# A Compartive Study of Loudspeaker Frequency Response in Car Doors



## shinjohn

All,
In the spirit of sharing, I'm posting my findings as I dive into the world of in-car measurement w/ a laptop & microphone data acquisition system. I hope others can benefit as I learn the ins and outs of using this tool, and I continue to move forward in that never ending quest for better sound. 

*Background/Purpose*

I've always wanted to better understand my car's acoustics.
I already had a laptop, so buying a mic and setting up a measurement system was both inexpensive and easy.
What measurable differences in frequency response will we actually see when speakers (raw drivers) are put in the "harsh" automotive environment?
Does a "car-audio" specific driver really work that much better than a "home" driver in a car door?
What impact does sound deadening and install effort have on the frequency response of a car door loudspeaker?
In the course of this thread, I hope to explore the answer to those questions.

*Setup/Procedure*
Figure 1: Measurement Setup









Acer "Ferrari" Laptop 
M-Audio MobilePRE USB
Behringer ECM8000 Measurement Microphone
Associated connection cables
ARTA Software
My 1999 Honda Accord LX 4 Dr., Phoenix Gold XS6600 Amplifier "rear" channels driving the door speakers
Seas W15LY-001 loudspeakers
Seas Lotus Reference RW165 loudspeakers

Figure 2: Microphone Placement (those are shadows, my car isn't that dirty! )










Hardware was set up per manufacturer's recommendations.
Microphone placement per Figure 2.
Sound output was input directly into the car amplifier, bypassing the processor completely. Only one channel measured at a time.
Impulse response measurement (MLS), 1/3 octave smoothing.
First round of measurements were done with two pairs of speakers: Seas Excel W15LY-001 and Seas Lotus Reference RW165. No modification or additions to the car door accept for the attachment of MDF mounting/spacer rings.

*Measurement Data*
Figure 3: Left Door, W15LY-001









Figure 4: Left Door, RW165









Figure 5: Right Door, W15LY-001









Figure 6: Right Door, RW165









Observations

Cone breakup is readily seen (just under 5 KHz) in the RW165 on figures 4 and 6.
No surprise: left and right side response are quite different, note the poor bass response on left side.
As expected, the magnitude of the swings in frequency response are quite astounding over the speaker's usable range when placed in a car door.

*Discussion/Analysis*
I exported the data from ARTA and graphed/overlaid the W15 with the RW165 so that a more direct (in door) driver-to-driver comparison could be made. The results are shown below.

Figure 7: Comparison of the the W15LY-001 to RW165, Left Door









Figure 8: Comparison of the the W15LY-001 to RW165, Right Door









Key Takeaways: (however obvious they may be)

The vehicle's transfer function (environment) has far more impact on frequency response than any other variable. Differences between drivers are relatively small in comparison.
Differences in driver performance (frequency response) are quite measurable. These drivers to me sound different, particularly in the midrange, and the differences in response from ~1KHz and up correlate well with my subjective evaluations.
I was surprised that the lower frequency response of the two drivers didn't differ more, but there does seem to be a _small_ measurable difference nonetheless. It's not much though, and error in accurate gain setting and in measurement repeatability renders that point completely moot.
If smooth frequency response is your goal, there's no way of getting there without having separate left/right EQ, AND alot of control via parametric or NUMEROUS graphic bands.

*Next Steps:*

Deadening/sealing the doors to see how that impacts speaker frequency response. I myself have experienced enormous subjective differences with installs in the past, and I'd now like to see how that measures.
Testing ensolite and/or other treatments behind the speaker to see how they impact frequency response. (How effective they are at killing "midrange echo"?)
If I'm ambitious, I may try to measure differences using clay as a door "decoupler", etc... We'll see. 
If there's something interesting you want me to look at, throw your ideas my way. 

Enjoy!


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## technobug

I think if one was to search for it, they will find a tutorial that Ngyen did a while back on in-car response measuring technique. He also posted the results of my 3way setup. I think the plot showed all 3 plus sub in different colors on the same plot and then a summed curve. It was ugly.


