# Horn Loading a Full Range / It'll End In Tears



## Patrick Bateman (Sep 11, 2006)

For the past couple of months I've been using a full range driver from about 300hz to 20,000hz in my Mazda CX-5. It's been working well, but it sounds a little bit 'strained.' Basically it's having a hard time keeping up with the rest of the system because it's output level is low.









Here's a pic. It's up-firing in a Sausalito Audio Works waveguide that I copied, and 3D printed.









Four months ago I made this waveguide for an AuraSound Whisper, and was able to raise it's SPL by about sixteen decibels.









Here's the "before" and "after"; you can see there's a big bump in output right where it's needed

So I was wondering if I could come up with something like the latter, but better optimized. A horn for a small full-range driver, like the Aurasound Whisper or the SB Acoustics SB65.









Here's the predicted response of an Aurasound Whisper in a 0.23 liter sealed box, versus a horn. *Note that the horn bumps up the output a LOT - about 18dB at 400hz.* If you look at the 'real world' measurement earlier in the post, you can see this is the real deal, it IS possible to squeeze 110dB out of a single $20 woofer.


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## Patrick Bateman (Sep 11, 2006)

If you look at the response of the white horn, it's output peaks at 1600hz. If you look at the sim, it's output peaks at 400hz. The reason it's different is the white horn is very very small, about 4" deep. The horn sim from post #1 is a whopping 14" deep(!)









Before I come up with a design, I need to figure out what'll fit in the car.
Here's a USD horn, mounted on the dash.
I don't think this form factor will fit; the hump in the instrument cluster wreaks havoc with everything.

















Mounting the horn vertically seems to work pretty well; it follows the 'curve' of the dash pretty well. Obviously, you'd have chop the horn up a lot to accomodate the dash, and a lot of time would need to be spent to get everything to fit.


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## Patrick Bateman (Sep 11, 2006)

I used a piece of cardboard to figure out the maximum 'mouth' I could fit on the dash. It ended up being 14cm x 22cm, for an area of 308cm^2. That's a little bit smaller than a 10" woofer. That's how we get big dynamics and efficiency out of a 2" midrange; we're basically transforming the output into something close to a 10" midrange.


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## Patrick Bateman (Sep 11, 2006)

To get the horn to fit in the space that I have, I set the mouth area of the horn to the space that I have (308cm^2) and then I tweak the depth of the horn until it's the same as the depth that I have (24.48cm)









Once I do that, I get this response curve









Here's the original response curve. The original plays about half an octave deeper, but it's also twice as big!


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## oabeieo (Feb 22, 2015)

Dood , try a ES mini up there , have you? 

I had minis on the dash of my santafe with amazing results, 
I'm now doing something a bit more extreme in the Honda and I just might reference your help with. 

I'm MIGHT have to make a custom horn. But I am trying very hard to not have to


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## Patrick Bateman (Sep 11, 2006)

oabeieo said:


> Dood , try a ES mini up there , have you?
> 
> I had minis on the dash of my santafe with amazing results,
> I'm now doing something a bit more extreme in the Honda and I just might reference your help with.
> ...


The Eric Stevens horns can't get down to 500hz, they're too small

I've only heard his gear once, but I'd love to listen to a car that has them.

Underdash horns are tricky to do in a CUV like my CX-5, because the seating position is so upright. And to make things worse, I'm 6'3" tall, so my ears are higher than the average listener.


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## Patrick Bateman (Sep 11, 2006)

I'm trying to figure out what driver to use.

Here are some candidates.

















This is a measurement of a 'naked' Dayton RS75. Basically note that it reaches to 20,000, though it's a 3" driver. 

I just measured mine, here are the specs:

my measurement / published
qes : 0.9309 / 0.97
qms : 5.571 / 5.76
qts : 0.7976 / 0.83
fs : 176.3 / 177

So it looks like this is one of the rare 'honest' spec sheets

The RS75 is about one dB more efficient, but the Whisper has more than twice the displacement. Their power handling is identical.

I like that the RS75 has a cast basket. I'm getting ENRAGED at how many of these micro drivers I've destroyed. Not from too much power - from breaking the basket! The SB Acoustics SB65 is by far the worst example of this I've ever seen, when I attached the leads to the driver the entire basket cracked in half. (It's made out of plastic.) Nearly all of my Peerless 830970s are dead too. Another case of using a plastic basket that sucks.


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## Patrick Bateman (Sep 11, 2006)

Here's the measured and published specs of the Aurasound Whisper:

I just measured mine, here are the specs:

my measurement / published
qes : 0.93 / 0.80
qms : 5.07 / 4.72
qts : 0.79 / 0.68
fs : 225.3 / 250

Because the Whisper has a tiny VAS, you can make a nice lil' enclosure by simply sealing off the back. If you do, this is what you get:

qes : 2.08
qms : 7.05
qts : 1.6
fs : 503


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## Orion525iT (Mar 6, 2011)

Patrick Bateman said:


> I'm getting ENRAGED at how many of these micro drivers I've destroyed. Not from too much power - from breaking the basket! The SB Acoustics SB65 is by far the worst example of this I've ever seen, when I attached the leads to the driver the entire basket cracked in half. (It's made out of plastic.) Nearly all of my Peerless 830970s are dead too. Another case of using a plastic basket that sucks.


Wow, that's terrible. I have some Celestion AN series drivers that I originally got for simple, outdoor, all weather boxes. The basket is polymer. I have not had a single issue with that or even blowing them with too much excursion. I have not been gentle with them in any way. They are pricey though for what they are.


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## Zippy (Jul 21, 2013)

Patrick Bateman said:


> Before I come up with a design, I need to figure out what'll fit in the car.
> Here's a USD horn, mounted on the dash.
> I don't think this form factor will fit; the hump in the instrument cluster wreaks havoc with everything.
> 
> ...


Why not mount the wave guide working up along the a pillar? The closer you get to ear height, the easier to set the stage height.


As to the looking at drivers comment you made. If you have not heard Fostex full range drivers, then you are missing out. They sound Amazing! The link below is to a 4" driver that I really like.

