# What's the theory behind placing TWEETERS in the A-PILLARS?



## BodegaBay (Dec 16, 2005)

I've seen some people installing their tweeters flushed in the A-pillars. These a-pillars slightly angled towards the windshield.































What's the benefit of this? I've always had my tweeters located near the woofer in the doors and last two years on the sail panels facing each other. I definitely like them higher at the sails vs. down in the doors but it's still lacking that something. It's a little flat/dull and lack airieness...

Yes, I can move them to experiment but I just wanted some people's real world experience with such a placements.


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## Vestax (Aug 16, 2005)

A-pillar installs give you great height in staging but depending on what type of drivers you're using, it's possible that it can make your stage width narrower than desired. On top of that, separation from the mid range drivers can decrease the cohesiveness of your overall output.


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## gray bishop (Nov 8, 2005)

Vestax said:


> A-pillar installs give you great height in staging but depending on what type of drivers you're using, it's possible that it can make your stage width narrower than desired. On top of that, separation from the mid range drivers can decrease the cohesiveness of your overall output.


yeah what he said


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## BodegaBay (Dec 16, 2005)

I use silk domes exclusively if that matters. I had a/d/s, CDT, and now Rainbow CAL26 -- all in the sail panel. And in about 10 days I'm going to experiment with the LPG 25NFA. Didn't realize that my stage width might shrink as a consequence...


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## Vestax (Aug 16, 2005)

BodegaBay said:


> Didn't realize that my stage width might shrink as a consequence...


...as oppose to kickpanel installs, it might. It also depends on your vehicle, the driver, and how you angled them. People with tweeter in kicks installs suffer a different trade off, low staging and other minor problems (center console and dash obstructions). 

Of course a lot of these things can be patched up by the right processor.


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## Vestax (Aug 16, 2005)

BodegaBay said:


> I had a a/d/s, CDT, and now Rainbow CAL26 -- all in the sail panel. And in about 10 days I'm going to experiment with the LPG 25NFA.


Must've been different going with the CAL26, you might find the 25nfa's sounding similar to the other 2 drivers, rather than the Rainbow. How do you like them?


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## GMo (Aug 9, 2005)

BodegaBay said:


> What's the benefit of this? I've always had my tweeters located near the woofer in the doors and last two years on the sail panels facing each other. I definitely like them higher at the sails vs. down in the doors but it's still lacking that something. It's a little flat/dull and lack airieness...
> 
> Yes, I can move them to experiment but I just wanted some people's real world experience with such a placements.


Look on Headwize, they have great info on how upper frequencies contain musical cues and determine image.

Separation from the other speakers, is usually adjusted using time alignment. FR and phase will be affected over the pass-band of both speakers as you separate them. But most of this is inaudible due to so problems with a car's environment.

I have mine high, near those a-pillar locations.


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## Guest (Mar 24, 2006)

While left/right (or horizontal plane) localization cues exist for just about _all_ frequencies above bass ... including ITD, IID, and more complex HRTF cues ... elevation cues (or vertical plane) exist _only_ for frequencies above about 2kHz. This is because the vertical symmetry of our heads & ear canals is ruined by the outer ear, but the dimensions of the outer ear can only influence frequencies with comparable wavelengths (or smaller).

So raising the tweets makes sense for stage elevation. Mounting the tweets high also helps avoid leg/foot obstructions, which also have dimensions comparable to treble frequencies ... which means that acoustic diffraction around these obstructions ain't happening.

The real negative to high-mounted tweets is not separation from the midrange ... this can be electronically compensated (time delay is one aspect). Rather, the real negative to high-mounted tweets is _reflections_ ... much harder, if not impossible, to compensate electronically. In particular, reflections from the windshield & dashboard.

Mounting the tweets in the pillars helps to minimize reflections from both of these surfaces, because the primary (on-axis) radiation pattern of the tweet will be _parallel_ to both surfaces. Furthermore, the near tweet being off-axis, coupled with the attenuated off-axis response of the tweet, helps to combat side bias ... for _both_ front seat listeners at the same time ... since left/right localization of high freqs is purely based on inter-aural intensity differences.

Is it perfect? No ... but what about car audio is?


