# One Horn to Rule Them All



## Patrick Bateman (Sep 11, 2006)

I'm a big fan of how Gary's car sounds. The center image on his car is rock-solid, and it's very dynamic. It reminds me of a horn car, but without the harshness that so often accompanies horns. I think that horn cars frequently suffer from a lack of width too.

My solution to the horn problem has typically been Synergy Horns. They basically allow you to cover more bandwidth than a conventional horn. The downside is that they get big in a hurry; I've bent over backwards to shrink them, but they still end up being about the size of a grapefruit. That's a lot of speaker to put on the dash of a car.

This afternoon I saw something at diyaudio which looked promising for the car. A member was using a large format compression driver, so he could crossover at 500hz, and then handing off to a super tweeter:










So you basically have your midrange loaded by a really REALLY big waveguide. Then a supertweeter to bring up the high end. And a big beefy fifteen to round out the system.










Actually, this is fairly similar to the setup in Richard Clark's Grand National. Based on the posts he made at audiogroupforum, he was winning with a pair of Altec 288s, where he'd replaced the 'stock' diaphragms with an aluminum diaphragm. His stories about using diamond diaphragms were probably just that... stories.

Here's the spec sheet for the 288, where you can see that it's good to 500hz:
http://www.greatplainsaudio.com/vintage_altec/288-K Series_hfdriver_spec_sheet.pdf


In summary:
1) No more Synergy horns, I could replace the Synergy with a large format compression driver on a waveguide
2) Pro-sound midbass cuts in at 500hz
3) super tweeter plays above 5000hz or so
4) I'd use a modern waveguide design, instead of those dated exponential horns.


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## Patrick Bateman (Sep 11, 2006)

Here's the system that caught my attention : Computer Audiophile - mitchco - Blogs


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## ErinH (Feb 14, 2007)

Sounds similar to the setup I have in my HT. CD is crossed at about 550hz with the 15" picking up the low end from there. No super tweeter because I haven't found it necessary. And in the car, depending on your goals and likes you could probably do without as well. 

I know some other fella working on a system that may end all the nostalgia as it ties the old school fun with new school smarts. Too bad he doesn't post anymore. But I can't blame him. :/


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## ErinH (Feb 14, 2007)

The one thing I have to ask you though...
Where the heck would you put that in your car? IIRC you have a newer model Hyundai, right? A horn that provided constant directivity down to 500hz is *HUGE* as your picture above shows. I mean, huge. I can't fathom what you'd do to get that in a modern car without cutting the dash at the least. 

For point of reference, I just took this. This is the horn I use in my HT which provides CD down to about 500hz.


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## Patrick Bateman (Sep 11, 2006)

Hmmm, that appears to be the same horn that Mitchco is using.

To control directivity down to 500hz you need a waveguide that's 27" wide by 27" tall. 









By far, the easiest solution in a car is to use the windshield as a waveguide. With a Synergy Horn, that was always a maddening pain in the ass. Because the tweeter has to be at the apex, and that makes it really hard to cram into the corners.

But if you're willing to sacrifice the two octaves from 5000hz to 20khz, you can mount the midranges offset, and then you can go allllllllll the way into the corners.









A Danley SH-50 is just a little bigger than that - about 30" in diameter. The Danleys go down to 80hz or so, but they lose directivity control at 450hz, due to the width.


TLDR: a 27" wide horn will get you directivity control down to 500hz.


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## seafish (Aug 1, 2012)

oops...double post


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## seafish (Aug 1, 2012)

ErinH said:


> The one thing I have to ask you though...
> Where the heck would you put that in your car? IIRC you have a newer model Hyundai, right?


Erin, you DO know that one of PB's waveguide design tenets is that forward vision is not necessarily a priority when it compromises SQ in a car?? JK/LOL


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## SkizeR (Apr 19, 2011)

Shameless plug.. If you want to buy some large format compression drivers, i have a few JBL ones. PM me and maybe we can work out a deal


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## Patrick Bateman (Sep 11, 2006)

SkizeR said:


> Shameless plug.. If you want to buy some large format compression drivers, i have a few JBL ones. PM me and maybe we can work out a deal


I'm going to build some 

Stay tuned...


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## thehatedguy (May 4, 2007)

To get the exits closest to the corners of the glass, you would have to do some cutting of a firewall.

Then a super tweeter is still HUGE.

I think it is a neat idea, but the size of the drivers in question would be prohibitive.

But I seem to remember talking about large format CDs on Carsound years back.


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## Patrick Bateman (Sep 11, 2006)

The plan is to build my own compression drivers and mount the drivers offset.

Basically like a Synergy Horn, but with no tweeter at the apex.


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## ndm (Jul 5, 2007)

thehatedguy said:


> To get the exits closest to the corners of the glass, you would have to do some cutting of a firewall.
> 
> Then a super tweeter is still HUGE.
> 
> ...


:bigcry: I miss the old carsound and fiberglassforums.


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## SQram (Aug 17, 2007)

Mark Eldridge used his dash mounted horns as a midrange (Altec 288 motors), and had super tweeters in the A-pillars to reinforce the top end in his old 4 Runner. Was just reading some old posts about it this morning.

From what I recall, the diaphragms in Richard Clark's horns were diamond etched aluminum to bring the overall mass down. They weren't diamond diaphragms.


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## Patrick Bateman (Sep 11, 2006)

Before I go waste my holiday vacation, has anyone heard the 4Runner with the midrange horns in it? Any opinions?


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## Mic10is (Aug 20, 2007)

Patrick Bateman said:


> Before I go waste my holiday vacation, has anyone heard the 4Runner with the midrange horns in it? Any opinions?


Yep. I heard it in 02 in Charlotte....and I still joke with Mark about it to this day. Mark had spent all night tuning, well beyond when listening fatigue had set in....this was still in the days of when there was very serious and solid competition in the expert class.
It was EXTREMELY bright from about 3k and up. So much so that I turned to Fred Lynch who was listening with me and said "is that how its suppose to sound?" and Fred said " No, no its not"

Fred went and mentioned it to Mark and Mark acknowledged it and explained what had happened.

Below 3k or so. It was very smooth and balanced and did what Mark was known best for--it had pin point imaging and staging. 
There was no guessing where and image was or what its boundaries were. They werent exactly lifelike, they were literally pinpoint and precise.


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## Mic10is (Aug 20, 2007)

Patrick Bateman said:


> I'm a big fan of how Gary's car sounds. The center image on his car is rock-solid, and it's very dynamic. It reminds me of a horn car, but without the harshness that so often accompanies horns. I think that horn cars frequently suffer from a lack of width too.


Noone who has ever heard either of my BMW installs would ever describe the stage as being narrow. In fact, Width scores were typically the highest score for staging on my sheet.

as far as rock solid imaging--thats a function of proper use of delay, phase and eq.....and Gary also uses a center channel....


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## thehatedguy (May 4, 2007)

I heard it at Steel Valley Regionals in 03 or 04 (Mic, it was the year Scott won the Lazy-Boy...which year was that?). It was spooky sounding...in a good way.

But back then Mark either had different presets or suffered from Anthony Davis-it is- wouldn't leave a tune a lone and always changing it, so it might be the best thing ever one time and the next time you left scratching your head wondering what they were hearing.


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## garysummers (Oct 25, 2010)

Mic10is said:


> as far as rock solid imaging--thats a function of proper use of delay, phase and eq.....and Gary also uses a center channel....


Just for the record, my center channel is never used when reproducing stereo program material. The center is only used when reproducing 5.1 discreet program material.


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## Patrick Bateman (Sep 11, 2006)

Mic10is said:


> Noone who has ever heard either of my BMW installs would ever describe the stage as being narrow. In fact, Width scores were typically the highest score for staging on my sheet.
> 
> as far as rock solid imaging--thats a function of proper use of delay, phase and eq.....and Gary also uses a center channel....


This, right here.

I have a set of Vandersteens at home, and they excel at phase and frequency response. I've measured them personally, and their performance is without peer in these respects, particular considering the cost. (I tried to sell my set on Craigslist for $300 and couldn't find a buyer.)

But Gary's car images noticeably better than my Vandersteens do.

My 'hunch' is that it's the waveguide effect that's created by the windshield. Basically there are a number of speakers that have good frequency response and phase response *at one point in the room.* But when you put the midrange on a waveguide, the phase and frequency response isn't just good at one point, it's good over a wide beamwidth. And I'm guessing that's what makes the difference here.