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## shinjohn

technobug said:


> I think if one was to search for it, they will find a tutorial that Ngyen did a while back on in-car response measuring technique. He also posted the results of my 3way setup. I think the plot showed all 3 plus sub in different colors on the same plot and then a summed curve. It was ugly.


Yep, for sure. Definite inspiration for what I'm now doing. Here's one of the threads:
http://www.diymobileaudio.com/forum/showthread.php?t=17


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## andthelam

Great study, Great info. Thanks for the forethought and execution. Things like this will def. change the way one thinks of car audio.


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## chuyler1

I don't know if you tried this or not, but check to see if placing the microphone on the passenger side reverses your L/R results. 

It would also be interesting to compare the off-axis response of the driver outside of your car with the response in the car to see how much is the door and how much is just the driver.


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## shinjohn

chuyler1 said:


> I don't know if you tried this or not, but check to see if placing the microphone on the passenger side reverses your L/R results.


That was something I was going to do, but didn't have time. I'll check things out before I deaden the doors.



chuyler1 said:


> It would also be interesting to compare the off-axis response of the driver outside of your car with the response in the car to see how much is the door and how much is just the driver.


This isn't something I'm interested in pursuing. It is more difficult to set up a test like this, and much of the data provided by the manufacturers already covers this, but I do see where you're coming from...

I also thought about taking some measurements with the door open (to just test the speaker "enclosure" and not the "listening room"), but didn't carry through with that either, because in the end, that situation doesn't reflect any kind of reality.

Thanks for the feedback, Chris. I'll report more when I get the chance to take more measurements.


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## chuyler1

The open door idea sounds good...and place the mic about 1 meter away outside the car. That should give you a readout of the enclosure as if it were in a vacuum...well almost.

That is just such a huge difference in output below 100Hz between L and R it makes me wonder if that is what you hear when you listen.

Perhaps the seal around the driver wasn't as good on the left?


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## SteveLPfreak

Great info so far. Thanks, shinjohn.


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## MarkZ

Nice post.

What happens when you play the two sides together?


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## shinjohn

MarkZ said:


> Nice post.
> 
> What happens when you play the two sides together?


All hell breaks lose!  

That's definitely coming. What I wanted to do was finish deadening, EQ each side individually to flat, and then see what happens when the two sides are combined. At that point, I'm hoping the space-time continuum doesn't collapse.  LOL....


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## alphakenny1

aah ima have to head over to your place to get my car measured


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## FoxPro5

Wow, thanks for posting this. Can't wait to get my MobilePre fired up to see how big of a mess mine is too!


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## shinjohn

alphakenny1 said:


> aah ima have to head over to your place to get my car measured


Next meet, we can definitely do that. Better bring me some beer or something though.  



B-Squad said:


> Can't wait to get my MobilePre fired up to see how big of a mess mine is too!


One thing I am considering is buying a (better) calibrated mic. The ECM seems to work fine, but it doesn't have a calibration curve, so there's some (unknown) absolute measurement error. For this study, it's no problem because I'm looking more for relative results. But if I want to be more serious about this in the future, a better mic is probably in order. Just FYI.

I like the MobilePre, BTW, really nice unit. I got mine off ebay for about $75 shipped, IIRC. Cool unit, and quite flexible with all of its inputs/outputs.


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## DS-21

Powerful evidence for the need to get mids and highs away from the lower doors!

One question, though: how is the driver mounted in the door? Is it firing straight out, or is it mounted on a metal panel with the outer door panel between? I ask because the 1kHz dip could be some sort of cavity issue. I've found something similar (except ~an octave up) in the NB Miata.

I ask because I've found a Miata's.


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## shinjohn

DS-21 said:


> Powerful evidence for the need to get mids and highs away from the lower doors!
> 
> One question, though: how is the driver mounted in the door? Is it firing straight out, or is it mounted on a metal panel with the outer door panel between? I ask because the 1kHz dip could be some sort of cavity issue. I've found something similar (except ~an octave up) in the NB Miata.
> 
> I ask because I've found a Miata's.


