# Left and Right EQ



## Grindcore (Dec 12, 2012)

Hey all....i have read up heaps on this subject in the forums but im a bit confused about something..

At the moment im eqing left and right seperatley to center frequencies...

After this im equing both sides together to smooth out the FR

I have had good results like this but should it be done the other way round?

Also i have read that you should eq each side seperatley and try to get the response curve you need...then do the other side and get it as close as possible...

By doing it that way do you mess up tonality?

By that i mean you may end up cutting or boosting fequencies un evenly to get the same FR left and right..or am i missing something? Will it be tonally correct because both curves are as close to each other as possible?..
Im presuming you would do this first then run both sides together to tweak the response further if need be.?
Any input would be greatly appreciated..


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## solacedagony (May 18, 2006)

If your car was symmetric, you'd get the same response on both sides. however, your car isn't, so you end up with an acoustic response at your seating position that is (probably) not the same on left and right. As a result, your EQ curves will also be non-symmetric.

The main idea is that you end up with the same acoustic response at your seating position from each side, even though the acoustic output of the driver may not be the same from side to side. Then, like you said, you can tailor the total response to be what you want.

I think it's a pretty good way to end up with a good sound. You should level match and T/A before EQ.


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## Rrrrolla (Nov 13, 2008)

I've found that eq'ing left and right for center messes with the combined frequency response, and vice versa... I usually wind up tweaking back and fourth 3 or 4 times to get things sounding their best. If you touch time alignment at any point during this process you might as well go back to flat and start over. PITA


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## sqnut (Dec 24, 2009)

Measure one side at a time using the 1/3 oct pink noise tracks and correct for L/R. Now assuming your TA is already set up, mark an X on the windshield just below your rear view and play the PN tracks. You want them all to image up in a tight bunch at the X. If they image left or right of the X use the eq accordingly. The low end frequencies may image lower than the X thats fine, just ensure they are vertically aligned with the X. If you do these two steps you should be good for L/R balance. Also, when you're checking against the X at each frequency move your head slightly to left and right. The image should stay stable. Some frequencies in the 1-5khz range may be an issue, they will not center no matter what you do on the eq and the slightest movement of the head will cause them to jump from side to side. Based on your xover figure out which is the primary driver playing that frequency. If the image is shifted left of the X, reduce one step of delay on the left driver and vice versa. 

If you measure and set 800 hz to say 85 db on both sides now when you play both drivers that 85 db could be 81 or 88db due to cancelling/summing effect. That has nothing to do with L/R. What a frequency measures with both drivers playing, is only relevant once you're dialing in tonality i.e. after you have balanced for L/R.


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## Grindcore (Dec 12, 2012)

Cheers fellas thanks for the replies...ive been mucking around all weekend messing with tuning and im slowly but surely getting there...

what i have found is that in playing with crossovers whilst tuning before using eq i can smooth some peaks etc but i have different slopes and/or crossover points left and right...is that a wrong way of doing things? I presume using less eq in the end would be better? Or it really makes no difference as the end result will be the same?


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## sqnut (Dec 24, 2009)

What do you have for dsp? 

Using min eq to get good sound in a car is like an oxymoron. In a car you *have* to use a *ton* of eq. http://www.diymobileaudio.com/forum/technical-advanced-car-audio-discussion/167547-why-do-so-many-people-use-focal-speakers-7.htmlScroll down the page on the link and you will see two graphs. The first is the FR of a door speaker measured 1" from the speaker and the other is a measurement at ear level. The effect will be similar irrespective of speakers, car, placement etc. There is no way to clean out the ear level mess w/o a ton of eq.

All the folks who claim that ear level response issues can be solved 80% by use of xover/slopes and hence you need min eq as well as those that claim 'it works for me' etc are just not listening closely enough. The only time I would use asymmetrical xover points and slopes are if I only had a 3 band eq.


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## Grindcore (Dec 12, 2012)

Im using a pxa-h800 so i have plenty of eq power..

So best bet would be just setting all your crossovers/slopes and just eqing out any problems?


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## sqnut (Dec 24, 2009)

Grindcore said:


> Im using a pxa-h800 so i have plenty of eq power..
> 
> So best bet would be just setting all your crossovers/slopes and just eqing out any problems?


For the most part yes.


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## Grindcore (Dec 12, 2012)

Cool...well tonight im gonna go through and measure left and right again with set crossovers/slopes and post up a couple of pics of my readings.i have truerta which im very familiar with...and its the level 4 version so high res..im still trying to get my head around REW...so many options in that program! And yeah some input from you would be greatly appreciated..

Cheers

Sam


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## Beckerson1 (Jul 3, 2012)

Grindcore said:


> Cool...well tonight im gonna go through and measure left and right again with set crossovers/slopes and post up a couple of pics of my readings.i have truerta which im very familiar with...and its the level 4 version so high res..im still trying to get my head around REW...so many options in that program! And yeah some input from you would be greatly appreciated..
> 
> Cheers
> 
> Sam


Well to high a resolution can make things more confusing and in many cases (unless your DSP allows for more adjustment) 1/3 or 32 bands/oct is more then enough resolution to get great results tuning. 

REW can be confusing at first but with the guidance in setup (setting up your soundcard correctly, mic, ect...) and what to look for, not to mention what to use, it is quite easy to get a hold of IMHO.


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## Grindcore (Dec 12, 2012)

Setting up REW was easy for me.....i have the soundcard and mic configured...its just the amount of options and windows that has me confused!....will be taking a few measurements very shortly and will post up results...

Cheers all for your input
Sam


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## sqnut (Dec 24, 2009)

Take your readings at 1/6 oct resolution. You can only correct at 1/3 but it helps to see the response at 1/6 and then correct at 1/3. Did you balance for L/R as I explained?


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## Grindcore (Dec 12, 2012)

<a href="http://s68.photobucket.com/user/grindalicious_2006/media/left%20and%20right%20jpg.jpg.html" target="_blank"><img src="http://i68.photobucket.com/albums/i27/grindalicious_2006/left%20and%20right%20jpg.jpg" border="0" alt="left 20 right 19 photo left and right jpg.jpg"/></a>

Ok 20 is left side and 19 is the right side


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## Grindcore (Dec 12, 2012)




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## Grindcore (Dec 12, 2012)




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## Grindcore (Dec 12, 2012)

So top pic is left and right seperate.4 averages each...set mic uo at 4 different places near head area.

Second pic is both sides playing...4 averages again...both in 1/6 octave resolution

Cheers fellas


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## Grindcore (Dec 12, 2012)

The orange colour in first pic is right side.no.19.
20 is left side


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## Alextaastrup (Apr 12, 2014)

Curve is still far away from the optimal. Even 2-3 dB change in intensity could change the sound reproduction drastically - but here it is probably the EQ limitation of pxa-h800.

Tuning very much depends on placement of all speakers according to the listening position, nothing new. So it is different from car to car. Everybody has its own experience, which is hardly could be recommended to export to another environment.

In my case after fine-tuning I tried to adjust frequencies above 1kHz in order to deminish irritating direct sound from the tweeters (different EQ's, of course) by changing the ratio between direct and reflected sound. The corrections achieved were in the range 1-2dB only but the result i audible: pleasant and more comfortable. 

My suggestion - rely on your ears, as a microfon can not work the same way your brain does, selecting unnecessary information, compiling images, etc. (pure psycho-acoustics, that many underestimate).


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## Grindcore (Dec 12, 2012)

Cheers for the reply....yeah i havent done anything with tuning.i reset everything...just reset crossovers and messed with TA....havent touched eq for this tune...

Yeah i understand that speaker placement is all part of it...


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## Grindcore (Dec 12, 2012)

I guess there is some merit to relying on your ears and it really is subjective...but getting a baseline and then tuning to suit would be the way to go...


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## sqnut (Dec 24, 2009)

Grindcore said:


> The orange colour in first pic is right side.no.19.
> 20 is left side


I must be going colour blind, I can't see an orange curve on either of the graphs. On the L/R graph, one of the sides is much otter in 60-125hz range. I see it as a bluish green line, which side is that?


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## fcarpio (Apr 29, 2008)

I do left and right separately and do not mess with the combined EQ. As mentioned earlier, your car is not symmetrical and in my experience EQing both sides at once will not yield the best results.


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## sqnut (Dec 24, 2009)

When balancing for L/R you measure and correct one side at a time. Post that when you're dialing in tonality you eq both sides together.


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## Beckerson1 (Jul 3, 2012)

fcarpio said:


> I do left and right separately and do not mess with the combined EQ. As mentioned earlier, your car is not symmetrical and in my experience EQing both sides at once will not yield the best results.


Combined EQ is the last step. Agree with sqnut

One must balance L and R. Measure both separately, put on same graph, balance them out. Measure, graph, adjust, and remeasure.... Continue that till your response is the same for both sides. Well as close to same as your DSP and EQ allow. Then one can do the final EQ combined adjustments


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## Grindcore (Dec 12, 2012)

Ok the hotter side you reffered to is the left hand side.it seems the colours have merged together when i saved the photo...will have to try that one again...


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## sqnut (Dec 24, 2009)

Tks got it now. Is the eq set to flat when you measured or is the measurement post eq?


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## Grindcore (Dec 12, 2012)

Beckerson1 said:


> Combined EQ is the last step. Agree with sqnut
> 
> One must balance L and R. Measure both separately, put on same graph, balance them out. Measure, graph, adjust, and remeasure.... Continue that till your response is the same for both sides. Well as close to same as your DSP and EQ allow. Then one can do the final EQ combined adjustments



One must balance left and right.what exactly do you mean here...this is where i think im getting confused...you mean stuff like output levels? Or are you referring to the balancing of frequencies to sound as if they are centered?


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## Grindcore (Dec 12, 2012)

So if the latter...you have already TA,d...level matched etc...both sides are playing frequencies and eq lwft and right to center them.then measure each side seperatley..graph them.then re adjust?


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## sqnut (Dec 24, 2009)

You can balance the L/R from your graph. Your eq is at 1/3 oct so take it one frequency at a time. For instance 60hz is ~ 7db louder on the left, so cut the left side -6 and raise the riight by 1 db. 80 hz is ~ 12 db louder on the left so cut accordingly and so on all the way to 20khz. After you're done go back and measure again.


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## Grindcore (Dec 12, 2012)

Ahhh sweet mate....i understand that now...there are some big differences between LR in some areas....im presuming also you wouldnt want to boost more than 1db if possible? For the bigger swings what would be the largest boost...no more than 1.5-2db?


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## sqnut (Dec 24, 2009)

Where the diff between L&R is a few db, just cut the louder side. If the difference is like 10-12 db on one side then yes cut one side by 10 db and slightly boost the weaker side by 1-2db.


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## Grindcore (Dec 12, 2012)

Cheers mate....will be having a go with it later tonight and i will repost some new graphs..thanks for the help


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## Beckerson1 (Jul 3, 2012)

Sqnut pretty much hit it on the head. 

Balancing l to R is the same as centering the freq. What your after is achieving the same output curve on both sides. IMHO this should be done before your universal Eq But some do it the other way around. The two sides being different results in wondering from side to side. This step is very time consuming and very important.


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## sqnut (Dec 24, 2009)

Is your sub to mid bass xover set ~ 125 hz?


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## Grindcore (Dec 12, 2012)

Thanks again for the posts...didnt get a chance to have a tinker with it last night will see how i go after work today...

My sub to mid crossover is 50hz...dayton 12's in rear and peerless xls 8 in front doors..is 125hz high?


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## Grindcore (Dec 12, 2012)

Ok.had a go with the tuning again...first pic is left/right seperate
Pre tune......average of 4 points near head area per side


next pic is first pass of tuning...i have re measured and adjusted again but i didnt have time to run the RTA again will di it tomorrow


it has improved somewhat but i should get much better with a couple more runs and re tunes


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## sqnut (Dec 24, 2009)

Grindcore said:


> My sub to mid crossover is 50hz...dayton 12's in rear and peerless xls 8 in front doors..is 125hz high?


The reason I asked is because of the deep dip ~ 150 hz. Nulls in this range are normally either due to modal issues (i.e. can't be fixed) or due to drivers being out of phase if the null is near the xover point. In this case it looks like a modal issue. The good thing is it's only ~ 1/3 oct wide so you're probably not hearing much of it. 125hz is too high a xover point imo, even I use a 50hz crossover point. An 8" driver at 50hz will give great impact.


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## sqnut (Dec 24, 2009)

Grindcore said:


> Ok.had a go with the tuning again...first pic is left/right seperate
> Pre tune......average of 4 points near head area per side
> 
> 
> ...


Already looking better. The imaging should be a lot more stable the location of everything should be more fixed. Tonality would still be off and we will get to that but yeah, imaging should be a lot more stable

This is a good time to check what you're measuring vs what you hear. Play the PN 1/3 oct tracks and check if all the frequencies image up under your rear view. If some frequency is slightly left or right of centre adjust it accordingly. Do it a few times and then measure. Let's see what happens.


