# Dash mounted mids. What would cause this response?



## Picassotheimpaler (Sep 21, 2014)

Hi guys, im still chugging along with my Toyota 86 build and its sounding pretty great so far, but im curious about my dash corner mounted GB25s response. They are upfiring in the corner of the dash in the factory position with a 1/4in acrylic baffle between 300hz and 3000hz. The part i find interesting is the 14-15db drop that happens right around 1.2k. The response just drops off a cliff. Im assuming that it is just due to destructive reflections off the windshield, but I would expect a peak and a dip instead of what looks like a second low pass filter if that was the case. Im sure there is a fair bit of horn loading down there as well that is contributing quite a bit, but that steep drop still is interesting to me.
As of right now I am just using a shelf filter around 1200hz where the drop off happens and pulling down most of the lower region by 14db. It works, but Isnt ideal for sure. Its missing a bit of that effortless sound if you will. Since im pulling down the lower region so much, im probably assaulting the speaker with power above that point to keep up the volume where I want (loud but anywhere close to spl build levels)
I am just mainly curious as to what would cause this low pass filter look smack dab in the middle of the speakers response. Hopefully that will lead me the right direction in figuring out how to remedy the situation! I plan on trying a few things this weekend to try and pin point the fix. Im probably going to end up going the way of bertholomys mids and make a new baffle in that design to pull the speaker a bit closer to the windshield and further to the outside of the windshield.
Thanks for the input guys!

Right mid unsmoothed











Right mid 1/6oct smooth










Left mid unsmoothed










Left mid 1/6 oct smoothed


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## Mauian (Jul 25, 2019)

That dip is not unusual between 1-2 kHz. I have it with just about any driver in the corner dash location pointed at the windshield.

Below are two plots of the GS25 and HAT U2.












Someone smarter than me will likely explain why this occurs...


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## Picassotheimpaler (Sep 21, 2014)

Interesting. That looks like more of what I expected from destructive windshield reflections. It dips heavily around 1k then recovers around 2k back to the average spl. 
Here are a few measurements of the mids with no crossover or EQ. After the dip, it levels out at the -15db level for some reason.


Left Mid no XO or EQ











Right Mid no XO or EQ


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## Mauian (Jul 25, 2019)

Are you sure you don’t have a LPF set around ~3k still? Maybe on the amps? DSP? Are the speakers covered by a dash mat? (Although this would be a bit drastic) I agree, that’s unusual for that kind of dropoff without a LPF. 


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## Picassotheimpaler (Sep 21, 2014)

Nah, they had the factory speaker grill on top at the time of these measurements, thats it. I have recently stripped them off for testing and the sound is less muddy but no change in RTA. I have checked the LPF on the amps (hd300) and they are off completely. I have a towel on my dash at the moment acting as a ******* dash mat until I finish my dash install and can get one custom made for it. but they arent covering the speakers. Im using a helix pro mk2, and the only xo I had running was at 80hz for protection.


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## Picassotheimpaler (Sep 21, 2014)

Ive taken my phone and put it much closer to the speaker at an angle acting as a reflector to simulate pushing the speakers closer to the windshield. It does sound like im getting the 2k+ back a fair bit but i havent been able to take any measurements of that yet. Trying to find a way to suspend a piece of glass above it without having my arm in the way skewing results.


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## Mauian (Jul 25, 2019)

Maybe double check that there aren’t any shelf filters applied on the helix pulling down the higher frequencies?


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## Mauian (Jul 25, 2019)

Ah, what are you using to measure? REW with a USB mic?


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## Ge0 (Jul 23, 2007)

The OP said he HAD a shelf filter applied at 1.2KHz. Direct quote from his first post:

"As of right now I am just using a shelf filter around 1200hz where the drop off happens and pulling down most of the lower region by 14db." 

Why???

Ge0


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## tjk_bail (Feb 2, 2012)

I had the EXACT same problem using my factory dash speaker locations, in my Colorado truck. I used different mid-range speakers (i.e. Illusion C3CX, Stereo Integrity M3's, GB25), all of them had the drop-off the cliff at 1.2k. Boosting the cliff OR cutting before 1.2k to get the frequency response flat just made the system harsh, thin, just horrible. 

I finally made the decision to cut a hole in my upper front door, and install the GB25 there. The same GB25 speakers that dropped off 1.2k in the dash locations, now drop off at 4k in the upper doors. Now its possible to tune my system to sound deep, natural and balanced.


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## Mauian (Jul 25, 2019)

Ge0 said:


> The OP said he HAD a shelf filter applied at 1.2KHz. Direct quote from his first post:
> 
> "As of right now I am just using a shelf filter around 1200hz where the drop off happens and pulling down most of the lower region by 14db."
> 
> ...


I interpreted this to mean he was cutting everything below the drop
off to get a flat response. I’m trying to see if he also has a shelf filter applied above the drop off. 

Again, I think the null between 1-2 kHz is common in this location but that roll off afterwards may not be (it doesn’t occur in my vehicle).... just trying to make sure nothing else is contributing.

I ask about what’s being used to measure as maybe the microphone (if using a phone) isn’t very sensitive in the higher frequencies and is adding a roll off on top of the GB25 roll off...


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## Picassotheimpaler (Sep 21, 2014)

Yeah I will take a look on my day off tomorrow.
And yes Im using REW and the AF mic setup. All measurements done with uncorrelated pink noise and swept ear to ear until the measurement is stable.


Ge0 said:


> The OP said he HAD a shelf filter applied at 1.2KHz. Direct quote from his first post:
> 
> "As of right now I am just using a shelf filter around 1200hz where the drop off happens and pulling down most of the lower region by 14db."
> 
> ...


I suppose I should have clarified that a bit more. Thats how I am dealing with the drop in 1.2k+; To bring the 200 - 1200 range down and equal to the lower 1.2k+ response.


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## Mauian (Jul 25, 2019)

Just as a sanity check on the microphone, does the tweeter measure OK? (as in, it doesn’t have a huge roll off in the upper frequencies?). If it does, that might point to a microphone issue (if the tweeter is in a different location) (or an issue with that location in your car if they are in the same place).

Is there a decent baffle in place to block any sound from wrapping around the speaker and cancelling out some of the frequencies? I don’t know man, just brainstorming here...


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## Picassotheimpaler (Sep 21, 2014)

Yeah the tweeters look good. GB10 flat from 6k to 20k on axis. So I think the mic is okay.

Heres a few pictures of the baffle im using inside and outside of the car _and my sexy legs_. Its sealed to the mounting area with a thin bit of butyl rope, and the outside where the tweeter would sit (that sloping area on the lift in the car picture) is sealed off with a few pieces of deadening sheet.
And I appreciate the brainstorming! Its just baffling me that the response wouldnt pick back up after the 1/2 wave cancellation off the windshield.


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## Ge0 (Jul 23, 2007)

Maybe try blocking this big hole off? This could be causing cancellation.









Ge0


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## 156546 (Feb 10, 2017)

The dash location cuts the area into which the sound radiates compared to free air by about 3/4 or a little more. That boosts the level below the region in which the dispersion of the speaker begins to narrow. Couple that gain with the foreward going reflection from the windshield and you have what you have. Cutting where the location boosts isn't what's killing "effortlessness". That's not how it works. Cutting by 12dB just reduces the amount of power you send the speaker. 