These are completely stock locations. The speakers are mounted via spacer rings directly to the infacing (relative to the cabin) door metal. The door "card" (which includes an integrated plastic speaker grill) was then reinstalled. Speakers are firing out pretty much normal to the door. This is the basic, "standard" door speaker install.


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## dBassHz

Wow, big up man! Thanks a bunch for putting together this study. I look forward to the results and your observations.


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## durwood

Dumb question but I think a reasonable request considering it might be realistic-how about taking a couple measurements with the windows just to demostrate what happens there. Some of us like to drive with the windows down.:blush:


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## durwood

Dumb question but I think a reasonable request considering it might be realistic-how about taking a couple measurements with the windows down just to demonstrate what happens there. Some of us like to drive with the windows down.:blush:


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## Fixtion

Great info John, this was the fist post that ate up my "break-time" at work ealier today. I look forward for more new and revealing tests, albeit this doesn't so much pertain to installs of my nature, it's still very interesting. Glad I bought a DCX-730, wooooo! Individual Channel EQing! 
-Fixtion


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## Fixtion

*Message deleted by poster.*


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## Suneet

Very informative post, and I can't wait to see the rest of your findings!


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## Suneet

I'm very excited to see the rest of your findings.


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## shinjohn

durwood said:


> Dumb question but I think a reasonable request considering it might be realistic-how about taking a couple measurements with the windows down just to demonstrate what happens there. Some of us like to drive with the windows down.:blush:


I'll see what I can do. I'm going to end up flooding this forum with data over the weekend.  Hope the server holds up!


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## shinjohn

durwood said:


> Dumb question but I think a reasonable request considering it might be realistic-how about taking a couple measurements with the windows down just to demonstrate what happens there. Some of us like to drive with the windows down.:blush:


I could probably do that. At this rate, I'm going to be generating tons of plots/data. Hope I don't crap out the server even more!


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## npdang

Try sitting in the driver's seat when measuring. It throws everything out of whack  Also, can you do any sort of spatial averaging?


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## t3sn4f2

npdang said:


> *Try sitting in the driver's seat when measuring. It throws everything out of whack * Also, can you do any sort of spatial averaging?


Another great point to concider a JBL MS-8 with its wear while tuning binaural microphone.


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## jmelan

Great idea to compare the two drivers!!

I used ARTA (with a ECM and MobilePre) for some measurements as well, and the only problem was the inability to save data with trial version. 

I was undecided on whether the drivers or car were responsible for the frequency response i was getting, but your results make it pretty clear.

In my tests, there were variations in the midrange depending on microphone placement (+/- 2 inches made a huge difference). The midbass and high end seemed pretty stable. 

I was going to try moving the microphone around like npdang had done to average the "left and right ear" response, but I hadn't figured out a good way to do that with a free program yet. I tried moving it between passes, but i'm not sure the results are accurate that way.

I would be interested to know if you observed the same thing with microphone placement considering that you are using the exact same setup i tried.


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## jmelan

chuyler1 said:


> The open door idea sounds good...and place the mic about 1 meter away outside the car. That should give you a readout of the enclosure as if it were in a vacuum...well almost.
> 
> That is just such a huge difference in output below 100Hz between L and R it makes me wonder if that is what you hear when you listen.
> 
> Perhaps the seal around the driver wasn't as good on the left?


I had very similar results in my car with RS180s right below 100 Hz. The left drops off faster than the right in every test I have done.


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## shinjohn

npdang said:


> Try sitting in the driver's seat when measuring. It throws everything out of whack  Also, can you do any sort of spatial averaging?


Time to read the ARTA manual more thoroughly.  I thought it has something like that built in, but I'll have to double check. Sounds like jmelan didn't have any luck though... 



jmelan said:


> Great idea to compare the two drivers!!
> 
> In my tests, there were variations in the midrange depending on microphone placement (+/- 2 inches made a huge difference). The midbass and high end seemed pretty stable.
> 
> I was going to try moving the microphone around like npdang had done to average the "left and right ear" response, but I hadn't figured out a good way to do that with a free program yet. I tried moving it between passes, but i'm not sure the results are accurate that way.
> 
> I would be interested to know if you observed the same thing with microphone placement considering that you are using the exact same setup i tried.


