flat isn't an absolute requirement, but it's ideal.
These are $9 at parts express.









I haven't heard the $9 units from Parts Express, but I've heard the Naims, twice, and everytime I've heard a BMR it sounded excellent. I don't know if it's the same technology as the NXTs (which sound kinda meh to me).


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## T3mpest (Dec 25, 2005)

Patrick Bateman said:


> ]
> I'd use one of these before I'd use the BMS
> 
> I considered using a dome tweeter, like Gary Summers did, but the small size of the Neo8 is compelling.
> ...


Only way I could fit that neo8 is sidways.. Vertically 7inches is too long to fit on my dash the way it would need to to be practical. That's why I was looking into compression drivers or coax.. I can't fit a standard 2 way design up there without it looking pretty rough. A little 3inch speaker could be done, but I listen loud and want as much dynamics as I can get.. The JBL driver seems ok, but I couldn't find any for sale on ebay right now. Looks like the compression driver itself is the d2. JBL D2430k?

edit: one on ebay right now if that's the right one lol. 390, got 4 days left on the auction.


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## Patrick Bateman (Sep 11, 2006)

Yes, the NEO8 *must* be mounted sideways.

If you mounted it lengthwise, there would be a huge phase difference between the edge that's closest to you, and the edge that's furthest from you.









Let's do the math:

1) we want the wavefront to be in-phase
2) the diaphragm of a NEO8 is 15cm long by 5cm wide
3) if you mount it the long way, one side of the radiator will be 15cm further from you than the other side of the radiator. 2266hz is 15cm long. Based on that, the maximum frequency for a NEO8 mounted the long way is somewhere between 566hz (1/4wl) and 2266hz (1wl). If set an upper limit of 1/3rd WL, then we can play the NEO8 to 756hz.
4) if you mount it the short way, one side of the radiator will be 5cm further from you than the other side of the radiator. 6800hz is 5cm long. Based on that, the maximum frequency for a NEO8 mounted the long way is somewhere between 1700hz (1/4wl) and 6800hz (1wl). If set an upper limit of 1/3rd WL, then we can play the NEO8 to 2266hz.



Not saying the NEO8 is the *only* solution. But if you're tight on space, it's a good one. I got pretty good results with a Fostex FF85Wk, but I got better results with a real two-way.


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## Patrick Bateman (Sep 11, 2006)

Another cool thing you can do with the NEO8, or any driver really, is mask off part of the diaphragm.

For instance, if you must mount it lengthwise, just mask off 2/3rds of the diaphragm with felt or foam so that only a fraction of the diaphragm is radiating high frequencies.

This is literally how the PDRs work, but it's just taking it to the next level to cover up the diaphragm entirely.

The whole reason that the NEO8 rolls off at 8khz has nothing to do with the diaphragm and everything to do with geometry. The radiator is so big, the sound from one side of the diaphragm is out-of-phase with the sound from the center. Soaking up the sound with felt or foam fixes that problem.


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## thebetaproject (Oct 17, 2009)

Patrick Bateman said:


> The coupling chamber does a few things:


Are there any of calculations or 'guidelines' for the chamber and it's exit hole?


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## Patrick Bateman (Sep 11, 2006)

thebetaproject said:


> Are there any of calculations or 'guidelines' for the chamber and it's exit hole?


I used to simulate it in Hornresp, but I stopped doing that because it's fairly easy to 'eyeball' it:

1) The holes should be as small as possible, but the total area should be no smaller than 1/10th of the cone area. For instance, if you have a cone that measures 4" in diameter*, then you should use a single hole that's at least 1.25" in diameter, or two holes that are 0.9" in diameter.
2) The depth of the holes should be as shallow as possible
3) the chamber should be as small as possible









Taken to the extreme, you end up with something like this. See how the blue part blocks off 90% of the cone, but you have these long narrow slits that lead to the throat? That's a real phase plug.

We don't have to make a "real" phase plug because we don't need the driver to play to 20khz.

1) The bigger the chamber is, the more the highs will be rolled off
2) The longer the holes are, the more the highs will be rolled off

So short holes with small chamber is best.