What's really cool is all the boost and the fact that after you equalize, the useable bandwidth of the speaker (on the low end) is massively increased without much power.


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## Frequentflyer (Mar 3, 2020)

I've got a very similar setup in my Subaru WRX (they share audio parts with Toyota's). Below is a before and after of my GB25's in the dash. I have mine in mini-enclosures. I don't have a full-range measurement of them though. I can possible take a few of those tomorrow just to see if the enclosure is doing anything different for me versus your IB setup. I just ordered for two IB-type mounts I designed about 5 months ago when I started my install be 3D printed because I want to test out IB for my GB25's. I had decided to go with an enclosure instead and never got around to testing the IB mounts.


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## bertholomey (Dec 27, 2007)

Thanks Picasso for the mention - I did love the install in the BRZ and the sound of my 3’s - would love to do it again in the Audi 

I spent a few minutes tonight measuring the 3’s in the Audi - firing straight up at windscreen to show somewhat similar to what others have posted. 

Just mid ranges playing - no Xovers, no EQ 










Just mid ranges with no Xovers, EQ applied. 










Mid Ranges with Xovers applied and EQ applied. Still need to do some work on them to smooth them out a bit. 










This will likely not be beneficial for you, but I thought I’d post these graphs in case they may be. 


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## Mauian (Jul 25, 2019)

Interesting to see the pattern of a dip in the 1-2 k area (or just before it) in these corner dash installs. I wonder if the size of the driver plays a role? Seems the 3” had a dip a bit earlier than the 2.5” and 2” drivers. The larger ones will start beaming at lower frequencies. Or maybe it’s driven more by the location of the driver and relation to windshield?

Or maybe it’s not a dip at all but a relative boost as Andy said to the frequencies just below where they start beaming?

At any rate, just interested to learn what causes this seemingly common concern on RTA.


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## DaveG (Jul 24, 2019)

Frequentflyer said:


> I've got a very similar setup in my Subaru WRX (they share audio parts with Toyota's). Below is a before and after of my GB25's in the dash. I have mine in mini-enclosures. I don't have a full-range measurement of them though. I can possible take a few of those tomorrow just to see if the enclosure is doing anything different for me versus your IB setup. I just ordered for two IB-type mounts I designed about 5 months ago when I started my install be 3D printed because I want to test out IB for my GB25's. I had decided to go with an enclosure instead and never got around to testing the IB mounts.
> 
> View attachment 277367
> 
> ...


I'll be anxious to see and compare the difference you come up with between IB & sealed. Also will be curious about your impressions between the 2. Dave


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## Frequentflyer (Mar 3, 2020)

What would also be interesting is to see is whether "wideband" drivers behave in this manner compared to midrange drivers. I know the GB25 is a midrange driver as opposed to the GS25, which is a wideband. I am running mine from 290-3,000 and my tweeters (GB10) from 3,000 up. My tweeters without EQ have similar, significant dips, but I was able to flatten them out nicely.

FWIW, I also modified the factory speaker grills by cutting holes out of them and covered with UV-resistant speaker grill cloth, but I never did before/after measurements.


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## Mauian (Jul 25, 2019)

Frequentflyer said:


> What would also be interesting is to see is whether "wideband" drivers behave in this manner compared to midrange drivers. I know the GB25 is a midrange driver as opposed to the GS25, which is a wideband. I am running mine from 290-3,000 and my tweeters (GB10) from 3,000 up. My tweeters without EQ have similar, significant dips, but I was able to flatten them out nicely.
> 
> FWIW, I also modified the factory speaker grills by cutting holes out of them and covered with UV-resistant speaker grill cloth, but I never did before/after measurements.


Yep. I can verify widebands do this. The graphs I posted above were for the GS25 and HAT U2 (both widebands).


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## Frequentflyer (Mar 3, 2020)

Ok, I did a measurement of my GB25's with a bypass on the LP filter and EQ. I don't seem to be getting the same drop-off after 1k hz. Mine keep going pretty strong all the way past 10k. Again, these are installed in a pod of about .2 cu liters. I would suspect the large spike between 200-300 hz is from the enclosure. I think an IB mount would get rid of that - more testing to come. My crossover settings are actually 350-3000, not 290-3000.


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## Picassotheimpaler (Sep 21, 2014)

Thanks for all the feedback guys!! I went out and took some measurements a bit ago and tried something out. I took my phone and used that as a reflector simulating the speaker being within closer proximity to the windshield and got some interesting results. Much closer to the dip and peak expected with distructive interference. Ill post up some pictures shortly and respond a bit more.


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## Frequentflyer (Mar 3, 2020)

How far are the speakers from the windshield? My GB25's are about 4-4.5" away.


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## DaveG (Jul 24, 2019)

Frequentflyer said:


> How far are the speakers from the windshield? My GB25's are about 4-4.5" away.


I would think the 200-300hz spike is from being corner loaded firing into the windshield? How about a measurement without the enclosure? Dave

Edit: your spike is between 400-500hz


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## Picassotheimpaler (Sep 21, 2014)

Alright so this is what I got from my playing around. 


This is the baseline with only a high pass filter at 287hz










This is roughly 1.5in away from the driver with an angle meant to mimic the windshield rake.











This is roughly .5in away from the driver at a higher angle to simulate a less steep windshield like a truck or something.











And lastly this is the same .5in away but at the same angle (_or atleast as close as possible_) as the windshield.


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## Frequentflyer (Mar 3, 2020)

Interesting results. We can see that distance from windshield and angle play a big part in response. In any event, I think you should cross them over at 3-4k. I will be getting my IB mounts within a few days and will compare responses between mounting options.

What is also interesting are the differences in the dips past 1k. My left mid doesn't suffer from this, but my right mid does. I am not even sure this can be classified as a "null".


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## Picassotheimpaler (Sep 21, 2014)

Ge0 - I have that portion blocked off with some deadening sheet and a small bit of scrap MLV at the moment, I happened to take those pictures while I was building that way I can post up a semi build log after im all finished out. It didnt seem to make really any difference when I did it though. I think the rest off the grill was sufficiently blocking it off. I appreciate the brainstorming though.

Gotfrogs - Thanks for stopping by. That was impeccable timing last night, you posted here as I was tacking this question onto my email. So if I understand that correctly it is basically being horn loaded and is par for the course with dash corner locations? If that is the case then relocating the driver further into the corners it should push the frequencies being boosted up higher in the frequency range right?

Bertholomey - Absolutely, I am disappointed I didnt get a chance to see the BRZ before it disappeared. Im taking quite a bit of inspiration from it though and am trying to DIY something similar. It looked like a superbly put together system! And those graphs do help in fact, but for a whole other reason. It looks like you manually EQ'd that dip in the 800hz range, what is the purpose? Just personal taste in sound signature or did it sound boosted when you were EQ by ear? Last question before i derail the thread too much, why is one of the two dips at ~800 cut 2-3db more than the other side?

Frequentflyer - What was it that made you go for a pod inside of the stock dash mounting point instead of going IB right off the line? Im curious to see how the switch to IB will change the response if it will at all. From looking at the measurements that Andy took of the GB25 in boxes of different volumes vs IB when he did the comparison of the GB25 and GB40 im assuming it shouldn't change much. I was also originally interested in doing a small pod test in the same sort of way since i have a 3D printer, but unfortunately the 86/BRZ have the AC ducts packaged in under the dash mounting point and they didnt leave much space for playing around.