IE, my Vandys are nearly ruler flat, with good phase response, when you're sitting at the correct height and equidistant from both. But if you stand up, POOF, no more image. Waveguide speakers are less prone to this, in my experience. With my Summas, when you moved even a foot off axis the soundstage stayed in the same place.

Mitchco is using DSP processing to really take this idea to the next level. He's trying to create a frequency and phase response that isn't just ideal at one seat in the room, it's ideal across the entire beamwdith of the horn. Which is pretty large - it's something like 90 degrees and maintains beamwidth down to 500hz.

Full disclosure, this is purely a hunch, but I have a couple weeks off and my 3D printer and I haven't had much quality time, so this is what I'm working on.


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## mitchyz250f (May 14, 2005)

Is this thread the child of the '28 weeks later' thread?

I think this Harmon paper on midranges placed on the dash might be on topic. In the paper they experiment with midranges placed in the corners of the windshield shield dash. They get very consistent results between driver and passenger positions and 6 to 10 db gain taking over 100 measurements in each position. 

https://www.yumpu.com/en/document/view/48264781/convention-paper-jjr-acoustics/10

Patrick, why do you think their getting a suckout at 3000hz and you didn't?


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## Patrick Bateman (Sep 11, 2006)

mitchyz250f said:


> Is this thread the child of the '28 weeks later' thread?


"If all you have is a hammer, everything looks like a nail."

Basically I think directivity control solves a lot of problems, so a lot of my solutions tend to looks the same.



mitchyz250f said:


> I think this Harmon paper on midranges placed on the dash might be on topic. In the paper they experiment with midranges placed in the corners of the windshield shield dash. They get very consistent results between driver and passenger positions and 6 to 10 db gain taking over 100 measurements in each position.
> 
> https://www.yumpu.com/en/document/view/48264781/convention-paper-jjr-acoustics/10
> 
> Patrick, why do you think their getting a suckout at 3000hz and you didn't?


Great paper. *Anyone who's ever contemplated putting speakers on the dash, or midrange pods, must read this paper.*

I've never seen it myself. The data is great, but I think they come to the wrong conclusion.

In the paper, they blame the asymmetry of the dash and the instrument pod for the frequency response problem. IMHO, this is incorrect.

The main reason that it's hard to put speakers on the dash is that you get a reflection at the apex of the dash and the windshield. Let me explain how this works:









If it was possible to put a speaker at the absolute apex of the dash and the windshield, this would not be a problem.

But it's not; the speaker MUST be offset by some distance. *Let's call that distance "X."* In the crude drawing above, I've called it 'the magic number.' The reason that it's magic is that it sets the upper limit of the speaker. For instance, if you manage to push your dash speakers so far back that they're just 1.125" away from the apex of the dash and the windshield, *you're going to get a suckout at 3000hz.*

The suckout occurs because the sound radiates into the apex, is reflected back, and then mixes in with the sound being radiated by the speaker. The formula is:
speed of sound / distance / 4

for instance:
13,500 inches per second / 1.125" / 4 = 3000hz









That's why there's a 'theme' in most of my projects, where I'm stuffing waveguides into the corner. The idea is to 'blend' a waveguide into the dash, put a tweeter at the apex, so we can reach 20khz.

But don't take my word for it, check out the data from Harman:









Here's how Harman tested various driver positions. The 'blue' position is as far back as you can get the driver.









And here's the frequency response of the RIGHT driver at the driver's position. We see a big ol' suckout at 4khz. A bit higher than I'd expect, but there nonetheless.

IMHO, *that suckout sets the upper limit of any loudspeaker on the dash.* Sure, you could use EQ to 'fill in' that hole. But that's a BIG hole! 10dB! If you're giving your tweeters fifty watts, you'd need five HUNDRED watts to fill in that hole. (It takes ten times as much power to raise the output by ten decibels.)

That's why all of my designs have used some variation of a waveguide. But looking at Mitchco's results, it got me thinking that maybe I need to "write off" everything above 5000hz or so, and just focus on getting good midrange performance on the dash, then put the tweeter(s) somewhere else.









Here's Harman's results of the left speaker at the driver's position. I imagine that these results are more chaotic because the apex of the dash and the windshield creates a waveguide in the car. The peaks and the dips in the frequency response of any waveguide are due to geometry. The closer you are to the center axis, the more symmetrical things are (because you're equidistant.) The more equidistant you are, the smoother things are.

By the way, if anyone's curious why the suckout in the Harman results doesn't get lower in frequency as the speakers are moved away from the apex, I think it's because you get one reflection going back towards the apex, you also get one from the first reflection against the windshield. So there's actually multiple suckouts.


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## oabeieo (Feb 22, 2015)

mitchyz250f said:


> Is this thread the child of the '28 weeks later' thread?
> 
> I think this Harmon paper on midranges placed on the dash might be on topic. In the paper they experiment with midranges placed in the corners of the windshield shield dash. They get very consistent results between driver and passenger positions and 6 to 10 db gain taking over 100 measurements in each position.
> 
> ...


Thx for the link  was good to read


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## Patrick Bateman (Sep 11, 2006)

BTW, in regards to your question about this measurement:









This is a measurement of xrk71's "trynergy" speaker. It's a waveguide with a TangBand W2 driver at the apex: 
















It caught my attention, because he's using the same driver I've used for my car projects, and he's getting the efficiency into the high 90s using a single driver.

Data here : Presenting the Trynergy - a full range tractrix synergy. - Page 108 - diyAudio

I've generally used 2-4 midranges in my projects; never considered using just one driver. Or putting the midranges at the apex.


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## SQram (Aug 17, 2007)

Why not fill the area between the speaker and the apex with some sort of hard foam block or other medium to prevent reflections?


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## Patrick Bateman (Sep 11, 2006)

SQram said:


> Why not fill the area between the speaker and the apex with some sort of hard foam block or other medium to prevent reflections?












Due to a couple things:

1) if you put some wool in there to fill in the gap, *you still have a reflection off the windshield.* The wool will definitely help, but then you have a second problem...

2) Any kind of absorbing material is going to reduce your efficiency. It's pretty shocking how quickly you can lose output. That's why all these horns I build nowadays rely on geometry to smooth the output, not absorptive damping.

If you want to get to 20khz, and you want efficiency, *you want the driver right at the apex.*

The cool thing is that you can keep the efficiency if you're willing to live with a suckout and just resign yourself to using the driver as a midrange only. IE, you don't need any absorptive material whatsoever if you let the suckout dictate how high your driver plays. (In the Harman graphs, you'd set the upper limit of the driver to 4000hz, which is perfectly fine if you're crossing over to a tweeter which is located somewhere else in the car.)

This is something I'd never really considered, as I'd generally used Synergy horns where there was a tweeter at the apex and I was trying to get the device to play to 20khz.


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## seafish (Aug 1, 2012)

So is the TOP drawing in the above post a good way to get both the widest possible response as well as decent efficiency?

In fact I am positive that I ail be able to mount the small (1/2" by 3/4" AAT) tweeter that way, crossfiring over the 3.5" midrange sunk into the dash of my truck…aka as the linkwitz/Pluto configuration.


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## SQram (Aug 17, 2007)

Patrick Bateman said:


> Due to a couple things:
> 
> 
> 
> ...



I was referring to a hard, non absorptive material to use as a filler. Carve a long strip of floral foam to fill the area. I mention this because that's what Mark E. suggested I do with my horns firing up in a similar manner.


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## Patrick Bateman (Sep 11, 2006)

seafish said:


> So is the TOP drawing in the above post a good way to get both the widest possible response as well as decent efficiency?
> 
> In fact I am positive that I ail be able to mount the small (1/2" by 3/4" AAT) tweeter that way, crossfiring over the 3.5" midrange sunk into the dash of my truck…aka as the linkwitz/Pluto configuration.





















The reason that the first graph has dips at 200hz and 4000hz is because the speaker isn't mounted perfectly at the apex. Basically if the speaker is mounted *exactly* at the apex of a waveguide, you get a slooooowly falling response, like the second pic. If it's NOT mounted perfect at the apex, you get a similar shape, but with dips that correspond with how far the driver is from the apex. (Hence, my 'magic number' as described at the bottom of page one.)