Madisound Fostex FE103En

I own a set of these in a ported enclosure and they are the best bookshelf speakers I've heard for the money. Also at their rated 15 watt power on 8 ohm speakers, you can power them off your head unit without need for an additional amp. I've been toying with the idea of a true budget build using them and a sub that will play up to the 200 Hertz range on each side.


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## oabeieo (Feb 22, 2015)

Patrick Bateman said:


> The Eric Stevens horns can't get down to 500hz, they're too small
> 
> I've only heard his gear once, but I'd love to listen to a car that has them.
> 
> Underdash horns are tricky to do in a CUV like my CX-5, because the seating position is so upright. And to make things worse, I'm 6'3" tall, so my ears are higher than the average listener.


Yeah, but you n I both know all you need to do is get the dash location down to 500hz and the rest speakers where ever and it will have a good image . So why not do a ES mini and a set of 4" next to it in a a pillar build , or a few them whispers clustered close to the horn to do 500-1k

The mini horn is tryed and true, sounds good on axis , and isn't ginormous


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## Patrick Bateman (Sep 11, 2006)

Orion525iT said:


> Wow, that's terrible. I have some Celestion AN series drivers that I originally got for simple, outdoor, all weather boxes. The basket is polymer. I have not had a single issue with that or even blowing them with too much excursion. I have not been gentle with them in any way. They are pricey though for what they are.











The basket is just a dumb design. See that ring of plastic that the terminals are attached too? It's less than 5mm thick. You apply a tiny bit of pressure and it cracks. I wonder if SB is dumping them now; I paid $35 for mine and now they're selling for $20 at Madisound. I wouldn't be surprised to see SB Acoustics come out with a new version with an improved basket.

In all other respects, it's a fantastic driver. There probably isn't a better driver for covering 500hz -20,000hz in a small package. I'd say it's even better than the Aurasound Whisper.









Here's the Celestion. Definitely a better basket design. The ribs are thicker and there's more of them.


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## Patrick Bateman (Sep 11, 2006)

Zippy said:


> Why not mount the wave guide working up along the a pillar? The closer you get to ear height, the easier to set the stage height.
> 
> 
> As to the looking at drivers comment you made. If you have not heard Fostex full range drivers, then you are missing out. They sound Amazing! The link below is to a 4" driver that I really like.
> ...


The Fostex drivers are fantastic. I had my FF85WK up on the dash for a while, but I removed it because it's just too big. If you want to push the driver all of the way into the corners of the dash it needs to be 3" or smaller, preferably much smaller.

It's too bad Fostex doesn't make neodymium woofers. A FF85WK with a neo motor to cut down the size would be great.


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## Patrick Bateman (Sep 11, 2006)

oabeieo said:


> Yeah, but you n I both know all you need to do is get the dash location down to 500hz and the rest speakers where ever and it will have a good image . So why not do a ES mini and a set of 4" next to it in a a pillar build , or a few them whispers clustered close to the horn to do 500-1k
> 
> The mini horn is tryed and true, sounds good on axis , and isn't ginormous


To get good response from a two-way speaker, you want the midrange and the tweeter to be about the same diameter.









For instance, this Revel speaker uses a waveguide to match the directivity of the midbass to the directivity of the tweeter.









To do the same thing with Eric's horns, you need to use a large diameter midbass, like Mic Wallace did in the picture above. If one used a 4" midrange with a horn that's 16" wide, there would be a huge directivity mismatch which would make it basically impossible to create a crossover that works on *and* off-axis.


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## Patrick Bateman (Sep 11, 2006)

As mentioned earlier in the thread, I was going to mount the horns vertically. The reason for this is that I drive a CUV and my ears are about two feet above where you'd put underdash horns.









Here's an Image Dynamics horn.




























I ran some sims on the Image Dynamics horns, and it looks like they create the 'right' wavefront, but my device doesn't. Here's what I mean by this:

In a car, we want the energy from the left driver to go to the RIGHT, and the energy from the right driver to go to the LEFT. Ideally, we'd design the speaker so that the output level doesn't vary from one side of the car to the other. Of course this is a difficult goal, and we use EQ and DSP to tweak things. But you don't want a speaker that's going to need a lot of it.

If you look at the wavefront of the Image Dynamics horn, it's creating a curved wavefront at 500hz, 1000hz, 2000hz, etc. (My sim was done with Hornresp, and the horn is drawn to scale. The thick line in the pic is intended to represent the dash of the car.)

























With my horn, the wavefront is flatter, it's narrower, most of the energy is going to the center of the car.









The obvious thing to do would be rotate the horn. But you can't do that. If you did, the mouth would hit the instrument cluster and the throat would have to be outside of the car. Maybe this is the reason that Mark Eldridge eventually switched from horns to arrays, with an array you can create nearly any wavefront shape you want, as long as you have a lot of amps and a lot of DSP.


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## rton20s (Feb 14, 2011)

Patrick, have you considered the Vifa NE65W?


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## Eric Stevens (Dec 29, 2007)

Patrick,

The best pattern from my horns is developed off axis and they have very wide vertical axis dispersion and narrow directed horizontal axis dispersion. On axis the energy directed towards the farthest listener is 3dB higher than towards the nearest listener, but when off axis 30 to 45 degrees they are more in the 6dB energy range to the farthest listener.

If the system isnt set up right it will have a low stage, but if you get it right or just close it will have a soundstage at least as high as the top of the dash.

Dont let your eyes and brain tell you where to hear the music.


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## Patrick Bateman (Sep 11, 2006)

rton20s said:


> Patrick, have you considered the Vifa NE65W?











Yes, I tried them a few months back, here's a pic

more info here : http://www.diymobileaudio.com/forum...udio-discussion/180497-28-weeks-later-11.html


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## Patrick Bateman (Sep 11, 2006)

Eric Stevens said:


> Patrick,
> 
> The best pattern from my horns is developed off axis and they have very wide vertical axis dispersion and narrow directed horizontal axis dispersion. On axis the energy directed towards the farthest listener is 3dB higher than towards the nearest listener, but when off axis 30 to 45 degrees they are more in the 6dB energy range to the farthest listener.
> 
> ...