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## Patrick Bateman (Sep 11, 2006)

GotFrogs said:


> The dash location cuts the area into which the sound radiates compared to free air by about 3/4 or a little more. That boosts the level below the region in which the dispersion of the speaker begins to narrow. Couple that gain with the foreward going reflection from the windshield and you have what you have. Cutting where the location boosts isn't what's killing "effortlessness". That's not how it works. Cutting by 12dB just reduces the amount of power you send the speaker.
> 
> What's really cool is all the boost and the fact that after you equalize, the useable bandwidth of the speaker (on the low end) is massively increased without much power.


What Andy said. (I assume that's Andy?)

For some additional detail:

If you stick a woofer on a flat baffle it will generally have a response that's fairly flat. Now if you place that same woofer on a waveguide, it will exhibit a rising response. The reason it has a rising response is because the waveguide is taking the same amount of energy and it's radiating into a smaller angle.

And that's what you're seeing in your measurement: the windshield is acting as a waveguide.

This increases your on axis efficiency and your maximum output. So all of this is A Good Thing.

If you want to increase output even higher, you might consider putting the GB3s into an enclosure, if you haven't done that already. Then again, if you're using a high pass on the mids already, it might not be worth the effort.

You WILL want to EQ the response to fit your target curve.

IE, if your intention is to cross over to a tweeter at 2khz with a 4th order slope, you will want to use a combination of filters and EQ to achieve that target response.


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## Mauian (Jul 25, 2019)

I totally get what you and Andy are saying, but it still is interesting to see that in his baseline measurement (at the driver seat position) the frequencies around 10k or so are at the level of his noise floor. It’s just such a drastic drop off. In FrequentFlyer and my measurements, in similar mounting positions, we don’t have that drop off.

We all see the boost on the low end, but that drop off after 4K and on we don’t see to that extent. What’s also interesting, to me, is that the drop off is less severe if measured near the driver. Like, I get the boost of efficiency but why the decrease in efficiency of the higher frequencies? It doesn’t seem to be totally due to a relative boost at lower frequencies. Of it was just that, then why do the higher frequencies measure higher with the microphone close to the driver? Just genuinely curious. 


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## Picassotheimpaler (Sep 21, 2014)

Thanks Patrick, if there is anyone to ask about waveguides on here, its you! How would I go about pushing the FQ range boosted higher on the octaves? If its possible I would like to have the area boosted go though the entire passband of the driver. Maybe its unnecessary but Ive been curious about the phase shift introduced with the shelf filters. Since the point that either speaker rises and where i have the shelf filters is different(one drops off at 1.2k and the other at 950) Ive been assuming im throwing the phase response between the two off a fair bit. Im probably incorect here, but I have been thinking that is why I am having trouble getting the lower midrange centered.

The other reason I am pursuing this the way I am is because the upper midrange sounds sort of cluttered and non distinct in some songs, rock and metal in particular. Even songs that I know are mastered well, the guitars dont sound distinct as they should. I have EQd them to target and tried a couple different ideas on XO slopes and whatnot between mid and tweet but the problem persists.


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## Frequentflyer (Mar 3, 2020)

Picassotheimpaler said:


> Frequentflyer - What was it that made you go for a pod inside of the stock dash mounting point instead of going IB right off the line? Im curious to see how the switch to IB will change the response if it will at all. From looking at the measurements that Andy took of the GB25 in boxes of different volumes vs IB when he did the comparison of the GB25 and GB40 im assuming it shouldn't change much. I was also originally interested in doing a small pod test in the same sort of way since i have a 3D printer, but unfortunately the 86/BRZ have the AC ducts packaged in under the dash mounting point and they didnt leave much space for playing around.


Picasso,

I decided to go with an enclosure just because most people were mounting the GB25's in sail or pillar pods and Audiofrog's site said they were designed for really small enclosures. I originally designed an adapter to fit the GB25 in the factory midrange location, but then took that design further by incorporating a cup underneath it. I used Autodesk Fusion 360 and sent my designs out for printing in ABS. After I got them, I heatsunk threaded inserts in them for machine screws to fasten the drivers. Like I said, I never tested my first adapter design and never even got a "final" set printed, but this week I decided that given the fact they were cheap enough ($20 for the pair), I got a set of enclosure-less adapters made for testing. To keep my tweeters on the same plane, I designed some tweeter mounts to put them next to the GB25's under the factory grill (with a bit of plastic removal).




























Original design:


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## Frequentflyer (Mar 3, 2020)

Just to add. I don't think I'd use shelf filters for your dash mids. You may need some all-pass filters, but not shelf. While my front stage still needs some work, I haven't had any problems tuning to a target response with my mids and tweeters despite their location.


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## tjk_bail (Feb 2, 2012)

This is a little of topic,.... Frequentflyer, one way to really match up your left to right, take the best tuned freq curve from each pair, and EQ the lesser curve to match the better curve. The easiest way to do it is, for example:

On your graph, take your right tweeter curve (it looks flatter then left), and export it as a .txt file (export measurement as text) from within REW main window. Then in REW/Preference/House curve browse to that file and make it your target curve. Take a new measurement of left tweeter, and go into the EQ window, set your parameters,(be sure to set Target level to 0) then 'Match responses to target', set your DSP EQ with the new EQ filters.

Do the same for each pair and it will really sharpen the stage and tonality.


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## Picassotheimpaler (Sep 21, 2014)

tjk_bail said:


> This is a little of topic,.... Frequentflyer, one way to really match up your left to right, take the best tuned freq curve from each pair, and EQ the lesser curve to match the better curve. The easiest way to do it is, for example:
> 
> On your graph, take your right tweeter curve (it looks flatter then left), and export it as a .txt file (export measurement as text) from within REW main window. Then in REW/Preference/House curve browse to that file and make it your target curve. Take a new measurement of left tweeter, and go into the EQ window, set your parameters,(be sure to set Target level to 0) then 'Match responses to target', set your DSP EQ with the new EQ filters.
> 
> Do the same for each pair and it will really sharpen the stage and tonality.


That is brilliant. Its super simple but sounds like it would be insanely effective


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## Mauian (Jul 25, 2019)

Picassotheimpaler said:


> That is brilliant. Its super simple but sounds like it would be insanely effective


Yep. This is a great way to do it. Use one side of the car as the target curve for the other side.


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## tjk_bail (Feb 2, 2012)

This process really does work well. You can get freeky with it too.. Like, on the above graph, The LP downslope for his Right Mid-Base looks bad between 300 to 1k, but the other side, the HP downslope for Right Mid-Base looks good. He could match 300 to 1.k to the Left side by using Left Mid-Base as Target Curve, then in the EQ module, use 300 to 1k as "Match Range". Then the opposite for the HP downslope.. meaning use the Right Mid-Base as Target Curve to make the Left Mid-base HP downslope match up to Right Mid-Base HP downslope, using "Match Range" of 30hz to 130hz.

... I see that modal dip on Left-side.. really not much you can do about that... boosting it a bunch isnt the answer....


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## ErinH (Feb 14, 2007)

Don’t view it as a drop in output above 1200Hz. View it as a boost in output below 1200Hz. Free gain.

Cross below beaming like you normally would and you’ll be fine.