By the way, it might LOOK like the response of the driver is falling. Oddly enough, it's not. It's RISING as we go lower and lower and frequency. Basically we're getting more and more gain on-axis as the wavelengths are being constrained by the waveguide. There's something like 10-15dB of gain on axis at 1000hz; so a 2" woofer that's good for 84dB on a flat baffle can do as much as 94-99dB with one watt on a waveguide or horn.

As for the LX Mini, the ideal 'tweeter' for an LX Mini isn't a tweeter at all; for an LX Mini you want a full range driver for a tweeter. This is because the design hinges on a low xover frequency; iirc the xover is something like 700hz.


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## mitchyz250f (May 14, 2005)

One interesting thing about the paper is they never say how big the 'midrange' is. In the picture provided on page 12 the 'center channel' midrange it looks like a typical 3" or 4" car speaker.

Patrick is "X" the distance from the apex of the window/dash to the farthest edge of the speaker radiating surface?


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## Patrick Bateman (Sep 11, 2006)

mitchyz250f said:


> One interesting thing about the paper is they never say how big the 'midrange' is. In the picture provided on page 12 the 'center channel' midrange it looks like a typical 3" or 4" car speaker.
> 
> Patrick is "X" the distance from the apex of the window/dash to the farthest edge of the speaker radiating surface?


Realistically, it's from the center of the speaker to the apex of the windshield and the dash.

But when you think about it, the entire surface of the speaker is radiating sound. So if you had a 3" diaphragm that's 3" from the apex of the windshield, the center of the cone will generate a suckout at 1125hz*, while the edge of the cone will generate a suckout at 2250hz.** And there would be suckouts all along that range, because the whole cone is radiating, not just the center.

* 13500hz / 3inches / 4 = 1125hz
* 13500hz / 1.5inches / 4 = 2250hz

In the real world, I'd imagine that a large cone would simply create a wider but shallower suckout. A small cone would create a narrow but deep suckout.

If I'm not mistaken, the Harmon plots are computer generated. Not sure if they modeled the speaker as a single point in space, or as a driver with an actual diameter. I know that Hornresp models speakers as being infinitely small, and that's why the peaks and dips in Hornresp look really deep and narrow, when in the real world they're broad and shallow.


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## Orion525iT (Mar 6, 2011)

Patrick Bateman said:


> Due to a couple things:
> 
> 1) if you put some wool in there to fill in the gap, *you still have a reflection off the windshield.* The wool will definitely help, but then you have a second problem...
> 
> ...


This literally what I did here with my pods. They were designed to prevent the "X" from entering the equation. The pods create a false apex where the driver is located. That is a single Aura Whisper for a midrange 
















Orion525iT said:


> Ok, so I got the new motherboard and cpu. The motherboard is nice because it has a dedicated and isolated audio implementation. I had some issues getting things up and running because the power supply is also dead. I am almost certain that the powers supply flaked out and killed the other motherboard since both are now bricked.
> 
> Anyway, I did what Erin suggested and ran a sweep with the whisper then disconnected the whisper at the amp and ran the tweeter through the same channel. This is to make absolutely sure the levels are matched. No EQ, just reasonable cross overs so protect the drivers.
> 
> ...


As noted, there is significant gain centered around ~1300hz. I think I am losing some gain at the bottom because of the size of the wave guide (maybe?) and also because the pod is not sealed where it meets the windshield, allowing the longer wavelengths to cause interference.

Compare my measurement to the spec sheets for the Whisper and the tweeter. 

https://www.parts-express.com/pedocs/specs/296-252_AuraSound_NSW2-326-8A_Specifications.pdf

https://www.parts-express.com/pedoc...sformer-automotive-tweeter-specifications.pdf

There is probably some improvements that could be made to the design. I took the placement idea from Garys' Mercedes and made an artistic guess and carved the pods out of body filler. I am sure if I knew how, and put some math into it, with knowledge of horn theory (which I lack), it may be possible to achieve even better results. But as it is, it's an artistic guess that seems to work. I have not quite achieved the impact I desire, but to my ears everything else is fairly impressive. I don't need to keep my head in a vise either.


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## mitchyz250f (May 14, 2005)

Patrick thanks for clearing that up.

In the paper Harmon did CAD simulation of a car interior. Then they tested and gave attenuation values of all interior surfaces (leather, hard plastic, cloth covered foam...). They then ran simulations using the data to predict results of actual testing. 

Plots were from actual readings, 100 per seating position per speaker location and speaker angle.


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## Patrick Bateman (Sep 11, 2006)

Just pulled the trigger on a laser cutter. Here's an example of what they can do:










I think my 3D printer is still optimal for waveguides, but this should be fun for sub boxes. The size isn't huge but I don't know how I'd move the big one, it's 250lbs


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## Patrick Bateman (Sep 11, 2006)

Orion525iT said:


> This literally what I did here with my pods. They were designed to prevent the "X" from entering the equation. The pods create a false apex where the driver is located. That is a single Aura Whisper for a midrange
> 
> 
> 
> ...


The two drivers I'm looking at are the Vifa TC6 and the Aurasound Whisper.

If I wind up going with the latter, lmk if you want me to send you a set of waveguides.

I'm thinking about a waveguide that's about 110 degrees wide by 70 degrees vertical. An average of ninety degrees of coverage.


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## ndm (Jul 5, 2007)

Patrick Bateman said:


> Just pulled the trigger on a laser cutter. Here's an example of what they can do:
> 
> 
> 
> ...


Which cutter did you get?
How much do those go for. I have been wanting to buy one. Preferably one that etches in 3d too.


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## Patrick Bateman (Sep 11, 2006)

The one I bought can only cut pieces that are about 8" x 12". I paid about $400 delivered. Ships out of CA and I live in CA so that helps. It's called a "K40" and is readily available on eBay and Amazon.

Here's some links : https://www.google.com/search?clien...8&oe=UTF-8#q=k40+laser+cutter+site:reddit.com

There was one I liked better, that can cut pieces about 3X the size, but it weighs 250lbs. I literally don't know how I'd move it.

On the upside, I figure I can break a model into a bunch of pieces and print them individually.


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## ndm (Jul 5, 2007)

Patrick Bateman said:


> The one I bought can only cut pieces that are about 8" x 12". I paid about $400 delivered. Ships out of CA and I live in CA so that helps. It's called a "K40" and is readily available on eBay and Amazon.
> 
> Here's some links : https://www.google.com/search?clien...8&oe=UTF-8#q=k40+laser+cutter+site:reddit.com
> 
> ...


What was that other model? I am really thinking about getting one. I may even build a cnc router.


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## Patrick Bateman (Sep 11, 2006)

Search eBay for "DIY 50W CO2 LASER ENGRAVER ENGRAVING CUTTING MACHINE AIR ASSIST USB U-FLASH"

I'd post a link, but there's easily a hundred of these for sale.

My brother built a CNC router before I bought my 3D printer, and his router was one of the reasons I *didn't* buy a router. I got the impression that he spent nearly a year getting the thing up and running.

On the upside, he can make objects that are way WAY bigger than what I can do.

My work is pretty sloppy, and when it comes to woodwork, that's a huge problem. I have a difficult time making a cube that's perfectly square. It was easier when I lived in Oregon and I had a lot of space; my garage really doesn't have room for the tools I have already, and there's absolutely no room for a table saw.

Basically the laser is appealing to me because it's accuracy is so high; I figure I should be able to make really nice and symmetrical objects if I cut them this way, instead of trying to make it work out with the miter saw and a circular saw.


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## Orion525iT (Mar 6, 2011)

Patrick Bateman said:


> The two drivers I'm looking at are the Vifa TC6 and the Aurasound Whisper.
> 
> If I wind up going with the latter, lmk if you want me to send you a set of waveguides.
> 
> I'm thinking about a waveguide that's about 110 degrees wide by 70 degrees vertical. An average of ninety degrees of coverage.


That would be awesome.

But to shoot myself in the foot, I'll throw this thought out there. The Whispers are nice and compact. Depth is only slightly greater than an inch. But, there is a downside to their construction. The driver is roughly cylindrical and this limits how far back you can push them into the apex of the dash and windshield. I driver with neo magnet and a traditional basket may allow better (further back) placement. So the neo version of the TC6 might be the way to go.


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## Patrick Bateman (Sep 11, 2006)

My plan is to use a couple of them and mount them offset


















Picture a strange hybrid of a Tymphany LAT and a Synergy horn, except with midranges only, and no tweeter at the apex.

