# Gary Biggs mid diffusor



## ECM (Dec 23, 2007)

I came across a few articles on Gary Biggs' Buick Regal and I'm interested in seeing the so called diffusors he used on the mids to break up nodes around the speaker edge.

I've seen star shaped felt "diffusors" installed around tweeters on home speakers, but never on mids. And being made of felt, they are more like absorbers rather than diffusors. The article stated the diffusors used on the mids were machined out of aluminum with random edges.

I'm still amazed that he won all those competitions with a pair of 5.25" mids, a set of tweeters, and one subwoofer in the dash for SQ (two more were installed in the rear for SPL).

On a side note, how does his buick compare to RC's buick? Totally different installs, but both won many championships. The one thing they do have in common is power. RC used 2X250 watt Alpine amps and GB used Kicker or JBL amps rated about the same.

ECM


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## kevin k. (May 5, 2005)

Doug Winker, now Dr. Doug Winker, is the individual behind the diffusor. If I'm not mistaken, his Doctorate dealt in large part with the diffusor and the physics involved. Word has it he is now an acoustical engineer with JBL.


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## dvsadvocate (Mar 17, 2008)

Any pics of this diffuser?


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## freemind (Sep 11, 2008)

Did you read the June CA&E article on his setup?


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## ECM (Dec 23, 2007)

I'm overseas, we don't get CA&E.

The articles I saw were from way back, nothing recent. I did see his car online recently, but I think it's been redone.

There were no pictures associated with the article, I read in online. That's what I'm looking for, some pictures. I may just have to look for Dr.Winker's thesis or published works.


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## freemind (Sep 11, 2008)

Yes the car has been redone. The article goes somewhat in depth about how he did his setup.


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## benny (Apr 7, 2008)

JUNE CA&E?!?

I thought they were out of print


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## sdsport92064 (Jan 22, 2009)

Any links to said article?


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## cmusic (Nov 16, 2006)

sdsport92064 said:


> Any links to said article?


Biggs' Regal In Car Audio - Sound Deadening, Sound Trap, Path Length - Car Audio and Electronics Magazine


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## ErinH (Feb 14, 2007)

does anyone happen to have pictures of his setup? The article linked above doesn't have any. I would love to see some of what they're talking about (ie: relocating volume knob on headunit)


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## falkenbd (Aug 16, 2008)

bikinpunk said:


> does anyone happen to have pictures of his setup? The article linked above doesn't have any. I would love to see some of what they're talking about (ie: relocating volume knob on headunit)


i was hoping for the same thing.


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## monkeyboy (Jun 12, 2007)

Prepare to be disappointed... For all the trophies that the car won, and all the hype surrounding the article when it was printed, I was hugely disappointed. Lots of talk, and very few photos of a car that had so much work in it. They could have easily made the printed article twice as long. There is so much more in that car than what was shown. 

It is better than nothing though.


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## thehatedguy (May 4, 2007)

I agree. Was a bit disappointed by how short the article was.

If you want to know what the ring looked like, find a picture of a Manger MSW speaker. It looks a lot like the star shape of the Manger.


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## fonque (May 30, 2008)

Gary Biggs Regal pictures by xpvibe - Photobucket


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## ECM (Dec 23, 2007)

Thanks for scanning the mag fonque. The diffusion rings look just like I thought they would look, but the "teeth" are a little bigger than I figured they would be. Then again, the wavelength of a midrange soundwave is longer than that from a tweeter so they have to be bigger to be effective I suppose.

From the looks of it, it appears to be a very basic install, but I'm sure that's not the case. The dash is rebuilt, kicks are welded in place, diffusors installed, "bass traps" in the rear. There's lots of stuff going on.

Thanks again for the scanning the magazine pictures.

ECM


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## Tonyguy (Nov 15, 2007)

Can anyone explain exactly what this diffusor does and its advantages?


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## WLDock (Sep 27, 2005)

Tonyguy said:


> Can anyone explain exactly what this diffusor does and its advantages?


