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Windshield destructive reflection remedies
So I've got my mids mounted in my stock corner of the dash locations in my Camry. They actually sound pretty great overall except for a terrible 1.5khz null as seen here. They are actively high passed at ~250-300hz using the crossover in the amp and low passed at 2200hz using the morel passives. Blue trace is after some eq work through the headunits dsp:
https://lh3.googleusercontent.com/bz...g=w800-h363-no
Here is how the speakers reside:
https://lh3.googleusercontent.com/1o...=w1638-h923-no
The null remains with the tweeters off and also with the polarity switched on them. So, I'm 99% sure its destructive reflections from the windshield.
Before I proceed with expanding my system with additional equipment, I'm determined to remedy this 1.5khz null as I can plainly hear it and I believe it's killing presence in voices/strings and the snappiness of snares.
Here are a few possible remedies which I am contemplating but I'm always open to other's suggestions/critiques. Please feel free to let me know if these ideas are poop or if you have any other ideas.
1. Dash Pod for the mid to tilt them up to be on axis and further away from the windshield. Like this but just for the mid (tweeter will go in piller or sail):
http://68.media.tumblr.com/4a06d62f2...stD1raoqwm.jpg
2. Move mids to kick panels. -Concerns of losing stage height.
3. Replace tweeter with something that can play lower to take this null out of the mids passband... perhaps something like a Pioneer TS-S062PRS mid in the pillar or sail and on axis. I realize it would not provide the same top end extension but I honestly can't hear anything above 11khz anyway. I would cross it over to the mid 900-1khz. I heard these in a vehicle recently and was really blown away by them albeit they were accompanied by the prs tweeter.
I'm really looking for direction here. I know some of you have dealt with this issue before and I would like to hear about your experiences in trying to remedy it.
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Re: Windsheild destructive reflection remedies
While I don't doubt this may be a suck out because of location of drivers (always a possibility), I also feel you should test bypassing the crossover before getting to hung up on changing stuffs around. May be a shot in the dark, but a quick test of just the mid high passed off of the amp could rule out any "voicing" of the driver set via the passives, something not that uncommon at all.
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Re: Windshield destructive reflection remedies
Quote:
Originally Posted by
Truthunter
2. Move mids to kick panels. -Concerns of losing stage height.
I had this exact same concern when moving my mids to the kick panels. I had been temporarily running them in PVC cups on the dashboard while debating making little pods like you are describing, but for me, they took too much away from the stock look I wanted. I was definitely worried about losing the height in moving them to the kick panels, but it is a non-issue. I have mine at 450Hz to 3500Hz, could be wrong on the 3500, might be higher, and the stage is currently about 4-6" above the dash height, vocals are right up in the middle of the windshield.
If you decide to go with kick panels, then don't worry about the stage height, especially since you will ultimately be putting the DSP in there as well.
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Re: Windsheild destructive reflection remedies
I have a couple of suggestions.
1. can you drop the front of the mid to create an angle similar to that of the windshield so that you try to minimize the reflection you have that may be causing the null you are experiencing?
2. Have you turned off the mic and just listened to music? Not trying to be an ass, just a suggestion we often times forget to do(myself included). 1.5-2K is where you get a lot of sibilant off notes in vocals that can come off as harsh and some nasal qualities. Having a natural dip there may be more beneficial than you know.
3. Is it possible to change the grill to allow you to corner load the mid range so its more on axis from the passenger side dropping the left side of the driver or raising the right side into the corner? Rather than build HUGE pods make a small cosmetic change to just the grill.
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Re: Windsheild destructive reflection remedies
Yeah, I was going to suggest changing the driver angle. Of course if you were feeling really industrious, you could make a whole new baffle similar to Jason's BRZ
https://lh5.googleusercontent.com/-k...0/IMG_3503.JPG
https://lh6.googleusercontent.com/-W...0/IMG_1688.JPG
https://lh6.googleusercontent.com/-1...0/_DSC4601.JPG
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Re: Windsheild destructive reflection remedies
Also, have you put something behind the driver to make sure the back wave isn't creating cancellations?
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Re: Windsheild destructive reflection remedies
Al, thats what I was thinking when I suggested the angling of the driver. I knew i had seen it but i couldnt remember where. Thanks for digging up the pics!!
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Re: Windsheild destructive reflection remedies
Quote:
Originally Posted by
BigAl205
Also, have you put something behind the driver to make sure the back wave isn't creating cancellations?