Yeah, it's looking promising. I'm putting together a better model of your horns, so I'll post some results shortly.


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## rton20s (Feb 14, 2011)

Patrick Bateman said:


> Yes, I tried them a few months back, here's a pic
> 
> more info here : http://www.diymobileaudio.com/forum...udio-discussion/180497-28-weeks-later-11.html


Those look to be different drivers than I was referring to. Maybe these Peerless by Tymphany 830987 3" Full Range Woofer or these Peerless by Tymphany 830986 3" Full Range Woofer? Maybe even the smaller drivers from the same line?

I was referring to the Vifa NE65W-04 found here https://www.parts-express.com/peerless-by-tymphany-ne65w-04-2-full-range-woofer--264-1046 Or perhaps the larger 85 or 95 version. 

Just curious if you had looked at those and if so, why they might be passed over for the RS74 or Whispers?


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## Patrick Bateman (Sep 11, 2006)

rton20s said:


> Those look to be different drivers than I was referring to. Maybe these Peerless by Tymphany 830987 3" Full Range Woofer or these Peerless by Tymphany 830986 3" Full Range Woofer? Maybe even the smaller drivers from the same line?
> 
> I was referring to the Vifa NE65W-04 found here https://www.parts-express.com/peerless-by-tymphany-ne65w-04-2-full-range-woofer--264-1046 Or perhaps the larger 85 or 95 version.
> 
> Just curious if you had looked at those and if so, why they might be passed over for the RS74 or Whispers?


In a horn it doesn't matter a great deal, the response shape and directivity will largely be dictated by the horn. The exception to this is when the wavelengths are shorter than the diameter of the horn.

For instance, in a horn or waveguide with a throat that's 1" in diameter, the sound above 13,500hz won't "see" the horn at all. The wavelengths are so short, they're shorter than the horn that they're traveling through. (13,500hz is one inch long.)

So when you're picking out a driver to put on a horn, you'll want to look at the response curve above 13,500hz or so and be sure that the 'raw' driver can get there, because the horn won't be doing it any favors above that point.

So that was one of my big criterias here, I wanted a driver that could get to 20,000hz, and a lot of drivers that can go down to 500hz can't get to 20,000hz.

As far as the Vifa and Peerless goes, I have a bunch of them here and many of them seem to use the same motor and cone, but a different basket.


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## bugsplat (Nov 7, 2014)

I'm always amazed at the length some of you go. I can't even fathom trying to fit horns in my car. I thought with the advancement of DSPs "building" your stage was no longer a physical issue (to a point). What can horns offer that a nice array and DSP can't duplicate? Its not distance, you are 2 feet away. Its not power, you have cheap high power amps now. Those aren't fighting words, I'm genuinely curious. Am I missing out on a better method?


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## rton20s (Feb 14, 2011)

Good to know. I was mainly pointing out the Vifa NE line because they do look like they can play up pretty high and the aluminum basket might help address some of the fragility issues you've been experiencing.

Because I have looked at so many midrange drivers, I do have mfr. response plot overlays for comparison. This is the NE65 (on axis: thick red, 30: thick blue, 60: thick green) compared to the RS75 (on: thin black, 15: thin red, 30: thin green, 45: thin blue). Understanding the horn shapes response below the throat diameter and only looking at the top end, I would tend to choose the Vifa over the Dayton, depending on how on/off axis you are aiming the horns. 










Not questioning what you are doing or the choices you are making. More of an opportunity for me to continue to learn.


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## Orion525iT (Mar 6, 2011)

bugsplat said:


> I'm always amazed at the length some of you go. I can't even fathom trying to fit horns in my car. I thought with the advancement of DSPs "building" your stage was no longer a physical issue (to a point). What can horns offer that a nice array and DSP can't duplicate? Its not distance, you are 2 feet away. Its not power, you have cheap high power amps now. Those aren't fighting words, I'm genuinely curious. Am I missing out on a better method?


Because it is what he does. Or something like that .


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## Patrick Bateman (Sep 11, 2006)

Eric Stevens said:


> Patrick,
> 
> The best pattern from my horns is developed off axis and they have very wide vertical axis dispersion and narrow directed horizontal axis dispersion. On axis the energy directed towards the farthest listener is 3dB higher than towards the nearest listener, but when off axis 30 to 45 degrees they are more in the 6dB energy range to the farthest listener.
> 
> ...


Hey Eric,

I created an improved model of your horns. So these sims more accurately represent your horns that the earlier sim.

These are neat! Did you and Bruce Edgar design these things without the benefit of finite element analysis? The reason that I ask is because this design has been around for a few years now, but the tools to simulate the horn haven't. (The wavefront simulator in Hornresp has only existed for about five years now. There are some other tools that can do it, but those are fairly new too.)









Here are your horns









I copied the dimensions and put them into Hornresp, then ran them through the wavefront simulator. We can see that the horn body is taking the spherical wavefront and it's "flattening it out." So the wave isn't flat, it isn't round, it's basically round and squished.

The cool thing here is that flare towards the mouth. If it's doing what I think it's doing, the flare is designed so that the wavefront can expand *vertically.* This is a neat trick, because one of the challenges with underdash horns is that the last couple of octaves can sound rolled off. You hear a lot of people complain that they have to add supertweeters to bring the stage up. But that flare in the horn is basically making the horn behave as if the source of the sound isn't under the dash, it's right at the EXIT of the dash. So even though the driver is eight inches back, the sound doesn't expand vertically until the very last moment.









I drew this pic to describe what's going on. The sound starts out at the throat, expands in a circle but is 'pinched' into a flatter wavefront. Once it's been 'pinched' it's then allowed to expand vertically by that flare that's visible towards the mouth.

I'm kinda stunned that someone came up with this without using Hornresp.


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## gijoe (Mar 25, 2008)

bugsplat said:


> I'm always amazed at the length some of you go. I can't even fathom trying to fit horns in my car. I thought with the advancement of DSPs "building" your stage was no longer a physical issue (to a point). What can horns offer that a nice array and DSP can't duplicate? Its not distance, you are 2 feet away. Its not power, you have cheap high power amps now. Those aren't fighting words, I'm genuinely curious. Am I missing out on a better method?