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## Grindcore (Dec 12, 2012)

sqnut said:


> Already looking better. The imaging should be a lot more stable the location of everything should be more fixed. Tonality would still be off and we will get to that but yeah, imaging should be a lot more stable
> 
> This is a good time to check what you're measuring vs what you hear. Play the PN 1/3 oct tracks and check if all the frequencies image up under your rear view. If some frequency is slightly left or right of centre adjust it
> 
> thanks for the advice...i will give it a listen and adjust if certain frequencies are out...if they are would the process be having both sides play and raising/lowering right/left accordingly by a db or so so if you lower a side by 1db you raise the other by a db? Etc


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## Grindcore (Dec 12, 2012)

sqnut said:


> Already looking better. The imaging should be a lot more stable the location of everything should be more fixed. Tonality would still be off and we will get to that but yeah, imaging should be a lot more stable
> 
> This is a good time to check what you're measuring vs what you hear. Play the PN 1/3 oct tracks and check if all the frequencies image up under your rear view. If some frequency is slightly left or right of centre adjust it
> 
> thanks for the advice...i will give it a listen and adjust if certain frequencies are out...if they are would the process be having both sides play and raising/lowering right/left accordingly by a db or so so if you lower a side by 1db you raise the other by a db? Etc


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## Grindcore (Dec 12, 2012)

As for that null....8s are playing 50hz up on a 36 db slope.subs playing down from 50hz 36db slope..subs are reverse phase only..nothing else is in the system...


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## Beckerson1 (Jul 3, 2012)

Grindcore said:


> As for that null....8s are playing 50hz up on a 36 db slope.subs playing down from 50hz 36db slope..subs are reverse phase only..nothing else is in the system...


Does that peak/null translate into the 1/3 resolution? This could be exaggerated due to the higher resolution.


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## sqnut (Dec 24, 2009)

Grindcore said:


> thanks for the advice...i will give it a listen and adjust if certain frequencies are out...if they are would the process be having both sides play and raising/lowering right/left accordingly by a db or so so if you lower a side by 1db you raise the other by a db? Etc





Grindcore said:


> As for that null....8s are playing 50hz up on a 36 db slope.subs playing down from 50hz 36db slope..subs are reverse phase only..nothing else is in the system...


Play the PN tracks from 500hz and up. These should image up at more or less the same spot under your rear view mirror. If some frequency images left, cut the left side by 1 db and vice versa. 

As mentioned by Beckerson, do a measurement at 1/3 oct resolution to see if the dip is less severe. For now just focus on getting L/R balanced.


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## subterFUSE (Sep 21, 2009)

Sub'd.


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## Beckerson1 (Jul 3, 2012)

sqnut said:


> ....If some frequency images left, cut the left side by 1 db and vice versa....


Hmmm I don't think that would work. If everything sounded off to one side then ya but if some are off its due to the l and R side being off.


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## Rs roms (Jul 12, 2012)

Beckerson1 said:


> Hmmm I don't think that would work. If everything sounded off to one side then ya but if some are off its due to the l and R side being off.


He means 1db or so on those specific steering frequencies to image centre.


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## Beckerson1 (Jul 3, 2012)

Rs roms said:


> He means 1db or so on those specific steering frequencies to image centre.


Hmmm lack of sleep = fail at reading.


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## sqnut (Dec 24, 2009)

The reason I like to do the L/R by ear is because of the effect of reflections. Measure to get in the ballpark and then do the final bit by ear. 

Below ~ 500 hz the wavelengths are too long for any significant level of reflections. The effect of reflections is to make the incident sound seem louder. Set the 300hz PN track and 1 khz tone to the same spl level say 80 db. Now listen to the two tones. You will hear 1khz much louder. 1 khz is perceived louder because of the effect of reflections, you're hearing the incident sound as louder. Our ears hear the effect of reflections, our mics don't. 

Measure way into the L/R ballpark and then use the ears to do the final tweaking. A frequency could have a stronger reflection from one side (assuming the timing is right) and that will pull the image towards that side, even though your measurements may say that the frequency is balanced. 

Twist your head a little to the left and right each frequency, if the timing and L/R balance is correct, the image should remain centred. Except in the 1-4 khz range. Here you may run into some frequencies that just don't centre no matter what you do on the eq. Let's say the frequency pulls to the left, try reducing the delay by one click on the left speaker and then try to eq.


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## subterFUSE (Sep 21, 2009)

Our ears are also more sensitive to 1 kHz so it will sound louder than lower or higher frequencies when the measured dB might be exactly the same. This is one of the reasons why a flat EQ response curve doesn't sound flat to humans.

This sensitivity has evolved in us because 1 kHz is the approx frequency range of a human baby crying.


Sent from my iPhone using Tapatalk


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## Grindcore (Dec 12, 2012)

Ok my fellow tweakers....its never ending....didnt get to my car before i got to the beers.....

Will reply soon....loving all the input


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## sqnut (Dec 24, 2009)

subterFUSE said:


> Our ears are also more sensitive to 1 kHz so it will sound louder than lower or higher frequencies when the measured dB might be exactly the same. This is one of the reasons why a flat EQ response curve doesn't sound flat to humans.
> 
> This sensitivity has evolved in us because 1 kHz is the approx frequency range of a human baby crying.
> 
> ...


The pitch will be different between 300hz and 1 khz and yes the higher pitch coupled with the reflections make 1khz louder. Play the 300 hz and 1 khz tone thru your home 2ch. The difference will be much less than in a car.


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## solacedagony (May 18, 2006)

sqnut said:


> Our ears hear the effect of reflections, our mics don't.


Why wouldn't the mic measure a difference with a reflection?



sqnut said:


> Measure way into the L/R ballpark and then use the ears to do the final tweaking.


Unless you 100% understand what the measurement(s) you took actually mean, this will always be true, especially in a car.


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## subterFUSE (Sep 21, 2009)

Microphones do measure reflections. Just try getting a clean impulse response phase plot using REW in a car and you'll see. Reflections muddy up the charts, bigtime.


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## sqnut (Dec 24, 2009)

solacedagony said:


> Unless you 100% understand what the measurement(s) you took actually mean, this will always be true, especially in a car.


Measurements are relevant so long as you correlate them to what you're hearing. Beyond a point it's all down to what you're hearing. A 0.5 db cut on your FR graph isn't going to tell you much, your ears will tell you a lot more about that cut. 



subterFUSE said:


> Microphones do measure reflections. Just try getting a clean impulse response phase plot using REW in a car and you'll see. Reflections muddy up the charts, bigtime.





solacedagony said:


> Why wouldn't the mic measure a difference with a reflection?


Our ears and brain sum the reflections with the incident sound thereby making it louder. The mic doesn't do this. If you'll cant wrap your head around measured loudness and perceived loudness in a car :shrug:


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## garysummers (Oct 25, 2010)

Equalization should be set for left and right channels independently to yield the target curve. Equalization of Left plus Right after the individual channels have been set will not yield the proper results. I know of nobody using this method to set up music or film mixing studios. Why would it apply to tuning the acoustical response of a car audio system? The resultant response errors from acoustically combining Left and Right signals are not correctable through equalization but should be mitigated with acoustical treatment of the interior of the vehicle. This is of course assuming that all other tuning settings are correct, ie: Crossovers, Time Correction. IMHO


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## sqnut (Dec 24, 2009)

garysummers said:


> Equalization should be set for left and right channels independently to yield the target curve. Equalization of Left plus Right after the individual channels have been set will not yield the proper results. I know of nobody using this method to set up music or film mixing studios. Why would it apply to tuning the acoustical response of a car audio system? The resultant response errors from acoustically combining Left and Right signals are not correctable through equalization but should be mitigated with acoustical treatment of the interior of the vehicle. IMHO


We are lucky to have talented folks like you in the recording industry, who are not a part of the loudness bandwagon. It's thanks to people like you that we have a large body of well recorded content. But the car is a totally different room from a recording studio. Based on a Harmon study a while back, in a normal living room type of setup, about 20% of the sound we hear is direct 40% are early reflections and 40% are late reflections. A recording studio would have spent a couple of million dollars just to dampen the room further, hence making it less reverberant. 

In a car 90% of what we hear are early reflections with about 10% direct sound. *A bulk of the work to get the car sounding right i.e. like listening to a 2 ch in a room, is down to equalizing L&R together after one has balanced for L&R.* You're doing this to shape the overall response at your ear level. These are FR graphs posted by Andy. The first is the FR measured 1" from the cone on a door mounted speaker.

http://www.flickr.com/photos/[email protected]/4240691825/in/photostream/

This is the response from the same speaker measured at ear level.

http://www.flickr.com/photos/[email protected]/4241476364/in/photostream/

In a car we are not eq for the recording we eq for what the environment does to that recording.


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## garysummers (Oct 25, 2010)

Establishing that most of the sound we hear in the car is reflected energy is nothing new. The question is how to mitigate those reflections.
Equalizing of individual channels to yield a timber matched response at the listening position is the proper way to calibrate an audio system. By attempting to equalize the combined response will only throw off the timber match you achieved.
If your theory holds true then how would I proceed to align the response of the system in my car which has five discreet audio channels. Once I have equalized each channel for proper timber match, are you advocating playing pink noise through all five channels simultaneously and attempting to correct overall response errors. 
I don't believe that Andy or Harmon would advocate such a practice.


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## sqnut (Dec 24, 2009)

garysummers said:


> Establishing that most of the sound we hear in the car is reflected energy is nothing new. The question is how to mitigate those reflections.


With extensive interior treatment we would mitigate about 5% of the reflections in the 5khz+ range. Very audible but it doesn't solve our problem.



garysummers said:


> Equalizing of individual channels to yield a timber matched response at the listening position is the proper way to calibrate an audio system. By attempting to equalize the combined response will only throw off the timber match you achieved.


I'm just trying to understand your process here. You're saying play left side get it tonally accurate then the same with the right side and then play both sides right? For instance a piano attack which is close mic'd with the top of the piano open, is not going to sound right unless the clang at 500-1khz and the woody notes ~ 160-200 and the harmonics around 3, 5 and 8 are in the right balance. For keeping it simple lets consider any two frequencies.

Once we have set it up for both sides lets take a quick measure of each side and let's assume that 500 hz is ~ 80 db on both sides and 3khz is 76db. Now when we play both sides these frequencies will not sum to 80 and 76 db, thanks to the reflections. 500 could sum to 85 db and 3khz to 80. Now the piano sounds thin, tinny and honky. You have to go back and readjust. 

The other issue with this process is that you're not getting an exact level match between L&R, so imaging may be a touch fuzzy. It just seems easier to level match one side at a time and then use the L&R eq together to dial in the tonal accuracy.



garysummers said:


> If your theory holds true then how would I proceed to align the response of the system in my car which has five discreet audio channels. Once I have equalized each channel for proper timber match, are you advocating playing pink noise through all five channels simultaneously and attempting to correct overall response errors.
> I don't believe that Andy or Harmon would advocate such a practice.


I've never had the pleasure of tuning a 5 channel setup. But for a simple stereo setup 2 way / 3 way with sub, once I've balanced L/R with the pink noise one side at a time, dialing in tonality and timbre is all by ear listening to music, with L&R equalized together.


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## garysummers (Oct 25, 2010)

A simple stereo set-up should be calibrated the same way a 5.1 discreet system is calibrated. The laws of physics do not change when more channels are added.


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## sqnut (Dec 24, 2009)

garysummers said:


> A simple stereo set-up should be calibrated the same way a 5.1 discreet system is calibrated. The laws of physics do not change when more channels are added.


Touche . I'd probably tune it the same way that I would for a 2 ch, just that I've never attempted one. In any case, I don't watch movies in the car.


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## claydo (Oct 1, 2012)

So gary....your saying you arrive at your final eq solely with a mic....After matching side to side? I have to go with sqnut on this one.......one would think you lock your eq global after matching left and right......then achieve your final tonality by ear, with actual music.....of course keeping the eq side to side match you worked so hard for...but adjusting overall tonality to a pleasing response. I'm curious how this would ruin the response when you keep your side to side match? Am I missing something?


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## subterFUSE (Sep 21, 2009)

That's one question I have about my new Helix DSP Pro which I don't know the answer to yet. If I balance the left and right sides via EQ and then want to adjust the tonality, I know that there is a feature to link the left and right sides together so you can adjust their relative positions simultaneously. 

But how does that work if you have applied parametric EQ to one channel? Wouldn't that effectively make it impossible for the left and right sides to then be adjusted together at once without throwing off the balance?

I will obviously know more once I get a chance to play with my DSP Pro, which should be very soon. But I have been wracking my brain over this question for a while now.

Sent from my iPad using Tapatalk


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## claydo (Oct 1, 2012)

Surely it offers a "global" as in affects all channels option........sorry I don't know how to do it on your unit......I tune via a lowly 99, it let's me eq l/r....then lock them and eq both together.....


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## Jepalan (Jun 27, 2013)

Interesting discussion. Am I understanding this correctly?...

It sounds like sqnut and Gary agree on first steps...
1) EQ left side (right side muted) to your target curve with mic at the listening position.
2) EQ right side (left side muted) to the same target curve with same mic at listening position.

Next step is where you differ?...
Gary says we are done after 1 and 2 because they will sum at listener.
SQnut says the combined main signal plus combined reflections will sum to a non-idea response (because reflections are strong in ratio to main in car) and will require additional tweaks to fine tune.

If I understand correctly, I have to side with SQnut on this one. Of course, the process has been simplified by leaving out fine tuning of levels & time alignment for optimal stage/imaging.


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## Beckerson1 (Jul 3, 2012)

subterFUSE said:


> That's one question I have about my new Helix DSP Pro which I don't know the answer to yet. If I balance the left and right sides via EQ and then want to adjust the tonality, I know that there is a feature to link the left and right sides together so you can adjust their relative positions simultaneously.
> 
> But how does that work if you have applied parametric EQ to one channel? Wouldn't that effectively make it impossible for the left and right sides to then be adjusted together at once without throwing off the balance?
> 
> ...


If its like the 360.3 as far as when you link the two it will erase any separation you have between the two. Basically erasing any progress you have. It's completely stupid and something I'd like seen changed. 