Yeah that's more important than a lot of people realize. Back wave isolation isn't just for midbass.
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Re: Windsheild destructive reflection remedies
I don't have access to CAJ from work... it's blocked while the other forum is not for some reason. And for some reason I'm not getting email notifications of replies (probably need to set my preferences for that :hmm:). So I was at work all day waiting for a notification email and wondering if anyone was ever going to respond. :lol:
Great questions and suggestions... So here we go:
Quote:
Originally Posted by
claydo
While I don't doubt this may be a suck out because of location of drivers (always a possibility), I also feel you should test bypassing the crossover before getting to hung up on changing stuffs around. May be a shot in the dark, but a quick test of just the mid high passed off of the amp could rule out any "voicing" of the driver set via the passives, something not that uncommon at all.
I did perform this test and the null remained.
Quote:
Originally Posted by
naiku
I had this exact same concern when moving my mids to the kick panels. I had been temporarily running them in PVC cups on the dashboard while debating making little pods like you are describing, but for me, they took too much away from the stock look I wanted. I was definitely worried about losing the height in moving them to the kick panels, but it is a non-issue. I have mine at 450Hz to 3500Hz, could be wrong on the 3500, might be higher, and the stage is currently about 4-6" above the dash height, vocals are right up in the middle of the windshield.
If you decide to go with kick panels, then don't worry about the stage height, especially since you will ultimately be putting the DSP in there as well.
Thanks Ian for reminding me of your setup. I remember now that your stage was on the dash and your mids in the kicks. I will keep this in mind.
Quote:
Originally Posted by
chefhow
I have a couple of suggestions.
1. can you drop the front of the mid to create an angle similar to that of the windshield so that you try to minimize the reflection you have that may be causing the null you are experiencing?
2. Have you turned off the mic and just listened to music? Not trying to be an ass, just a suggestion we often times forget to do(myself included). 1.5-2K is where you get a lot of sibilant off notes in vocals that can come off as harsh and some nasal qualities. Having a natural dip there may be more beneficial than you know.
3. Is it possible to change the grill to allow you to corner load the mid range so its more on axis from the passenger side dropping the left side of the driver or raising the right side into the corner? Rather than build HUGE pods make a small cosmetic change to just the grill.
1. Yes, I plan on experimenting with this to see if it makes a difference...
2. Yes, I've been listening to it like this for a while now and overall it sounds good with most music. And I understand that some may cut this area to reduce harshness. But I feel like voices/strings sound as though they are muffled because of this deep and wide null causing a lack of presence... like there playing down in a hole. It's not really noticeable with transient electric music but it sounds off with tracks that contain vocals/strings or similar sounding instruments that play through this range with smooth amplitude variations.... I hope that makes sense :p
3. I think this is similar to what you are saying in point 1?... but maybe tilt the driver toward the center more?.. Yes, I did think of this as I demo'd Jason's car at Ian's this spring and asked him why his mids were tilted like they were. I do plan on experimenting with this to see if it helps... I really like how Jason's dash mounted mids came out and it sounded incredibly realistic but unfortunately I don't think I have the skills to make it look so nice :(
Quote:
Originally Posted by
BigAl205
Also, have you put something behind the driver to make sure the back wave isn't creating cancellations?
The dash locations are mostly open to out the bottom of the dash but they do have HVAC ducting that runs about an 1" under where the mid resides in about 30% of the area. I have stuffed two layers of 5lb carpet padding in there to try and absorb any reflections they may be occurring... whether or not that's helping is unknown.
I also made sure that any openings like the back edge of the dash (by the windshield) and the holes the grills clip into are sealed to prevent any back wave energy from escaping. This actually made a positive change to the sound... more controlled/snappy and improved low end output.
So, I think I will perform the following tests and go from there:
1. Unmount the mid and measure it free air on-axis to off axis to verify it's not just a problem with the driver FR itself.
2. Experiment with tilting the mid in different directions like Howard suggested to see if the issue improves.
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Re: Windsheild destructive reflection remedies
What do you have to "temporarily" block these reflections ? Redirection via a 90 degree / right angle pvc elbow of sufficient size ( 6 inch ).
Ie: rubber / carpet / towels / et cetera , think softest surface and extremely thick , facing drivers in direction that allows you to avoid majority of reflections - " temporarily ". Perhaps towels wrapped around rear of speakers and speakers firing at each other ! I believe your ears will suffice for your temporary testing to determine that reflective energy is your issue ( my bet ).