I can't really put midranges at the top and bottom, only the left and the right, because of the way the dash is shaped. Basically a waveguide that's wide fits on the dash better than a waveguide that's square or round.









Actually, it would look a lot like this, but rotate 90 degrees so those midranges are on the left and on the right, not the top and the bottom.


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## mitchyz250f (May 14, 2005)

Patrick Bateman said:


> Picture a strange hybrid of a Tymphany LAT and a Synergy horn, except with midranges only, and no tweeter at the apex.


I just can't picture a strange hybrid of a Tymphany LAT and a Synergy horn, except with midranges only. What are the dimension of the horn? What frequencies would it control?


Up until now I thought you were going to take a compression driver, mount it in the area available for the dash mounted tweeter and route the output to the apex of the windshield? All problems solved, I thought.

If you were remaking your dash could you make your dash one of the walls of a synergy horn? Could you place a midrange under the dash with only two outlet holes (like the Synergy Horns) placed at the location location?


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## Patrick Bateman (Sep 11, 2006)

mitchyz250f said:


> I just can't picture a strange hybrid of a Tymphany LAT and a Synergy horn, except with midranges only. What are the dimension of the horn? What frequencies would it control?
> 
> 
> Up until now I thought you were going to take a compression driver, mount it in the area available for the dash mounted tweeter and route the output to the apex of the windshield? All problems solved, I thought.
> ...












Like this.

Basically a Synergy horn, minus the tweeter at the apex. The removal of the tweeter allows me to get it closer to the windshield. The whole idea is NOT to cut up the car, basically make it fit the corner as seamlessly as possible.

The midranges are placed face-to-face, to reduce the depth. (Similar to a Tymphany LAT)

If there was a compression driver that fit here, I'd buy it. But there's not, so I'm making my own compression driver. (A compression driver is simply a conventional driver with a compression chamber in front of it, that's designed to be mounted on a waveguide or horn. So we're making a compression driver here.)









The JBL ring radiators work in a fairly similar way


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## mitchyz250f (May 14, 2005)

Do the two speakers in the synergy horn have to be opposite of each other? If you place one of the speakers on top you could really jam the horn into the corner.


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## Patrick Bateman (Sep 11, 2006)

I'm really starting to wish that some of my experiments would actually work lol

I spent literally twelve hours in front of the PC yesterday, tried half a dozen different configurations, and all of them ended up looking a lot like the midrange and tweeter that I built a few weeks ago. (That's the one pictured above.)

There were three problems that I kept running into, over and over again:

1) I can easily make a waveguide for a single 2" woofer, but if I use a single 2" woofer, I'm not 100% convinced it will be sufficient. It might. I dunno. Gary uses a single 3" midrange, but the power handling of his midranges is dramatically higher than what I'm working with. (Aurasound Whisper.) I'd use a neodymium midrange if I knew of one that costs less than $50. The Dayton neo mid is great, but the flange is ****ing ridiculous. It's a three inch driver with a flange the size of a subwoofer. Literally an inch on each side. Dumb.

2) If I stack two midranges vertically, I raise output by six decibels, but then it's too tall. If you're going to have a throat that's 4" tall, you might as well use a 3" or even a 4" driver.

3) Based on all that, the obvious thing to do is build a two-way, but then I'm right back to where I was about six weeks ago, with the waveguide pictured above.

I'm semi-tempted to just build an array again. My main gripe with the last array that I built was that it sounded 'grungey' and had no treble. But I was using $2 drivers, and "garbage in / garbage out." I have enough Whispers to build a four element array for each side...


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## thehatedguy (May 4, 2007)

The Whispers are incredible speakers, but I don't think they are ever going to get you the dynamics you are used to...no matter what you do to them.

I liked them in a 1.5 configuration, I rolled the top of one off so it could do treble and had the extra cone area for the midrange.


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## Patrick Bateman (Sep 11, 2006)

Patrick Bateman said:


> Here's some pics of the Dayton RS52, sawed in half. Gives you an idea of how similar it is to a compression driver.
> 
> 
> 
> ...


It might be possible to chop up a Dayton RS52 and horn load it. Above is a quote I made from a couple years ago, in context of the project I was working on for my previous Mazda. (At least that system I finished  )

I just measured my RS52 again, and here's what I got by making the back chamber a little bit bigger than what I used in 2013:

fs = 660hz
qts = 1.4
qes = 1.75
qms = 7.27
re = 5.4
le = 0.12

Looks like a fairly good candidate for horn loading. I'd need to come up with some kind of phase plug.


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## Patrick Bateman (Sep 11, 2006)

Here's some (really) quick sims comparing the Dayton RS52 vs an AuraSound Whisper on a horn.

Some observations:

1) The Dayton RS52 has about 3dB more output at high frequency. I'm not entirely sure why. Normally this is due to a higher EBP, but they're virtually identical. The Whisper has an EBP of 313hz, the RS52 has an EBP of 306hz. (read here for more : https://en.wikipedia.org/wiki/Thiele/Small )
2) The Dayton RS52 has 25% more BL than the Whisper. (Horns like drivers with high BL.)
3) The Dayton crushes the Whisper when it comes to power handling; it's four times as high. The Dayton has higher efficiency too. The surface area of the Dayton voice coil is about double that of the Whisper, and the diameter is 50% higher.
4) The Whisper crushes the Dayton on displacement; it's five times higher.

The two are matched up quite nicely. It would probably just boil down to how durable the Whisper is. The Dayton is going to generate a lot more output due to higher power handling and efficiency, but on the low end displacement sets the limits.


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## Patrick Bateman (Sep 11, 2006)

I just measured one of the AuraSound Whispers that PE has on sale. These are slightly different than the ones I used for my 2006 set of Unity horns. (I bought those from Madisound.)

Here's how they measured in free air:
fs = 216hz
qes = 0.97
qms = 4.6
re = 6.2
qts = 0.8


And here's how they measured when I sealed off the back. Basically created an ultra-small enclosure, to push up the F3 and raise the efficiency:
fs = 492hz
qes = 2.0
qms = 6.7
re = 6.2
qts = 1.53

the QMS and QTS will probably go down with time; these were fresh out of the box.


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## Patrick Bateman (Sep 11, 2006)

The flange of the Dayton RS52 is definitely a problem. If the flange was half the size, it would work way better.
















A single Whisper fits great, but there's no easy way to place more than one here vertically. Horizontally wouldn't be problem, but then you have to filter one driver to fix the interference pattern.


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## Orion525iT (Mar 6, 2011)

Seems like we have run down the same road and came to the same inference. I looked many times at the RS52 as a way to get more output and higher power handling...but that flange is a huge impediment even if you are willing to hack away at the dash. 

I really like vertical arrays using two drivers. They seem to solve many issues that a single larger driver cannot achieve. But if your target is >600hz to match your midbass, limitations on physical placement start to illicit too many compromises.

I had casually mentioned this before at some point in another thread, but I had sketched up what I referred to as a "conjoined phase plug" that could be applied to a pair of Whispers aligned 90 degrees to one another. The Whispers lack a dust cap or a whizzer cone typical of most wide/full ranger drivers. This makes the design of a phase plug much easier. But, I couldn't convince myself that the phase plug would work, and designing and carving one by hand was not something I was willing to take on at the time. But if the idea is valid, then maybe it could then used in a horn. Also, I never realized the advantages of a sealed back.


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## Patrick Bateman (Sep 11, 2006)

I painstakingly measured five of the Dayton 1/2" midranges, which may or may not be the same drivers as what Don Keele uses for tweeters in his CBT array. And then the stupid forum timed out when I posted the message.

Anyways, all five measured about the same. These are the specs for the last one I measured:

re = 7.38
fs = 503hz
qts = 1.6
qes = 3.4
qms = 3.08
le = 0.07

A reviewer at PE basically said these were junk, but I don't agree. Due to the very high qts, they're going to have a rise at the FS of 503hz. But we WANT that for horn loading; we intentionally use tiny enclosures because that rise at Fb complements the gain that you get from the horn. Basically it's a yin-yang thing; as the horn starts to unload, the rise from the high Fb offsets the falloff of the horn. Combine the two and you wind up with a fourth order rolloff instead of a second order rolloff, and the response is flat across the bandwidth.

If you were using these on a flat baffle you'd want to use a low pass filter to fix that bump at Fb though 

But it doesn't mean they're junk; they're just, um, "unconventional."