Of course its easy to remedy but can be a pain. This is something you could test out on the software if it offers a demo option


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## subterFUSE (Sep 21, 2009)

Beckerson1 said:


> If its like the 360.3 as far as when you link the two it will erase any separation you have between the two. Basically erasing any progress you have. It's completely stupid and something I'd like seen changed.
> 
> 
> 
> Of course its easy to remedy but can be a pain. This is something you could test out on the software if it offers a demo option



I think the feature works as intended if you are just using graphic EQ. But when you adjust parametric settings for one channel, that would make the EQs asymmetrical and therefore impossible to adjust simultaneously while keeping them in relative balance.


Sent from my iPad using Tapatalk


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## garysummers (Oct 25, 2010)

claydo said:


> So gary....your saying you arrive at your final eq solely with a mic....After matching side to side? I have to go with sqnut on this one.......one would think you lock your eq global after matching left and right......then achieve your final tonality by ear, with actual music.....of course keeping the eq side to side match you worked so hard for...but adjusting overall tonality to a pleasing response. I'm curious how this would ruin the response when you keep your side to side match? Am I missing something?


My final equalization curve is arrived at by starting with an industry accepted base target curve. Applying this curve to all channels individually so that they are timber matched to this curve. Then after many hours of listening and fine tuning that curve very precisely, a final target curve is plotted.
Each channel is now adjusted to this Final Target curve individually.
Timber match is checked by ear using circulating pink noise, L,C,R,LS,RS.
If a channel's timber does not very closely match the other channels, to my ear, then that channel is analyzed for possible tuning errors. This analysis is done with a RTA utilizing Timed Spacial Averaging of 4 mics at the driver head position. If the tuning method you are using is correct, what you are hearing will most often be what your RTA is showing. That is when you can start to make very precise repeatable adjustments and measurements.

All the above measurements both by mic and by ear are only performed once the system is confirmed to be Time and Phase correct as well as level matched.

The only reason to listen to combined channels is to verify proper phase and coherency between channels, not to adjust tonality.


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## claydo (Oct 1, 2012)

Ok.....so you do adjust for personal tastes/tonality after matching all channels to your selected curve.....but then as a final step, you go back to eq each channel individually to the new curve that pleased you tonally, after measuring said curve? Jeebus this is complicated! I think I understand what you're saying now.....well....maybe....


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## garysummers (Oct 25, 2010)

claydo said:


> Ok.....so you do adjust for personal tastes/tonality after matching all channels to your selected curve.....but then as a final step, you go back to eq each channel individually to the new curve that pleased you tonally, after measuring said curve? Jeebus this is complicated! I think I understand what you're saying now.....well....maybe....


Yes, exactly.
Nobody said it would be fast or easy.


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## claydo (Oct 1, 2012)

Lol...werd on the fast and easy......ok, I get where you're coming from now......for the most part! Thanks for the explanation. I am curious when you say you confirm phase and time settings.....is this confirming with software what you set by using measurements and by ear? Is this something that can be done with a simple rew program and mic, or are using some industry insider or super pricey rig to attain these measurements?


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## Beckerson1 (Jul 3, 2012)

garysummers said:


> My final equalization curve is arrived at by starting with an industry accepted base target curve. Applying this curve to all channels individually so that they are timber matched to this curve. Then after many hours of listening and fine tuning that curve very precisely, a final target curve is plotted.
> Each channel is now adjusted to this Final Target curve individually.
> Timber match is checked by ear using circulating pink noise, L,C,R,LS,RS.
> If a channel's timber does not very closely match the other channels, to my ear, then that channel is analyzed for possible tuning errors. This analysis is done with a RTA utilizing Timed Spacial Averaging of 4 mics at the driver head position. If the tuning method you are using is correct, what you are hearing will most often be what your RTA is showing. That is when you can start to make very precise repeatable adjustments and measurements.
> ...



Who cares how one achieves the end result when said end result pleases the individual. We all can argue the best method to achieve the end result 

Even though all this is very interesting and in many ways both Sqnut and Gary's routine to tuning is both acceptable and achieve IMHO the same result in the end (methods are different and one may or may not be more efficient). There isn't a blueprint for this and in the end if the end user is happy why argue?


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## truckguy (Sep 2, 2013)

garysummers said:


> My final equalization curve is arrived at by starting with an industry accepted base target curve. Applying this curve to all channels individually so that they are timber matched to this curve. Then after many hours of listening and fine tuning that curve very precisely, a final target curve is plotted.
> Each channel is now adjusted to this Final Target curve individually.
> Timber match is checked by ear using circulating pink noise, L,C,R,LS,RS.
> If a channel's timber does not very closely match the other channels, to my ear, then that channel is analyzed for possible tuning errors. This analysis is done with a RTA utilizing Timed Spacial Averaging of 4 mics at the driver head position. If the tuning method you are using is correct, what you are hearing will most often be what your RTA is showing. That is when you can start to make very precise repeatable adjustments and measurements.
> ...


Can you tell me the positions you use when you say timed spacial averaging at the driver head. Are they different for left and right side measuring. Thanks for summing everything up in one post so don't have to search all over the place!


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## claydo (Oct 1, 2012)

Beckerson1 said:


> Who cares how one achieves the end result when said end result pleases the individual. We all can argue the best method to achieve the end result
> 
> Even though all this is very interesting and in many ways both Sqnut and Gary's routine to tuning is both acceptable and achieve IMHO the same result in the end (methods are different and one may or may not be more efficient). There isn't a blueprint for this and in the end if the end user is happy why argue?


I don't believe their really is an argument........just that gary adds extra steps in his process.......besides, when folks more knowledgeable than myself argue, who knows what info I can glean from the debate......if there's only one path presented how are ya gonna choose yer own route? You're never too good too learn from what others are doing.....


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## garysummers (Oct 25, 2010)

claydo said:


> Lol...werd on the fast and easy......ok, I get where you're coming from now......for the most part! Thanks for the explanation. I am curious when you say you confirm phase and time settings.....is this confirming with software what you set by using measurements and by ear? Is this something that can be done with a simple rew program and mic, or are using some industry insider or super pricey rig to attain these measurements?


There are "industry insider or super pricey rigs" out there that can do the measurements you speak of with great accuracy. I do not happen to own or use them. One reason is that the Alpine PXI-H990 processor will not allow inputting a test signal and directing it's output to a given channel, which would be required for many of these tests. Test signals are inputted via the DVD player.

I have an excellent 5.1 test disc with every test signal required to do a full alignment of the audio system.

I did all the time alignment adjustments by ear using this test disc. These adjustments are then confirmed by playing recorded music.


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## claydo (Oct 1, 2012)

Ok....thanks! I was just wondering if there was an openly accessible way to accurately measure these parameters. Was kinda hoping there was.......particularly phase measurements......I know that alignment can be measured using loop back tools and programs.......


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## garysummers (Oct 25, 2010)

truckguy said:


> Can you tell me the positions you use when you say timed spacial averaging at the driver head. Are they different for left and right side measuring. Thanks for summing everything up in one post so don't have to search all over the place!



















Same mic positions for equalizing all channels.


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## truckguy (Sep 2, 2013)

That contraption is amazing. Thanks. As soon as it warms up around here I have a few things to try.


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## james2266 (Sep 24, 2009)

garysummers said:


> View attachment 59022
> 
> 
> View attachment 59023
> ...


Wow, what a great thread we have here. When Gary speaks on this stuff, my ears perk right up and listen attentively. Gary's vehicle is the best sounding vehicle I have ever heard. I guess there is a reason he has won all of those awards. 

Thanks so much for posting your pics of your measuring apparatus. So you have your mics pointing up and not forward. I might just have to try that out. I think it might actually be easier to set up this way anyways with my current mic stand. I only have one mic I can use at a time so it takes me alot longer to get things moving. I never had much luck using mic measurements for setting left and right eq when it comes to midbass anyways. Seems to work well for me for everything above about 200 Hz however. I think it has more to do with the install limitations than anything tho. My midbass is inside my doors facing each other and I really think just bringing the drivers to the front of the door card (eliminating the bouncing sound waves between door card and metal) would do wonders. Haven't brought myself to chopping up a Lexus door panel yet tho. Wish I could find one from a wrecker to play with.


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## bbfoto (Aug 28, 2005)

^ Agreed. Great thread.

I believe that the mics that Gary is using have Omni-directional pick-up patterns, so orientation isn't super critical (as long as they are not pointed ~180° off-axis from the main source), in addition to the fact that he actually wants to measure the rear/side speaker's response, too, without changing the mic positions. Also, due to the mic's body lengths, it would not be possible to position them all facing forward and achieve the minimum 3" distance from the headrest. Just my thoughts, could be wrong.

Gary, I'm curious if you might have a Neumann KU-100 at your disposal for in-car measurements? Would there be any advantage to taking the measurements this way so it somewhat factors in the HRTF? It seems that L/R & Side/Rear readings would differ quite a bit using the KU-100 due to the HRTF...especially how it would affect the response due to the reflections off of the side window glass and rear/side sources. Or do you obtain enough "good/usable/interpretable" information from your current mic setup so that there would be no tangible advantage?

James, you might also pick up an inexpensive Dual/Stereo/ORTF Microphone Bar Mount to make consistent mic placement easier. I use the On-Stage MY700, but there are many others.

http://www.google.com/webhp?client=tablet-android-samsung&source=android-home#q=microphone+bar


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## 1996blackmax (Aug 29, 2007)

Great thread indeed! I'm always happy to learn more things regarding this hobby.


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## Grindcore (Dec 12, 2012)

Ok guys i see there has been a lot of activity in here!! Will get to reading after i post these results...have been busy with work but i got a couple of hours to muck around with it all...i have a 1/6 and 1/3 rta to look at..i have gotten the l and r responses very close but still have a bit of a trouble area up from 1khz..everything else is pretty close but i will return to it again when i have time.

I have listened to the system as is and it doesnt sound as bad as i thought it would only because i have had to cut certain frequencies by 7-8 db and a couple were around 12-13db out..


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## Grindcore (Dec 12, 2012)

Garry love that mic set up! Also checking your measurements for mic positions....they are pretty close to what i was doing only i had to take four measurements because i only have 1 mic! So it drags the process out a bit longer but results should be the same?


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## Grindcore (Dec 12, 2012)

Ok... .did a little more....These are the latest ones..i wrote down the differences in this tune between L and R and put them into the eq but didnt get a chance to RTA those changes i made..hopefully tomorrow i can have them dialled in pretty close


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## sqnut (Dec 24, 2009)

How does it sound?


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## Grindcore (Dec 12, 2012)

Its sounding much better than it has previously..i played the 1/3 pink noise tracks and they all image up pretty well in center..like i said i have adjusted a couple of frequencies from the last RTA but havent checked the response yet..

I threw on a couple of tracks just to have a listen...i put on stuff i am real familiar with..AIC unplugged...rage against the machines first CD and Alanis Morissettes unplugged album and they sound pretty good...image wise its excellent..
Instruments and vocals are all placed where they should be..now if anything it seems a bit flat...not very dynamic...also the highs are a bit bright....harsh even...

Im going to give it a rest tonight and listen with some fresh ears tomorrow...


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## james2266 (Sep 24, 2009)

bbfoto said:


> ^ Agreed. Great thread.
> 
> I believe that the mics that Gary is using have Omni-directional pick-up patterns, so orientation isn't super critical (as long as they are not pointed ~180° off-axis from the main source), in addition to the fact that he actually wants to measure the rear/side speaker's response, too, without changing the mic positions. Also, due to the mic's body lengths, it would not be possible to position them all facing forward and achieve the minimum 3" distance from the headrest. Just my thoughts, could be wrong.
> 
> ...


Thanks so much for that link. I probably will pick one of those up and see if that helps. Probably need to look at a new mic stand as well - one small enough to sit on the seat bottom and yet tall enough for the mic's to be sitting at ear height. The one I have now is just way too tall. It has a boom however so I have been removing the headrest and having the micstand in the back seat floor. It is most definitely not an ideal situation.


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## subterFUSE (Sep 21, 2009)

I have a nice little boom mic stand which fits well in the driver seat, but the shape of my car seat makes it rather difficult to get the microphone itself positioned well. My car seats have a 1-piece backrest/headrest, so there is no "adjustable headrest" which can be used to pinch a microphone and hold it in position.

The boom stand fits nicely in the seat and can get the microphone at ear height, but the microphone cable extends behind the mic and forces the microphone to be positioned rather far forward from the headrest. If I tilt the mic upward I can get it closer to the headrest, but it still sits farther away than my ears would be. Therefore, if I want the mic to be positioned exactly where my ears are, I must place the boom stand in the back seat and extend the boom horizontally forward into the front.

My other option has been to sit inside the car while taking measurements and hold the mic in my hand next to my head. This has been my general technique so far. What are the thoughts on measurements with the listener sitting in the car?


I have always been under the impression that the mic should be pointed forward in a horizontal orientation. Has my assumption been incorrect? Looking at Gary's setup with the upward facing mics certainly leads me to think I have been forcing myself into a forward orientation perhaps unnecessarily. Facing the mic upward would definitely make using the boom stand easier for me.


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## 14642 (May 19, 2008)

garysummers said:


> Equalization should be set for left and right channels independently to yield the target curve. Equalization of Left plus Right after the individual channels have been set will not yield the proper results. I know of nobody using this method to set up music or film mixing studios. Why would it apply to tuning the acoustical response of a car audio system? The resultant response errors from acoustically combining Left and Right signals are not correctable through equalization but should be mitigated with acoustical treatment of the interior of the vehicle. This is of course assuming that all other tuning settings are correct, ie: Crossovers, Time Correction. IMHO


Gary, If you only knew how stuff gets tuned at that company. There are several fiefdoms all vying for supremacy and almost every systems tuner has his own process, which is ultimately governed by the 'audio guy" at each of the car makers. For example, one of the German car companies dictates that the EQ filters used must be symmetrical for left and right channels because different EQ would cause "phase problems". The result? ****ty sounding cars and they don't have to manage two separate files for left and right hand drive vehicles.