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## Cris (Sep 28, 2005)

Sans an extremely complicated and surely confusing explanation, placing my tweeters in the a-pillar created a much better soundtage for me. My tweeters are slightly angled toward me and create a satisfying soundstage for me. When they were in the doors, the sound sounded below me (i'm 6"2.. so that didn't help) I essentually didn't really like the sound coming from below me.


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## BodegaBay (Dec 16, 2005)

werewolf said:


> The real negative to high-mounted tweets is not separation from the midrange ... this can be electronically compensated (time delay is one aspect). Rather, the real negative to high-mounted tweets is _reflections_ ... much harder, if not impossible, to compensate electronically. In particular, reflections from the windshield & dashboard.
> 
> Mounting the tweets in the pillars helps to minimize reflections from both of these surfaces, because the primary (on-axis) radiation pattern of the tweet will be _parallel_ to both surfaces. Furthermore, the near tweet being off-axis, coupled with the attenuated off-axis response of the tweet, helps to combat side bias ... for _both_ front seat listeners at the same time ... since left/right localization of high freqs is purely based on inter-aural intensity differences.


Thanks for that excellent explanation Werewolf. So would go so far to say that it is "better" to move the tweeter from the sail panel up onto the A-pillars. From your explanation, am I correct in thinking that the sail panel tweeters, while not having windshield reflection problems, might have greater dashboard relections due to their radiation pattern often hitting the dash? It's interesting to see in most of these A-pillar installs, the majority of the on-axis patterns are parallel to both surfaces, with some cases having them pointed inwards towards the listener, and rare cases of them being pointed towards the windshield.


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## BodegaBay (Dec 16, 2005)

Vestax said:


> Must've been different going with the CAL26, you might find the 25nfa's sounding similar to the other 2 drivers, rather than the Rainbow. How do you like them?


Indeed Vestax. I'm not quite sure what to make of the CAL26 other than it's very good and very smooth. It's more refined and warmer than the a/d/s and the CDT; the latter tweeters had some sparkle that some will or won't like. I liked that and am very curious to hear what the 25NFA will yield for me.

Thanks for the excellent input above.


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## mvw2 (Oct 2, 2005)

Yeah, it seems to depend on preference/car as well. An example would be my and my brother's cars. He ran his up on the a-pillar initially, didn't like the end result. He ended up moving them down near the woofer and likes it a lot better. I'm the opposite, had mine down by the woofer, not up on the sailpanes. I want to move them up to the a-pillar eventially for distancing, but the car hacking, glassing is a bit intimidating. Those first two pics look beautiful though, wouldn't mind having an install looking like those.


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## Vestax (Aug 16, 2005)

BodegaBay said:


> Indeed Vestax. I'm not quite sure what to make of the CAL26 other than it's very good and very smooth. It's more refined and warmer than the a/d/s and the CDT; the latter tweeters had some sparkle that some will or won't like. I liked that and am very curious to hear what the 25NFA will yield for me.
> 
> Thanks for the excellent input above.


One of the remedies for reducing dash reflections is using a dash mat. Most would be deterred for it's old school fugliness but hey, if you're a serious audiophile, why not?


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## BodegaBay (Dec 16, 2005)

Not that reasonable Vestax.  

I like the clean look and even abhor sound disfusers in my own home theater room. Luckily I have enough room correction (via Audyssey MultEQ) processing there to negate the ill effects. I'm hoping to see room equalization become more affordable for the car market to bring products en masse.


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## raamaudio (May 4, 2005)

If I am doing a two way install without kicks(prefered in most vehicles) I will go with door midbasses and pillar tweeters and have had some excellent results, sometimes remarkable, sometimes just really decent. 

I always use or at least strongly recommend a dash mat(really for all installs) but more so for A pillar tweeters. 

I start off with them firing directly at each other, wired out of phase from the midbasses, and around 2" above the highest point of the dash. 

Ultimate placement depends on the design of the vehicle as the ones with long sloping windshields can be mounted higher if needed. On vehicles like my 96 Tacoma, the windshield is very close, to high means to close to you, just have to find the sweet spot.

Something I read years ago about firing right at each other but can be slanted upwards and or forward but only 10 degress max, has proven true in all I have installed. Never firing down or aft, I have tried, never worked well at all. 

Running a steep crossover as low as possible frequency can help keep the stage wider as well. 