I'm going to play around more today and tomorrow and see. I'll let you know. I'm thinking of trying "left ear" position (already did "right ear"), center of car, and passenger side to be thorough.



jmelan said:


> I had very similar results in my car with RS180s right below 100 Hz. The left drops off faster than the right in every test I have done.


Very interesting.... and good to have some other confirmation of these results!


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## durwood

shinjohn said:


> I could probably do that. At this rate, I'm going to be generating tons of plots/data. Hope I don't crap out the server even more!


It might be kind of hard to get good results if your environment around you isn't quiet. I tried something like this before but the garage was way too noisy to get good results or anything worth a crap for analyzing. I hope it works out.


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## Locke

this is probaly to much to ask, but if you get a chance to measure some doors with AP enclosures in the future would love to see how that helps or not, thanks for the results


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## UZIKIEL

jmelan said:


> I had very similar results in my car with RS180s right below 100 Hz. The left drops off faster than the right in every test I have done.


Is your leg getting in the way? 

I'd bet just having a "soft" mass in the general vicinity of the front of the speaker would cause a loss of output. Well, a loss of energy from the speaker, to the diaphram of the mic...especially if you are between them.





I'm not calling you soft. hehe


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## Astral

chuyler1 said:


> The open door idea sounds good...and place the mic about 1 meter away outside the car. That should give you a readout of the enclosure as if it were in a vacuum...well almost.
> 
> That is just such a huge difference in output below 100Hz between L and R it makes me wonder if that is what you hear when you listen.
> 
> Perhaps the seal around the driver wasn't as good on the left?


I found similar measurements in my car and I also thought that the seal was not as good, but I remember the results being reversed when I moved the mic to the other side.


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## Astral

shinjohn said:


> One thing I am considering is buying a (better) calibrated mic. The ECM seems to work fine, but it doesn't have a calibration curve, so there's some (unknown) absolute measurement error. For this study, it's no problem because I'm looking more for relative results. But if I want to be more serious about this in the future, a better mic is probably in order. Just FYI.


ECM is pretty darn flat. TrueRTA software comes with a calibration file for it and I'll try to find and post a screenie of the correction here, but I recall that it was just very slight roll-off in the highest highs and lowest lows, something on the order of 1-3db.


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## DS-21

Astral said:


> ECM is pretty darn flat. TrueRTA software comes with a calibration file for it and I'll try to find and post a screenie of the correction here, but I recall that it was just very slight roll-off in the high and mid freqs, something on the order of 1-3db.


Here's a good thread on the ECM-8000.


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## npdang

Locke said:


> this is probaly to much to ask, but if you get a chance to measure some doors with AP enclosures in the future would love to see how that helps or not, thanks for the results


It won't help at all in that respect.


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## Fixtion

Bump for updates and any of those whom may find this post interesting. I know I did. :]
-Fixtion


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## shinjohn

Sorry. 
Just been a little busy (and I must admit, lazy) these days...
I have data from other positions, door open, and I deadened a door last weekend. I'll post some new results this weekend.


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## Fixtion

Haha, sounds like me and my current install. There gear is coming in, yet the install is at a stand-still. I mainly wanted other users to check out your findings :] I'd be interested in finding out the thickness of f/b required to simulate a type "x" wood enclosure and compare the various "matting" fabrics for better responses. Seeing as how many of diy go the f/b route or mdf baffle door installs. Density consistency is a big factor in choosing an enclosure. So, I'll stop rambling and await new results. 
-Fixtion


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## shinjohn

OK, I'm going to attempt to "catch up" a bit on what I've been up to. 

First, here are measurements I took varying microphone position across the vehicle.

*Setup*

 doors not yet deadened in these measurements
 Seas Lotus RW165s
 5 mic. positions, about head high, approximating:
driver's left ear
driver's right ear
center of vehicle
passenger's left ear
passenger's right ear

 everything else as before

*Results*
Left Speaker Measurements:









Right Speaker Measurements:









Note that, as expected, microphone position dramatically impacts measured response.