The research guys have proposed a uniform process many times. Several autotune routines have been developed including the one I helped develop for MS-8 but all were rejected by the army of systems tuners who fear for their jobs. 

In any case, all of the research people agree that general acoustics principles apply to cars just like larger rooms, the difference being the amount of reflected energy and the "eqability" of high frequencies that are often NOT EQed in larger rooms. This is one that I had to prove in order to get high frequency equalization included in the MS-8 algorithm. 

I also USED to use a 6-mic array and MS-8 includes a spatial average--that's why there are 2 mics and three measurement positions per speaker and per location.

In subsequent work on another autotune version for MS-2, we discovered that a spectral average and a single mic can achieve about 95% of the same accuracy. The 6 mic array that I used to use included a multiplexer box that switched between microphones with a selectable speed setting. So long as the mics switch a bit faster than the reset time on the RTA, the spatial average isn't compromised by the phase and you get a pretty good approximation of the spatial average. The better and more accurate way is to make impulse response measurements, run an FFT, delete the phase and average the magnitude. This process is slower and makes it really difficult to adjust filters in real time. 

At this point, I find that using a single microphone and multiple measurements with REW, calculating an average and applying the REW auto EQ is a speedy and often successful way to tune, so long as the EQ is a parametric one. This method doesn't work with a 1/3rd octave EQ.

Since there's really no standard in aftermarket car audio for the bandwidth of 1/3 octave EQ filters, those things are a serious crapshoot and few people realize that they DON'T follow the curve that's been drawn with any precision. The 1/3 octave EQ that's in MS-8 is a drawing tool and it automatically adjusts all the bands to arrive at the curve that is drawn. no no one realizes this either. 

Anyway. I agree with MOST of your process and I tune in a similar way. Matching left and right to a particular curve as closely as possible and matching the center to the left and right is the most important part of making the car sound good. For systems with LCR steering and bass management in the upmixer, it's important that those curves match WITH the subwoofer, so after matching the LCR, I add the sub and use steered noise to clean that up for each of those three locations.

Finally, I do use decorrelated pink noise (which engages all the channels in Logic7, DTS and Dolby upmixers) to check to see if there are any nasty peaks in the overall response. If listening to a bunch of different program material exposes those peaks, then I remove them. Since those peaks (and any dips) are the result of constructive or destructive interference between the channels, attempting to add output doesn't work, but removing output does. Since the channels are already matched, removing output from ALL the channels maintains the match.That's what the 31-band EQ in MS-8 is for, but because the auto EQ matches all the channels, it can also be used as a target curve adjustment because it's applied to the 2-channel signal before the upmixer and the crossover. 

I seldom use room treatment in cars because I find that the ugliest errors often occur in the range where the treatments have to be big or thick (100-Hz-1kHz). I like (and so do many others) the effect of high frequency phase errors because they add some spaciousness.

Anyway, I'd love to hear your car one of these days. I'm local. One of these days when I finish my next car, I'd like for you to hear it.


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## subterFUSE (Sep 21, 2009)

Now that I am looking back at Gary's post about matching L and R to the target curve I have another question.

If we match a target curve and then find we want to adjust the tonality, would a good way to do this be to adjust the target curve and then re-match the L and R to the new curve?

My tuning experience thus far is very technical. I was a physics major in college so I guess my technical leanings make some sense. I want to learn the more artful approach to tuning by ear but that's something I need to work on over time.
For now, I like taking measurement and using REW to match my response to a house curve. I guess I just need to play with different house curves if i want to experiment with the tonality?


Sent from my iPhone using Tapatalk


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## ErinH (Feb 14, 2007)

I have a few concerns when these kind of threads arise. 
1) The process. This has been discussed ad nauseum here so I won't stir the pot up again. Suffice it to say, the manner in which you test can yield anywhere from marginally different to wildly different results from what common practice has shown me to be a pretty repeatable method.

2) The analysis. This is so incredibly important but yet gets washed over. When someone posts a graph everyone immediately jumps to telling them what to start EQ'ing. The problem is no one has enough data at hand to make a good determination of why the response is the way it is. This goes back to #1 obviously, but it also goes in to experience. As the user of the system it's extremely important to measure from different locations in the seated area. And it's important to measure each speaker by itself at a time to understand that a peak may be from one single modal issue in the car, relative to a single speaker, as opposed to an entire side of responses. For example, a midbass with a particular modal issue at 300hz may need the EQ adjustment alone; not the midrange that has not been influence by this modal issue because it's path length in reflection is different than the midbass. Another example I harp on a lot is the case of a peak: is it really a peak or is it just an area surrounded by two dips? "It's the same thing"... no. It isn't. If you EQ out the peak because it looks offensive then you're taking content out of the system. Understandable. But what if the two dips nearby are the real problem and the peak is just part of the standard bandpass: you've removed content that doesn't need to be removed and altered the tonality of the system. Now, if you apply that to the L/R matching people do then you've altered the response for both sides for no reason at all. 

Then there's the aspect of applying EQ to a single speaker at a time. Note earlier I didn't say to EQ each speaker: I simply said to measure each speaker. This is of particular importance in the region where modes are dominating (below the Schroeder frequency). You know that silly idea of 'distributed midbass'? The purpose of that is simple: to distribute the drivers in the room so the overall response below the Schroeder frequency is smoothed naturally. Apply this logic to the response below 300hz in your car. If you have a mono sound (voice, instrument, whatever) in your music and you play it back in your car, your midbass/subs are playing this together (crossover dependent on the sub) and in their own way all alter the overall response at your ear (a non-intentional distributed midbass method). What happens, then, if you measure the response of your left midbass only and EQ trouble areas, then switch on your right midbass and measure the response of the L+R sides? They're different. What happens when you turn the midbasses off and apply EQ to your sub, then turn the midbasses on and measure? The point I'm trying to make is this: subs/midbass... all these operate into and below the Schroeder frequency. These drivers all help to work with and/or against each other. So measuring JUST ONE at a time and applying EQ to it is a bad way of going about it. What you should be doing, however, is to measure each individual speaker's response as well as the summed response. Then if you see problem areas, use the individual response of each to determine which is causing it (or if it's caused by the summation). This method has yielded MUCH better results for me and allowed me to removed all EQ from my subwoofer; the region below the midbass' high-pass was still enough to alleviate some response issues near the sub/midbass crossover point.



At the end of the day, everyone is going to take something different from these kind of threads and apply it to their own methods. Some of it may be lost in the shuffle. What really matters the most is the critical thinking aspect. Asking yourself WHY you're doing something the way you are, why the response might look a certain way (ie; is there a console reflection causing a combing pattern that you can't do anything about or are you running a speaker to it's ragged edge and therefore getting modal issues from the speaker cone breaking up)... this is how you get better results in your system. Just throwing a picture up on a forum and letting people tell you what to do isn't really *and I mean this without condescension* the best way to go about it. I realize that starting out, nothing makes sense. But that's when you post it up and start asking for help. That's when you start moving the mic to the side and measuring. Taking a head average is a great way to go about getting a rough start but I find MUCH more useful information in individual measurements in the head area. Comparing a few measurements from center/left ear/right ear in a few different locations at the seated position directly (BEFORE AVERAGING THEM) can tell you a lot about the response of the system that you may otherwise never catch which can lead you to making poor assumptions or just generically adjusting the response, ultimately making it sound worse.


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## bbfoto (Aug 28, 2005)

Erin, that's crazy talk, bro! 

So much effing good info in ALL of these posts.


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## garysummers (Oct 25, 2010)

Excellent post Erin

My description of my tuning method I posted is the basic cliff notes version.
Erin's point of "Analysis" is paramount to achieving a proper tune.

*Every adjustment you make needs to be evaluated for it's purpose and result.*

Just moving EQ bands to make your plot sit on the target curve is dead wrong.

Also I agree that posting your plot and hoping others on the forum can tell you how to fix your issues is folly as well.


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## ErinH (Feb 14, 2007)

Going off what I said before, let me give some further discussion with examples.

My issues with the common convention of tuning via the RTA:

*1) The graph doesn't tell the whole story. *

For example, here's measured response in my car of a recent change in gear. 

How would you adjust the EQ to achieve whatever response you personally desire? Give it a shot. I'd be curious to see what others would suggest I do. And then I will reply with my own thoughts later.

Note: Most just post the results with no discussion on how the response was measured. This isn't trivial stuff and needs to be noted. Because of that, I'm not going to tell you how I did it. I'll post it in a reply later after I get some input. It'll go further to prove my point. 





*1a) Presentation:*

Further, the way you present the data can be misleading. Here's the same graph used above compared against a tweaked version. 1/3 Octave in 10dB y-scale. It looks pretty good, huh?





Now here it is again in the same resolution (1/3 octave) but with a higher resolution y-axis (5dB steps instead of 10dB steps):




Pretty noticeable difference, huh? And all I did was increase the y-scale...

Here's the same thing again, but now instead of 1/3 octave it's in 1/12 octave:



For the most part the response below about 400 hz looks pretty much the same in either resolution but the response above is quite different in these two different resolutions. 



*1b) Time. *

Time isn't represented in a single graph. Want an example of what time/phase can do to the response? Here you go. All the examples below are of the same crossover settings (no EQ). *The only thing adjusted between each measurement is time delay. *1/3 octave with the x-axis trimmed down to 20-500hz just for ease of viewing.



same thing as above, just in 1/12.




Next time someone says time delay doesn't do anything to the response, show them the graph above.


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## sqnut (Dec 24, 2009)

Wow!! All I can say is that tuning is not rocket science.


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## sqnut (Dec 24, 2009)

ErinH said:


> Note: Most just post the results with no discussion on how the response was measured. This isn't trivial stuff and needs to be noted. Because of that, I'm not going to tell you how I did it. I'll post it in a reply later after I get some input. It'll go further to prove my point.


I always ask for xover points and slopes and screen shots of the eq before making any call.


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## ErinH (Feb 14, 2007)

sqnut said:


> I always ask for xover points and slopes and screen shots of the eq before making any call.


Crossover is approximately 220hz.

There is no EQ on the response provided.


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## Beckerson1 (Jul 3, 2012)

sqnut said:


> Wow!! All I can say is that tuning is not rocket science.


Rocket science no but there is a learning curve to it. Quite evident in ErinH's post. People have to understand what they are looking at, how or why they got what they got, how to setup properly to get proper results and this list goes on and on as we know. I'm extremely glad I got with a diyma member who knew what was going on and gave me that important nudge in my limited knowledge of tuning compared to some.


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## ErinH (Feb 14, 2007)

sqnut said:


> Wow!! All I can say is that tuning is not rocket science.


I don't recall anyone saying it is. However, it's not as trivial as flipping on a light switch. There are many factors to be considered before just saying "oh, yea, you need to drop 1khz on the left by 3dB and ...". Providing suggestions without a real understanding of what's going on isn't as useful as you may think it is.

The two things you asked for above (crossover and EQ used) are an okay start. But there's more to the equation. For that matter, you missed one *very* important question. And there's another question you should be asking that you missed as well. These are all just pieces of a puzzle. And that gets back to my point: without knowing or understanding those pieces, someone telling you what to do with your graphs on the internet can only do so much. 

What was that sarcastic reply about rocket science, again?


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## Orion525iT (Mar 6, 2011)

ErinH said:


> Note: Most just post the results with no discussion on how the response was measured. This isn't trivial stuff and needs to be noted. Because of that, I'm not going to tell you how I did it. I'll post it in a reply later after I get some input. It'll go further to prove my point.





ErinH said:


> Crossover is approximately 220hz.
> 
> There is no EQ on the response provided.


Might change xover slope or make small adjustments to TA.


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## Grindcore (Dec 12, 2012)

All im asking for is advice..im trying to learn as much as i can from fellow members...everyone has different opinions etc but i can try numerous things and see what works out..its a lot of practice and trial and error for me...i dont just want to send the car off to someone and say tune this....i really want to be able to do it for myself then help my friends or whatever...

The tuning for left and right seperatley to get the same response is great advice...i never knew that part of it before.I would just try and center frequencies by using the eq like a balance control which i had read on numerous posts in here...

Im not saying that yeah heres my graph tell me how to fix it...im posting what i know and am after advice..how else is one supposed to wrap their head around all this?!!


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## Grindcore (Dec 12, 2012)

i have also provided any info that sqnut asked for....crossovers/slopes even how i got my measurements on TrueRTA..


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## ErinH (Feb 14, 2007)

Grindcore said:


> Im not saying that yeah heres my graph tell me how to fix it...im posting what i know and am after advice..how else is one supposed to wrap their head around all this?!!


I'm not talking about you in particular. I'm talking about the general state of things. People often post up a graph and ask for tuning advice. Then they get a bunch of replies telling them what to do. That's where trouble starts.


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## Grindcore (Dec 12, 2012)

From what i have read in here the basic thing that people agree on is the equalling of l and r response....but not what to do after that....


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## ErinH (Feb 14, 2007)

Orion525iT said:


> Might change xover slope or make small adjustments to TA.


By "small adjustments", what do you mean, exactly? 

FWIW, the graph provided is not at all going to be based on gear I end up with. It was simply a means of me tweaking a sub+5" mids setup to get something I can bear for the next couple of weeks until I am able to install the rest of the system. 