Rick


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## BodegaBay (Dec 16, 2005)

raamaudio said:


> Something I read years ago about firing right at each other but can be slanted upwards and or forward but only 10 degress max, has proven true in all I have installed. _*Never firing down or aft, I have tried, never worked well at all.*_


 Thanks for the input Rick. So according to your satement and experience, the tweets in the A-pillars should not be pointing back towards the listener? I've seen a few pics here with users angling the tweets aft but crisscross to the other listener's headreast.







> Running a steep crossover as low as possible frequency can help keep the stage wider as well.


No problems there as an Alpine PXA-H700 is coming my way. 30db. However, I think the LPG 25NFA's recommended min cross is 3kHz -- according to NPDang.


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## GMo (Aug 9, 2005)

werewolf said:


> While left/right (or horizontal plane) localization cues exist for just about _all_ frequencies above bass ... including ITD, IID, and more complex HRTF cues ... elevation cues (or vertical plane) exist _only_ for frequencies above about 2kHz. This is because the vertical symmetry of our heads & ear canals is ruined by the outer ear, but the dimensions of the outer ear can only influence frequencies with comparable wavelengths (or smaller).
> 
> So raising the tweets makes sense for stage elevation. Mounting the tweets high also helps avoid leg/foot obstructions, which also have dimensions comparable to treble frequencies ... which means that acoustic diffraction around these obstructions ain't happening.
> 
> ...


Lobing and node cancellation can occur in polar patterns when drivers are separated. Given nulls are based on crossover freq, driver spacing and crossover order, you still change one of the variables when you separate them.


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## raamaudio (May 4, 2005)

The only luck I have had with aiming tweeters back was in kick panels using a trick I learned from the masters at ID, I wrote this a few years ago from my understanding and practice of what I learned. The mids where the primary driver to be concerned with and the tweeters usually aim at the same spot as the mids or a bit forward of them.



_______________________________


1) Put your front seats where you intend to either drive the car or where you will have them if you plan to compete, this is very very important. I am talking about fore and aft, height, seat back tilt angle. If not competing then where you will drive the car at and the passenger side the same.
If you are competing in car audio comps, then all the way back and low but even with the passenger side for height, lean the seats back a bit but not real far to make them uncomfortable. 

2) Sit in your seat as you would driving or listening as per above, make sure you are correctly placed, if you tend to drive leaning way forward like some do, you should adjust how you sit, better for your posture anyway, lol, lean back in the seat

(here is an additional hint, almost all will do better if the seats are lowered, leaned back quite a bit, etc. but in my Tacoma I had to raise the seats, go figure

3) Have somebody you trust to do this correctly, critically important. Roll the windows up, have them look very very carefully at where the entrance to your eardrum is on your window side ear, left ear, mark it on the window or on the pillar with a small spot of tape. 

4) Move to the other front seat and do the same except of course on the right ear this time. 

5) Ok to get out of the car now Measure 5" forward and 1.5" down from the spot marked for your ear entrance points on each side of the car, should be two marks on the car now, one for your ears and one forward and down as above.

6) Build some temp baffles for the speakers or the ones you will use, what I do. Have the tweeters mounted very low and to the door side of the baffle, the woofers go furthest forward and low as well. 

7) Aim the woofers(midbasses) exactly at the forward and down spot on the glass you marked. 
This is the sweet spot, instead of fighting the glass reflections you are using them to your advantage. The right speaker will reflect off the left glass into your left ear and help equalize the sound you hear from both speakers, seems odd but it works, exceptionally well. I beat a prior world champ twice in two months, two seperate installs in my truck and two totally seperate comp installs in his truck and a customers truck using these methods of alignment.

8)Take a kitchen towel and put it behind the baffels can cover the back of the speakers, then do some serious listening tests to see if you need to align them differently but this should be pretty darn accurate. 

9) Be very carefull when glassing the kicks as the glass can pull them out of alignment when drying as tends to shrink so mount the baffles very well before glassing. 

10) Wire the midbass on the passenger out of phase with the drivers side midbass, you may lose some midbass output but the sub can help make up for that quite well when tuned properly, better yet to have some midbasses in the doors. Try all the phasing setups you can, sometimes the drivers side is best, sometimes but not often, both in phase works) 


For those not building kicks here is a simple install plan that works quite well, has been used alot in competion cars. 