Here's what interesting: the car does, for the most part, act quite symmetrically. Below, I've plotted symmetric measurement positions across the vehicle, and you can see that responses are very similar. Of course a car isn't perfectly symmetric, but my car isn't too bad in this regard.


























Looking at the responses more carefully, there's lots of interesting things to note. A couple of comments:

bass response is worse as you get closer to the speaker
cone breakup for this speaker is MUCH more noticeable the more on axis you are.
even frequency response in two seats is not an easy accomplishment. 

much more soon to come....


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## npdang

Excellent... let's see the time response for those measurements


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## shinjohn

npdang said:


> Excellent... let's see the time response for those measurements


LOL. Unfortunately, I only exported the frequency domain plots of all my measurements and ARTA (demo) doesn't allow me to save the raw data.  I need to upgrade my setup.


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## shinjohn

Here's my attempt to "eliminate the room" by measuring door speaker response with the door wide open. Here's what my setup looked like:










I plotted response against right door speaker response measured at driver's ear inside the vehicle. One thing to note is that I significantly increased drive level with the door open so as to reduce the impact of outside ambient noise (I live near a freeway). Keep that in mind when looking at the next plot.










If this isn't proof of Nguyen's quote: "A speaker is only as good as the room you put it in." then I don't know what to say. 

It's very easy to see how much smoother the response is without the harsh room (car) environment. It is also very obvious that cabin gain has a HUGE impact on bass response. Bear in mind that the door in these measurements has yet to be deadened, so you wouldn't expect the response to be super smooth; the enclosure still sucks rocks.

More coming....


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## shinjohn

OK. Let's now look at door treatments.

Click here to see how I treated the front doors:

http://www.pbase.com/shinjohn/accordstereo2&page=all

I pretty much did it the Rick McCallum (Raamaudio) way.

A couple of notes on my method:

I like to work fast and efficiently, so you'll notice I cut rectangular strips and used the overlap method.
This also allowed me to put extra layers where I needed it more, and less material in places that were very solid.
I used the tap test and my own threshold of what I thought was "dead enough".
I put ensolite on the door panel instead of directly on the door itself for better future ease of service.
I avoided covering fasteners because I've had to get inside these doors more than once!

Now the data:
Left door, in comparison with untreated baseline:









Right door, in comparison with untreated baseline:









My key take aways:

Door treatments do improve bass response. (correlates to subjective experience)
Door treatments (foam) do smooth out midrange response. (correlates to subjective experience)
The car transfer function is still the most dominant factor in frequency response. (i.e.- regardless of what you do with install/speaker placement, you'll need to do some electronic manipulation/eq if you are aiming to get relatively flat frequency response)


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## shinjohn

Moving on.....

What happens when you open the windows?

Plots below comparing windows open vs. windows closed baseline. Mic still at driver's ear, doors have been treated per above post. Both front windows were open during measurements. Rear windows were still up.

Left Door Speaker









Right Door Speaker









Take away:
Don't drive around with your windows open.   

I think you guys have enough data for today. Questions, comments, suggestions always welcome. Enjoy!


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## npdang

Is that mic taped to the end of a golf club 

Glad to see you taking your own measurements. I've had such a hard time trying to find a way of measuring that actually correlates well with what I'm hearing.

So far, what I find measuring most useful for is 1) level setting 2) verifying crossover points 3) time alignment 4) and finding unusually large peaks in the midrange.

What I find it completely useless for (as far as the methods I've tried) is actually tuning for flat response, setting up the subwoofer tonally, and tuning from the upper midrange and top end beyond 10khz.


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## durwood

npdang said:


> Glad to see you taking your own measurements. I've had such a hard time trying to find a way of measuring that actually correlates well with what I'm hearing.
> 
> So far, what I find measuring most useful for is 1) level setting 2) verifying crossover points 3) time alignment 4) and finding unusually large peaks in the midrange.
> 
> What I find it completely useless for (as far as the methods I've tried) is actually tuning for flat response, setting up the subwoofer tonally, and tuning from the upper midrange and top end beyond 10khz.


Cool. I think I have experienced the same things.