My reason for posting the information was to show that what you might think is there, isn't. Guaranteed if I had let the post stand on it's own someone would have said I need to raise my tweeter level. Or I need to lower my subs to match my midbass. Well, I don't have tweeters or midbasses in the setup which produced those results. Kind of hard to adjust things on drivers I don't have. That's the kind of point I'm trying to make: without all the necessary information you can't make suggestions on what to do. And it seems that's kind of just forgotten in cases.


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## garysummers (Oct 25, 2010)

sqnut said:


> Wow!! All I can say is that tuning is not rocket science.


It is "Audio Science" however. It requires just as much critical analysis as rocket science.


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## ErinH (Feb 14, 2007)

Grindcore said:


> From what i have read in here the basic thing that people agree on is the equalling of l and r response....but not what to do after that....


I don't disagree that L/R matching is important. Again, what I'm trying to drive home is there are LOTS of details that are important if you really want to get this right.

If you post up a graph that has a peak at 1khz and I tell you to drop it by 3dB and to match the other side you do the same, now you've attenuated 1khz in the total system response by 3dB per side. Cool. 

Let's say now, a month later, you're messing around with the system and mic and you find out that you only have the peak if you move your head forward about 5 inches. And, as it turns out, you've been placing the mic at the headrest, and the mic tip extends out a few inches further than your ears are in the seated position. The peak at 1khz isn't even audible. It just simply shows up on the graph, and you trusted the graph over your ears because you didn't realize you were measuring at a different location than where your ears are. 

Or let's say you ultimately find out, through testing something else in the future, there is no peak on the left. Instead, it's a right side speaker reflection off the left side window that results in a dip around 1khz on the right side speaker response, making the left side look like it's hotter there when you overlay them.

Or, let's say the peak is a very narrow Q peak, at 915hz. You realize this because you set the resolution to 1/24 octave. But, when looking at the graphs in 1/3 octave previously, that 915hz peak took shape at the nearest 1/3 octave point to it (1khz). You always thought even though you were cutting 1khz that you weren't exactly getting to the root of the problem. Now that you know where it is, you apply a parametric EQ filter with a Q=10, drop it by 6dB and ... voila ... problem solved. 




This kind of logic can be applied to multiple aspects. Look back at the post I gave earlier; specifically 1b. There I adjusted time delay on JUST THE SUBWOOFER. Notice how adjusting the time delay on that single channel altered the response through the passband and not just at one location? This is because of the wavelength relationship. While at the crossover point of ~220hz I may have been out of phase with the midranges by 45 degrees, at 160hz I may now be out 90 degrees (making up numbers, but the logic still carries). This brings to light another aspect; crossovers, slopes, and relative phase. Let's say at 90 degrees out of phase at 160hz brings to light an out-of-phase issue at the seat ... almost like a mechanical resonance. That issue draws my attention to the subs behind me rather than the stage in front of me. Wavelength is key here.


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## ErinH (Feb 14, 2007)

Just so my posts aren't misconstrued as me just being argumentative for the sake of it, allow me to make my intentions here very clear:

There are many aspects to tuning and speaker selection, install, etc as well as methods of measurement that affect the results you get. They are all parts of a whole. Ignoring them may still result in pleasing sound but it's simple fact that knowing more can allow you to make more logical adjustments and better understand what is really going on. Then you can discover areas that you can ignore (ie; a null in response due to proximity that you cannot boost) and areas that you can remedy by better crossover points or slopes.... or just time delay. In the end I'm just posting this information to keep people aware that there is more to tuning a system via 'RTA' than just EQ'ing peaks or matching left and right sides together. I've been at this for a very long time, making tons of mistakes and learning a lot from various measurements along the way. I'm truly just trying to pass some of that experience down to the community. Take it or leave it.


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## Grindcore (Dec 12, 2012)

No dramas Erin...anyway i have had a listen with fresh ears on the way to work and the matching of...or getting as close to as possible the response between left and right has certainly made a difference...i have saved those settings and will mess around with the combined response...you can only try eh?!


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## Grindcore (Dec 12, 2012)

^Ps all very good info by the way^


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## asif uya (Feb 15, 2015)

you touch time alignment at any point during this process


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## Grindcore (Dec 12, 2012)

I set crossovers/slopes etc then level matched and time aligned before i messed with EQ


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## 14642 (May 19, 2008)

Or you can just ignore all of this and tune by ear. Once you like it, you can claim to have mastered a process and make all kinds of generalizations about what you did even though you have NO objective data you can show to anyone else and you likely can't reproduce the effect twice.

But who cares? This ain't science. It's art, right?


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## Grindcore (Dec 12, 2012)

Haha!


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## garysummers (Oct 25, 2010)

Andy Wehmeyer said:


> Or you can just ignore all of this and tune by ear. Once you like it, you can claim to have mastered a process and make all kinds of generalizations about what you did even though you have NO objective data you can show to anyone else and you likely can't reproduce the effect twice.
> 
> But who cares? This ain't science. It's art, right?


I like to look at it as:

"Science revealing the Art"


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## james2266 (Sep 24, 2009)

garysummers said:


> I like to look at it as:
> 
> "Science revealing the Art"


Well stated Gary. I will be honest, I have lately turned into one of those 'tune by ear guys' but I really want to get back to the science end of it again. I, first, have to get the install all perfectly sound first and that is going to take time. Can't state that enough, if your equipment is failing in any way, tuning is meaningless. Both extremely important but if the install is not perfect, the tuning will never be perfect either.


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## Orion525iT (Mar 6, 2011)

ErinH said:


> By "small adjustments", what do you mean, exactly?


I am not sure I know, to be honest. It could be more than just a "small adjustment". It just looks like a phase issue with a dip centered at the ~320hz mark. If you try to eq that out, you will just make things worse. You could end up with huge peaks on either side of the dip, but with no change to the dip itself. I don't have a lot of experience tuning, just playing along and throwing out ideas.




garysummers said:


> I like to look at it as:
> 
> "Science revealing the Art"


Or, there is always science behind the art. Even if we don't know or can't measure the data points, they _are_ there. However, in this case, we have the tools so there is little excuse. 

I dream of a world where people present data and evidence _before_ diving into the pluralistic realm of subjective impressions and emotional response. Radical idea, I know, but I can dream can't I?


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## truckguy (Sep 2, 2013)

So many great posts on this thread! Being a major tuning noob, it seemed Erin was talking specifically to me and everything I've done wrong since I've started tuning. LOL. There is a huge learning curve. I thought I could just toss some high end speakers in my truck have and them just magically sound they way I wanted. Wrong. I started looking at this thread for the same advice as grindcore. His charts looked very similar to mine and maybe most people's when they first get started. Some days I just want to tear all the crap out and sell it but I know there is a light at the end of the tunnel somewhere. So I keep searching for info...

When talking about modal nulls in the mid bass I see lots of comments about how there isn't much you can do about it. The common area's seem to be a null around 125-160(left midbass), peak around 250-350ish, then another null soon after that. Can anybody explain to how you are supposed to handle those areas after you've tried different time alignments, slopes and crossovers? For 125-160 as an example, is it best to try and bring down the right to match the null on the left? What are you supposed to do with the giant peak at 300. From the "target curve" you're trying to follow it's +10-15db out from where you want it. 

I'm pretty sure I keep making the same mistakes over and over and expecting a different result. There's a word for that right? 

I'm not really even sure what my end sound is supposed to sound like. I figure when I hear it I'll know. I'm ordering a good set of headphones soon in hopes I might help me know what to listen for or how my truck is supposed to sound. Is that a dumb idea? I think I need more work on tuning my ears on what to listen for.


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## garysummers (Oct 25, 2010)

"I'm not really even sure what my end sound is supposed to sound like. I figure when I hear it I'll know. I'm ordering a good set of headphones soon in hopes I might help me know what to listen for or how my truck is supposed to sound. Is that a dumb idea? I think I need more work on tuning my ears on what to listen for."

Acquisition of some good headphones is a good start. It will give you a good reference point to set the tonal balance of your system. If you can have them in the car while tuning that is a plus. Our aural memory is very short, even for the best trained ears, so the sooner after you listen to the headphones that your can play the same recording on your system the better.
IMHO, A good stereo reference system in your home will help you to improve your listen skills. I am also an advocate of hi-resolution recordings for this purpose as well. If you spend a good amount of time critically listening to very well recorded music, mastered to a hi-resolution format, over a properly set-up reproduction system, your will begin to improve your listening skills.


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## Hanatsu (Nov 9, 2010)

I've seen countless of methods around different forum how to measure, how to interpret measurements and supposedly "why measurements are meaningless". I've done so much research into this by now that I have made my own conclusions in the subject. In the same install, I can repeatedly recreate the same tonality time after time using measurements only. My goal was to successfully make a "preference setting" for different types of installs and recreate them for similar new installs.

My opinion is that measurements can get you 50-95% there (here over a forum). So what's up with that wide successful rate?

1. You need to measure with the same method/conditions every time.
2. You need to apply the same settings every time you comparing measurements.
3. You need to know why some issues occur and what's fixable and what's not.
4. You also need to be aware how measurements correlate with what you hear.

The last point is crucial. This is what I've put all my efforts into once I had learned to master the first three steps. 

Erin highlighted this in a few posts back. Some issues can be modal and not fixable with processing, should you introduce the same dip into the the other channel just to EQ match the channels? Probably not a good idea. I could make a lengthy post about this topic right now but I'll save it for a new thread instead.

For those interested, I can say that I mostly ignore the combined response completely. I've found that it has little relevance when tuning. Setup left and right channels individually to a predetermined target response, ignore using symmetrical electrical filters. Make sure the acoustic response matches instead. The only exception I can think of is within the modal range where the subwoofer's response affect the lower midbass, you should take a look at the summed response to see what happens roughly one octave below and above the acoustic crossover point. If excessive summing occurs and if you can correlate this with what you hear (should sound annoying) then by all means pull down the response the problem frequencies, a little from each speaker that playing the same range generally is a good method but rather have the higher SPL on the fronts than on the sub to keep the imaging in place. If excessive nulls show up then you most likely have an "out of phase" condition and needs to offset phase to get rid of the issue. 

In a completely time coherent system the combined response should be similar in shape to the individual channels.


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## Grindcore (Dec 12, 2012)

Cheers mate....

Ignore using symmetrical filters....so different slopes and crossovers for individual speakers as long as you can get the required curve you are after?


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## garysummers (Oct 25, 2010)

Hanatsu said:


> 1. You need to measure with the same method/conditions every time.
> 2. You need to apply the same settings every time you comparing measurements.
> 3. You need to know why some issues occur and what's fixable and what's not.
> 4. You also need to be aware how measurements correlate with what you hear.


Excellent points here! Follow these every time you tune.


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## Grindcore (Dec 12, 2012)

Just wondering does anyone have some house curves they are using? Might try a few different ones..
If ya could post up some numbers it would be a big help

Cheers all


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## Alextaastrup (Apr 12, 2014)

How the EQ'ing of L and R differently results in "out-of-phase" issue? Using EQ will change phase at certain frequency, correct (at least for the most of filters)? What could we expect then when both L and R channels are playing simultaniosly? Extra nulls and peaks, which should be again treated separately for each channel?

Agree that final check of the both channels playing together is necessary for achieving the end result (desired target curve).

Dispersion issues - not to forget. It is hardly to expect that similar angles could be achieved at the listening position in the car environment. How to EQ equal in this case?


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## Rs roms (Jul 12, 2012)

Alextaastrup said:


> How the EQ'ing of L and R differently results in "out-of-phase" issue? Using EQ will change phase at certain frequency, correct (at least for the most of filters)? What could we expect then when both L and R channels are playing simultaniosly? Extra nulls and peaks, which should be again treated separately for each channel?
> 
> Agree that final check of the both channels playing together is necessary for achieving the end result (desired target curve).
> 
> Dispersion issues - not to forget. It is hardly to expect that similar angles could be achieved at the listening position in the car environment. How to EQ equal in this case?


When you are doing L & R together, you can't interpret the data accurately. Doing L & R separately from each other can identify the potential peaks and nulls.
Gary's point is that match the response of left side with your target curve and then right side to your target curve. If they both match nicely they will sum up fine at the listening position.

Secondly dispersion is not and issue if you play the drivers well within their piston range or where Lambda doesn't increase the diameter of the cone. Well it would be a tweeter if you are worried about dispersion angles or directivity.


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## Alextaastrup (Apr 12, 2014)

Regarding dispersion - yes, I ment first of all problems with high frequency range (mainly for tweeters, of course). But even my left midbass (in the stock placement in the front door) gaves problem when listening from the driver's seat.

My question was about influence of the front channels on each others when playing together? Separate tests will not reveal possible problems with this, right?


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## Rs roms (Jul 12, 2012)

Alextaastrup said:


> Regarding dispersion - yes, I ment first of all problems with high frequency range (mainly for tweeters, of course). *But even my left midbass (in the stock placement in the front door) gaves problem when listening from the driver's seat.*
> 
> My question was about influence of the front channels on each others when playing together? Separate tests will not reveal possible problems with this, right?


Modal issues i say, i experience the same, one can't do anything about it but to ignore.

Separate tests help you identify the problems which always show up in the combined PR of both sides. So how will you know that the frequency steering is caused by the left or right side. So measuring left and right separately is the way to go as it has been established previously. Initially it is difficult to wrap head around it but once you understand the logic, every piece will fall at its right place and will start making sense.

Oh wait perhaps i have insomnia 
Please re read the Post # 119


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## Alextaastrup (Apr 12, 2014)

Separate EQ end tests for L and R channels have been made a number of times i my car (precisly according to post 119). Do not misunderstand me, Rs roms.

Let make it easy and clear: In the case of interference between right and left front channels - what actions should be done for both channels? The same EQ correction for both channels or they should be treated differently (due to listening position, other reasons)?