Well, a proper array isn't exactly easy either. You need a lot of channels, and a lot of processing. Not to mention, when getting into a proper array, space becomes just as big of an issue.


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## Patrick Bateman (Sep 11, 2006)

If anyone thinks that all horns are created equal, here's a quick comparison.









This pic was my rough estimate of the Image Dynamics HLCDs









This pic was my second stab at simulating them. In this pic, *I looked up the width, the depth, I figured out the coverage angle, etc.* Note that the wavefront shapes of the two are different. Of particular note, notice that the flare in the real world horns is right where it needs to be, it mimics the wavefront shape very well.

I need to tinker with this a bit more, but it appears that flat walls create a flatter wavefront, and curved walls create a wavefront with more curvature. But don't quote me on that because I haven't done enough sims to be 100% certain.


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## Patrick Bateman (Sep 11, 2006)

bugsplat said:


> I'm always amazed at the length some of you go. I can't even fathom trying to fit horns in my car. I thought with the advancement of DSPs "building" your stage was no longer a physical issue (to a point). What can horns offer that a nice array and DSP can't duplicate? Its not distance, you are 2 feet away. Its not power, you have cheap high power amps now. Those aren't fighting words, I'm genuinely curious. Am I missing out on a better method?


There's a misconception that horns are more efficient.

For the most part, *this isn't true.*









For instance, here's a sim of a Aurasound Whisper in a sealed box, and in a horn. In the sealed box, it's good for 86dB and it rolls off at 280hz.
In a horn, *it's good for 105dB.*

Now where did that 19dB come from?!

The answer is simple : all of the energy is being focused in one direction. We can make the beamwidth narrower and narrower, until all the energy is basically focused at your ears, and nowhere else.*

The next question, *why is this important?* I think it's important for a couple of reasons. The first reason is because I'm not too keen on having crossovers in the midrange. To me, a crossover at 2000hz or 3000hz is really audible. So I'm taking a wideband driver and I'm pushing it all the way to the wall, squeezing every last ounce of output and bandwidth out of it. There are plenty of wide band drivers that can cover 500hz to 20,000hz, but if you want to hit 110-120dB, *you're going to need a waveguide or horn.*

The other advantage is that eliminating early reflections gets you this 'giant headphone' effect that I find pleasant. It's a little weird at first, and I imagine that a lot of people who've listened to horn systems may have found the effect off-putting, but I like it. The car basically sounds like you're wearing headphones but you're not.


* I'm too lazy to look it up, but IIRC, every time you reduce the space that you're radiating into, *your output goes up 6dB.* So if you have a 2" driver on a flat baffle and it's good for 86dB, *if you halve the space, it goes up to 92dB.* Halve it again and you're radiating into a corner, and now you have 98dB. You can take this further by radiating into a fraction of a corner. But don't take my word for it, mess around with Hornresp and see for yourself.


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## Patrick Bateman (Sep 11, 2006)

I just made a rough model of the Image Dynamics waveguides, and it *does* look like it will work with direct radiators!

Very cool. In regards to my earlier commets to Oabeieo, it looks like I was wrong. I need to crunch the numbers but it looks like you can mount a conventional driver to these things.

I think the 'trick' will be getting the phase plug right, and getting that "flare" correct.


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## oabeieo (Feb 22, 2015)

Patrick Bateman said:


> I just made a rough model of the Image Dynamics waveguides, and it *does* look like it will work with direct radiators!
> 
> Very cool. In regards to my earlier commets to Oabeieo, it looks like I was wrong. I need to crunch the numbers but it looks like you can mount a conventional driver to these things.
> 
> I think the 'trick' will be getting the phase plug right, and getting that "flare" correct.


Do you remember the cd1ev1? Lol, It was a paper cone diaphragm, yeah so what if it was a piezoelectric still had same principle as a speaker cone. 

One time I mounted a 3"jbl coax on a ID horn with a pvc cap behind speaker. **** it worked way way better than I thought it would. I did it while waiting for a new diaphram, ended up running it like that for almost a year I liked it that much.


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## Patrick Bateman (Sep 11, 2006)

I've been putting this off for years, but I think I'll have to learn BEM to solve this monster 

So here's how we do this:









step 1: get Abec from R&D team, the same people that make Akabak : R&D-Team - Products

step 2: make a 3D model of the horn in your 3D program of choice. I like 123D.

step 3: export the 3d model as an STL

step 4: import the 3d model into meshlab, export as a step file

somewhere in here, import the step file into ABEC and simulate the horn

If anyone is wondering why you'd torture yourself like this, the reason you'd go this route is because Akabak and Hornresp only work in two dimensions. ABEC works in three dimensions. This is handy for horns like Eric sells, where the vertical and horizontal dimensions are dramatically different. For a horn that's close to round or square, hornresp is way easier.


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## Patrick Bateman (Sep 11, 2006)

Here's some pics of how to do this. It sounds complex but it's not; I did the whole thing in about 15 minutes.









First, you make the horn your 3D program of choice. I used 123D.

Export that 3D model as a "stl" file









In ABEC, I've imported the stl model. See how there's too many polygones? We need to fix that.


















So we import the 3D model (in stl format) into Meshlab, and we reduce the polygons. This takes all of fifteen seconds, just hit "Filters > Remeshing, simplification and construction > Quadratic Edge Collapse " Details here : Polygon Reduction with Meshlab - Shapeways









Once we do that, we can re-import the STL into Abec, and now we have something that's easier to solve.

By the way, I'm still trying to figure out why I have four horns in ABEC, but only one in 123D. There's probably something wrong with my ABEC script.

I'll fix that.


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## Mic10is (Aug 20, 2007)

Patrick Bateman said:


> The Eric Stevens horns can't get down to 500hz, they're too small
> 
> I've only heard his gear once, but I'd love to listen to a car that has them.
> 
> Underdash horns are tricky to do in a CUV like my CX-5, because the seating position is so upright. And to make things worse, I'm 6'3" tall, so my ears are higher than the average listener.