This article describes it better than I can : http://www.centauriaudio.com.au/diy/plugs.html


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## thehatedguy (May 4, 2007)

Those chambers are bandpass enclosures and ports for the bandpass.


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## thebetaproject (Oct 17, 2009)

Patrick Bateman said:


> I used to simulate it in Hornresp, but I stopped doing that because it's fairly easy to 'eyeball' it:
> 
> 1) The holes should be as small as possible, but the total area should be no smaller than 1/10th of the cone area. For instance, if you have a cone that measures 4" in diameter*, then you should use a single hole that's at least 1.25" in diameter, or two holes that are 0.9" in diameter.
> 2) The depth of the holes should be as shallow as possible
> ...


Thanks , I'll give a go.


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## Regus (Feb 1, 2011)

I just looked at the availability of the BMR drivers in the UK - not sure of the model number for the pictured driver (I tried the Tectonics Elements site but it's not listed under BMRs), but looking at the round drivers, as opposed to the square ones, RS have the HIBM65C20F-8 on back-order until September. :-( 

Also, here's an article which mentions the NXT BMR and its applicability to car audio:

Inside IT: Small speakers hit the sweet spot | Technology | The Guardian


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## Regus (Feb 1, 2011)

Oh, and here's the link to the Tectonic Elements site for those who might be interested:

BMRs | Tectonic Elements


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## T3mpest (Dec 25, 2005)

Patrick Bateman said:


> Yes, the NEO8 *must* be mounted sideways.
> 
> If you mounted it lengthwise, there would be a huge phase difference between the edge that's closest to you, and the edge that's furthest from you.
> 
> ...


When mounted vertically the Neo 8 has a wide dispersion pattern in the width dimension of the vehicle, when mounted horizonatally it'd have a wide dispersion pattern in the depth dimension of the vehicle.. Wouldnt' I want a wide horizontal dispersion for a center channel?


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## Patrick Bateman (Sep 11, 2006)

T3mpest said:


> When mounted vertically the Neo 8 has a wide dispersion pattern in the width dimension of the vehicle, when mounted horizonatally it'd have a wide dispersion pattern in the depth dimension of the vehicle.. Wouldnt' I want a wide horizontal dispersion for a center channel?


First, we have to figure out our crossover points.
When you mount the NEO8 the usual way (with the long axis mounted vertically), *your crossover point maxes out around 800hz.*

When you flip it a hundred and eighty degrees, *your maximum crossover point is about 2300hz.*

OK, so we've established a couple of crossover points. These crossover points are dictated by geometry. The math is in the post I made a few days ago.

Now, let's figure out our directivity.
When you mount the NEO8 vertically, it will start to beam at 4500hz. This is because it's about 3" wide. (The ribbon, not the entire device. Directivity is based on the radiator size.) The math is here:
speed of sound / size of radiator=
13500" per second / 3"=
*4500hz*

If you flip the NEO8 on it's side, it will start to beam an octave lower, at 2250hz. *This is because it's about 6" wide.*



Bottom line : if you cross the NEO8 over at 2250hz or less, *the beamwidth is exactly the same.* It's beamwidth will be about 180degrees.




TLDR : If you keep the crossover to 2250hz or less, it doesn't matter if you orient a NEO8 vertically or horizontally. It's beamwidth will be about 180 degrees in both cases. You'll only run into issues if you cross it over higher. But IMHO constant beamwidth is a good idea, and I wouldn't want a speaker to have a varying beamwidth, so I can't think of a good reason to run a NEO8 very high.


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## thehatedguy (May 4, 2007)

Actually 180 degrees wouldn't change anything other than terminal location...if they were on bottom now they would be on top.

Now, 90 degrees would do it...





Patrick Bateman said:


> First, we have to figure out our crossover points.
> When you mount the NEO8 the usual way (with the long axis mounted vertically), *your crossover point maxes out around 800hz.*
> 
> When you flip it a hundred and eighty degrees, *your maximum crossover point is about 2300hz.*
> ...


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## Patrick Bateman (Sep 11, 2006)

Correct!