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## 14642 (May 19, 2008)

YOu can remove energy from a peak caused by constructive interference but you can't add energy to a dip caused by destructive interference. 

Removing the energy is tricky, though. If you remove it completely in the sum, then you'll leave a hole in the response for only left or right. Best to confirm that it really exists with several measurement in different positions and also verify that it sounds annoying before removing it.


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## ErinH (Feb 14, 2007)

Andy Wehmeyer said:


> YOu can remove energy from a peak caused by constructive interference but you can't add energy to a dip caused by destructive interference.
> 
> Removing the energy is tricky, though. If you remove it completely in the sum, then you'll leave a hole in the response for only left or right. Best to confirm that it really exists with several measurement in different positions and also verify that it sounds annoying before removing it.


right.

this gets back to one of my earlier posts here discussing the response below the Schroeder frequency where it's all modally driven.

I can smooth out the response of a single side (single midbass in this example) and get it worked out great. But what if a hump in that midbass HELPED a hole in the subbass. IOW, the single driver shows issues in the RTA but the whole is smooth. I can tell you from experience that doing the former results in poorer system performance. 

Again, it gets back to the notion of distributed midbass. You place them around the listening area in a manner that smooths the overall response. If you try to take one driver out of the loop and treat it as a single and not a contributor you're doing yourself (the system response) a disservice.


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## Rs roms (Jul 12, 2012)

If one doesn't have an option for distributed mid bass drivers than it is going to be a compromise. As Andy states, first make sure that where the problem lies and do you really need to fix the constructive or destructive interference which has narrow Q.

Erin, is it ideal to switch crossover points and slopes if they help to smooth out the response which was altered by modal issues.


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## 14642 (May 19, 2008)

So we did an experiment with distributed midbass at the company I used to work for and it was based on exactly this. One of the research guys developed a DSP algorithm that worked with distributed BASS with several subwoofers and this was to be applied to cars at higher frequencies since the car is smaller.

Cool, right? Well, it was a simple matter with 4 door midbass drivers to get a smooth frequency response in all the seats, but there was no image in any seat. 

Works fine at frequencies where we don't easily perceive the location of the sound, but not so well at frequencies where we do.


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## ErinH (Feb 14, 2007)

Rs roms said:


> If one doesn't have an option for distributed mid bass drivers than it is going to be a compromise. As Andy states, first make sure that where the problem lies and do you really need to fix the constructive or destructive interference which has narrow Q.


Please don't take my post out of context...

Just to make myself clear, I didn't say to do a distributed midbass system. I was simply pointing out the *similarity *in the distributed midbass thinking and how it works to smooth the response vs tuning only a single driver where it shares bandwidth with another like driver (ie; two midbasses playing a mono sound or a subwoofer/midbass playing a mono sound just within their crossover).


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## 14642 (May 19, 2008)

ErinH said:


> Please don't take my post out of context...
> 
> Just to make myself clear, I didn't say to do a distributed midbass system. I was simply pointing out the *similarity *in the distributed midbass thinking and how it works to smooth the response vs tuning only a single driver where it shares bandwidth with another like driver (ie; two midbasses playing a mono sound or a subwoofer/midbass playing a mono sound just within their crossover).


OH, got it. 

One really helpful fix for a bunch of this since we sit off center is a center channel that plays down to about 100 Hz and some signal steering. Then, the center channel can be tuned for correct response and we don't have to care quite so much about the sum of left and right.


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## thehatedguy (May 4, 2007)

I had been wondering about distributed midbasses in the car. I wonder if it would work if you bandwidth limited them and kept them within the circle of confusion.


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## james2266 (Sep 24, 2009)

Andy Wehmeyer said:


> OH, got it.
> 
> One really helpful fix for a bunch of this since we sit off center is a center channel that plays down to about 100 Hz and some signal steering. Then, the center channel can be tuned for correct response and we don't have to care quite so much about the sum of left and right.



This is the angle that I am going to go with. That is when the weather, my time and finances all converge into something that will allow that to happen.


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## Orion525iT (Mar 6, 2011)

thehatedguy said:


> I had been wondering about distributed midbasses in the car. I wonder if it would work if you bandwidth limited them and kept them within the circle of confusion.


It would be interesting to know exactly how the guy Andy was referring to set them up. Both physical and electronic.

I know Patrick has played with this. I am currently trying to implement a version too. 

I think Erin tried at one point to solve his modal issues with sub/midbass crossover. The idea (I think) is to basically cross the sub and midbass over in the area where the modal issue occurs. In essence, this creates a "distributed midbass" because both the sub(s) and midbass are playing the same frequency in the problem area. However, I think that he ran into issues with sub localization. In my opinion, variations of the distributed midbass and sub/midbass crossover manipulation can still work, but you might have to plan for it from the outset, instead of applying it as an afterthought or as a part of tuning. Which is why I went to huge effort to put stereo subs wide and in the quarter panels of my current build.


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## truckguy (Sep 2, 2013)

Grindcore said:


> Just wondering does anyone have some house curves they are using? Might try a few different ones..
> If ya could post up some numbers it would be a big help
> 
> Cheers all


I'd love to see a few target curves as well. I attached 2 that can be used with REW. The first one I believe is a curve I got off another thread that belonged to Hanatsu. The 2nd is one I put together from suggestions of other threads on here. I think I ended up trying to follow the first one.

Since Andy W. is on here. Any chance of developing some Audiofrog headphones? Hmmmm!? You'd think headphones and car audio would go together well but maybe not.

How long does it take for each of you to tune your vehicles. As I'm at the novice level it takes me around 6-8hrs over a few days so I can listen to the disaster I'm creating. I make it thru 4-5 rounds before being extremely unhappy and cursing at the results. I save often and usually go back to the least worst setting until I decide to try again.


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## Grindcore (Dec 12, 2012)

Ha!! Sounds like me mate! Cheers for the curves....they work in truerta also...just had a look at them...


If i can be arsed i will stuff around with my tuning..if not i will just resort to my sounds pretty good i think memory no.5 haha!


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## Alextaastrup (Apr 12, 2014)

Some curves measured in my car in order to solve dispersion problems are presented here:
http://www.diymobileaudio.com/forum...l1-equalizer-system-acoustic-power-lab-3.html, see post 65.


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## Hanatsu (Nov 9, 2010)

truckguy said:


> How long does it take for each of you to tune your vehicles. As I'm at the novice level it takes me around 6-8hrs over a few days so I can listen to the disaster I'm creating. I make it thru 4-5 rounds before being extremely unhappy and cursing at the results. I save often and usually go back to the least worst setting until I decide to try again.


1 hour to make it sound pretty good. 1 month to perfect...


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## Alextaastrup (Apr 12, 2014)

Agree with Hanatsu, but after 1 month you will have even better sound - so it is Infinite battle for superb sound reproduction...
Sorry - I am one from the infected group.


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## Rs roms (Jul 12, 2012)

Orion525iT said:


> It would be interesting to know exactly how the guy Andy was referring to set them up. Both physical and electronic.
> 
> I know Patrick has played with this. I am currently trying to implement a version too.
> 
> I think Erin tried at one point to solve his modal issues with sub/midbass crossover. The idea (I think) is to basically cross the sub and midbass over in the area where the modal issue occurs. In essence, this creates a "distributed midbass" because both the sub(s) and midbass are playing the same frequency in the problem area. However, I think that he ran into issues with sub localization. In my opinion, variations of the distributed midbass and sub/midbass crossover manipulation can still work, but you might have to plan for it from the outset, instead of applying it as an afterthought or as a part of tuning. *Which is why I went to huge effort to put stereo subs wide and in the quarter panels of my current build*.


This is fairly smart and i am sure you must have crossed them where the modes are. I think Geddes did a thesis on this and the problem is cured noticeably if the subs are not much correlated, and to do that place them as far as possibly but he also says by adding a third sub made a significant difference. So you may better add 3rd sub 

Also if one can shed some light on this 

"One "radical" point of view that I took away from this work was that it is not "modes" that are a problem, it's the lack of modes that is the problem. It is simply not true that one does not want to excite the modes, one actually wants to excite as many modes as possible, which will result in a notably smoother response. This is quite different from (virtually the opposite of) the usual dogma in audio. Damping the low frequency modes causes them to spread and overlap more, which also reduces the variances in the response"


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## ultimatemj (Jan 15, 2009)

My apologies if too far off topic...

A few years ago Lycan posted an idea about combining distributed midbass with ambience/refill



> I think there IS some merit to a midbass array in a car. The main virtue is to help the rough/irregular amplitude response in the midrange in most vehicles....response can be rough/irregular (peaks & nulls) because of exciting constructive & desctructive "modes" in the midbass. More "random" placement around the cabin can help "smooth" out these modes.
> 
> Previously, I had argued against midbass arrays because of *possible stage collapse*. That is, with no attention paid to ITD's and confusion conses, midbass localization will suffer with an array of randomly placed drivers. I offered this thread, because I think the technique described can help solve that problem
> 
> ...


Still on my list to experiment with...just got to get past the 3 other projects that are in front of it :blush:



thehatedguy said:


> I had been wondering about distributed midbasses in the car. I wonder if it would work if you bandwidth limited them and kept them within the circle of confusion.


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## thehatedguy (May 4, 2007)

Maybe the wolf needs to come back and post more.

But there was one car built this way that I know of. Bing and Joey built one last year that had midbasses on the rear deck that were done like this. Myself and Mikey7182 have asked about how it worked out, but never got any answers.


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## Orion525iT (Mar 6, 2011)

Rs roms said:


> This is fairly smart and i am sure you must have crossed them where the modes are. I think Geddes did a thesis on this and the problem is cured noticeably if the subs are not much correlated, and to do that place them as far as possibly but he also says by adding a third sub made a significant difference. So you may better add 3rd sub
> 
> Also if one can shed some light on this
> 
> "One "radical" point of view that I took away from this work was that it is not "modes" that are a problem, it's the lack of modes that is the problem. It is simply not true that one does not want to excite the modes, one actually wants to excite as many modes as possible, which will result in a notably smoother response. This is quite different from (virtually the opposite of) the usual dogma in audio. Damping the low frequency modes causes them to spread and overlap more, which also reduces the variances in the response"


Well, it is yet to be seen how smart I am. Least I can say is that I did some math. How that translates to in car response will not be know for another few weeks where I have the install mostly complete and can start taking measurements. It's something that I feel is somewhat easy to model and calculate, but is impractical to actually test before hand. 

I think Patrick, in one of the distributed midbass threads (there are more than a few that touched on this) said that one of the theoretical problems is that the midbass will sound enveloping with an array type setup. This might be good, but it might not be accurate as far as reproduction. So you tackle the modes, but might end up causing issues with the stage. I think this might be the issue Andy referenced, but without more information, I am just being speculative.

I any case, I am going to play with the midbass and sub setup as is, but have plans on an additional pair of midbass to experiment with.


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## Rs roms (Jul 12, 2012)

Orion525iT said:


> Well, it is yet to be seen how smart I am. Least I can say is that I did some math. How that translates to in car response will not be know for another few weeks where I have the install mostly complete and can start taking measurements. It's something that I feel is somewhat easy to model and calculate, but is impractical to actually test before hand.
> 
> I think Patrick, in one of the distributed midbass threads (there are more than a few that touched on this) said that one of the theoretical problems is that the midbass will sound enveloping with an array type setup. This might be good, but it might not be accurate as far as reproduction. So you tackle the modes, but might end up causing issues with the stage. I think this might be the issue Andy referenced, but without more information, I am just being speculative.
> 
> I any case, I am going to play with the midbass and sub setup as is, but have plans on an additional pair of midbass to experiment with.


Andy's advice is fairly practical, i have to try that as well and will try to get it same as Andy suggests. 
Where would you be mounting the additional midbass drivers. As Patrick mentions that the midbass sound will be coming from everywhere.
At this instant how you describe the sound and how does it affects the modes in your car?


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## truckguy (Sep 2, 2013)

Any updates on tuning grindcore? Things you've tried or implemented in your process? You don't need to post pics if you don't want but curious about how its going.

I finally got back out there to try a few things from this thread. I tried to position my mic upwards and using the 4 spots around the head to get the average. I don't have a stand so I just sit in the vehicle while tuning. I spent more time than usual on each speaker working on crossovers to match each side up better and fix some peaks and dips. I have a helix dsp and decided to not mess with any "fine adjustments" and keep it more simple. I think I cause more harm that good at this point when I start making those adjustments. Also adjusted mid frequency area using 1/6 octave instead of 1/12 and upper/tweeter area using 1/3 octave. My starting point to match the house curve was different as I "ignored" some modal areas and focused more on peaks instead of major dips. In the end I focused a little more on the matching the left and right sides instead of focusing so much on the house curve. You get to a point where your speakers can only do so much and I'm tired of trying to force something that's not possible in my 2 way setup. My end result after 3 rounds of tuning. Tonally it's much better but my imaging is further off to the right than my past set ups. I'm wondering if its the 4 mic average? In the past for averaging I did a vertical hold(mic facing forward) with a 5:3(left ear:right ear) ratio for left speakers and 2:6 ratio for right speakers. Tweeters on-axis in pods on dash and mids in factory door locations. For full sweep I do a 3:1:4 with the one being on the nose. That seemed to give me a better centered image and will probably to back to that. I'm sure everybody has their own way of averaging. My mic is a Dayton umm6 if that matters.

Grindcore do you have a dash mat? I don't and I'm wondering it that might be my next step in trying to reduce some issues. Does anybody have any suggestions for a dash mat?