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## bertholomey (Dec 27, 2007)

Picassotheimpaler said:


> Bertholomey - Absolutely, I am disappointed I didnt get a chance to see the BRZ before it disappeared. Im taking quite a bit of inspiration from it though and am trying to DIY something similar. It looked like a superbly put together system! And those graphs do help in fact, but for a whole other reason. It looks like you manually EQ'd that dip in the 800hz range, what is the purpose? Just personal taste in sound signature or did it sound boosted when you were EQ by ear? Last question before i derail the thread too much, why is one of the two dips at ~800 cut 2-3db more than the other side?


That dip at ~800hz is there simply because I was having a tuning issue there - it certainly wasn’t because my ears were telling me that freq was hit and needed to be brought down. I actually took some time this morning to futz with it a bit and got it smoothed a little better. It still isn’t as clean as others have posted, but shows that processing can address some of the issues potentially inherent in this mounting configuration. It would be great to not have to use processing for that purpose, but I chose to use that install location in this car. 












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## Frequentflyer (Mar 3, 2020)

It's definitely give and take with dash mounted drivers, but with enough processing power there are other benefits of using this configuration that can outweigh the tuning challenges.


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## Frequentflyer (Mar 3, 2020)

Here's a new response plot from my most current tune with the GB10's and 25's in the dash of my WRX. I need to make a few more tweaks here and there, but I'm pretty happy with it. This took me awhile... 😓


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## Picassotheimpaler (Sep 21, 2014)

That looks awesome! Good job dude.
Sorry I've been silent. I've been working on a new strategy and install to try and get around the issue I'm having ( and just to have dome fun lol)
I'm doing a dash mount with new fabbed baffles in the style of bertholomys like I was saying before








I mocked up some baffles and gave a few attempts on the 3dprinter until I got something i like and had them milled out of aluminum. they came out looking fantastic when I finally got them. 








So I'm in the middle of cutting up some of the dash to install these and its looking quite good so far.


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## Frequentflyer (Mar 3, 2020)

Wow. That looks interesting! Can't wait to see the results.


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## bertholomey (Dec 27, 2007)

That does look awesome! I’ll be very interested to hear your thoughts once you get them installed! I was very impressed with the sound in my car once I got over the shock and puzzlement of ‘The Doctor’s’ suggestion. The thesis also looked pretty good in that orientation as well. But the improvement in sound is what got me stoked. 


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## DaveG (Jul 24, 2019)

Frequentflyer said:


> Here's a new response plot from my most current tune with the GB10's and 25's in the dash of my WRX. I need to make a few more tweaks here and there, but I'm pretty happy with it. This took me awhile... 😓
> 
> View attachment 277812


Looking good! Is this with your GB25's mounted IB or still in your enclosure?


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## DaveG (Jul 24, 2019)

@Picassotheimpaler what is the black material stapled to the grill? And what's going on with the speaker on the a-pillar?


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## tjk_bail (Feb 2, 2012)

Frequentflyer said:


> Here's a new response plot from my most current tune with the GB10's and 25's in the dash of my WRX. I need to make a few more tweaks here and there, but I'm pretty happy with it. This took me awhile... 😓
> 
> View attachment 277812



That peak on your Right mid at 8.7k, just wondering why you dont knock that down. It could be audible at mid to upper volume listening levels. Do voice's and cymbals bleed through your stage and pull to right a little at higher volumes?


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## Picassotheimpaler (Sep 21, 2014)

Its actually just some cheap stretchy t-shirt material that I got at Joanne fabrics for something like 2 bucks a yard. Its thin enough that it contours really for stretching well but needs a ton of reinforcement.
And yeah, that is the temporary location of my tweeters while I try positioning them. Just used part of the mounting brackets that come with the gb10s and screwed them to the pillars. Really ******* looking but it works for quick testing lol. I think I'm going to try to tuck them into the dash corners right above the mids next to see what that does.


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## Picassotheimpaler (Sep 21, 2014)

I also made the baffles large enough to hold on to the silver trim ring and grill to attempt to keep the look going through all of the front stage.















Before anyone asks, that is a loop of floss to make the grills easy to take off while I'm still working haha.
the plan is to match the interior oem alcantara trim pieces on all of these


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## Frequentflyer (Mar 3, 2020)

DaveG said:


> Looking good! Is this with your GB25's mounted IB or still in your enclosure?


Still in the enclosure right now. I got the IB mounts in the mail. Will try getting one of those in for testing soon.


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## Frequentflyer (Mar 3, 2020)

tjk_bail said:


> That peak on your Right mid at 8.7k, just wondering why you dont knock that down. It could be audible at mid to upper volume listening levels. Do voice's and cymbals bleed through your stage and pull to right a little at higher volumes?


To be honest I haven't listened to any "real" music yet to hear that level of detail, but yes, I am going to try to flatten out some peaks a bit more by linking channels and making small adjustments next.

As far as the peak at 8.7k; I didn't bother with that because I thought it'd be inaudible, but I guess I will try to get rid of it. Not even sure why that's there. I've pretty much run out of EQ bands on that channel, but I may be able to consolidate a band that's close to another one to free one up for 8.7. Having dash mounted speakers really takes a lot of EQ'ing.


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## bertholomey (Dec 27, 2007)

I thought I may toss up a few pics of what Picasso is referring to in the event anyone is wondering. My installer Mark has the idea - my contribution was to ask for grills that I could press fit, that I never used, which caused there to be the ‘lip’ around the baffle that so many folks commented on......so my contribution was the only real negative aspect of the dash build in my BRZ  

Make sure you have plenty of material under the speaker to absorb the back wave. The first iteration - Hogan and my home audio guy could hear the back wave. 





































I’ve got the same speakers in the dash of my Audi, but they are point straight up at the dash under a grill. 


Sent from my iPhone using Tapatalk Pro


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## Truthunter (Jun 15, 2015)

bertholomey said:


>


Ahhh, brings back good memories. My first mind blowing car audio demo was in this vehicle.


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## dumdum (Feb 27, 2007)

bertholomey said:


> I thought I may toss up a few pics of what Picasso is referring to in the event anyone is wondering. My installer Mark has the idea - my contribution was to ask for grills that I could press fit, that I never used, which caused there to be the ‘lip’ around the baffle that so many folks commented on......so my contribution was the only real negative aspect of the dash build in my BRZ
> 
> Make sure you have plenty of material under the speaker to absorb the back wave. The first iteration - Hogan and my home audio guy could hear the back wave.
> 
> ...


It genuinely makes me cry when I see tweeters mounted like that, reflections from the opposite side window have always played havoc with staging when I’ve jumped in a car with that aim


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## jtrosky (Jul 19, 2019)

dumdum said:


> It genuinely makes me cry when I see tweeters mounted like that, reflections from the opposite side window have always played havoc with staging when I’ve jumped in a car with that aim


I don't know - people that went to the last get-together were saying that his car was one of, if not _the_ best sounding car there! So I'm not so sure reflections or staging issues are a big problem for him.  It sounds like his system sounds pretty damn good as-is.


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## Mashburn94 (Apr 28, 2017)

jtrosky said:


> I don't know - people that went to the last get-together were saying that his car was one of, if not _the_ best sounding car there! So I'm not so sure reflections or staging issues are a big problem for him.  It sounds like his system sounds pretty damn good as-is.