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## Patrick Bateman (Sep 11, 2006)

After wasting about eighteen hours in front of the laptop, I decided that what worked before would probably work pretty good here.

So I took one of my waveguides and chopped it into pieces until it fit in my Mazda...









Here's how it looked when I started. This is a Pyle PH612. It's a clone of the JBL progressive transition waveguide. Zilch (rip) popularized this waveguide in his "econowave" speakers.









The waveguides from my 2006 project* are virtually identical in coverage. Here's the mold I made, nine years ago.





































Here's some pics of the waveguide after I chopped it up until it fits in the corner. You can see about half of the waveguide is gone.









In this pic I'm trying to show how tight the fit is; my fingers barely fit in the widest gap, and most of the edges touch the car. This is really important; you want a perfectly seamless transition from the waveguide to the car itself, so the car "extends" the waveguide seamlessly.









In this pic, I've added a couple of midranges to the waveguide.



* here's the 2006 thread : http://www.audiogroupforum.com/csforum/showthread.php?t=62789


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## Patrick Bateman (Sep 11, 2006)

Here's the waveguide coming together. I used the same method as described here to model it:

3D Modeling Tips and Tricks - diyAudio

The vertical beamwidth is thirty three degrees, versus 40 degrees for the JBL. I used a narrower vertical beamwidth so that the midrange will fit at the top easier.


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## rton20s (Feb 14, 2011)

Patrick Bateman said:


> 1) I can easily make a waveguide for a single 2" woofer, but if I use a single 2" woofer, I'm not 100% convinced it will be sufficient. It might. I dunno. Gary uses a single 3" midrange, but the power handling of his midranges is dramatically higher than what I'm working with. (Aurasound Whisper.) I'd use a neodymium midrange if I knew of one that costs less than $50. The Dayton neo mid is great, but the flange is ****ing ridiculous. It's a three inch driver with a flange the size of a subwoofer. Literally an inch on each side. Dumb.


You're obviously progressing from here, but I wanted to mention a couple of options (you are probably already aware of) that meet your requirements of smaller (than the NS52) 2"-3" Neo midranges under $50.

FaitalPro 3FE22
SB Acoustics SB65WBAC25-4
Wavecor FR070WA01
Sundown SA-2.75FR (I have a set for sale)

The Scanspeak 5F/8422T-01 is also available just outside of your price range. Perhaps a used set?


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## Patrick Bateman (Sep 11, 2006)

rton20s said:


> You're obviously progressing from here, but I wanted to mention a couple of options (you are probably already aware of) that meet your requirements of smaller (than the NS52) 2"-3" Neo midranges under $50.
> 
> FaitalPro 3FE22
> SB Acoustics SB65WBAC25-4
> ...


I have some 3FE20s and I'm not a fan. Can't figure out why they're so popular. The Fostex FF85Wk is much better and costs about the same.

I really want to use my SB65s; haven't found an excuse yet.

The Sundowns look interesting...


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## Patrick Bateman (Sep 11, 2006)

I'm "pushing" the midranges right into the horn, but I think I have to, as I want to push the whole thing as far back as humanly possible. I'm hoping that the spherical caps will minimize the damage that doing this causes.


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## rton20s (Feb 14, 2011)

Patrick Bateman said:


> I have some 3FE20s and I'm not a fan. Can't figure out why they're so popular. The Fostex FF85Wk is much better and costs about the same.
> 
> I really want to use my SB65s; haven't found an excuse yet.
> 
> The Sundowns look interesting...


The more I looked into the FaitalPros, the less I had a desire to test them out. 

This is the manufacturer supplied response graph for the Sundowns (1/3 octave smoothing). So certainly not on par with the upper tier stuff.









If you're interested in trying them though, shoot me an offer. I'll make you a good deal.


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## mitchyz250f (May 14, 2005)

Patrick, how is the location of the midrange port determined?


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## ggk (Sep 5, 2008)

Patrick,

You need a 3d scanner now. It would make it so much easier to just print a pod that can integrate with the dash and windshield perfectly.


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## Patrick Bateman (Sep 11, 2006)

mitchyz250f said:


> Patrick, how is the location of the midrange port determined?


The short answer is that you put the midrange one quarter wavelength away from the tweeter's crossover frequency.









For instance, in the Danley SH50 the midrange 'taps' are 3.5" from the throat of the horn. Sound travels 13.5 inches in one thousandth of a second, so 1000hz is 13.5" long. Therefore, with the midrange taps 3.5" from the throat, *you want to use a crossover frequency of 962hz.*

With that in mind, you'll notice that the CLOSER you are to the throat, the higher the xover frequency, and the further, the LOWER.

This is one of the many reasons I use these tiny midrange; it allows me to push the xover frequency up to 1500hz or so. The 'real' Synergy horns use a much larger compression driver, and are able to get away with a xover frequency around 1000hz.


By the way, there are reams and reams of discussion about this over at diyaudio in the thread titled "suitable midrange cone for unity horn."

Despite all the pages of discussion, I generally just 'eyeball' it. I used to measure it and calculate it, but after building a pile of these I found that you basically just want to get the midranges as close as possible.

You have a LOT more leeway with the midbasses because the xover frequency is so much lower; for instance you can put the midbasses 10" away with a xover frequency of 350hz from midbass to midrange:

13500 / 340hz / 4 =
9.92"


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## Patrick Bateman (Sep 11, 2006)

ggk said:


> Patrick,
> 
> You need a 3d scanner now. It would make it so much easier to just print a pod that can integrate with the dash and windshield perfectly.


Never had very good results with 3D scanners. Maybe I need more practice? I dunno. My laser cutter arrived yesterday, hopefully I won't have to learn Sketchup to use it. (I use 123D for 90% of what I do.)


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## Patrick Bateman (Sep 11, 2006)

Here's a couple pics of what I'm printing. Some random observations:

1) the 'box' thing at the bottom of the model is there so that the model won't 'slip' on the 3D printer. Once it's printed, I cut that off
2) the waveguide is split down the middle because it's too big for my 3D printer to print in one pass. So I'll print each half and glue them together. That sounds like a lot of hassle, but I've grown accustomed to welding models together from multiple pieces. Due to the accuracy of 3D printing, it works quite well.
3) Note that the midranges 'push' into the waveguide quite a bit. This will probably have an impact on the polar response at the edge of the waveguide, but I think that's a better compromise to take than having a 'gap' due to the midranges sticking out from the edge of the waveguide.

It's going to take a day to print each waveguide.


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## mitchyz250f (May 14, 2005)

Patrick in your opinion what is the ideal theoretical dispersion for the horn and will all the speakers be on axis with the driver? Is the how Gary has his car setup?


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## Focused4door (Aug 15, 2015)

Patrick Bateman said:


> Search eBay for "DIY 50W CO2 LASER ENGRAVER ENGRAVING CUTTING MACHINE AIR ASSIST USB U-FLASH"
> 
> I'd post a link, but there's easily a hundred of these for sale.
> 
> ...



Table saws are over rated IMHO.

I use a guide like this for the circular saw Shop BORA WTX 100-in Clamp Edge Saw Guide at Lowes.com


I also have a Kreg jig, but rarely use it. I like the simple guide much better.

I would get a panel saw long before a table saw, way easier to handle large sheets that way. They are accurate for competent users. 




Patrick Bateman said:


> Here's a couple pics of what I'm printing. Some random observations:
> 
> 1) the 'box' thing at the bottom of the model is there so that the model won't 'slip' on the 3D printer. Once it's printed, I cut that off
> 2) the waveguide is split down the middle because it's too big for my 3D printer to print in one pass. So I'll print each half and glue them together. That sounds like a lot of hassle, but I've grown accustomed to welding models together from multiple pieces. Due to the accuracy of 3D printing, it works quite well.
> ...


The midrange is firing through an aperture? How do you calculate the frequency response of that aperture?


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## Patrick Bateman (Sep 11, 2006)

mitchyz250f said:


> Patrick in your opinion what is the ideal theoretical dispersion for the horn and will all the speakers be on axis with the driver? Is the how Gary has his car setup?


In a car, the ideal dispersion is simply whatever angle you're presented with by the car itself.









For instance, in my car the corner forms a ninety degree angle. If I tilt the speakers inward by 45 degrees, then I wind up with a waveguide that's 90 degrees with the sound shooting right down the center.