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Re: Windsheild destructive reflection remedies
Towels taped to windshield at bottom , some way of tenting towlels over top of speakers .
Facing one another if the off-axis response is not an issue , may work well !
With hard surfaces all covered or softer surfaces blocking the reflections , the null/node/suck-out may lessen or dissappear.
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Re: Windsheild destructive reflection remedies
www.pioneerelectronics.com/PUSA/Car/Stage4/
2 5/8 inch reference level ( would be ideal )
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Re: Windsheild destructive reflection remedies
Quote:
Originally Posted by
Hic
What do you have to "temporarily" block these reflections? Redirection via a 90 degree / right angle pvc elbow of sufficient size ( 6 inch ).
Ie: rubber / carpet / towels / et cetera , think softest surface and extremely thick , facing drivers in direction that allows you to avoid majority of reflections - " temporarily ". Perhaps towels wrapped around rear of speakers and speakers firing at each other ! I believe your ears will suffice for your temporary testing to determine that reflective energy is your issue ( my bet ).
I tried some temporary reflection blockers I found roaming around the neighborhood...
https://i.pinimg.com/236x/d4/14/cf/d...edb3f56aff.jpg
https://encrypted-tbn0.gstatic.com/i...1c0Ml6FUAz-FWl
https://i.pinimg.com/736x/0e/d6/8a/0...-cute-cats.jpg
http://files.automama.eu/200011694-8...d0/lachtan.jpg
https://i.pinimg.com/736x/77/91/8d/7...ny-animals.jpg
Anybody know a good product to clean off the dashboard? :p
Actually all good suggestions Hic... just need to find the time to try some things out...
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Re: Windsheild destructive reflection remedies
Quote:
Originally Posted by
Hic
Yes, those are the ones I'm considering as a last resort... really was impressed when I heard them and I believe they play pretty high so won't really miss anything if I replace the tweeters with them.
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Re: Windsheild destructive reflection remedies
This one will help tame those unwanted " ReflectionS "
Quote:
Originally Posted by
Truthunter
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Re: Windsheild destructive reflection remedies
Quote:
Originally Posted by
Truthunter
Yes, I plan on experimenting with this to see if it makes a difference...
2. So, I think I will perform the following tests and go from there:
1. Unmount the mid and measure it free air on-axis to off axis to verify it's not just a problem with the driver FR itself.
2. Experiment with tilting the mid in different directions like Howard suggested to see if the issue improves.
Get anytime to do some experimenting yet ?
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Re: Windsheild destructive reflection remedies
Quote:
Originally Posted by
Hic
Get anytime to do some experimenting yet ?
Hopefully this weekend...
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Re: Windsheild destructive reflection remedies
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Re: Windsheild destructive reflection remedies
Was able to do some experimenting. I popped the mids out of their mounts and jammed them between the windshield and dash using some towels; basically on axis:
https://lh3.googleusercontent.com/6b...c=w562-h316-no
Here is the resulting RTA comparison; Red is dash mounted, Blue is on axis in towels:
https://lh3.googleusercontent.com/2E...g=w800-h380-no
Next experiment is to start playing with tilting up the back of the them (side near the windshield) at several different increasing angle to see if I can find a sweet spot...
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Re: Windsheild destructive reflection remedies
Graphs are not showing up , but , more importantly , how did they sound ? Did the null , node or suckout dissappear ?
I'm glad you got some time to try some things !
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Re: Windsheild destructive reflection remedies
Relinked photos... let me know if they are showing up?
Yes, the null is completely reversed! :thumbup:
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Re: Windsheild destructive reflection remedies
Nicely done ! :nod:
I can see em , now .
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Re: Windshield destructive reflection remedies
Quote:
Originally Posted by
Truthunter
So I've got my mids mounted in my stock corner of the dash locations in my Camry. They actually sound pretty great overall except for a terrible 1.5khz null as seen here. They are actively high passed at ~250-300hz using the crossover in the amp and low passed at 2200hz using the morel passives. Blue trace is after some eq work through the headunits dsp:
https://lh3.googleusercontent.com/bz...g=w800-h363-no
Here is how the speakers reside:
https://lh3.googleusercontent.com/1o...=w1638-h923-no
1. Dash Pod
[IMG]http://68.media.tumblr.com/4a06d62f281001e75cf4340e8f07e2c3/tumblr_inline_nkalbgTstD1raoqwm.jpg[/IMG
Before
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Re: Windsheild destructive reflection remedies
Quote:
Originally Posted by
Truthunter
After
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Re: Windsheild destructive reflection remedies
Did some more experimenting tonight. Just tilted the mids about 20-25deg toward cabin.
https://lh3.googleusercontent.com/p0...=w1641-h923-no
Response comparisons: RED = original dash mount, GREEN = On axis, BLUE = Tilted toward cabin
https://lh3.googleusercontent.com/wo...4=w800-h382-no
I'm really surprised that just tilting the mids slightly like that made such a difference.... I really didn't expect it. Some eq work can bring down the humps in response.