_"*Secret Kick Panels*
Like most competitors, the design of the kick panels is the single most closely guarded secret to the Regal. This is where the most smoke and mirrors are used to keep other competitors from figuring out their tricks. Biggs has played a great game, and the truth is quite surprising. The kick panels you see when looking inside the car contain no speakers, they are simply grilles, hiding the actual panels. 

The speaker locations themselves are not really even panels, but metal plates welded to the car. The speakers are mounted parallel to each other, 90 degrees to the door, in 11/44" aluminum plate. The JBL components are designed for a 30-degree off-axis response. That means that the best sound is heard when sitting 30 degrees from the center of the speaker. In Biggs' car, each listening position places the listener in the primary lobe of the speaker, yielding the best possible sound from that speaker. 

*Dashing Effects*
The design of the dash also affects the sound. The dash is symmetrical, which equalizes the reflections. The firewall is as smooth as possible; again, it's all about reflections. The grille on top of the dash is nothing more than decoration - more smoke and mirrors. The Regal has no center channel, contrary to popular belief. 

There is one other little trick Biggs used on the midrange driver in the front stage. Doug Winker, an acoustical engineer at JBL, designed a "diffraction ring." What this ring does is help minimize the secondary lobes coming off the side of the speaker. The ring is made of aluminum and starting just past the surround, a star-pattern is cut from the center. The teeth are of a random shape and size. There is serious engineering behind the rings' design, too much to get into here, but it seems to work for Biggs. 

The diffraction ring shown here on the mid driver is designed to eliminate the secondary lobes of the woofer from disrupting the primary lobe. The seats were built and positioned to optimize the audio in the primary lobe; any interference would not be good. "
_


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## qstarin (Mar 25, 2009)

> ... roof received *31/48"* of fiberglass mat and ... three PX300.4 amplifiers are mounted using aluminum stand-offs, creating about a *31/44"* gap underneath the amps ...



I think its his use of unconventional fractional measurements that produces such quality sound.

lolz.


I mean, seriously, "about 31/44"? How about, "about 3/4" or maybe even "about 7/10".


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## BMWTUBED (Aug 25, 2007)

Has there been any more published on the diffuser technology? I searched high and low and can not find any theory, calculations, thesis, papers, etc on the application. I suppose it may be in patent review...? If anyone has any info that would help with implementation (2118H), I would be all ears. Congrats to Dr. Winker BTW...
Thanks


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## thehatedguy (May 4, 2007)

Read Doug's dissertation...it's in there. He uses something similar with his 2118s too.


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## BMWTUBED (Aug 25, 2007)

Is it this one?
Improving Speech Intelligibility with a Constant-Beamwidth, Wide-
Bandwidth Loudspeaker Array

I'll start reading...


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## foosman (Oct 14, 2007)

Dr. Winker is now designing huge anecoic chambers, he graced us with a short tutorial about diffusers at Mark E.s advanced SQ seminar.


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## Oliver (Jun 25, 2007)

qstarin said:


> I think its his use of unconventional fractional measurements that produces such quality sound.
> 
> lolz.
> 
> ...


He is obviously very technical 

Guess he doesn't just throw em in the stock locations and wonder why it sounds bad


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## TXwrxWagon (Sep 26, 2008)

cmusic said:


> Biggs' Regal In Car Audio - Sound Deadening, Sound Trap, Path Length - Car Audio and Electronics Magazine


great article with the most amazing pics ever... 

if anyone has any old-school hot-rod experience its similar in concept to the K&N carburetor "stub stack".. which contours air coming into the carb throat area for a better transition... the design of Gary's car is on the same principles, just reversed, it controls the outgoing dispersion to a specific final pattern to the listener.,

http://www.knfilters.com/Racing/stubstacks.htm

rob


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## Patrick Bateman (Sep 11, 2006)

Tonyguy said:


> Can anyone explain exactly what this diffusor does and its advantages?


The baffle around the midranges is used to improve the off-axis response. The key to the system is that you have to design it to be listened to _off axis_, not on-axis. That's mentioned in the CA&E article.

My thread on soundstaging gets into why you want to listen off-axis, particularly on the first page of the thread:

http://www.diymobileaudio.com/forum/diy-mobile-audio/60146-creating-perfect-soundstage-3.html

The thing you have to understand is that the diaphragm area is what determines when a speaker starts to beam. Doug's solution is to use "teeth" around the midrange to vary the size of the diaphragm itself.