The vertical angle is a little trickier. At first I set it to the rake of the windshield, which is 30 degrees. But that's not 100% correct, because the dash *also* slopes down. Put those two together and your angles are ninety by forty.









The Pyle PH612, which I chopped up yesterday, is exactly that: ninety by forty.


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## Patrick Bateman (Sep 11, 2006)

Focused4door said:


> Table saws are over rated IMHO.
> 
> I use a guide like this for the circular saw Shop BORA WTX 100-in Clamp Edge Saw Guide at Lowes.com
> 
> ...


Back in the day I used to get wrapped up with the math to calculate the perfect chamber, but this is another one of those things that I just "eyeball" now.

The optimum chamber would be basically as small as possible.









In the Danley SH25 you can see they have a disc in there to reduce the volume of that chamber









The EAW Anya is even slicker; there's a plastic contraption that reduces the volume in the chamber to basically nothing.

The smaller you make the chamber, the higher the midrange will play.









Here's the Anya with all of the drivers tucked away. That's a three way loudspeaker. IIRC, there's two woofers, four midranges and two compression drivers.


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## Orion525iT (Mar 6, 2011)

Patrick Bateman said:


> Back in the day I used to get wrapped up with the math to calculate the perfect chamber, but this is another one of those things that I just "eyeball" now.
> 
> The optimum chamber would be basically as small as possible.


Is it just the chamber size that determines the high freq cutoff? Doesn't the location of the aperture relative to the cone also come into play? Like it does with a phase plug? How does a hole near the center of the cone differ from a hole at the edge of the cone when it comes to frequency response?


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## Patrick Bateman (Sep 11, 2006)

Yes, it's a phase plug.

The location of the midrange taps should make a difference, but at 1000hz or 1500hz, the wavelengths are long enough that the location isn't really a huge deal. I've tinkered around with some fairly complex phase plug designs, including a 3D printed tangerine phase plug, and found that the difference in frequency response is fairly minimal.









I did something fairly unusual for these phase plugs, they're a copy of the phase plugs from the L'Acoustic arrays. The reason that I did this is that the L'Acoustic phase plug maintains a constant area over the length of the plug:










The phase plug in the Danley SH50s works a bit like the water jets at the Bellagio, the plug gets smaller and smaller as it reaches the exit. This should have the effect of increasing the velocity of the air exiting the phase plug. I've generally used this type of design in most of my horns, and I have a pair of horns at home that start to make some ugly noises at fairly low power. I think this is because the phase plug can't move enough air.

So I'm hoping the V-DOSC style of phase plug should move more air. Or at least that's the idea. It's probably overkill really, because I've never had this issue with Synergy horns. The horns that I have at home, that make some ugly noises at moderate power, are 8" horns. So they move a lot more air because they play lower.


By the way, a huge amount of this stuff depends on the frequency. At high frequency we have to be insanely careful about pathlength because the wavelengths are so short. At midrange, not so much. At low frequency, it doesn't matter much at all, but then the *volume* of air that you can move becomes an issue.


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## ggk (Sep 5, 2008)

Patrick Bateman said:


> Never had very good results with 3D scanners. Maybe I need more practice? I dunno. My laser cutter arrived yesterday, hopefully I won't have to learn Sketchup to use it. (I use 123D for 90% of what I do.)


3D scanning has come a pretty long way, the resolution and the ease of use has gone through the roof. You can buy a 3D scanner that mounts on your ipad that is accurate down to .9mm. I mean it is a far cry from a faro laser or something along those lines, but should work for this.

Autodesk Fusion360, great little CAD tool, and it is free for personal use. It has the ability to export waterjet Gcode, so it should work with your laser. (I know it works with a plasma table)


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## Patrick Bateman (Sep 11, 2006)

ggk said:


> 3D scanning has come a pretty long way, the resolution and the ease of use has gone through the roof. You can buy a 3D scanner that mounts on your ipad that is accurate down to .9mm. I mean it is a far cry from a faro laser or something along those lines, but should work for this.
> 
> Autodesk Fusion360, great little CAD tool, and it is free for personal use. It has the ability to export waterjet Gcode, so it should work with your laser. (I know it works with a plasma table)


I'll definitely have to check out Fusion. Looks like it's a more powerful version of what I'm already using (123D.)

And I'm already fairly decent with gcode, as it's what I use for my Printrbot.


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## Patrick Bateman (Sep 11, 2006)

I *love* the fact I can make things with a tolerance of a millimeter now. I left exactly one millimeter of space for the midranges and they fit like a glove.


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## Patrick Bateman (Sep 11, 2006)

Oh, I forgot, if anyone wants to make one of these things, the usual offer stands. I'll upload the model to Shapeways if you want to print it. Due to the size of this thing - twice as big as the previous models - it will probably be kinda pricey. I'd guess about $80 per side.

If you DIY it, a Printrbot is $599 : Assembled Printrbot Simple | Printrbot

And the filament is under $10 per side: http://www.amazon.com/HATCHBOX-1-75mm-3D-Printer-Filament/dp/B00MEZEEJ2









You need three of these ($12) : Peerless TC6WD02-04 Silver Series 2" Midrange









And one of these per side ($21): SB, SB18ST-C000-4


So the 3D printer is a fairly significant investment, but the parts cost for the speaker is $43 per side.


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## WeDgE (Oct 25, 2005)

Patrick, how do you plan on blending the horns into the windshield/dash to make it seamless? 

Would like to do a set in my 06 Silverado, just unsure because the instrument cluster would prevent a direct line to my ears.


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## Patrick Bateman (Sep 11, 2006)

WeDgE said:


> Patrick, how do you plan on blending the horns into the windshield/dash to make it seamless?
> 
> Would like to do a set in my 06 Silverado, just unsure because the instrument cluster would prevent a direct line to my ears.











Here's the new waveguide in the car. As you can see, it's still in two pieces. I need to 'weld' the two together with epoxy, seal off the waveguide with bondo, mount the drivers, etc.









Here's the Pyle/JBL waveguide, after some aggressive chopping to make it fit. You can see the transition to the windshield and the dash is pretty seamless









Here's the 2009 project*, which worked pretty well. Maybe I should've just used that set lol. (I trashed this set a long time ago, it's too bad I'm so ADHD about this stuff.)









Here's @ClinesSelects project**, really nice work here I wish I could make my stuff look this good.

















Basically I need to weld the waveguide with epoxy, seal it off with bondo, mount the drivers, then chop off that corner so that I can push the waveguide all the way back into the corner of the dash

* My 2009 project, probably my definitive waveguide install: http://www.diymobileaudio.com/forum...ussion/60146-creating-perfect-soundstage.html

** @ClinesSelect waveguide install : http://www.diymobileaudio.com/forum...allery/13527-dodge-ram-install-thread-15.html


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## Patrick Bateman (Sep 11, 2006)

Here's the response of my 3/4" tweeter on the waveguide. A couple of notes:

1) the response is falling because all constant directivity waveguides do this. They require EQ to flatten out the top end. The main thing here is that the response is smooth and can be easily EQ'D flat
2) The dip at 3000hz is caused be a reflection from the unterminated mouth of the waveguide. This shouldn't exist in the car, because it's terminated when it's in the car.









Here's a SUPER early measurement of the midranges. I don't have the back of the enclosures sealed off properly, I literally covered them with Saran Wrap. So this will give you a general idea of what the bandwidth and efficiency is, but the final verdict will come when I have them properly sealed. (Saran Wrap is a barely-sufficient way to seal a box.)

I'd take the distortion measurement of the midranges with a grain of salt. I could hear the saran wrap flapping during the measurement, and it's definitely polluting things.

The distortion measurement of the tweeter is legit, and it looks like I can cross them as low as 1500hz.

The midnrages are ridiculously efficient; I have them wired in series for a twelve ohm load and they're still over ten decibels more efficient than the tweeter.



Both measurements were made in my garage, not the car. I wanted to get a rough idea of how the horn would perform. Looks like it will be able to do six octaves, from 350hz to 20khz.


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## mitchyz250f (May 14, 2005)

Patrick Bateman said:


> 2) The dip at 3000hz is caused be a reflection from the unterminated mouth of the waveguide. This shouldn't exist in the car, because it's terminated when it's in the car.


Can you explain this a little better? Shouldn't exist but does!