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## james2266 (Sep 24, 2009)

truckguy said:


> Any updates on tuning grindcore? Things you've tried or implemented in your process? You don't need to post pics if you don't want but curious about how its going.
> 
> I finally got back out there to try a few things from this thread. I tried to position my mic upwards and using the 4 spots around the head to get the average. I don't have a stand so I just sit in the vehicle while tuning. I spent more time than usual on each speaker working on crossovers to match each side up better and fix some peaks and dips. I have a helix dsp and decided to not mess with any "fine adjustments" and keep it more simple. I think I cause more harm that good at this point when I start making those adjustments. Also adjusted mid frequency area using 1/6 octave instead of 1/12 and upper/tweeter area using 1/3 octave. My starting point to match the house curve was different as I "ignored" some modal areas and focused more on peaks instead of major dips. In the end I focused a little more on the matching the left and right sides instead of focusing so much on the house curve. You get to a point where your speakers can only do so much and I'm tired of trying to force something that's not possible in my 2 way setup. My end result after 3 rounds of tuning. Tonally it's much better but my imaging is further off to the right than my past set ups. I'm wondering if its the 4 mic average? In the past for averaging I did a vertical hold(mic facing forward) with a 5:3(left ear:right ear) ratio for left speakers and 2:6 ratio for right speakers. Tweeters on-axis in pods on dash and mids in factory door locations. For full sweep I do a 3:1:4 with the one being on the nose. That seemed to give me a better centered image and will probably to back to that. I'm sure everybody has their own way of averaging. My mic is a Dayton umm6 if that matters.
> 
> Grindcore do you have a dash mat? I don't and I'm wondering it that might be my next step in trying to reduce some issues. Does anybody have any suggestions for a dash mat?


Check out dashdesigns.com. I have picked up one for my last two vehicles and have had no issues. Good fitment and the Ultra Suede looks good to me. My first vehicle it seemed to make alot more of a difference than in my current one. In my last one I had my midranges and tweeters much closer to the dash and more off axis so maybe that is why. In my current ride I aimed everything up and away from the dash as much as I could and that is probably the reason for the much less impact the dash mat makes.


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## Grindcore (Dec 12, 2012)

Hey all...yeah i have been stuffing around with tuning...and yes i have a dash mat in the car...my mids and tweets are up on the dash in pods in the corners of the front windscreen.

The rta i put up is left and right averaged...mic facing up and the measurements for the mic were taken off the pic that was posted up in this thread...

Sounds ok.....i cant for the life of me eq that spike at 5kh...no matter what i do....could playing with crossovers help with that?

Also this was just midbass mids and tweets playing...not subs...by getting the left and right pretty close the center image is very good and left and right cues are all spot on..i.e instruments in soundstage etc..

Problem with that tho is some freq have been cut by up to 12 db on a side to get them close as possible...on some frequencies i have lowered a side then boosted the other side by no more that 2.5db...

Problem is tonally its rubbish...should i play both sides together and then adjust both sides for tonality?

E.g i have ut 5k by 12db and i still have a peak there...i know why it sounds like crap because i have had to cut about 4 freq in the midrange by 6db and up just to get left and right as you see it now..

Basically should my left and right seperate eq sound amazing after i have done just that as some have mentioned in here or after this you must adjust left and right together as the final step?


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## Hanatsu (Nov 9, 2010)

Run a slow frequency sweep 3-7kHz. Does 5k sound louder than the rest?

You adjust both LR to adjust overall tonal balance. Either do it by ear or set L+R individually to the same target response.

Sent from my Samsung Galaxy S5 using Tapatalk


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## thehatedguy (May 4, 2007)

The peak might be constructive interference between the tweeters and the windshield.

Measure the distance and see if it corresponds with the wavelength.


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## sqnut (Dec 24, 2009)

Grindcore said:


> Hey all...yeah i have been stuffing around with tuning...and yes i have a dash mat in the car...my mids and tweets are up on the dash in pods in the corners of the front windscreen.
> 
> The rta i put up is left and right averaged...mic facing up and the measurements for the mic were taken off the pic that was posted up in this thread...
> 
> ...


Can you post screen shots of your eq?


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## Grindcore (Dec 12, 2012)

Cheers for the responses guys...will give all the ideas a go tommorrow....the mids and tweets are facing into the cabin and not firing up at the windshield...drivers side slightly off axis..i think any major reflection would be off drivers and passenger side glass...passenger side is about 25-30 degrees off axis....not ideal but i did my best with what i could do during installation....sq i can screenshot eq will just have to hook up the laptop...i will have time to do that tomorrow afternoon...

Would it pay to run the rta at night when its quiet with the windows down? Just to see if side reflections are responsible?

Thanks again people


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## masswork (Feb 23, 2009)

The thing is... we should make the sound good with windows closed, right?
Rta needs quiet place.

Looking at your rta result, sounds like muddy but edgy in female vocal?
Try increasing midrange level and cut that 5k peak.


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## Hanatsu (Nov 9, 2010)

Sine sweep is almost immune to external noise. MLS or other noise based excitation signals are less resistant to this.

Sent from my Samsung Galaxy S5 using Tapatalk


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## masswork (Feb 23, 2009)

Oh, right, didn't notice it's using sine sweep 
Thought it's default pink noise with averaging


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## Hanatsu (Nov 9, 2010)

RoomEQ can do both. However I think this one was RTA/Noise...

I was just pointing it out generally xD

Sent from my Samsung Galaxy S5 using Tapatalk


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## sqnut (Dec 24, 2009)

Real life grabbed me by the throat and yanked me out of this thread last week. I think we had a great discussion going, based on differing view points. Last I remember the scientists were hemming me in with some carefully calibrated jibes, probably too strong a word . I hope we get this thread going again. The time out from this thread actually helped me put together hopefully a coherent response to the scientists.

I agree that when balancing L/R do it one driver at a time then one side at a time. I can also understand dialing in tonality one side at a time, although that's not how I do it. Maybe music is engineered / mastered this way. For sure dialing in tonality one side at a time is easier. If you're tuning for combined response and it's honking slightly on one side sometimes it's easier to just play that side and isolate and correct the problem. I don't have an issue with doing the tonality one side at a time. You have to measure to balance L/R and to dial in your base curve, if that's what you're doing. But it seems pointless to measure an empty car. I would think measurements must be taken with you in the car. Beyond this lot of measurements you have to let your ears take over. One other thing, unless I'm constrained for eq power, I would almost never use asymmetric slopes to tune the response. That's painting with too broad a brush. Coherence always suffers when I use asymmetric xover points and slopes. 

No matter how carefully you calibrate L&R side to be balanced and tonally accurate, the minute you play both sides you are changing the response pattern from what you dialed in simply because the summing is going to be different across the 1/3 octaves from what you set each channel to. Look at graphs for well balanced L/R response one driver at a time and then for combined response. 

Some may say that differences are nominal and my response is change any 5-6 frequencies on your eq. Raise some by 0.5db cut others by the same amount (although the difference between one side and combined will normally be more than +/- 0.5db). Do you hear an appreciable difference? No matter how carefully you set each side you have to come back and tweak the combined response. Beacuse it is going to be tonally off from where you set each side.

In a car the devil _is in the combined response_. To my mind, there are no two ways around it. After you have balanced for L/R one has to come back and tweak the combined response by ear. Otherwise you're leaving a huge amount of SQ on the table. The best sounding cars, cars tuned by folks like Scot Eldridge, Matt Roberts, KP, Mike, even the magic bus and others in that league are all tuned this way. I am not saying my car sounds anywhere as good, I'm just saying that's the way I was taught and the way I've tuned for 7 years. If you think about it logically it makes sense. Once you're done measuring to your hearts content to get it sounding right, someone who _knows how to tune by ear_ can make it much better in 15 min without really measuring anything.

Sometimes we get too wrapped up in the science of things without taking a pause and asking, so how does it sound? A case in point is the issue about modes. So if 50hz is 6 db louder on the left, you can measure it but what are you hearing? Our perception of what we hear is based on a combination of what our ears hear and how the brain interprets it. At 50 hz we aren't very good at telling left from right. Now as long as the other frequencies are balanced for L/R the brain just fills in the blank and puts 50hz where its hearing everything else. So now you just adjust 50hz so that it is tonally balanced with the frequencies around it.

Then there is mention of the fact that we must learn to correlate whet we're measuring with what we're hearing. Again this is correct but only upto a point. If you tune based solely on how it measures even with a house curve you will sooner or later run into a brick wall, this normally culminates into swapping gear. New amps and speakers for better SQ. A simple exercise. Raise 500 hz by 1 db, cut 1 khz by 1 db and raise 5 khz by 1 db ( you can take any 3-4 frequencies). Now A/B the two sound how much of a difference do you hear? Now measure the two sounds. Do you measure a significant change to go along with the difference you're hearing?

At the end of the day you have to correlate what you're hearing with what you're doing at the eq at 1/3 oct. Almost everyone will say they tune by ear to varying degrees. Try the Harmon How to Listen app. Harman How to Listen Download the app on your desktop and go to the band ID section. Select bands at 24 (max) and set resolution to +/- 1db. The program will play a track and make +/- 1db cut/boost at one of the 24 bands and you have to guess if its a cut or boost and which band. Now you're correlating what you're hearing with your eq. I tried this a couple of times before making this post first time I was spot on 7/10 and the other time 8/10 (crappy computer speakers...or not). The balance times I was within +/- 1/3 octave. The SQ champs I mentioned earlier in this post would be bang on 10/10 at 0.5db resolution. Again keep in mind this one frequency changing at a time and it's easier to pick. In your car it's 30 frequencies being out of kilter at the same time. So you pick what stands out the most correct that and now something else becomes prominent and you work on that and so on. 

For me this is what tuning is all about.


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## Alextaastrup (Apr 12, 2014)

Agree with SQnut about importance to take into account the way our brain treats an audio information. In many cases it is difficult to explain, but the same music on the same road with the same presets of EQ sounds different in a car. Some of it could be explained by the psycological state, stress, how tired you are - but only some...

Measurements with a microfon are not able to reveal this difference. Therefore - rely on your ears - finally they should be pleased with the nice music, but not the calibrated omnidirectional condenser microfon with 48V supply .


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## james2266 (Sep 24, 2009)

Alextaastrup said:


> Agree with SQnut about importance to take into account the way our brain treats an audio information. In many cases it is difficult to explain, but the same music on the same road with the same presets of EQ sounds different in a car. Some of it could be explained by the psycological state, stress, how tired you are - but only some...
> 
> Measurements with a microfon are not able to reveal this difference. Therefore - rely on your ears - finally they should be pleased with the nice music, but not the calibrated omnidirectional condenser microfon with 48V supply .


Couldn't have said it better myself. TRUST YOUR EARS above all other things. Measurements can give you a gigantic step in the right direction but I have also found that it likes to lie and contradict what my ears tell me on occasion. Take my latest tune. I spent an hour getting things nice and flat but when I hopped back in for a listen it sounded flat and almost nasally to me. I ended up going back to my previous settings and scraping everything I had done. Playing with it by ear I found that most of my shoutiness that I had previously was being caused by an apparent peak around 800-1kHz and that didn't show any rise there at all on the measurements. It did show a large bump at 500 Hz and 5 kHz (around 5-7db at both spots) but upon playing my band limited pink noise tracks I picked up no hotness at either frequency area. Maybe my ears just need those bumps. Everybody hears different after all.


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## bbfoto (Aug 28, 2005)

After I finish my measurements and adjustments I'll save a preset. Then I listen to a Slow Sine Sweep, with all of the Left Side Only + Sub, then all of the Right Side Only + Sub, then all combined with L+R+Sub. I check for imbalance when playing each side individually, make notes, and check for imbalance AND stage shift/drift when playing L+R+Sub combined. Phase anomolies might also be revealed at different frequencies as well. As a musician, I feel that I am *maybe* a little bit more sensitive to these minute changes.

If you've ever been in a woodwinds/horns section or strings section (violins/cellos) of an orchestra while everyone is "tuning up" next to each other, you can really experience some interesting phase and harmonics nasties...enough to make you cringe, like fingernails on a chalkboard, haha. I also remember Gavin Harrison (drummer for Porcupine Tree) describing that when the bass player hit particular notes (with the bass cabinets just beside him & loud), that it would actually modulate the fluid/tears in his eyes, like they would flutter uncontrollably. 

I also created a full Sine Wave "sweep" track in Audacity, and it's 4 seconds of each frequency, but in Staccato 8th or 16th notes, kind of "machine gun" style. Listen with the same process as above. This helps me to more easily hear amplitude imbalance (peaks/dips) as well as stage placement/positional shifts and "phasiness" (when playing both Left & Right + Sub). It can also tip you off when you have problems with your XO's. 

There are of course those certain bands between about 125Hz-250Hz, depending on the width of your vehicle and driver placement, that will always be wacky.


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## sqnut (Dec 24, 2009)

james2266 said:


> Playing with it by ear I found that most of my shoutiness that I had previously was being caused by an apparent peak around 800-1kHz and that didn't show any rise there at all on the measurements. It did show a large bump at 500 Hz and 5 kHz (around 5-7db at both spots) but upon playing my band limited pink noise tracks I picked up no hotness at either frequency area. Maybe my ears just need those bumps. Everybody hears different after all.


Shouty vocals are often a combination of 300 and 8khz. Raising 800 makes vocals stand out from the mix while cutting it submerges the vocals into the mix. 500 hz is for vocal clarity. Too little and vocals are dull, too much and the sound is honking. 5 khz is for the light in your sound. Too little and the sound is closed and dark. Too much and it will exaggerate the brightness of the sound and kill off some of your low end. The balance between 500 and 5khz is _critical_ for getting the sound right. Typically one shouldn't have to cut much at 5khz. Be careful when you tune by ear. You need to build a strong corelation between your eq and what you're hearing. Without this correlation equalizing may be a hit or miss kinda thing. The Harmon app really helps here. Download it and see how accurate you are today. Keep playing with it over a period of time you will start building that correlation, but it's a painfully slow process. 



bbfoto said:


> Phase anomolies might also be revealed at different frequencies as well. As a musician, I feel that I am *maybe* a little bit more sensitive to these minute changes.