Thanks Shin John for taking the time out to do this and thanks for taking measurements with the windows down. I think I experience the peaky repsonse at 60Hz and then a massive dip around 100Hz with my windows down too. Note to self use A/C instead of windows. 

Hey Shin-

When you tested at head positions, was the mic facing directly forward or was it turned to each side. I don't know how much it will affect your measurements but it seemed to make a difference for myself right aroudn the midrange area between 1-2Khz (might be window reflections I dunno). One of these days I need to start capturing data myself.


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## chuyler1

npdang said:


> Is that mic taped to the end of a golf club
> 
> Glad to see you taking your own measurements. I've had such a hard time trying to find a way of measuring that actually correlates well with what I'm hearing.
> 
> So far, what I find measuring most useful for is 1) level setting 2) verifying crossover points 3) time alignment 4) and finding unusually large peaks in the midrange.
> 
> What I find it completely useless for (as far as the methods I've tried) is actually tuning for flat response, setting up the subwoofer tonally, and tuning from the upper midrange and top end beyond 10khz.


Sounds like my experiences. My ears are a far better tuning instrument than any microphone/rta in a car. The RTA helps me find the right band to tune if I have already determined it by ear but any anomaly in the RTA curve that I haven't discovered on my own is usually not worth pursuing.


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## shinjohn

Yep, that's a golf club. I think it was my 3 iron. I really like those velvet cord grips too.  Well, it's all that I had around at the time to use, LOL.

Anyhow, thanks for the comments, guys! My intent hasn't been to use this data as gospel per say in tuning my car a particular way, but as a tool (just like anything else we do) to try to better understand and give me some direction. Also, what can I say, I was just curious how things would measure.

What's encouraging to me is that I can at least measure some differences (though there is also some measurement error) and many things seem to make some sense and echo my subjective experience. What I can't reconcile really is the absolute measurements themselves. A +/-10dB swing in response is pretty darn big, and to me it doesn't subjectively sound that bad....


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## shinjohn

One other thing I would say in this thread is that I really think that door treatments subjectively make the biggest difference in bass response; much more than the compartive measurements would suggest. Something I'm still scratching my head a bit on..... It's not subtle; it's very substantial subjectively!


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## npdang

Were the door treatments going from nothing, to fully treated? I measured a substantial increase in low end sensitivity below 60hz.

I think you'd notice a big difference in your time measurements as well using an accelerometer on the door.


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## shinjohn

npdang said:


> Were the door treatments going from nothing, to fully treated? I measured a substantial increase in low end sensitivity below 60hz.
> 
> I think you'd notice a big difference in your time measurements as well using an accelerometer on the door.


Yeah, measurements are comparing nothing to fully treated. 

Like your experience, my measurements do also show quite a difference below 50 Hz. I just figured that I'd see a bit more difference in the mid-bass region...

Next time I pull out the laptop and mic, I'm definitely going to look more closely at the time domain responses.

Thanks!


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## jmelan

shinjohn, 

great job with all of the different comparisons!! i have been checking this thread once a week hoping to see your results for a while now.

i had tried measuring with the windows open as well thinking that i would see the effect of fewer reflections and saw very little change of the overall response.

Also, have you found any easy way of averaging readings together (eg. left ear plus right ear) with free software? my past method was to hurry up and move the mic between a series of tests, but it is difficult to see what effect it has that way.

i really like the calibration method that is described for the jbl ms-8, with simultaneous left and right ear capture, but there are no cheap solutions for that right now.


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## shinjohn

jmelan said:


> shinjohn,
> 
> great job with all of the different comparisons!! i have been checking this thread once a week hoping to see your results for a while now.
> 
> i had tried measuring with the windows open as well thinking that i would see the effect of fewer reflections and saw very little change of the overall response.
> 
> Also, have you found any easy way of averaging readings together (eg. left ear plus right ear) with free software? my past method was to hurry up and move the mic between a series of tests, but it is difficult to see what effect it has that way.
> 
> i really like the calibration method that is described for the jbl ms-8, with simultaneous left and right ear capture, but there are no cheap solutions for that right now.


Glad the data is of some interest to the community here. 