HLCD like the ones Eric makes are meant to be listened to off axis. Being more on axis with them reduces the stage height drastically. 
In my BMW for example when I had anyone 5' tall or shorter listen to the car the stage height was almost at the floor. If I raised the seat up then stage height became eye level. Taller listeners over 6ft tall had stage height near the mirror.


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## Patrick Bateman (Sep 11, 2006)

I created a 3D model of the Image Dynamics horn in 123D, and have been able to load it into ABEC.

Now I need to mount a driver at the throat and then I'll be able to simulate the directivity and frequency response in three dimensions.

Although ABEC looked horrendous, I gotta admit it wasn't that bad. A lot of use have already been using Sketchup and 123D to design waveguides and subwoofers; if you have too, ABEC is pretty easy to pickup. The first time I ever used ABEC was today.


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## Eric Stevens (Dec 29, 2007)

Patrick Bateman said:


> Hey Eric,
> 
> I created an improved model of your horns. So these sims more accurately represent your horns that the earlier sim.
> 
> ...


Patrick,

Yes alll done without FEA, most of the area progressions were done using a caclulator or a excel spreadsheet. 

I knew what I wanted for dispersion and I read as much as I could on horn theory and design to learn the factors that determine dispersion. Unfortunately what works effectively at 500 hz isnt very effective at 5000 hz and is completely useless at 15000 hz. So it becomes an engineered balance of trade offs to get the best overall performance.

Your Horn design you did for the simultions looks conical and not exponential, there are significant differences. 

The basic design was created by me and I got help from an engineer who did custom horns for churches and other venues and later Dr Edgar helped with some tweaks.


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## Patrick Bateman (Sep 11, 2006)

I'm still getting the hang of ABEC, I've only been using it for about sixteen hours, but I managed to make a working HLCD model.

Here's a couple of screenshots showing 6khz and 2khz respectively.









For comparison's sake, here's really good performance, this is from a LeCleach horn loaded with a TAD driver. Of course, this model is in 2D, and things get complicated when you go to 3D. It took nearly two hours just to crunch the numbers on the sim I posted above!

If I can find the time I'll start tweaking things to improve the performance. And note that this isn't an accurate copy of the Image Dynamics horns, this is a crude copy, still a lot of work to do here.


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## Patrick Bateman (Sep 11, 2006)

Here's a couple more sims of the same horn, this time at 1khz and 12khz. At high frequencies, the wave fronts are full of lobes. (The lobes are those things that look like flames, basically those 'flames' indicate that the response will change dramatically depending on whether you're listening on axis or off.)

I'm not sure if the lobes are due to the conical walls, or the fact that the horn is dramatically asymmetric, but I intend to find out! 









Here's the polar response and the frequency response. Note that the polar response of the horn is good below 2000hz. *So this may indicate that shortening the height of the horn will improve the polar response.* (Note that Eric's horns are very short, under an inch tall for most of the pathlength.)

I'm still tinkering with the model, so this is hardly the 'final product,' I learned how to use ABEC yesterday.









For comparison's sake, here's a symmetrical horn, with curved walls. Note how the wavefronts are really well behaved.


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## Patrick Bateman (Sep 11, 2006)

Here's another interesting thing that ABEC shows:

*Note that the wavefronts on the underdash horn are screwed up *inside the horn.**

IE, if you look at the big horn, the last pic in the last post, you can see that the wavefront is starting to diffract at the exit of the horn. But in the underdash horn, the diffraction is happening INSIDE the horn.

That might indicate why I had such good results when I treated an underdash horn here : The HOMster! (or How I Learned How to Fix a Horn) - diyAudio

But it also confirms what Eric has argued before, that if you design the horn correctly from the get-go, *you don't need to treat it.* IE, eliminate the diffraction in the horn body and treating the horn body is unnecessary.

I'd speculate that the solution may be reducing the volume of the horn. We can see in the sims at 2000hz that the underdash horn works pretty well. At high frequencies, things get tricky. Diffraction won't occur when the wavelengths are larger than the horn. Therefore, *the solution may be to reduce the size of the horn.* And since we care about horizontal directivity control, reducing the *height* of the horn is probably the way to go.

I've been coming around to this way of thinking myself, as I've found that treating the really good horns, like the QSC horns, is inaudible. I own some underdash horns, but they're not Eric's horns, they're a different brand.


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## Patrick Bateman (Sep 11, 2006)

lol, just realized the SPL guys could use ABEC to figure out exactly where to put the woofer and the port of their subs. Just make a model of the car interior and you're off to the races.

Neat thing is that the data would work for anyone with the same car. IE, "what is the optimum location for a subwoofer in my car?" Or, "what is the optimum location for two subwoofers in my car?"


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## Patrick Bateman (Sep 11, 2006)

Eric Stevens said:


> Patrick,
> 
> Yes alll done without FEA, most of the area progressions were done using a caclulator or a excel spreadsheet.
> 
> ...


These BEM sims really seem to confirm some of the design decisions you made.









For instance, here's the profile of an older design. Note that it's quite tall - over an inch tall in the middle of the body.









Your design is very short throughout the body, and flares at the mouth

























When I lowered the height in my sim by 66%, it had the following benefits:

1) it lowered diffraction in the horn body
2) by lowering diffraction, the wavefront is closer to perfect
3) much to my surprise, it extended the high frequencies. This was unexpected; all of the 'conventional' tools like Akabak and Hornresp simulate horns in two dimensions, and can't predict this. If I'm not mistaken, ABEC is the only one that can simulate this.

















Here's an A/B comparison.
The top pic is with a height of about 1.5" in the body.
The second pic is with a height of about 0.5" in the body.
You can see that the wavefront is improved. It's kinda interesting that the high frequencies don't "see" one side of the horn, the wave shape is basically established deep in the horn, and as it moves down the horn, it doesn't "see" that one side of the horn.

Of course, as the waves get larger, they'd start to "fill in" the entire body.

