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Discussion Starter · #1 ·
So i threw my little jbl boombox into various places in my car and took measurements. I used the smae level for each measurement except for in the trunk, I turned it up for that one. I was looking to find a spot to help me fill the gap my subs have in the 80hz range due to their position in the trunk. My little boombox doesnt play below 60hz but thats ok, I have no issues with my sub output below that anyways. Looks like the passenger footwell area is the winner in my car for that upper sub bass region. Looks like the cabin gain is fairly flat around 80Hz and seems to extend down a little further than the other positions. So I think I will fabricate a little flat box to put there with one of my shallow 8" poineer subs, or maybe use 2 if I can get the air space. I think it will sound much batter than using all that gain from my subs in that region. I'm avoiding messing my doors to try and get those frequencies from my door speakers.
Rectangle Product Slope Font Plot
 

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Brilliant, let us know how it goes


Sent from my iPhone using Tapatalk
 

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You’re killing it with the approach.
Well done sir!
 

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This is a really good idea man, and you picked good variables too. Very informative.
 

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Cool. Just to add a little verification that you've done good, man. Here are some similar measurements I made in a jetta a long time ago. Passenger KP is the spot here, too, in terms of midbass output.

Rectangle Slope Plot Font Parallel
 

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Discussion Starter · #7 ·
Cool. Just to add a little verification that you've done good, man. Here are some similar measurements I made in a jetta a long time ago. Passenger KP is the spot here, too, in terms of midbass output.

View attachment 311398
Oh nice! I wonder if my passenger footwell area will extend down as far as yours did in the Jetta? My measurements were taken in an accord with a pretty small JBL bluetooth speaker. I have another bluetooth speaker than extends down a bit further I'm pretty sure, although its also a bit bigger. I'll have to try again with that one. It might blend better with the subs in the trunk if it was actually flat down that far. I've got 15 dB of gain on my subs in the 80Hz range trying to fix the null, and its fine for low level listening, but when I turn it up past moderate listening levels, bad things happen to the midbass, as well as some very ugly trunk rattles.
 

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yeah yeah…
But who cares?

it’ll be a lot more exciting for your passengers (and you) if you put it under the break peddle, as the graph showed.
 
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Oh nice! I wonder if my passenger footwell area will extend down as far as yours did in the Jetta? My measurements were taken in an accord with a pretty small JBL bluetooth speaker. I have another bluetooth speaker than extends down a bit further I'm pretty sure, although its also a bit bigger. I'll have to try again with that one. It might blend better with the subs in the trunk if it was actually flat down that far. I've got 15 dB of gain on my subs in the 80Hz range trying to fix the null, and its fine for low level listening, but when I turn it up past moderate listening levels, bad things happen to the midbass, as well as some very ugly trunk rattles.
You shouldn’t/can’t fix a null with eq, that’s not how it works, welcome to phase relationship nightmares on the crossover region 😏

I get the issue you’re having, but that isn’t the way to fix it
 

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Oh nice! I wonder if my passenger footwell area will extend down as far as yours did in the Jetta? My measurements were taken in an accord with a pretty small JBL bluetooth speaker. I have another bluetooth speaker than extends down a bit further I'm pretty sure, although its also a bit bigger. I'll have to try again with that one. It might blend better with the subs in the trunk if it was actually flat down that far. I've got 15 dB of gain on my subs in the 80Hz range trying to fix the null, and its fine for low level listening, but when I turn it up past moderate listening levels, bad things happen to the midbass, as well as some very ugly trunk rattles.
Where is your sub? In my experience and according to these measurements, behind the back seat (essentially in the middle of the car) is the worst spot even though it's the most convenient in terms of design.
 

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You shouldn’t/can’t fix a null with eq, that’s not how it works, welcome to phase relationship nightmares on the crossover region 😏

I get the issue you’re having, but that isn’t the way to fix it
That's not what's happening here. This isn't a phase relationship between drivers at the crossover. This is a null at the listening position in the subwoofer's output because of its placement and the listener's placement in the car.
 

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That's not what's happening here. This isn't a phase relationship between drivers at the crossover. This is a null at the listening position in the subwoofer's output because of its placement and the listener's placement in the car.
I know. I didn’t say it was between drivers?? He has a null in his subwoofer and is piling a load of boost in to try and eq it right

i mentioned crossover region because he has it currently in his crossover region, so he should move his crossover to get it better not fill the null with eq, it will also make the phase at the big boost worse also
 

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Discussion Starter · #13 ·
Where is your sub? In my experience and according to these measurements, behind the back seat (essentially in the middle of the car) is the worst spot even though it's the most convenient in terms of design.
Yes its right behind the backseat, I dont really have much of a choice in that matter unfortunately. Unless I want to get into some serious fabrication work which I am terrible at.
 

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Discussion Starter · #14 ·
I know. I didn’t say it was between drivers?? He has a null in his subwoofer and is piling a load of boost in to try and eq it right

i mentioned crossover region because he has it currently in his crossover region, so he should move his crossover to get it better not fill the null with eq, it will also make the phase at the big boost worse also
I CAN eq it, which I have done, but it doesnt leave me much headroom for output. It sounds great at low listening levels, but I would like more clean flat output.
 

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Discussion Starter · #15 ·
Well, I did it! Its incredible that I didnt need any eq at all to be flat down to 70Hz, and great output too, that was shocking from this POS sub thats been sitting in my shed for 5 years. I'll get some measurements later but so far, this is 100 percent the best place for a front sub in my car. Not sure how low it will go cuz I ran out of daylight and laptop battery, but do far it looks like the measurements I took were bang on, and it might even play down all the way with half decent output.
 

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