Agreed! The Audi sounds amazing for sure. I think it's funny someone who has never heard the vehicle is knocking an install in a vehicle they have never heard, based on a picture. I'm sure the other cars with tweeters in that location had an installer as good as Mark (or better). I'm also sure that the other cars had no chance of the tune being bad. Sounds like DUMDUM is appropriate.


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## Picassotheimpaler (Sep 21, 2014)

Different installs call for different locations and aiming. Lets please not go off on each other. Dumdum has said his piece based off of his experience, no need to start being argumentative just because of that.

That being said, what would you have preferred to see in his install dumdum? Keep in mind there are no sail panels to use in this car.


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## dumdum (Feb 27, 2007)

jtrosky said:


> I don't know - people that went to the last get-together were saying that his car was one of, if not _the_ best sounding car there! So I'm not so sure reflections or staging issues are a big problem for him.  It sounds like his system sounds pretty damn good as-is.


Sounding pretty good is down to the tune, but you can’t out tune a bad placement or aim especially with tweeters which always play to beaming

if you don’t know what your listening for you wouldn’t know what I’m talking about, most people are blissfully unaware, it doesn’t mean it’s not an issue though, like I say, from experience I’ve never heard a car with that aim that didn’t have issues

so at some frequency the opposite side window will give input to the opposite side window, it’s something me and lojze often discuss and feel strongly about


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## dumdum (Feb 27, 2007)

Picassotheimpaler said:


> Different installs call for different locations and aiming. Lets please not go off on each other. Dumdum has said his piece based off of his experience, no need to start being argumentative just because of that.
> 
> That being said, what would you have preferred to see in his install dumdum? Keep in mind there are no sail panels to use in this car.


In all the excellently staging and imaging Emma cars I’ve heard, inc lots of Emma championship winning cars the tweeters are normally aimed down the car, depending on the tweeters dispersion some degree of off axis away from the opposite side window is a good starting point

For example my car has the tweeter on the passenger side and a drivers side aimed at a point roughly at the centre of the car just behind the headrests, it puts each tweeter roughly 15ish degrees off axis to the ears, and more importantly it takes a lot of energy away from the opposite side window, in some cases the drivers need to be aimed at the headrests so even more off axis, but if I can get them equally off axis I will always try to as the freq response will then match if that makes sense

Think how we determine the position of drivers (aka the outer boundary’s of the stage)

play the right speaker in a lhd car and if you get a lot of input from the reflection on the drivers window the brain will put the speakers location inside the drivers actual location (the timing of the sound from the window is so close the brain can’t separate it from the direct as the window is normally very close even in the biggest car, seating position also plays a role

Taking it off axis from the window puts less info into the left ear and so the source of the sound appears to be more point source and therefore wider

I hope this clears up what I mean and why it upsets me 👍🏼 I have no issue explaining why I believe things happen, when you’ve heard it so often and in this case every time I’ve had chance to critically listen to a car and tune with dsp control to solo individual drivers

most top cars have issues, most also do a good job of masking the issues, but if I can setup a car to have less issues in the first place I will always take that option if that makes sense


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## dumdum (Feb 27, 2007)

Mashburn94 said:


> Agreed! The Audi sounds amazing for sure. I think it's funny someone who has never heard the vehicle is knocking an install in a vehicle they have never heard, based on a picture. I'm sure the other cars with tweeters in that location had an installer as good as Mark (or better). I'm also sure that the other cars had no chance of the tune being bad. Sounds like DUMDUM is appropriate.


I am not knocking an install, merely passing comment on something I have massive experience off and found to be a flaw every time I’ve come across it, see my explanation above, cars are the same shape roughly, and I have genuinely never found a car with that aim that didn’t have an issue with width in the tweeters, whether the tuner does a good job of making it sound good is irrelevant, the best installs have optimised driver locations before tuning to then fix less issues, I am sure the car sounds excellent, it doesn’t mean there are no flaws in it, and as this is a discussion forum I think discussing something that is a possible flaw is good, the same as anyone who commented about my car I would take it as constructive criticism, I have had many pieces of help with my install

if I’d said it looks like a pos that would not be valid, but a comment based on how we hear which is a fact and accepted is not a waste of time to me if someone reads it and try’s something different


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## bertholomey (Dec 27, 2007)

Thank you for that response, and you are correct - this is a discussion forum. You are also correct that a superior install design may alleviate a great deal of tuning to overcome poor planning. Many purchase a vehicle with the system as the reason for purchase - they can install with greater flexibility, lending to a better plan, better execution, and ultimately the potential for superior sound all things considered. I'm specifically thinking of my friend Steve and his transit van.

You are also correct that in my BRZ, that tweeter orientation caused some issues. The pics I posted above (which I debated with myself whether to post) are from the first gen tweeters / pillars. I dropped off the car to get my amp rack completed.....while my installer had it, he sensed what you are referring to. He created a new set of pillars that did angle the tweeters more to the center of the car - kicking out the inner flange to make them a bit more on-axis - and not aiming more-or-less at the opposite side window. Still likely not as angled in as what you are describing - the Thesis are largeish tweeters, and I didn't want vision blocked any further in this small car. Of course I'm sure there are full flange home tweeters that have been used in cars that are angled as you are describing. 

So, unfortunately we did have to overcome a lot with the tune. It is very likely that you would have heard the same issues you are describing even with the 2nd iteration of the pillars.....I was blissfully ignorant. But.....there are lots of compromises I've made with the sound based on decisions made......I hear some of my friend's cars with extremely solid IB sub installs - wonderfully fast, deep, 'real' presentations........my car doesn't do that because I chose to put my sub in the glove box area - it provides many things that I like, so for me, it works. But many would likely prefer the sound of the other options.


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## Mic10is (Aug 20, 2007)

Truthunter said:


> Ahhh, brings back good memories. My first mind blowing car audio demo was in this vehicle.


for real, There was 1 tune on the BRZ that made me go home and retune my car that weekend. Good times


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## dumdum (Feb 27, 2007)

bertholomey said:


> Thank you for that response, and you are correct - this is a discussion forum. You are also correct that a superior install design may alleviate a great deal of tuning to overcome poor planning. Many purchase a vehicle with the system as the reason for purchase - they can install with greater flexibility, lending to a better plan, better execution, and ultimately the potential for superior sound all things considered. I'm specifically thinking of my friend Steve and his transit van.
> 
> You are also correct that in my BRZ, that tweeter orientation caused some issues. The pics I posted above (which I debated with myself whether to post) are from the first gen tweeters / pillars. I dropped off the car to get my amp rack completed.....while my installer had it, he sensed what you are referring to. He created a new set of pillars that did angle the tweeters more to the center of the car - kicking out the inner flange to make them a bit more on-axis - and not aiming more-or-less at the opposite side window. Still likely not as angled in as what you are describing - the Thesis are largeish tweeters, and I didn't want vision blocked any further in this small car. Of course I'm sure there are full flange home tweeters that have been used in cars that are angled as you are describing.
> 
> So, unfortunately we did have to overcome a lot with the tune. It is very likely that you would have heard the same issues you are describing even with the 2nd iteration of the pillars.....I was blissfully ignorant. But.....there are lots of compromises I've made with the sound based on decisions made......I hear some of my friend's cars with extremely solid IB sub installs - wonderfully fast, deep, 'real' presentations........my car doesn't do that because I chose to put my sub in the glove box area - it provides many things that I like, so for me, it works. But many would likely prefer the sound of the other options.