In summary:
It looks like we want a very wide horn body, that is as short as we can get away with without screwing up the frequency response. (As you make the height lower and lower, it will start to make the response ragged, particularly at low frequency.) So as you noted in an earlier post, it's a balancing act between using a very very low height to extend the high frequencies and improve the directivity, while using a larger height to accomodate a lower cutoff. It's neat to realize that you can use a width that is wider than you'd expect because the very high frequencies do not "see" one side of the horn.

Fun stuff!


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## Patrick Bateman (Sep 11, 2006)

I know that I have a tendency to think that Synergy Horns solve everything, but this application is just screaming for some midranges on the horn body.

In that last pic, you can see that the high frequencies basically don't "see" the left hand side of the horn body. So it would be really easy to put a midrange on that side of the horn body.


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## Patrick Bateman (Sep 11, 2006)

The sims seem to indicate that you want a really short height for an underdash horn. So I made a really crude conical horn, where I could vary the height of the horn.

This horn is hardly ideal; I basically wanted to find out how short you could make the horn before the frequency response goes to hell.









Here's the unequalized frequency response with a height of 0.25".
The red line is on-axis and the blue line is 45 degrees off axis.









Here's the unequalized frequency response with a height of 0.5".
The red line is on-axis and the blue line is 45 degrees off axis.
Note that the scale is shifted up 5dB on this one; when you raise the volume of the horn you raise the output level (Hoffman's Iron Law.)

Some observations:

1) doubling the height of the horn raises the overall output by about 5dB
2) If you look at the BEM sims from yesterday, you'll notice that lowering the height makes the horn more directional, basically the wavefront "clings" to the horn wall when you lower the height. You can see this in these measurements; at high frequencies, the shorter horn 'throws' the sound off axis.


















A few months ago I made this underdash horn, a bit of an 'homage' to the old school HLCDs from the 90s, but loaded with an Aurasound Whisper instead of a compression driver.









Here's the on and off-axis frequency response, measured at the same voltage as the other horn in this post. Lowering the height seems to make a big difference. Although the horn from today is incredibly crude, it lacks the dip at 3500hz that this one has. On the upside, the high frequencies go all the way to 16000hz, likely due to the fact that the driver is firing straight down the horn, instead of reflecting like in the other horn from this post. I believe that the 'wiggles' in this measurement are due to the horn body resonating, as it's flimsy PLA plastic with no reinforcement. Generally when I 3D print waveguides, I reinforce with fiberglass and epoxy.


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## Patrick Bateman (Sep 11, 2006)

Here are Eric's horns


















Here's something I worked on yesterday. It's a LeCleach curve carefully squashed into an HLCD.

Not sure if I'll build it though; I'm nervous that the height is still too high. (As noted in the previous post, very low heights seem to perform best.)









If anyone at home wants to build something similar, the curve is remarkably similar to this bamboo plate from Ikea. For the low low price of six bucks, you could build two waveguides in less than an hour.

Naturally, I never do anything the easy way so I'll continue to tweak my design in 123D :O


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## Patrick Bateman (Sep 11, 2006)

Took another stab at making one of these, but not too keen on it. Think I'll try again.









Reminds me of the Veritas HLCDs


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## Patrick Bateman (Sep 11, 2006)

It took about four tries, but I finally came up with a design that I'm happy with (for now.)









The sidewalls are straight, for constant directivity, but the vertical angle sloooooowly expands as the sound travels down the throat. I'm using a LeCleach expansion because it seems to be the king of the horn profiles. You could probably improve on it a tiny bit with FEA but I'm too lazy to spend a month doing that.


















moar pics









Lots of mortite to deaden and seal the horn. This is one third of the horn, it's so big I have to print it in three pieces. Total print time is forty one hours!









The throat is basically a mirror image of the Whisper's cone









The height is insanely low. Based on the BEM sims, and the fact that Eric's doing this, it seems to be the way to go. From what the sims show, *reducing the height smooths the frequency response, raises the soundstage, and improves imaging.*









When I said "short" I wasn't kidding; here's an old school HLCD for comparison's sake.

More pics to come. Parts two and three will be finished printing tomorrow.


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## SQram (Aug 17, 2007)

Patrick Bateman said:


> It took about four tries, but I finally came up with a design that I'm happy with (for now.)
> 
> 
> 
> ...




Looks eerily similar to:



May be a good thing...


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## Patrick Bateman (Sep 11, 2006)

Yeah that's definitely similar! The height of the Illusion Audio horn is about twice as high though. I think Eric has the right idea, keep that height very low, it extends the highs.


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## Patrick Bateman (Sep 11, 2006)

Here's some pics comparing my horn to a classic HLCD


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## Patrick Bateman (Sep 11, 2006)

This turned out pretty well. I've been building underdash horns since the nineties, *and this is probably the best one yet.*

The big innovation here was *dramatically* reducing the height of the horn. I stole that idea from Eric, and it looks like it works.

But this is a Patrick Bateman project, so in typical fashion, I'm going to re-do the whole thing, a few feet away from the finish line.

Here's why:

I've been listening to the horn all morning, and it's satisfied the goals that I set for it. The response is relatively smooth, and the bandwidth is probably the widest that I've ever squeezed from a single driver. With one aurasound Whisper on a horn, I'm covering over half the audible spectrum, about 400hz to 16,000hz.

But...

I love me some Synergy Horns, and it's really obvious that a Synergy will take this to The Next Level. As it stands, this horn has two weaknesses:

1) Because I'm squeezing so much bandwidth, it takes quite a bit of power to get loud. After I EQ'd it, I reduced the efficiency from about 100dB to 90dB. It's handling the power like a champ, but I can tell that the dynamics are reduced because I'm pushing a 2" driver pretty hard. (I've been listening to the horn in my living room; in a car it would definitely need less power.)

2) The bigger issue is compression. *I'm using a compression ratio of about four to one.* Compression drivers use very very high ratios, like ten to one, *but they get away with it because they have TONS of motor force.* One way to picture this is like picturing water being pushed through a hose. If you have a big powerful pump pushing water through a small hose, the pump will handle the job with ease. But if you reduced the size of that pump by 75%, it's going to overheat. I'm having similar issues with the Whisper; I'm pushing it hard.