Phase in a car is nothing more than correct timing and matching slopes. Beyond this, the combined response you're hearing in the car is so messed up that thinking / worrying about phase in a car is a bit pointless.

Edited for better context .


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## Alextaastrup (Apr 12, 2014)

Some points here for adjustment of vocal reproduction:
Fullness - at 120 Hz - still hard to locate the sound source (with regard to left-right EQ)
Boominess - at 200 - 240 Hz (common problem in caraudio - just little bit down until it sounds OK)
Presence - at 5 kHz (up in dB will bring the singer closer to the listener) - some use the whole range 5-8 kHz for this.
Sibilance - at 7.5 - 10 kHz (normally should have a slope down in this area).

These are well known basic things for mixing and mastering engineers, so do not make it even worth. Smooth RTA curve for both left and right channels is just a mean to hear as many instruments as possible without unnecessary masking... It has been mastered once in audio studio. To my mind, the sound reproduction should be as close to the original material as possible (remembering common car environment problems with reflections, speaker placement and road noise). Do not "help" badly mastered music, just listen to a good ones (f.ex. from Chesky Records - just to mentioned one).

On the other hand - deviation in the sound perception made me to save 4-5 different presets to DSP, which I use in different occasions (despite the sound source quality) - mainly to fit my present need in extra sub-nodes, to overcome road noise, to assist the stressed day, etc.


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## 14642 (May 19, 2008)

Orion525iT said:


> Well, it is yet to be seen how smart I am. Least I can say is that I did some math. How that translates to in car response will not be know for another few weeks where I have the install mostly complete and can start taking measurements. It's something that I feel is somewhat easy to model and calculate, but is impractical to actually test before hand.
> 
> I think Patrick, in one of the distributed midbass threads (there are more than a few that touched on this) said that one of the theoretical problems is that the midbass will sound enveloping with an array type setup. This might be good, but it might not be accurate as far as reproduction. So you tackle the modes, but might end up causing issues with the stage. I think this might be the issue Andy referenced, but without more information, I am just being speculative.
> 
> I any case, I am going to play with the midbass and sub setup as is, but have plans on an additional pair of midbass to experiment with.


In the experiment the drivers were placed in all 4 doors and two in the rear package tray with a subwoofer in the trunk of a Toyota Camry. The tuning tools used to distribute the midbass evenly in the cabin were EQ filters, delay and level. Measurements were made in all 4 seats and the necessary settings computed. 

In all 4 seats, the midbass came from everywhere. When optimized for one seat, the algorithm reduced the level of the side and rear midbass speakers to the point at which they were unnecessary. Almost no audible difference between two drivers in the front and all 6. 

In looking at the filters and delays that were generated in the first experiment, the basic correction was to delay the sides and rears to REDUCE bass in the rear seats located near the subwoofer. Pretty straightforward.


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## Orion525iT (Mar 6, 2011)

Andy Wehmeyer said:


> In the experiment the drivers were placed in all 4 doors and two in the rear package tray with a subwoofer in the trunk of a Toyota Camry. The tuning tools used to distribute the midbass evenly in the cabin were EQ filters, delay and level. Measurements were made in all 4 seats and the necessary settings computed.
> 
> In all 4 seats, the midbass came from everywhere. When optimized for one seat, the algorithm reduced the level of the side and rear midbass speakers to the point at which they were unnecessary. Almost no audible difference between two drivers in the front and all 6.


Good to know. It was something I was thinking about after reading all I could on distributed midbass, and midbass "arrays". It is the reason I did not put effort into additional midbass enclosures before experimenting with the current configuration. 



Andy Wehmeyer said:


> *In looking at the filters and delays that were generated in the first experiment, the basic correction was to delay the sides and rears to REDUCE bass in the rear seats located near the subwoofer. Pretty straightforward.*


Makes perfect sense. Thanks again for the input.


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## Grindcore (Dec 12, 2012)

Ok ok all...im back....and i have changed my methods and have come up with some new results...

I was sick of having to use the laptop and bulky pre amp etc...

I had audiotools on my phone already...i bought an irig pro and im using my same mic tha i was using previously..a dayton emm-6 with correction file loaded into audio tools...i spent a few hours today on tuning and this is what a came up with..also you cant average seperate mesurements together with this program but you can average one measurement at a time...so i did the left hand side and set the rta to average...i sat in the car while holding the mic and i moved it left and right around my head to get some rta readings...now i know it wont be as accurate as using truerta and averaging seperate mic postitions but doing it this way i had some pleasing results...i looked like a moron doing it but i managed to get a curve i liked set up left hand side then got the right very very close..then combined l/r and it didnt need much tweaking at all...like a couple of db here and there..here are some pics
Here is right after tweaking



here is left...

and here is combined


I will explain why it looks like it looks very shortly


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## Grindcore (Dec 12, 2012)

Ok i set the baseline at 70db...as the scale on this program sucks i used the the x curve....just for midrange and top end.and worked to that..sub bass i havent messed with...this was just trying to get flat through midrange and then the roll off at the top end.
First i had a huge dip at 250hz...i flipped phase on the left mid and that sorted that..when testing the right i didnt have such a dip so left it at as then just continued to flatten things out..when i gave it a first trial listen...using the sheffield disc..things sounded ok...but the phase test was ok..his vocals were diffuse..i instantly flipped the right mids phase so now they are both 180 degrees out of phase but vocals immediately sounded better...

I went back into the eq and checked what happened by flipping the phase on the right hand side..now it didnt create a valley but it created a peak which i could bring down with the eq..was nothing majour.kept tweaking tryin to glatten some more...so left hand side there was a valley at 1250hz..at 0db.i boosted that 2.5db max..the right there was the same valley...i boosted it the same then left it to hear if it was audible..by this i played some music and dropped the left and right seperatley while listening to music to see how it sounded...to me it sounded better with the 2.5db boost..
so after all the fiddling with the eq i managed to flatten of what i wanted to and got left and right within .5-1db...boosting was kept at a minimum...

played some more music and it really sounded good..that was just left and right eq..not combined...so i saved that in a preset and then played pink noise again but both sides playing...that calley at 1250 was still there...but overall the curve was pretty much like the left and right seperate eq..i just had to lower a couple of things here and there...i put on more music etc and went back and forth..playing with a few frequencies etc..

I honestly have got to a point where i am enjoying the sound that im hearing...im going to head out in the morning and make sure it still sounds how i think it does....if you know what i mean....

had another listen....


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## Grindcore (Dec 12, 2012)

Now 20khz is like that because of my crossover at the top end..i should have changed it but it was set to 18khz with a 24db slope...so will sort that out tomorrow when i stuff around with the sub bass region..

So i gues the main thing here is it ok to get averages the way i did? Like i said i seem to have got some decent results doing it this way...i think i have read somewhere about people doing it that way but dunno if its very accurate..it seems to to me because your head isnt constantly still in the same spot....ah anyway would like to hear any feedback from the pros in here!


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## Grindcore (Dec 12, 2012)

Now looking back at the pics im going to go back to my seperate left and right eq preset and try and get that right hand side a bit smoother and closer to the left hand side....once i do that i will give the combined another going over while listening to music after making changes and see how it all sounds..


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## Grindcore (Dec 12, 2012)

Looking back at the older rta with truerta i had that dip at 1250hz.....
i should have shown photos previous to eq work...had that big peak at 5khz as well....so just by looking at the old and new graphs the new set up seems to be pretty accurate when taking readings


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## fcarpio (Apr 29, 2008)

So how does it sound? In my system that would sound a bit too muddy. I like my highs to keep going a bit more straigh and not taper down as steeply as yours.


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## Grindcore (Dec 12, 2012)

Heya mate.....nah not muddy at all in my car...sub bass is abit over the top but i havent touched that yet...but from 125hz-2khz its really clear..the roll off from 2khz is a bit steeper than other curves i have seen but it works quite well in my car....

Mids and tweets are up on the dash in pods..drivers side is pretty much on axis and passanger side around 30deg off axis..i own an older car also so my dash isnt that deep at all and the speakers are kinda close to driving position...i think it does affect depth somewhat but even how that curve is the upper midrange and highs are very clear sounding


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## Grindcore (Dec 12, 2012)

Like i said will give it another listen fresh tomorrow And see how i like it...i know after listening to pink noise for a few hours may affect how you hear things when you finally get some music on...there will def be more tuning to be had and i may even see how it sounds with a less steep top end...but yeah as of now im liking the sounds but as mentioned in here before its never ending! Haha


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## Grindcore (Dec 12, 2012)

Had a good listen this morning and im very happy with the way it sounds...put a whole heap of different music on/sources etc and i can say its the most pleased i have been with it since delving in to this hobby....gonna leave it all as is for awhile and get some people to listen to it etc and get whatever feedback i can..

Whilst stuffing around with audiotools i decided to upgrade to smaart tools...60 bucks but the rta has a lot more features/higher resolution better db scale that can be zoomed in on etc...its a little pricey but i like it coz its so portable...it will also use the same mic set up.so if anything i might run a 1/6 resolution rta and a 1/3 and just compare the results with what i have come up with previously...


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## subterFUSE (Sep 21, 2009)

sqnut said:


> One other thing, unless I'm constrained for eq power, I would almost never use asymmetric slopes to tune the response. That's painting with too broad a brush. Coherence always suffers when I use asymmetric xover points and slopes.


Can you elaborate on this point? Crossovers are a topic I've been working hard to learn more about recently.

When you say to avoid asymmetric crossover points, do you mean acoustically or electrically?

Are you talking about symmetry between "like" drivers (left tweet vs. right tweet), or about symmetry between the pairs (left tweet vs. left mid)?


For example, let's say you want the midbass to both have an acoustic LP crossover of 800 Hz @ 24 dB Linkwitz. You set them both that way in the DSP, but when you measure the slopes are not lining up. So you enter a different electrical crossover setting on one driver until the slopes measure the same. In the DSP, one driver might be set at 800, and the other at 736. They both will measure at 800Hz but need different settings to get there.

Is this OK, or is this something you would prefer to correct with EQ?


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## sqnut (Dec 24, 2009)

Due warning served : I am not a scientist and I tune by ear. 



subterFUSE said:


> When you say to avoid asymmetric crossover points, do you mean acoustically or electrically?


Both. At the end of the day you're hearing the acoustic xover and want these to match. So starting with matching electrical xovers and then use the eq to get matching acoustic xovers.



subterFUSE said:


> Are you talking about symmetry between "like" drivers (left tweet vs. right tweet), or about symmetry between the pairs (left tweet vs. left mid)?


Again, both. I use symmetric xovers for both L/R and across the drivers, except the sub. I would never run asymmetric for L/R, one loses all sense of cohesion, but I have run mids and tweets on different slopes with matching xover points for L/R. But I always came back to a symmetric setup. It just sounded more cohesive and cleaner. If one doesn't have an eq and asymmetric was the only way to balance response, that's the only time I would use it. Even with something basic like a p80 which is currently my processor I don't feel the need to run asymmetric networks. 



subterFUSE said:


> For example, let's say you want the midbass to both have an acoustic LP crossover of 800 Hz @ 24 dB Linkwitz. You set them both that way in the DSP, but when you measure the slopes are not lining up. So you enter a different electrical crossover setting on one driver until the slopes measure the same. In the DSP, one driver might be set at 800, and the other at 736. They both will measure at 800Hz but need different settings to get there.
> 
> Is this OK, or is this something you would prefer to correct with EQ?


This exactly why I loved the bit10 cause it gave me an eq for each channel. So I could set the electronic xover, check the response and then match L/R using the relevant channels eq. Once the bit10 crapped out and I had to rework the response with the p80 I felt I'd be dead without channel independent eq and that the sound would suck. With the p80 the sound is no where near the bit10, but not once did I feel the need to run assymetric for managing response issues. So I guess a 16 band L/R is good enough to manage the issue you raised. Yes I believe the real magic of a dsp is in the eq.


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## subterFUSE (Sep 21, 2009)

Cool. I'm going to give it a try using the EQ to match the crossover slopes. 

Thus far, I had been operating under the general impression that EQ should be minimal outside of the passbands. The thinking being that there are diminishing returns to EQ in the sloped region due to another driver taking over the sound, and to avoid over-processing the sound in areas where the benefit might be less noticeable.


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## sqnut (Dec 24, 2009)

I was taught to always pay special attention to the range an octave above and below the xover point. Let's take my case. I'm crossing the woofer and the tweeter at 2.5khz. So I'm looking to manage the response in the 1.25 to 5khz range. Why am I looking at one octave around the xover point? Cause I use 4th order slopes and in the mix / combined response from all drivers, 24 db down is testing the threshold of audibility. 

In this zone I am trying to get a matching L/R roll off for each set of drivers first by measuring and eq and finally eq by ear. Of course I can't do any of this now. The other thing I would do is to cut the eq for each driver in the stop band beyond this one octave zone. So on my bit10, with a xover of 2.5 I would cut everything below 1.25 khz on the tweeters eq by -12db. I did this on all the drivers and the sound was much cleaner. With a tweeter that's reducing audible distortion. You would be surprised how much cleaner the tweeter sounds once you have cut down low in the stop band. Try this if you aren't already doing it. An extra four points on your next score sheet

So much for not eq in the stop band.


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