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## Patrick Bateman (Sep 11, 2006)

Every time I build a SAW lens, I'm thrilled with how good they sound.
I work at home - I write software all day.
I baaaaaarely ever use my car.

This ambio setup for my car gave me an idea for an ambio setup that would be great for people that sit in front of the computer all day. Here's the build thread:

Soundbar Bateman Style - diyAudio

It's a neat project I think. Many of us sit in front of a computer monitor all day. It's really hard to get good sound in this scenario.









If you have a set of speakers near the computer monitor, reflections off of the monitor destroy your imaging. And computer speakers tend to be small and "polite." I like a speaker with big brass balls.









Here's how my computer ambiopole works:

1) We are listening to the speakers 180 degrees off axis. So the primary lobe is aimed at the side walls. This means that the sound that 'wraps around' the box will be attenuated. Bottom line : it reduces reflections off of the computer monitor
2) The tweeter is coaxial with the woofer, which improves phase response, frequency response, and polar response
3) The big innovation is that putting the speakers on the side of the box creates a large center-to-center spacing. This improves stereo seperation; basically the sound from the left would have to wrap all the way around the box to interfere with the sound from the right. To increase stereo seperation even further, I will likely add in a "ambio4you" processor from miniDSP for crosstalk cancellation

And the speaker has big brass balls. It uses a pair of B&C 8NDL51 woofers, and two BMS compression drivers. This thing can flex the walls.


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## T3mpest (Dec 25, 2005)

Patrick Bateman said:


> First, we have to figure out our crossover points.
> When you mount the NEO8 the usual way (with the long axis mounted vertically), *your crossover point maxes out around 800hz.*
> 
> When you flip it a hundred and eighty degrees, *your maximum crossover point is about 2300hz.*
> ...


edit: Misread your post, i got it.. Up to 2500hz the polars are the same so it doesn't matter which way. Thanks  What's this 800hz business about are you talking about it's low end response? That seems almost counter productive to me as the neo 8 can do 800-20k but we'd be using it for 800-2khz or so where the lense and compression driver would take over.. Seems like it would make more sense to use something that can go lower than 800hz if I only need to get to 2k


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## Patrick Bateman (Sep 11, 2006)

T3mpest said:


> edit: Misread your post, i got it.. Up to 2500hz the polars are the same so it doesn't matter which way. Thanks  What's this 800hz business about are you talking about it's low end response? That seems almost counter productive to me as the neo 8 can do 800-20k but we'd be using it for 800-2khz or so where the lense and compression driver would take over.. Seems like it would make more sense to use something that can go lower than 800hz if I only need to get to 2k


800hz isn't the LOWER limit; it's the *upper* limit.










This is because the diaphragm is so large, one side of it is starting to get out of phase with the tweeter. If you mount the NEO8 horizontally, it's easier to reduce the center-to-center spacing, and your tweeter and midrange begin to behave as if they're a single driver. Maths is here : http://www.diymobileaudio.com/forum/2114791-post301.html

Whether you care about this really depends on what your crossover slope is, and whether keeping things in phase is a priority for you.

For me, it IS a priority, so I want to get the two drivers within about 1/3rd of a wavelength.



If you don't care about phase, and polar response, you can mount the NEO8 any which way you want, and then try to fix things with crossover and EQ.


But I'm not from that school; I try to keep my mids and tweets within about one third of a wavelength, and due to that, I gotta pack 'em tight.



Andrew Jones and I agree on a lot of things. He has an interesting podcast here that covers a lot of the beliefs that I have:

Podcast 112: Andrew Jones | Sound & Vision

Andrew worked on the concentrics at Kef and TAD


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## T3mpest (Dec 25, 2005)

Patrick Bateman said:


> 800hz isn't the LOWER limit; it's the *upper* limit.
> 
> 
> 
> ...


oh so it's center to center spacing between lens and the BG that dictating the 800hz crossover if mounted vertically. Since your trying to make both drivers work as close to a point source as possible? Is that corect? Well isn't that driver only good down to 500hz? That's what the spec sheet says.. If thats the case it's not even covering an octave.


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