That's one of the reasons that horn loaded domes like this are very "open." Dome tweeters don't have enough motor force to deal with a high compression.









And that's why deep narrow horns use compression drivers, not domes

In summary : this horn does what it was designed to do, it even gets loud, but it sounds 'fatigued' doing so. The fact that it sounds this way at fairly low volume levels tells me that the issue is the high compression ratio.

So... I need to lower the compression ratio. There's a few ways to do this:
1) use a larger throat
2) use a smaller driver

I don't want to use a smaller driver. 2" is about as small as I can live with.
I don't want to use a larger throat, because it's proven that underdash horns work better when they're short

One way to fix this is to mount the drivers offset from the apex. By doing this, we're basically 'tapping' into the horn at a point where the throat is bigger. That lowers the compression ration, lowering the compression ratio makes the horn sound less 'strained,' it's a win-win









Here's the response of the current horn, modeled as a LeCleach horn, and modeled as a series of conical horns stacked on top of each other. I'm just showing this comparison because I have to model things a bit differently when my driver isn't at the apex. *I basically want to illustrate that some of the 'lumpiness' in the response is an artifact of the simulator*, it won't be there in the real world.









Now if I move my midranges down the throat by two inches, *you can see that we get some comb filtering.* That's expected; it's the price we pay for moving the midranges away from the apex. There's an upside here, we can filter out everything above 1500hz, and use the midranges for just 1.5 octaves, basically a very narrow and clean midrange driver. Filter out the harmonic distortion.









One cool thing about mounting the drivers offset is that we have space for two of them now. Here's what the response looks like with two drivers, and the same voltage. Output goes up by about 3-4dB.









Here's the fun part. I'm still using two drivers on the horn, *but now I've reduced the depth by 33%.* The reason that I did this was to lower the compression ratio even further. Basically I want to be (fairly) gentle with these Aurasound Whispers. We're not using big beefy prosound midranges here, we're using tiny little multimedia drivers, so I want to make it easy on them. Going back to the analogy of the water pump, I am using a short wide pipe instead of a long narrow pipe. The idea is to reduce the stress on the pump (the speaker) as much as possible.









Here's an idea of what it would look like.


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## SQram (Aug 17, 2007)

Patrick Bateman said:


> Yeah that's definitely similar! The height of the Illusion Audio horn is about twice as high though. I think Eric has the right idea, keep that height very low, it extends the highs.


If you mean vertical height, no, the Illusion is "shorter" than Eric's horn (I have them both here). The Illusion starts with a 1" entry, immediately narrows down to less than an inch through most of the length, then has a similar vertical transition at the mouth as Eric's horn(s), and the Veritas for that matter. It's the "shortest" vertically of all the car audio horns (I've had em all).

For what it's worth, I find the Illusion horn the smoothest tonally of the car audio horns. It's a very similar design as what you are working on.


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## Patrick Bateman (Sep 11, 2006)

SQram said:


> If you mean vertical height, no, the Illusion is "shorter" than Eric's horn (I have them both here). The Illusion starts with a 1" entry, immediately narrows down to less than an inch through most of the length, then has a similar vertical transition at the mouth as Eric's horn(s), and the Veritas for that matter. It's the "shortest" vertically of all the car audio horns (I've had em all).
> 
> For what it's worth, I find the Illusion horn the smoothest tonally of the car audio horns. It's a very similar design as what you are working on.


Interesting. 

If you could take a photograph of the profile of the two horns, and a photo looking right into the mouth(with the flash turned on) that could help solve this riddle.

I started messing around with paralines and SAW lenses about five or six years ago. I got pretty good at making them. This is the first year that I've had them in my car full time. I noticed that there's a hint of high order modes with them. Not a ton, like a bad horn, but definitely some.

The funny thing about Paralines and SAW lenses is that I've never heard a real Paraline in person, and the last time I'd heard a real SAW lens was in 2007. So 99% of my experience with the devices was based on listening to my clones, not The Real Deal.

Six months back I was at the B&O suite at CES, and had a chance to listen to a real SAW lens, for the first time in nine years. Much to my shock, it sounded terrible. *Lots of high order modes, very audible.*

Long story short: getting that reflector to work is an art and a science. That may explain why the illusion audio sounds so smooth - there's no reflector.

The obvious solution then is to remove the reflector. But the funny thing is that the reflector can actually improve performance! For instance, the SAW lens works so damn well, I can usually get BETTER response with a SAW lens than with a straight throat! So I can see the reasoning behind the reflector in the image dynamics horns; done carefully, it can measure better than a straight horn.

My favorite reason to use a reflector is that it allows the use of conventional domes and cones on a horn or waveguide. The SAW lens doesn't just reflect sound, it works as an elegant phase plug.


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## Patrick Bateman (Sep 11, 2006)

It looks like I'm not the only person that noticed that Ikea's bowls are the right shape for a horn. Some dude named Phil Mundi has been selling these on eBay. It's basically the Ikea salad bowl, with an added baffle to mount the driver to it. 

Clever.


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## Patrick Bateman (Sep 11, 2006)

I spent Monday coming up with a Synergy Horn that's similar to the horn I built from page two of this thread.

*But I think I may be pounding a square peg into a round hole.*

Here's why:

What I've been doing is taking a LeCleach horn and 'squashing' it vertically. So if you look at my horn profile, it's expanding rapidly, like a LeCleach or an exponential horn does. But look at the horizontal axis and the walls are flat, I've done this to attain constant directivity.

So my horn is a hybrid, it has some of the gain of a horn, but with the directivity control of a waveguide.


















But the whole idea of a LeCleach or Iwata horn is to create a slooooooooow transition from the speaker itself, to the room. That's why there's that huge roundover, the idea is to eliminate any abrupt transitions from one surface to the next. (In this case, the first surface is the diaphragm of the loudspeaker, the next surface is the air in the room itself.)

You can see in Hornresp that this works; the LeCleach frequency and impulse response is ridiculously good. I built some LeCleach horns a couple years back, they sound fabulous. (Monster Massive - Page 7 - diyAudio)

So I think I'll redesign this horn. But instead of pounding a square peg into a round hole, by cramming the LeCleach expansion profiles into an underdash HLCD, I'll simply adhere to the spirit of the design, which means very very very gentle transitions from one surface to the next.