1) use the door locations for the midbasses, both in phase.
2) tweeters in the A pillars firing directly at each other, as wide apart as possible, both at the same exact height and about 2" above the highest point on the dash. Wire both tweeters out of phase(pos and neg wires reversed but this may have to be reconsideded depending on the midbass wiring, take your timem and try them all! Make sure to try many different aim points as well. 
3) Use a dash mat, fugly but they work.

In fact, a dash mat will improve just about any install ever done, including kick panels, have one in my truck, been there for years"

_____________________________________

Hope this helps
Rick


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## BodegaBay (Dec 16, 2005)

Interesting. Thanks for the read Rick. 

And Rick and Vestax, I may have second thoughts on the DashMat. I just looked on their website and some of the offerings are not bad. They've come a long way with materials with the "UltiMat" is being a single mold without any seams; softer and less "carpety" looking.


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## raamaudio (May 4, 2005)

I never said I like how they look, just how they help

I bought some really sweet fabric for our project car, killer deal really. Then I had an estimate done at a very good upholstery shop, $650 for labor to do the dash right and I know they would. I am far to much of a DIY guy for that, I did all the interior of my Tacoma except the stitching 100k miles ago and it is still holding up well in most all areas. So, though I have no idea where I would find the time, I have searched and found a used sewing machine good enough to do this kind of work for $850 and could probably find one for less. I would do the whole interior of course, headliner included(what is left of it, lol) but damm, the time, where can I buy some more of that at! I only need a few months worth to finish this car!!!!

Anyway, I can do the rest of the car fine but the dash is a bit troublesome, to say the least, not easy to make it right so a dash mat may have to do. Then again, I bought two, one for a buddy, installed his, fit great, installed mine, fit like crap!

The one in my truck has been there for years and still looks just fine, go figure eh!!

Rick


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## BodegaBay (Dec 16, 2005)

I was thinking about the same thing. A nice suede covered dashboard using high quality material such as UltraSude/Alcantara. But it does look like a PITA to do without some extensive stiching and wrapping. That's where the guys in SoCal have it good; there's a plethora of good upholsters down there! I sueded my headliner last fall and it was still a bear!


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## Guest (Mar 25, 2006)

GMo said:


> Lobing and node cancellation can occur in polar patterns when drivers are separated. Given nulls are based on crossover freq, driver spacing and crossover order, you still change one of the variables when you separate them.


Agreed ... but the more we learn about localization, the more we can electronically manipulate source location:

- HRTF's can be identified, measured, inverted and ultimately replaced to "move" a driver's location. The excellent car tuners already employ this principle to raise the stage of kick-panel tweets. But I recognize that the illusion can be fragile ... quite dependent on outer ear shapes, precise listener position, etc.

- Slope, phase and time control can manipulate (modify, steer) the interference pattern at the xover.

But we simply don't have as much electronic control over reflections. Comb nulls can't be equalized, and neither can the loss of pin-point sourcing in close reflective environments (as far as I know). So separating the mid and tweet ... in order to raise the stage while still preserving the important path lengths through the midrange ... does not, in itself, present an insurmountable problem. Putting the tweet in a highly reflective local environment is the _real_ risky proposition, in my opinion ... but the A-Pillar location, with the possible addition of a dashmat as Rick has described, seems to be a decent compromise in this regard. On-axis is parallel to the reflective surface, off-axis response employed to combat side bias, no obstructions nearby with dimensions comparable to wavelengths ... all things considered, it ain't half bad  And these are the elements of the "A-Pillar Theory" as originally requested.


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## Guest (Mar 25, 2006)

A highly scientific approach for using acoustic absorbers to reduce early reflections from A-pillar mounting:








A byproduct of this technology is that the ladies love it. Too bad I keep getting speeding tickets and running out of gas. 

Cheers,

AJ


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## FoxPro5 (Feb 14, 2006)

BodegaBay said:


> Interesting. Thanks for the read Rick.
> 
> And Rick and Vestax, I may have second thoughts on the DashMat. I just looked on their website and some of the offerings are not bad. They've come a long way with materials with the "UltiMat" is being a single mold without any seams; softer and less "carpety" looking.


Link please, Bodega. 

Nevermind....found it..www.dashmat.com, right?


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