The thesis being a big tweeter may actually be better due to beaming a little lower 👍🏼 I know in my car I get a little more feedback from across the car with a 5” mid which pulls the stage inward a little vs a 6” which was sounding like it’s at the speaker

my intent was not to poke fun or belittle, but to be constructive and help others, thankyou for not taking it as such 👍🏼 It’s all a big happy game this audio, and the more we can share the better we become 😎


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## Frequentflyer (Mar 3, 2020)

dumdum said:


> In all the excellently staging and imaging Emma cars I’ve heard, inc lots of Emma championship winning cars the tweeters are normally aimed down the car, depending on the tweeters dispersion some degree of off axis away from the opposite side window is a good starting point
> 
> For example my car has the tweeter on the passenger side and a drivers side aimed at a point roughly at the centre of the car just behind the headrests, it puts each tweeter roughly 15ish degrees off axis to the ears, and more importantly it takes a lot of energy away from the opposite side window, in some cases the drivers need to be aimed at the headrests so even more off axis, but if I can get them equally off axis I will always try to as the freq response will then match if that makes sense
> 
> ...


So how would these theories all apply to a tweeter install in the dash using windshield reflection?


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## dumdum (Feb 27, 2007)

Frequentflyer said:


> So how would these theories all apply to a tweeter install in the dash using windshield reflection?


That all depends on the rake and angle of the screen, not all cars suit that style of mounting due to the dispersion pattern of the driver/windscreen combination, I tried 20+ different aims for the mids in my car, some of which were unconventional... well why not when you have no dash... and screen firing didn’t really cut it for the left of stage, drivers side was fine though, but that’s easier to get right to me every time due to reflections being more above and to the right side effectively


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## Picassotheimpaler (Sep 21, 2014)

Just a bit of follow up here. I got the Right side mid mostly finished the other day and it made a notable improvement. The right side now seems to come from MUCH further away and widen the stage a ton on that side. It also took away quite a bit of cancellation on that side as well and made that side of the stage much more focused that it was before. It also seemed to smooth out the top end out as well and stop the huge drop off like there was before. I only have a few measurements at the moment, but will post some later when I get off work.


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## Ge0 (Jul 23, 2007)

Picassotheimpaler said:


> View attachment 277828


Oh sh!t. Now there ya go. Exactly what my next project is going to be . I like it a lot.

Ge0


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## Picassotheimpaler (Sep 21, 2014)

With the first layer of body filler, looks good so far. I do have to say, after starting to use epoxy resin and filler things have gotten much easier. Not having to worry about shrinkage of poly resin makes aiming a piece of cake.


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## Ge0 (Jul 23, 2007)

Picassotheimpaler said:


> View attachment 278043
> 
> With the first layer of body filler, looks good so far. I do have to say, after starting to use epoxy resin and filler things have gotten much easier. Not having to worry about shrinkage of poly resin makes aiming a piece of cake.


Oh sh!t. Did you check the temp rating on that epoxy resin? I was going to buy some to do a similar mod. But, the guy at US Composites talked me out of it. Epoxy will get soft at 140F and will melt at around 170F. 

Car interiors get real hot during summer. There is a reason I test all the interior electronics I develop for auto makers up to 85C (185F). You may want to reconsider this...

Ge0


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## Picassotheimpaler (Sep 21, 2014)

I havent checked it directly but I use total boat high performance epoxy, but I believe the heat deflection temp is around 150 F. Luckily I live in RI so it isnt crazy hot, but even on days that it is 90 F out i havent had any issues with it softening.
I had some laying around from some other furniture projects so i made a sample laid up with glass and took a heat gun to it as a test. With 3 layers of cloth it JUST started to bend a bit right before it started to burn and darken up to brown. That was enough for me to just go for it. It does soften up with heat for a few days after the lay up but it seems to be okay after 4 or 5 days after a complete cure. The last project I did for my VW has held up well for 5 years though.


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## Frequentflyer (Mar 3, 2020)

I recommend getting a custom fit sun shade (like Weathertech) and using it religiously, even in the winter. Worth the $50-60 I think. I am using one to keep the UV off my grill cloth as much as I can.


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## Ge0 (Jul 23, 2007)

Picassotheimpaler said:


> I havent checked it directly but I use total boat high performance epoxy, but I believe the heat deflection temp is around 150 F. Luckily I live in RI so it isnt crazy hot, but even on days that it is 90 F out i havent had any issues with it softening.
> I had some laying around from some other furniture projects so i made a sample laid up with glass and took a heat gun to it as a test. With 3 layers of cloth it JUST started to bend a bit right before it started to burn and darken up to brown. That was enough for me to just go for it. It does soften up with heat for a few days after the lay up but it seems to be okay after 4 or 5 days after a complete cure. The last project I did for my VW has held up well for 5 years though.


Nice test .

Now I'm kind of pissed US Composites talked me out of epoxy.

Ge0


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## Picassotheimpaler (Sep 21, 2014)

That would actually be a fantastic test to do for the website. Take a bunch of different types and brands of resin and test them for shrinkage %, heat deflection, stiffness, ect. I do have a few different types sitting around so maybe ill kick it off at some point.


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## Picassotheimpaler (Sep 21, 2014)

Ge0 said:


> Nice test .
> 
> Now I'm kind of pissed US Composites talked me out of epoxy.
> 
> Ge0


I just realized something. The epoxy resin that I used and that most others would probably recommend is the same stuff that is used to make carbon fiber parts. So if it was to get super soft and melt at temps that the car can get to on the inside,you wouldnt be able to put carbon fiber parts in the interior of a car either.
Total Boat High Performance. Its expensive but it is fantastic and sticks to ANYTHING as long as it has ANY sort of texture. That is one of the reasons I wanted to use it with these aluminum rings in this case. Also is nearly indestructible when it comes to impact and torsion (Its made for high performance boats)


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## Picassotheimpaler (Sep 21, 2014)

So ive gotten both mids mounted (still in bondo stage due to limited time) but they sound great.
Ive also been able to bump the XO in the mids up to 4k now because of that. I am back to an issue though. I cant get the mids and tweeters to integrate and sum properly. I am either getting ripples around the xo or just a large trough. It isnt what you would expect to see from being out of phase though, it is much wider and not as deep you would expect from being out of phase. I did get some of the ripple out of one of them by delaying one of the tweets a full cycle, but now I have this wide trough instead. It would be awesome if you guys had any ideas for me to try as far as the mid-tweet XO, or anywhere else for that matter!


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## Picassotheimpaler (Sep 21, 2014)

Left stage with 4k XO point. this is that strange trench i am talking about.










Right Stage with the ripple in the XO region.











Any ideas on what I can do to make this response any better than it is? I am a fan of a boosted mid and sub bass region. A little bit more than half Whitledge but not nearly as much as true Whitledge. I am also using a half Whitledge as a baseline here.


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## Frequentflyer (Mar 3, 2020)

Try either an all-pass filter at 4k or reversing the polarity on your left tweeter, but there is a about a 3db difference between your left and right midrange at 3.5k.