Patrick Bateman said:


> The midnrages are ridiculously efficient; I have them wired in series for a twelve ohm load and they're still over ten decibels more efficient than the tweeter.


What db at 1 watt?


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## Patrick Bateman (Sep 11, 2006)

mitchyz250f said:


> Can you explain this a little better? Shouldn't exist but does!
> 
> 
> 
> ...


When a horn isn't terminated, the sound reflects back into the throat. You can see this in the impulse response; there's a peak that corresponds to it, and that reflection is creating that dip.

The fix is simple: you terminate the horn

When I put the waveguide in the car, I'll terminate it on all sides, problem solved.

As for the efficiency, I'd guess it's somewhere around 95-100dB on the midranges.

In the Danley Synergy Horns, the midrange array is so efficient, they have to pad it down so that it doesn't overpower the compression driver... And the compression driver has an efficiency of 109dB!

You get really ridiculous efficiencies with front loaded horns. The Jericho horn is capable of 147dB, full range.


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## Patrick Bateman (Sep 11, 2006)

Factors Affecting Sonic Quality of Mid & HF Horns & Waveguides

Here's a great explanation of horn termination and its benefits


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## Kevmoso (Jun 4, 2013)

This is looking REALLY good! Did you happen to capture some polar measurements of the tweeter?


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## mitchyz250f (May 14, 2005)

I understand. The horn hasn't been fitted or tested in the car yet. When can we see some pics?


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## Patrick Bateman (Sep 11, 2006)

mitchyz250f said:


> I understand. The horn hasn't been fitted or tested in the car yet. When can we see some pics?


I went to CES last week and was blown away by the Beolab 90. The 90 is an array with a narrow horizontal coverage. This is unorthodox; loudspeakers generally have *wide* horizontal coverage and *narrow* vertical coverage. The reason that they do this is so that there's a wide sweet spot for multiple listeners, and narrow vertical to reduce the effect of reflections off of the ceiling and the floor.

Beolab 90 flips that on it's head and I started screwing around with narrow angle designs over the weekend. I came up with something that works fairly well, so I'm going to hit the 'pause' button on the Synergy Horn that's documented up until this page. (How many freaken waveguides have I built now? 10? 20? lol)




























Here's my new toy. It's basically an underdash horn. I got my start with underdash horns, back in the 90s. I abandoned them for the most part because I found that up on the dash works better. The reason that I embraced it again here is because this underdash horn is different. Instead of using a 1" compression driver at the throat, it uses a 2" midrange. *So it's designed to play lower, but at the expense of output.* IE, if I was using a compression driver I could probably squeeze 109dB out of an underdash horn, but my low end would be limited to about 1000hz. By going with a low efficiency midrange, I'm hoping I can push the lowend down to 500hz, at the price of lower efficiency. (Probably around 95dB I'd guess.)









Aurasound Whisper. It's hard to see in the photograph, but the chamber in front of the Whisper reduces the exit to 1" in diameter. I do this to extend the highs; the smaller the throat is, the higher you can play. You have to be careful though; make it too small and the compression gets to high and it will sound nasty. With a 2" driver and a 1" throat, *I'm using a compression ratio of four to one.*





































Look familiar?

















Thanks to the wonders of 3D printers, I can make a *really* tight match to the diaphragm. (That silver thing in the throat is the diaphragm of the Aurasound Whisper.) This is *essential* with horns and waveguides; if you're off by even a fraction of an inch it can wreck the response across the entire bandwidth. Basically you get reflections right at the throat that create a series of peaks and dips across the whole bandwidth.


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## Kevmoso (Jun 4, 2013)

Those look awesome! Are you thinking a traditional mounting location under the dash or stuffing them back against the firewall?


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## Patrick Bateman (Sep 11, 2006)

Kevmoso said:


> Those look awesome! Are you thinking a traditional mounting location under the dash or stuffing them back against the firewall?


I think it's important to see the throat; if you can't there's a lot of diffraction. So if I had a car like Mic Wallace, I'd mount them back at the firewall. But I don't, my seat is quite upright. So I'll put them under the dash and flush with it.


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## Kevmoso (Jun 4, 2013)

If you expect 95ish db efficiency and the whispers are good for 20ish watts your looking at 108ish db output? That doesn't seem like a Patrick Bateman loudness target to me. lol


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## Patrick Bateman (Sep 11, 2006)

Kevmoso said:


> If you expect 95ish db efficiency and the whispers are good for 20ish watts your looking at 108ish db output? That doesn't seem like a Patrick Bateman loudness target to me. lol


There were a couple things that got me to this point:

1) I know I always reference Gary's car, but as references go, it's a good one. And Gary's car gets plenty loud for me. It uses a 3" midrange with an efficiency of something like 90dB. With a hundred watts, that gets you to 110dB.

2) Nola Audio was doing a demo at CES using a two-way that's about 87dB efficient. It sounded really good but it wasn't as dynamic as I'd like. I know what drivers they're using, and I can estimate that their system "maxed out" around 105dB.

Based on that, I'd say that 108dB will be sufficient. I'm not gonna lie, another 3dB of headroom would be nice, but that would require an array or a more efficient driver. I'm not aware of any 2" drivers that are much better than a Whisper. Basically there's a gap between the really nice widebanders like the Whisper, and the uber-efficient drivers like the JBLs. Nobody has really produced anything in the gap in between. The TangBand 852SH lives in that gap, but I think the Whisper sounds cleaner.










If you look at the 'typical' curve that you'd use in car audio, you can see that the lows are about 25dB louder than the mids. So if your low end is capable of 120dB, your mids only need to do 95dB.

The tricky part is the octave from 100-200hz, where we need to generate a lot of output but we don't have the benefit of cabin gain. THAT is the toughest part to get right IMHO.


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## Orion525iT (Mar 6, 2011)

Patrick Bateman said:


> There were a couple things that got me to this point:
> 
> 1) I know I always reference Gary's car, but as references go, it's a good one. And Gary's car gets plenty loud for me. It uses a 3" midrange with an efficiency of something like 90dB. With a hundred watts, that gets you to 110dB.
> 
> ...


Ok, I gotta rib you a bit here, Patrick. When you first got your printer (iirc) you talked about printing horns/waveguides for various drivers. One I suggested to you, since I had two pair, was the Whisper...and you shut it down citing EBP. Anyway, carry on .


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## Patrick Bateman (Sep 11, 2006)

Yeah that's one of the things that sucks about horns is that sometimes drivers which shouldn't work DO work

This is particularly important if you're using high compression ratios. For instance, I have some P-Audio midranges which have great specs for horn loading. But if you look at the cone you can see it's flimsy; if you pushed a really high compression ratio you'd probably dent the cone.

OTOH the Whisper is quite sturdy for such a small driver, and I'm hoping that will allow for high compression.

I've already printed and measured one waveguide using a fairly "normal" compression ratio of four to one.

I designed three more and printed two, and each one has a progressively higher compression ratio. The one that's drying right now has a compression ratio of about eight to one, and a throat that's actually smaller than a compression driver, just 7/8" across. I was tempted to try a 3/4" throat but I thought that would really be pushing it, particularly with a high pass of around 500hz. (There's only so much air that you can push through a duct.)

So basically I'm seeing how hard I can push a single driver.

I'll post some pics and measurements soon.


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## Kevmoso (Jun 4, 2013)

Someone, (maybe Orion?), suggested phase plugging two whispers together. Any further thoughts on that now?
I look forward to seeing your measurements.

I can't be alone in waiting to hear the Bateman audio machine having a eureka moment and proclaiming a project as the 'best sounding car speaker system ever heard' lol


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## Kevmoso (Jun 4, 2013)

BAM! I think I just named your brand Patrick!! Lol


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## Patrick Bateman (Sep 11, 2006)

Kevmoso said:


> Someone, (maybe Orion?), suggested phase plugging two whispers together. Any further thoughts on that now?
> I look forward to seeing your measurements.
> 
> I can't be alone in waiting to hear the Bateman audio machine having a eureka moment and proclaiming a project as the 'best sounding car speaker system ever heard' lol


That's the funny thing, I love to tinker but I'm terrible at finishing anything. I build supercomputers for a living, literally flying to Mexico next week to work on one that will be used by millions of people. But when it comes to critical listening I generally just purchase something that's finished. That's why my home speakers have been JBL, Gedlee, Vandersteen, etc... Tinkering is my thing but finishing isn't my specialty 

As far as putting two of them together, I think if I decided to do that I'd just do a Synergy horn, since you'll get better loading if you offset the midranges.