Does that make sense? The "teeth" don't affect the on-axis frequency response in a material way, but they *do* change the off axis response, and that's the key.

Doug alludes to that here:

http://www.audiogroupforum.com/csforum/showthread.php?t=61792


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## TREETOP (Feb 11, 2009)

BMWTUBED said:


> Is it this one?
> Improving Speech Intelligibility with a Constant-Beamwidth, Wide-
> Bandwidth Loudspeaker Array
> 
> I'll start reading...


That's it. There's definitely some good info there.


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## thehatedguy (May 4, 2007)

Think of a speaker having multiple tiny point sources on the cone. Beaming happens when all of those little sources focus...just like adjusting a flashlight from a diffuse light scatter to a sharp point. His solution more or less helps those tiny points scatter and not focus so tightly.


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## mitchyz250f (May 14, 2005)

Has anyone ever attempted to copy it? and plot the results?


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## Patrick Bateman (Sep 11, 2006)

Inspired by the Biggs Regal, I've decided to try a three-way front stage, using a relative of the midbass that he uses, along with a larger waveguide than what's in the Regal. If anyone curious, I'll document it here:

http://www.diymobileaudio.com/forum...forum/71993-unity-v-midbass-strikes-back.html


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## ALL4SQ (Mar 28, 2009)

The real question is, Did the mid diffuser ring actually stay in the car or was the picture just for creativity points? Garry Biggs is the Man! But sometimes its hard to tell fact from fiction with Gary. Sound quality competition is a game and when Gary was in the Lanes he played the Game real well. 


There are some people out there that still Use soft materials to play with a speakers dispersion. 
Here are a few pics:


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## thehatedguy (May 4, 2007)

Very true Mike. There is no telling as to what was really going on in the Buick or Mark's old 4 Runner.

The ring was in Doug's BMW though.


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## Tonyguy (Nov 15, 2007)

Patrick Bateman said:


> The baffle around the midranges is used to improve the off-axis response. The key to the system is that you have to design it to be listened to _off axis_, not on-axis. That's mentioned in the CA&E article.
> 
> My thread on soundstaging gets into why you want to listen off-axis, particularly on the first page of the thread:
> 
> ...


Nice! Thanks a lot Patrick. This is a great help for me to understand this.


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## Patrick Bateman (Sep 11, 2006)

The dreamliner uses it too, but I think it's to reduce turbulence


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## Patrick Bateman (Sep 11, 2006)

Tonyguy said:


> Nice! Thanks a lot Patrick. This is a great help for me to understand this.












Here's another midbass diffuser. This is from the Nexo prosound speakers. I believe Nexo has a patent on these, but I'm not 100% certain.

B&C 8PS21 8" Woofer 294-654









One of their other speakers uses the diffuser and the B&C 8PS21, which is one of the best drivers you can get for $100.

Here's how the Nexo diffuser works:

1) Most radiators that 8" have the same directivity. For instance, and 8" waveguide and an 8" woofer have directivity that's very similar
2) Sometimes you need directivity that's different. For instance, if you have a 1" tweeter you might want the directivity of an 8" diaphragm. So you put it in a waveguide.
3) But what happens if you want to go the other direction? For instance, what if you have an 8" driver and you need the directivity pattern of a 3" woofer? *Well that's where the Nexo diffuser comes in handy.* The Nexo diffuser takes an 8" woofer and it makes it behave like a smaller driver. So you get all the advantages of an eight, such as high power handling and output, with the directivity of a smaller driver. (IE, wider directivity than a conventional eight.)

Neat, no? And the diffuser also protects the woofer. Very cool and elegant.

It might seem like the diffuser would screw up the frequency response, but it likely won't as long as the driver's bandwidth is limited. For instance, two kilohertz is 7" wide, so it will basically 'wrap around' the diffuser. But the same is not true of 4khz; if you tried to run the Nexo up to 4khz you'd probably run into issues. But with a crossover between one and two kilohertz, the Nexo diffuser is basically acoustically invisible.