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## Picassotheimpaler (Sep 21, 2014)

Yeah that difference makes it pull a fair bit in the upper mid range but fairly centered everywhere else. Would using the phase delay in the helix make sense here? I haven't messed with APFs too much yet so I am not too certain where to start there. I have tried to do some reading on here about them but there isn't much


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## Frequentflyer (Mar 3, 2020)

I had good results reversing polarity on a mid on one side and a tweeter on the other. Not sure if that was the right way to do it over using all-pass filters, but it seemed to get rid of some phase issues.


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## Mauian (Jul 25, 2019)

Agree with frequent flyer. Try flipping the polarity (especially on the left side). It’s often the easiest and best way to fix a dip like the one on the left side in the crossover region. You can try it on the right as well. 

If trying all pass filters use second order and use a center frequency near the middle of the big dip and a Q that covers the width of that dip...much like PEQ. You can experiment a bit to see what works best. You can try it on the tweeters response, or the midrange.


Sent from my iPhone using Tapatalk


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## tjk_bail (Feb 2, 2012)

I had a very similar problem in my tune using 4k XO's, I tried tweeking the timing, and tried all pass filters, but didn't fix the issue. I didn't try flipping phase on a channel or two, to me that does not sound like a good idea. I changed the XO on Mid-Range and Tweet from 4k down to 3.5k, and re-tuned. Now I have nice summing.


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## Picassotheimpaler (Sep 21, 2014)

I may give that a shot just to see when I have another day to tune. I was having a similar issue before when I had the previous setup, but at 3k as well. Which leads me to believe that either I am missing something somewhere or I am just getting too many reflections off the drivers window with the current tweeter position. I would also be very curious as to what would cause the wide yet somewhat flat dip the xo region.


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## tjk_bail (Feb 2, 2012)

I used a XO of 320hz between Mid-Base & Mid-Range like you are using for over a year. Used 340hz for a while too, was never really happy with it, but it seemed to work... then I found this info in a thread>>

"Here’s how that works in a typical car stereo system with speakers mounted in the doors. Let’s say we measure from the driver’s speaker to the microphone and the distance is 40”. When we measure from the microphone to the passenger’s door speaker, the distance is 67”. The difference between them is 27”. 27” corresponds to half a wavelength at about 250 Hz. (The speed of sound is roughly 1132 feet/second or 13,582”/second. 13,582” divided by 2 times 27” is about 250 Hz.) The measurements in different cars may differ slightly, but the concept is the same any time the speakers are not equidistant from the listener."

I used the above info to determine the best XO for Mid-Base/Mid-Range. It calculated out that the best XO for Mid-Base in my truck for LP 399hz, and best for my Mid-Range is HP 411hz. I split the difference and used 405hz as my settings... I am VERY happy with the results, especially with my Mid-Range... its remarkable how much deeper the bass notes are as the mid-range/mid-base blends so much better with the sub. Reduced vocal harshness, and improved whole system deepness and natural sound, the stage moved deeper away from my face. It should not work this way, 320hz is lower than 405hz, so why would my bass sound so much better at 405.. it just does....


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## tjk_bail (Feb 2, 2012)

I'm no expert, but if you apply an All Pass filter to a dip in a crossover area, and it has NO effect in the response, the problem is more with Summation of frequency's, not Cancellation of frequency's. There is a difference between dips caused by summing probs, dips caused by cancellation, dips caused by Modal, and dips caused by crappy EQ'ing technique. It will be fixed with using the correct XO's between the Mid-Range & Tweets, and getting the frequency response to match exactly to a House/Speaker curve between L&R tweets and L&R Mid-Range, and T/A. (although T/A is a part of phase)


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## Mauian (Jul 25, 2019)

The OP is getting no summation at the crossover region on the left side. This really strongly suggests that the speakers (the two playing) are out of phase with each other. Flipping the polarity on a speaker is completely ok and absolutely the right thing to do to address the problem of two speakers being out of phase with each other.

If flipping polarity doesn’t do it then you have a null there from the car geometry and/or speaker positions or you might have an all pass filter on your input signal (if using a factory HU) or you have a different kind of phase issue that is more complex than the speakers being completely out of phase with each other. Definitely agree that if flipping polarity or adding an all pass doesn’t work than you may need to move the crossover to avoid that dip.

Does it respond to EQ?


Sent from my iPhone using Tapatalk


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## Picassotheimpaler (Sep 21, 2014)

Yeah responds fine to eq. It just seems odd that it is such a wide dip vs a sharp dip that I usually correlate with being out of phase. The acoustic crossovers are also nearly dead on to what i would be looking for within 1db or so. So I figured they should be having no issues summing but that doesn't seem to be the case.
Would using ta to bring them back into phase using TA work just as well as flipping the phase and going that route? Or since it is out of phase to begin with, it isn't going to sum properly regardless of the TA distance setting?
I am also using an aftermarket kenwood excelon HU, and a helix dsp pro mk2


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## Mauian (Jul 25, 2019)

Yeah, I’d give the polarity flipping on the helix a shot. A wide dip like that at a XO can be caused by a speaker having a flipped polarity from the other.


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## Frequentflyer (Mar 3, 2020)

You'll actually be able to hear it when you flip the polarity without even RTA'ing it. It may immediately sound more full. Like I said, I had to do this with one of my mids and one of my tweeters. I used to have before/after pics of the RTA, but I deleted them. If I get around to it, I may take some additional measurements.


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## Mauian (Jul 25, 2019)

This talks about the subject nicely:








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## Picassotheimpaler (Sep 21, 2014)

If I flip the phase without changing TA settings it imediatly breaks the coherence it sound. If I flip polarity and give the TA an extra few 1/10ths it will loop back into sounding coherent. Thats the odd part I've been finding. It sounds like they are blending when it had that wide dip it is just clearly lower volume. If I give it a few clicks it sounds like it sums better but I get that ripple look that the other side has. I did check the wiring as well today, the gs10s are wired correctly.


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## jtrosky (Jul 19, 2019)

Are you sure that your time alignment measurements are 100% correct (sorry if this has already been answered - didn't recheck the whole thread)? Maybe take measurements one more time and spend a little extra time making sure that they are 100% accurate (measurements from head to voice coil of speakers). Also, make sure they are entered into the DSP correctly. You've probably already done this, but just bringing it up just in case.

Personally, I've never really understood why you would need to flip the polarity of a driver (or drivers) if they are all wired correctly, you are using 24dB LR acoustic slopes for everything and the time alignment is correct. That just seems strange to me. 

But yeah, that huge dip at the crossover on the one side can't be a good thing. Need to figure out what is going on there....


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## Mauian (Jul 25, 2019)

jtrosky said:


> Are you sure that your time alignment measurements are 100% correct (sorry if this has already been answered - didn't recheck the whole thread)? Maybe take measurements one more time and spend a little extra time making sure that they are 100% accurate (measurements from head to voice coil of speakers). Also, make sure they are entered into the DSP correctly. You've probably already done this, but just bringing it up just in case.
> 
> Personally, I've never really understood why you would need to flip the polarity of a driver (or drivers) if they are all wired correctly, you are using 24dB LR acoustic slopes for everything and the time alignment is correct. That just seems strange to me.
> 
> But yeah, that huge dip at the crossover on the one side can't be a good thing. Need to figure out what is going on there....


Having the wiring crossed is a big reason  if the terminals are mislabeled is another. Unless you’ve verified with a battery test you can’t be 100% sure. There are others too (I think a downfiring subwoofer can be another cause). But really the reason doesn’t matter, it’s a common enough experience and it works very nicely if that’s the reason.