So now I will be trying to figure out a way to permanently tilt the mids toward the cabin on a sealed baffle and make it look nice... I really don't want to get into glassing (I've never done it, I don't have any materials or tools for it, and I'm not really interested in learning it) so I'm going to try and come up with some other method :hmm:
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Re: Windsheild destructive reflection remedies
A round tube made from ? ( pvc , cardboard tube, several rings of wood , glass bottle , flexible metal piping [ exhaust piping semi-trailer] ) and a saw to cut angle [ skill , hacksaw , keyhole , sawzall , etc.., ]. Fiberglass and a piece of material with small popsicle sticks and rings of wood , some glue from a hotmelt glue gun [ craft store items ]. Something to stuff in the enclosure ( batting type material , pillow stuffing , etc.., ]
Could use a 4 inch dryer vent they are round and flexible , anything that circumference is adequate to allow speaker to be enclosed [ think rear wave separated from front wave ].
Some eq smoothing VOILA
Quote:
Just tilted the mids about 20-25deg toward cabin.
!http://www.homedepot.com/p/4-in-Styr...FQwFaQod0pwMHw
This angle is close ,interior matching paint/flocking/wrap with material , etc..,
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Re: Windsheild destructive reflection remedies
didn't Matt have a truck, '90 Chevy? that he did a mild angle with the mid nearly touching the windshield, to give his best reflection vs. no dash pod look, and so many people found it to be highly congruent with SQ...
I think it was red, there was a granite topped console, hard to forget it because I had both a '91 and a '93, and that mild angle was an easy copy... I used a Bose cube for a test enclosure up there in the dash, but it couldn't quite get as good.
There's a lot of people who just dismiss the stock dash location because they don't want to compromise, but even here with a mild tilt the answer is hiding in plain sight, no need for the A-pillar builds, especially with such tools as APL1 and FIR in miniDSP garb, perhaps this is a retro thought process but moving the drivers is probably as good as it gets in the land of no-DSP or graphic, non-parametric head unit signal manipulations.
I am glad for this build and the testing done, corroborating previous attempts that keep the midrange somewhere near stock vicinity, even if a small volcano is waiting for it's turn in the usual spaces...
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Re: Windshield destructive reflection remedies
Yep, and he still has it. You can find the build log on that other forum.
Sent from my iPhone using Tapatalk
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Re: Windsheild destructive reflection remedies
Quote:
Originally Posted by
Truthunter
Yes, those are the ones I'm considering as a last resort... really was impressed when I heard them and I believe they play pretty high so won't really miss anything if I replace the tweeters with them.
Some midranges go up to 10,000 hZ , which is more than enough for my ears , then if you are used to "air or sizzle" a tweeter is called for !
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Re: Windsheild destructive reflection remedies
Other than competitors , stock locations are de riguer for the masses. Stage and imaging are way behind convenience ! If you upgrade speakers , the music becomes much more immensely enjoyable.
Quote:
Originally Posted by
cajunner
There's a lot of people who just dismiss the stock dash location because they don't want to compromise.
I am glad for this build and the testing done, corroborating previous attempts that keep the midrange somewhere near stock vicinity, even.
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Re: Windsheild destructive reflection remedies
Do you have measurements of *JUST* the midrange playing? Those look like they are the whole system playing...
Also, try stuffing some towels down in the dash behind that driver to soak up the rear wave and measure again.
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Re: Windsheild destructive reflection remedies
Listen to him ^^^ He's pre-law. Or pre-med. What's the difference. :D
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Re: Windsheild destructive reflection remedies
Quote:
Originally Posted by
captainobvious
Do you have measurements of *JUST* the midrange playing? Those look like they are the whole system playing...
Also, try stuffing some towels down in the dash behind that driver to soak up the rear wave and measure again.