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## Patrick Bateman (Sep 11, 2006)

JBL is doing it now.


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## Patrick Bateman (Sep 11, 2006)

https://www.youtube.com/watch?v=vXhwPT0W3Ew#t=101

Here's a video from JBL explaining how it works.

I gotta say, this is a REALLY smart solution. Here's why:









The conventional way to crossover from a midrange to a tweeter is to match the directivity at the crossover point. In the pic above, you can see my Gedlee Summas, *and you can see that both the tweeter and the woofer are 15" in diameter.* This isn't an accident; it makes the directivity the same at the crossover. Doing that yields good polar response, good power response, etc. It's just a good solid solution.









Most prosound speakers "squash" the waveguide, and make it shorter. This is done for a number of reasons. It makes the cabinet smaller, it narrows the vertical directivity, it makes the on-axis output a little louder. There's lots of reasons to squash it vertically.

The PROBLEM, and it's a big one, is that squashing the waveguide screws up your vertical polars. Most prosound companies simply don't PUBLISH vertical polars. But if you were to measure that vertical axis, you'd see that it's not as nice as you'd get if the midrange and the tweeter were matched. (Like in the Summa.)









But the aperture on the new JBL does something very interesting. It *widens* the horizontal directivity, so that it's a better match for the waveguide. The conventional solution to JBLs problem is to use a waveguide that matches the woofer. (Like the Summa does.) But JBL has done something interesting here; they've changed the directivity of the *woofer* to match the waveguide.

Very very cool.









BTW, this could be scaled down. For instance, it would work very well with a ribbon.


Also, some might look at this, and think "well that's a gimmick" or "that's overkill."
The thing is, *if you get the crossover and the polars right at the crossover point, it sounds like one big speaker.* In all seriousness, getting this right is the difference between a speaker that sounds like a loudspeaker, and a speaker that sounds like music. Because we're REALLY sensitive to problems in the midrange; our hearing acuity is extraordinary at 2khz. Even a little bit of waistbanding or comb filtering at 2khz is readily audible. Get that transition correct, and it sounds seamless and it sounds like music.

Ever listen to a good car stereo, and you notice that it's clean and it's dynamic but it *sounds* like a stereo, not like live music? Yeah, that's what causes that. It's the polar response at the xover. Your ears are really good at detecting the difference between a loudspeaker and live music, and to create the illusion of live music you must get the octave from 1-2khz correct.


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## Lycancatt (Apr 11, 2010)

pardon my somewhat helpless question but I cant see the pics so, these diffusers are sort of like metal teeth that come over the cone and surround of the speaker a bit? kind of like kickers old subwoofer grills but more random? I'm sure the pics make this obvious.


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## JoshHefnerX (Jun 13, 2008)

I've got a pic at home I believe. I'm not sure where the original article was though. If I remember I'll post tonight


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## Patrick Bateman (Sep 11, 2006)

Here's the JBL diffusor circa 2014









Here's Douglas Winkers diffusor. This is around 2004 iirc? I think he worked for JBL at some point also. I'm too lazy to look him up on Linkedin.


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## jode1967 (Nov 7, 2012)

also remember that that car won world finals in 1994 I believe it was. think he missed winning a year after 1 or 2 of his first championships and then went through the streak.
he also did the work on Robby Rices car and it was winning consistantly


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## Lycancatt (Apr 11, 2010)

Patrick Bateman said:


> Here's the JBL diffusor circa 2014
> 
> 
> 
> ...


thanks for posting those images..i should have been more clear, I'm totally blind so cant see images of any kind, not just within this thread or your post in particular. I'm very special so trying to better understand whats going on with the diffuser.


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## JoshHefnerX (Jun 13, 2008)

Patrick beat me to it.

Lycan, imagine a circular saw blade inverted w/ the teeth on it inside of the circle. The teeth are random.

Josh


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## TOOSTUBBORN2FAIL (Jan 31, 2011)

And the jbl version is more of a purposely shaped version, narrower than it is tall to help match the woofers dispersion to the waveguide.


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## Lycancatt (Apr 11, 2010)

cool, thanks guys..thats how I pictured it actually.


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