Sent from my iPhone using Tapatalk


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## Picassotheimpaler (Sep 21, 2014)

Yep all 24db LR crossovers that I've tuned to. Also checked the acoustic roll off with Jazzis tool to make sure they are close to ideal. I will go over the time alignment again. I did find it sounded better to delay the tweets a cycle to get them to sum better. Im assuming that is because of the 360 phase shift from the lr filters. But that got me to the trough I have now instead of a ripple around the xo frequency. 
I was thinking that maybe my measurement method could do something similar? I sweep around my head from ear to ear so maybe it is picking up a cancelation from a window reflection? Idk just spitballing


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## Picassotheimpaler (Sep 21, 2014)

I am eventually going to bite the bullet and drive to NY to have Skizer tune it for me but I need to have the pillars done first. Maybe I can learn something while I am at it if he is feeling generous lol


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## Picassotheimpaler (Sep 21, 2014)

So ive been having some luck getting better summation. The Left side is looking much better but the right side still has some issues. It is much smoother but now i am getting a sharp dip right at 4k at the XO point on the Right. Here are a few graphs that are smoothed and unsmoothed to see if it helps at all.

Left side smoothed and unsmoothed compared to both sides playing at the same time


















Right side smoothed and unsmoothed with the both side measurement as a comparison.


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## Frequentflyer (Mar 3, 2020)

Did you do this with EQ, phase shifting and/or all-pass? How about individual driver RTA's?


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## SloVic (Oct 1, 2016)

GotFrogs said:


> The dash location cuts the area into which the sound radiates compared to free air by about 3/4 or a little more. That boosts the level below the region in which the dispersion of the speaker begins to narrow. Couple that gain with the foreward going reflection from the windshield and you have what you have. Cutting where the location boosts isn't what's killing "effortlessness". That's not how it works. Cutting by 12dB just reduces the amount of power you send the speaker.
> 
> What's really cool is all the boost and the fact that after you equalize, the useable bandwidth of the speaker (on the low end) is massively increased without much power.


If you don't mind me asking what would be the lowest you'd recommend crossing the GB25 in this scenario? 

Planning on putting small mid in my dash corners to run from about 100-150hz to 1000-2000hz. Right now it's a toss up between the GB25 and the Purifi 4".


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## Picassotheimpaler (Sep 21, 2014)

SloVic said:


> If you don't mind me asking what would be the lowest you'd recommend crossing the GB25 in this scenario?
> 
> Planning on putting small mid in my dash corners to run from about 100-150hz to 1000-2000hz. Right now it's a toss up between the GB25 and the Purifi 4".


150 is too low for that driver imo, 100hz definitely. The FS of the GB25 is 170, and running a speaker below its FS is generally not a good thing. Expecially not one you are relying on to play midrange.
If you listen at a fairly low level often, you MAY be able to get away with a 200hz xo in the dash corners. There is a ton of boundary/horn loading up there that helps the low end. But even then, 150hz over an octive lower than I would suggest crossing them normally without the effect of the dash corners.
I personally never ran them below 300hz up there, and actually settled on 400hz before I did something in a different location.
That being said, they worked very well up there. But I suspect you would run into some distortion issues running them below 200hz with any sort of spl behind them.


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## SloVic (Oct 1, 2016)

Yeah, right after I posted that I remembered the FS was around 170hz and Andy recommends staying away from FS. Just thought maybe with the corner loading I could get a way with something like 150hz and still have fairly low distortion.

I was mainly thinking of having a tune with them crossed low and listening at reasonable levels. Then also my day to day tune with a 200-300hz cross over.

Will probably just get the Purifi 4", will be a little harder to fit but I'm sure I can run it down to the 100-150hz range with no issues.

Sorry for the brief hijack and thanks for the reply.


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## Picassotheimpaler (Sep 21, 2014)

SloVic said:


> Yeah, right after I posted that I remembered the FS was around 170hz and Andy recommends staying away from FS. Just thought maybe with the corner loading I could get a way with something like 150hz and still have fairly low distortion.
> 
> I was mainly thinking of having a tune with them crossed low and listening at reasonable levels. Then also my day to day tune with a 200-300hz cross over.
> 
> ...


Well, if you are using it for an occasional kind of tune and can cross at 200, I would say it can be done at moderate levels. There are absolutely benefits to having a smaller diameter cone up there since you are typically playing quite off axis. You're able to push the mid to tweeter xo higher without beaming issues.
That can be quite important depending on the rake of and distance to the windshield. If you wanted to run the 4in up to 4k, it could potentially be an issue due to the directivity. Depending on how the windshield is shaped and angled, it could potentially cause some weirdness that would make it difficult to cross that high. Where it is most likely less of a potential issue with a smaller diameter driver.


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## 156546 (Feb 10, 2017)

The purifi drver has a really big magnet and it's 73mm deep compared to the GS25 at 41mm. A LR4 filter is -6dB (1/4 power) at the crossover so you could go as low as Fs. But why a 4" at 100Hz in the dash? Is there a midbass in the car somewhere or just a sub?


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## 156546 (Feb 10, 2017)

Picassotheimpaler said:


> Well, if you are using it for an occasional kind of tune and can cross at 200, I would say it can be done at moderate levels. There are absolutely benefits to having a smaller diameter cone up there since you are typically playing quite off axis. You're able to push the mid to tweeter xo higher without beaming issues.
> That can be quite important depending on the rake of and distance to the windshield. If you wanted to run the 4in up to 4k, it could potentially be an issue due to the directivity. Depending on how the windshield is shaped and angled, it could potentially cause some weirdness that would make it difficult to cross that high. Where it is most likely less of a potential issue with a smaller diameter driver.


Beaming isn't much of an issue when the speaker is pointed at the glass.


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## 156546 (Feb 10, 2017)

Unless there's no rake on the windshield like a jeep or an old beetle, etc.


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## SloVic (Oct 1, 2016)

GotFrogs said:


> The purifi drver has a really big magnet and it's 73mm deep compared to the GS25 at 41mm. A LR4 filter is -6dB (1/4 power) at the crossover so you could go as low as Fs. But why a 4" at 100Hz in the dash? Is there a midbass in the car somewhere or just a sub?


Cool, thanks for the answer Andy.

Mainly to experiment with and for novelty. Putting one or two 8" subs in the passenger footwell. Will also have a pair of a pair of 15" subs in the back.

If I use the Purifi 4" in the corners of the dash I'm also going to get a pair of Tectonic TEBM46C20N-4B and put them in the bottom of the A pillers just above the 4". Have Bliesma silk tweeters for the sails panels so that leaves me with 3 possible set ups/tunes (not counting subs)

Purifi 4" and Tectonic 2.5" playing everything from 100-150hz up. Think this would be a good two seat set up for most people I know, most aren't very critical of music reproduction.

Purifi 4" and Bliesma T25S-6. Can try a simple 2 way.

Purifi 4", Tectonic 2.5", and Bliesma T25S-6. Would allow me to really play around with different cross over points. Main idea is getting a solid polar response to 4-5khz from the dash corners then use my tweeters to widen things a bit.

Off axis plot of the BMR's from hificompass.com only down 5 db at 60 degrees off axis at 5khz.


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