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## Patrick Bateman (Sep 11, 2006)

This is my Whisper. There are many like it but this one is mine.









Here's the frequency response and harmonic distortion of my Whisper measured in my garage, using a groundplane technique. As you can see, it's bandwidth is very wide, and it's efficiency is very low - about 82dB.

Here's the spec sheet : https://www.madisoundspeakerstore.com/images/products/secondary/nsw2-326-8at-1.png
It's pretty accurate; if anything it plays higher than they say it does.









This is the first underdash waveguide I made for it. That was last weekend. It's quite a small device, measuring about 7" wide by about 4" deep. Much much smaller than the commercial HLCDs out there. The reduction in size will decrease the amount of output (deeper horn = more gain) but it will also extend the highs (deep horn = rolled off highs)









Here's the frequency response and distortion of my Whisper on my first waveguide, the white one.









Here's the frequency response and distortion of my Whisper with no waveguide, and WITH a waveguide. Note that we get seventeen decibels of gain, peaking at 1700hz. That raises the on-axis efficiency from 82dB to 99dB(!) So we're not quite in compression driver territory, but we're not too far from it either. A compression driver is about 109dB efficient. But a compression driver won't play to 700hz, a compression driver doesn't cost $20, a compression driver doesn't have three millimeters of xmax. So there's definitely some compelling reasons to horn load a conventional driver.









I added a really basic high pass filter, a single capacitor, in a attempt to flatten out the response. Basically the horn raises the output at the low end, and then you flatten it with a filter. You're left with a driver that plays flat, but is only getting a fraction of the power that it would normally get. This reduces excursion, which reduces distortion. You can see this on the low end of the measurement; see how the distortion is unmeasurably low at 1000hz?

This graph is also a polar graph, and it demonstrates a problem that I have here. *Due to the very small size of the device, it only controls directivity to 5000hz.* I did two measurements, one on axis, and one off-axis. See how they're basically identical below 5000hz? That's because the waveguide isn't large enough to be effective below 5000hz...


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## Kevmoso (Jun 4, 2013)

Pretty nice gain in output! It doesn't look like there is enough gain from the horn at the ~500hz highpass target to really be able to make use of the efficiency gains elsewhere? Total output would have the ~same excursion limited level unless the highpass is moved up into the 7-800ish hz region? Will a higher compression ratio have an affect on the low end?


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## Tgangsta (Jan 20, 2009)

Patrick why can't you put a paraline and attach two to three on it side by side then exit into the waveguide would this work


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## jwsewell01 (May 28, 2015)

Would a 2" compression midrange be possible?

http://www.bmsspeakers.com/index.php?id=bms_4591

Expensive though. Not as expensive as their newest Neo one. Lol


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## mitchyz250f (May 14, 2005)

Patrick when you compared Gary's setup to yours you didn't include the gain Gary's speakers where getting from the dash placement. So you could be Gary's system (above 500Hz) to be at 100db which is getting into the horn neighborhood.

Another thing about Gary's CDM-880 its 89-90db until about 700Hz then it start dropping. By the time it gets to 400 hz it down another 7db. I couldn't find a graph for the 880 but below is the chart for the CDM-88 the precursor to the 880. 

Morel CDM 88 Installation Manual (Page 2 of 2)


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## Patrick Bateman (Sep 11, 2006)

Tgangsta said:


> Patrick why can't you put a paraline and attach two to three on it side by side then exit into the waveguide would this work


heh that's exactly what I'm working on this morning 

















The midrange taps on the waveguide from two weeks ago were based on something from L'Acoustic called a "VDOSC." A Paraline is very similar to a VDOSC, both are basically a phase plug that can change the wavefront shape.

*I never had much luck with Paralines - they always crapped out around 10khz, and were pretty rough before they reached that point.*

But at these frequencies, there's really no margin for error, so the ability to 3D print them is critical. (All of my Paralines were made of wood, except for one. And the single Paraline that I printed months ago was printed before I understood that 3D printed speakers MUST be sealed because the plastic is NOT airtight.)









Here in the measured response of that waveguide, from two weeks ago, you can see that the midranges are going all the way to 4000hz. This is extraordinary, because it's usually difficult to get them to go to 2000hz. So the VDOSC style phase plug may hold some promise.

Here's a couple of videos to show how these devices sound (the real ones, not mine)

https://www.facebook.com/DanleySoundLabs/videos/vb.126113687424773/10201592108278626/?type=3&theater

https://www.facebook.com/DanleySoundLabs/videos/vb.126113687424773/10201597659497403/?type=3&theater


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## Patrick Bateman (Sep 11, 2006)

mitchyz250f said:


> Patrick when you compared Gary's setup to yours you didn't include the gain Gary's speakers where getting from the dash placement. So you could be Gary's system (above 500Hz) to be at 100db which is getting into the horn neighborhood.
> 
> Another thing about Gary's CDM-880 its 89-90db until about 700Hz then it start dropping. By the time it gets to 400 hz it down another 7db. I couldn't find a graph for the 880 but below is the chart for the CDM-88 the precursor to the 880.
> 
> Morel CDM 88 Installation Manual (Page 2 of 2)


That's a good point. One of the first things I noticed about the car was the dynamics.

On a side note, I was at CES last week and there was a speaker that was so dynamic I actually jumped out of my chair! Never seen one that could do that. It was somewhat similar to the Avantgarde horns, but it was horn loaded from top to bottom. (Most of the Avantgarde speakers use direct radiators for the bass.)


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## mitchyz250f (May 14, 2005)

Patrick your falling in to a trap. I remember buying my first home stereo. Made my choice on a system that fit my budget and then on the way to the register the salesman said these seemingly innocent words, 'you should listen to this system'. They sounded great but cost 50% more than my budget. 

And so it began. 2 months later I bought a system that cost 300% more than my budget.

You need to stop going to the shows. 

I am going to put 3 PHL1120s on my dash like Gary has his morels, so I should get really good response to 300-400hz. But just listening to you I feel the pull to the dark side...are my 12" midbass going to sound weak? I know they will not be weak but I am thinking there may be better. Do I need 15" midbasses? 15" midbasses are impossible in an ordinary sized cars quarter panels. I know cause I tried.

Mikey7182 had 18" midbasses/woofers in his truck and he said it put his 12s to shame. I have to live knowing that.

So for both of our sakes stop going to the shows.


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## Patrick Bateman (Sep 11, 2006)

mitchyz250f said:


> Patrick your falling in to a trap. I remember buying my first home stereo. Made my choice on a system that fit my budget and then on the way to the register the salesman said these seemingly innocent words, 'you should listen to this system'. They sounded great but cost 50% more than my budget.
> 
> And so it began. 2 months later I bought a system that cost 300% more than my budget.
> 
> ...


True, but I mostly like to tinker. My 2009 setup worked pretty well but lasted less than a month before I put it up on a shelf and started again.

And it's also fun to take elements from one project and use them with another. For instance, about nine months ago I did a crosstalk cancellation project which yielded an ultra-wide stage. Though my plan was to simply do crosstalk cancellation, it occurred to me that the uber-wide stage of the Beolab 90s may be due to a similar process.

IE, you can get a wide stage by cancelling crosstalk. B&O is using cancellation to change the speaker beamwidth. But since there's a lot in common between the left and the right channel when you listen to music, this might explain why the two techniques SOUND similar.

And once you start going down that path, it will occurr to you that you can do things similar to what B&O is doing, but instead of putting the cancellation drivers near the loudspeaker, you could put them somewhere else.

For instance, imagine if you had a stereo set of speakers on the dash of your car, along with *another* set of speakers that's designed to null out the reflection off the side windows.

The cancellation stuff works pretty amazing; IMHO there will likely be dozens if not hundreds of speakers for sale that do this. It's just too effective to ignore, particularly at low frequencies. At the moment there are only two speakers I'm aware of that do it, but that number will certainly grow.


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## mitchyz250f (May 14, 2005)

Please explain how you did the noise cancelations for reflections.

On a slightly different topic what about noise cancellation for the intrusive road noise that comes when a car moving? Couldn't you have microphones and small speakers as part of your headrest that would pick up the noise and cancel them. Since most of the road noise is below 500Hz small timing issues would not be such a problem. What are your thoughts?


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