So far, I have not found an easy way to do spatial averaging, but to be honest, I haven't really tried hard to get more capability with my ultra-cheap measurement setup. I was thinking of buying a nicer setup, but I realize that making time for this hobby is increasingly difficult, however fun it may be.

One thing is for sure though: I have learned a bit about the acoustics of my vehicle, and that has given me some good ideas on how to better tune my system. Of course my ears are the final judge, but sometimes they can use some help! 

Good luck to you too! Keep up your great work!


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## npdang

If you can dump your IR plot into a txt file... doing a straight average is pretty easy. You could also do it with a FR plot, but may not be as accurate. I mean, let's say at 100hz your left side is 90db, and on the right side is 95db... what's the average right? X+Y/2.


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## invecs

shinjohn,

Can you do a comparo between a high qts mid vs a low qts mid? I've always found any low qts mid to sound like what you have measured...can extend very low but not much midbass response despite the deadening.


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## t3sn4f2

Maybe also a run with no factory grills if its poosible. With the the door panel still in place to see if modifing the grill would help much.


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## Oliver




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## msmith

Can you turn the car upside down and suspend it from an 18 foot beam, and then do spatial averaging?

Just kidding.


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## IBcivic

holy thread revival batman!!


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## jsun_g

I don't know how I missed this thread, but thanks for "resurrecting" it. I have an Acura TSX and am working to balance the L/R EQ on my front stage. I have noticed the same trough around 450Hz as the Accord in this thread...and there isn't anything I can do about it with my 1/3 oct graphic EQ bands at 400 and 500 without also affecting <400 and >500


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## Elgrosso

shinjohn said:


> (...)
> Key Takeaways: (however obvious they may be)
> 
> The vehicle's transfer function (environment) has far more impact on frequency response than any other variable. Differences between drivers are relatively small in comparison.
> Differences in driver performance (frequency response) are quite measurable. These drivers to me sound different, particularly in the midrange, and the differences in response from ~1KHz and up correlate well with my subjective evaluations.
> I was surprised that the lower frequency response of the two drivers didn't differ more, but there does seem to be a _small_ measurable difference nonetheless. It's not much though, and error in accurate gain setting and in measurement repeatability renders that point completely moot.
> If smooth frequency response is your goal, there's no way of getting there without having separate left/right EQ, AND alot of control via parametric or NUMEROUS graphic bands.


Wow, that was a cool thread!
Look at us carefully picking drivers on their flat FR...


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## Picaro

Elgrosso said:


> Wow, that was a cool thread!
> Look at us carefully picking drivers on their flat FR...


Ha, ha, yes, great thread. Glad to see people put so much effort into such data collecting.


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## shinjohn

Holy thread resurrections Batman! Wow that was a long time ago!!!!
Brings back memories......


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## TallTexan

Great thread. Another take away from this thread is that these days USB mics can be had for under $100 (I have the UMIK-1 from the miniDSP guys that was $75) and measurement software (REW) is free. Most of the mics come with calibration files so software setup isn't too hard.

So, after spending hundreds (if not thousands) of dollars on audio equipment, the measurement equipment is darn right cheep. Plus the mic ought to last nearly a lifetime and used over and over for different installs or changes to existing setups. Yes, technically the software can be a bit daunting, but there are several good tutorials and online help guides. Heck if those stupid home theater guys can figure this out, we DIY mobile audio guys ought to have no trouble (j/k) 

You couple this with the now lower cost DSPs you have unprecedented control over your sound.


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## Bacovish

OK. Glad to see this back up. A few pages earlier someone mentioned mounting the speaker to the door panel instead of behind it. My doors are treated but was thinking about this because thinking I could use a angled spacer to get my sound a little higher if you will. I have a tahoe and the speaker placement is in the very bottom of a giant door. By my ankle basicly. I was going to do little bit of fiberglassing to make a pod and cut out the stock grill. I was going to leave the mdf rings about two inches worth behind the door panel and foam or should I fill that space up with more foam???maybe even completely block that opening up. Any thoughts. By the way I'm not using a dsp and wasn't planning on it. Thanks.


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## Bacovish

Well decided to mount on the panel. We will see how it sounds


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