18 Sound does something similar in their horns









JBL got with the program too.


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## Patrick Bateman (Sep 11, 2006)

Here's an overhead pic of the new horn coming together. I'm using these huge sweeping curves, to adhere to the principles of the Iwata and LeCleach horns.









Avantgarde's spherical horns follow the same idea. Giant radiused curves from the exit of the speaker to the room.


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## Patrick Bateman (Sep 11, 2006)

The above shape extruded


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## Patrick Bateman (Sep 11, 2006)

Three walls are finished.

I need to figure out how to make a threaded insert now. (Going to use a screw-on compression driver.)


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## Patrick Bateman (Sep 11, 2006)

I invested an insane amount of effort on the screw-on adapter. It sucks because I can buy an adapter for $6, but I'd really prefer to have it molded right into the horn. If this horn works well I'd like to post it online, and I don't want to put other people in a situation where they have to graft a throat adapter onto the horn to make it work. In addition to that, putting the threads right on the horn makes it more compact, which is particularly important when we're cramming all of this under the dash.

No joke, I probably spent two hours working on the threads.

On the upside, I can use this in the future, and that will be really handy. I've had a lot of 3D printed speakers where it would be simpler to screw the pieces together.









I'll be using a BMS 4540ND









But it will also work with any of the JBL clones. For the most part, JBL seems to be doing screw on compression drivers exclusively, at least for the speakers under $5000.









Here's the top half of the horn. This is a really funky looking part, so let me explain it.

















Here is a horn with a diffraction slot. The idea of a diffraction slot is that you have good directivity coverage on one axis, but the slot raises the output of the horn.

The upside is that you take a speaker and you convert it into a radiator that's similar to a ribbon; see how the slot is tall and narrow? The sound doesn't radiate from the speaker, it radiates from the tall narrow slot.

The downsides are significant. The sudden change in expansion creates high order modes, and those sound pretty raspy. The Mantaray horns in particular are famous for sounding terrible.









The way to fix that diffraction problem is to smooth the transition from the diffraction slot to the rest of the horn. Here's a picture of an 18Sound XT1086, you can see that they've done this.

So what you see in the top of my horn is a slooooowly expanding diffraction slot. No sharp edges, no abrupt transitions.









Here's a side view of my horn; you can see how it slooooowly shrinks. That's the diffraction slot, but the sharp edges have been eliminated.









Here's the top view.









Here's Eric's horns for comparison










Here's the front view









Reminds me a bit of the JBL Synthesis Array 1400, except the diffraction slot on the JBL is more pronounced.


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## seafish (Aug 1, 2012)

PB, I am thinking (and HOPING..lol) that you are going to finally nail it with this horn design!!!


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## Patrick Bateman (Sep 11, 2006)

seafish said:


> PB, I am thinking (and HOPING..lol) that you are going to finally nail it with this horn design!!!


There have been quite a few that worked well. The Unity horn project from 2006 worked, and the one from 2009. I kinda regret trashing that last one in particular, almost as soon as it started to work I tore it down to try and improve it. Then got distracted.

But it worked really well, and that was without DSP. 

The cardioid Synergy Horns from about five or six months ago worked really nice, but damn they were huge.

I wouldn't rule out the possibility that speakers on the dash will work better, but I'd still like to explore underdash speakers, as I haven't done that in ages.


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## Dewey (May 29, 2013)

Perhaps I missed the answer in your posts but:

Does 3D printing offer any design/production help in your
QUEST?



dan


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## Patrick Bateman (Sep 11, 2006)

Dewey said:


> Perhaps I missed the answer in your posts but:
> 
> Does 3D printing offer any design/production help in your
> QUEST?
> ...


Yep, I'm a big believer in 3D printing. I design in 123D and print on my Printrbot Simple.


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## Dewey (May 29, 2013)

Your posts from years ago have stuck in my mind as in the '70s my good friend did folding horns and I was his 'ear', before many extended range sessions with S&W .44MAG took the high end out of my left ear.

Anyway, way back then I even looked at some of your math and was impressed.
When I saw 3D printers for some reason your equations popped into my head.

All the Best- dan

Your Orwell quote sounds like the>vastMilitaryArmsComplex<


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## Patrick Bateman (Sep 11, 2006)

Patrick Bateman said:


> Here's a couple more sims of the same horn, this time at 1khz and 12khz. At high frequencies, the wave fronts are full of lobes. (The lobes are those things that look like flames, basically those 'flames' indicate that the response will change dramatically depending on whether you're listening on axis or off.)
> 
> I'm not sure if the lobes are due to the conical walls, or the fact that the horn is dramatically asymmetric, but I intend to find out!
> 
> ...




I've been tackling ABEC again lately, and posted this on another forum.

Thought I'd cross post it here, since it's relevant:

In ABEC I was tinkering with some car audio waveguides, which generally have a wide beamwidth.









Here's a pic of one. As I understand it, these were designed by Eric Stevens with consulting help from Bruce Edgar.









Here's an ABEC sim of something somewhat similar. As frequencies get higher and higher, the wavefronts start to 'detach' from the waveguide, and at some frequencies there's lobes inside of the waveguide itself. You can see that the listening axis varies with frequency too.

NOTE: This isn't a rigorous model, whatsoever. The compression driver isnt angled, there's no roundover at the mouth, at the throat, the diaphragm is square! So please don't make any assumptions about the Stevens waveguides, I'm just tinkering with ABEC here.









Here's a few of these types of waveguides that I've designed and printed, along with a USD audio waveguide.









Here's a measurement of one I made. You can see that the response fits in a window of +/-3dB, *but the listening axis varies.* These variances are caused by what you're seeing in these ABEC sims, that there's lobes inside of the waveguide itself.

Understanding the problem, you can see that there's two solutions:

1) Just narrow the walls 

or 

2) Do the JBL thing, and tweak the geometry until the lobes go away

Hope that makes sense.


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