Yes, I did measure with just the mids (though did not capture the results) and found the same response anomaly around 1.5khz.
There was several layers of 5lb carpet padding behind the mids back when these measurements were taken. The padding is being replaced with Ultratouch denim insulation... actually any empty void in and under the dash and elsewhere in the car will be filled with ultratouch.... thanks to you :p
Working with Mr. Apicella for a permanent driver tilt solution kinda in the fashion of Mr. Bertholomy's mids ;)
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Re: Windsheild destructive reflection remedies
Thats good stuff right there. Harman had a writeup regarding windshield reflections and found a sweet spot of sorts, long as the speaker had a specific angle to the windshield.
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Re: Windsheild destructive reflection remedies
Quote:
Harman had a writeup regarding windshield reflections and found a sweet spot of sorts, long as the speaker had a specific angle to the windshield.
Do you have a copy of this article. I had it on my laptop but have recently switched to a new one and can't find it on either.
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Re: Windsheild destructive reflection remedies
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Re: Windsheild destructive reflection remedies
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Re: Windsheild destructive reflection remedies
Quote:
Originally Posted by
Truthunter
I don't have access to CAJ from work... it's blocked while the other forum is not for some reason. And for some reason I'm not getting email notifications of replies (probably need to set my preferences for that :hmm:). So I was at work all day waiting for a notification email and wondering if anyone was ever going to respond. :lol:
Great questions and suggestions... So here we go:
I did perform this test and the null remained.
Thanks Ian for reminding me of your setup. I remember now that your stage was on the dash and your mids in the kicks. I will keep this in mind.
1. Yes, I plan on experimenting with this to see if it makes a difference...
2. Yes, I've been listening to it like this for a while now and overall it sounds good with most music. And I understand that some may cut this area to reduce harshness. But I feel like voices/strings sound as though they are muffled because of this deep and wide null causing a lack of presence... like there playing down in a hole. It's not really noticeable with transient electric music but it sounds off with tracks that contain vocals/strings or similar sounding instruments that play through this range with smooth amplitude variations.... I hope that makes sense :p
3. I think this is similar to what you are saying in point 1?... but maybe tilt the driver toward the center more?.. Yes, I did think of this as I demo'd Jason's car at Ian's this spring and asked him why his mids were tilted like they were. I do plan on experimenting with this to see if it helps... I really like how Jason's dash mounted mids came out and it sounded incredibly realistic but unfortunately I don't think I have the skills to make it look so nice Tutuapp 9apps Showbox :(
The dash locations are mostly open to out the bottom of the dash but they do have HVAC ducting that runs about an 1" under where the mid resides in about 30% of the area. I have stuffed two layers of 5lb carpet padding in there to try and absorb any reflections they may be occurring... whether or not that's helping is unknown.
I also made sure that any openings like the back edge of the dash (by the windshield) and the holes the grills clip into are sealed to prevent any back wave energy from escaping. This actually made a positive change to the sound... more controlled/snappy and improved low end output.
So, I think I will perform the following tests and go from there:
1. Unmount the mid and measure it free air on-axis to off axis to verify it's not just a problem with the driver FR itself.
2. Experiment with tilting the mid in different directions like Howard suggested to see if the issue improves.
hi
i have a very interesting question can you help me please ?
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Re: Windsheild destructive reflection remedies
Quote:
Originally Posted by
klimbo
hi
i have a very interesting question can you help me please ?
Hi,
Maybe I or someone else here can help... what is your question?
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Re: Windsheild destructive reflection remedies
The comb is determined by the distance of the mid from the screen, you may get more energy from the screen at higher freqs with them tilted up a little, but that’s likely due to the mids being a touch less of axis
a shallow angle and the rear lip as close as you can get to the screen will push the comb higher, you’re also getting a reflection from the a pillar, by moving the mids closer to the screen upwards you will change the relationship between the two reflections and spread them more, there will be an optimum height and distance from the a pillar to get the two out of sync with each other and one will reinforce the others dip so the net gain or loss due to combing will be way less than a symmetrical spot if that makes sense, also the left will need a different spot to the right without question as you are at different angles to both drivers, reflections will be at different freqs
by making them symmetrical you are putting combs and phase issues due to reflections at different freqs, this makes it harder to get good phase coherence between left and right... the drivers side wants to be a little further away from the pillar to the passenger side, passenger side will suffer worse with reflection dips due to the angle your listening to it from as they will be lower in freq normally