Absorption in cars

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Hey all. Im an active member over on DIYMA and a big car audio enthusiast. Currently i am running some Eric Steven's hlcd mini bodies and some MB8s in kick panels.

I did have some midranges in door pods for many years but switching to horns has led my door pods to be a little useless. So im curious as to what i can do with the space. I've messaged a few people on Diyma about putting a large block of acoustic foam in there and they all told me i should be more focused on diffusion rather than absorption.

So im thinking of doing something like this on the bottom part of my door panel with maybe some small melamine foam blocks(2in x 2in x 3/4in) in between the spaces.

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Im not exactly sure what doing that would do to help but i figured it wouldnt hurt and i know i could do it in an aesthetically pleasing way. Below are some pics of my install for reference.

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Anyone think this would be worth time to do and to why absorption in such a close field highly reflective environment would be so bad?
 

6L6

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It's not that absorption is bad, but rather than you can't actually have enough material in such a small space to do much good. Diffusion will have a fighting chance (albeit small) to actually do something.


Never seen floor speakers before. I can imagine there being a lot of "toe-tapping" advantages to that configuration. :D
 
It's not that absorption is bad, but rather than you can't actually have enough material in such a small space to do much good. Diffusion will have a fighting chance (albeit small) to actually do something.


Never seen floor speakers before. I can imagine there being a lot of "toe-tapping" advantages to that configuration. :D
It gets you better PLD as well as breathing outside rather than into a resonate door.
 
You really can’t absorb much in a small car environment other than focusing the speakers directly at you at the mid/high frequencies and that means placing them higher up in the interior.
You are really operating in a bad surrounding arena, and at best if you can aim the speakers at the center of the interior, it will lessen the delayed arrival times as much as possible Giving the best compromise. And I do mean compromised sound in a vehicle. All you can do is minimize the damage to the sound field.

Bass frequencies should be in small sealed enclosures letting the small space environment it’s operating in give a natural boost to the deep end giving you deep tight bass overall.

The one eyed cat looks cool..

Regards
David
 
Just from experience doing installs in the big, soft American cars of the 70's-80's. I should have added a ;), it's not a practical idea.

Seats were thick and soft, padded cloth door panels, plenty of bitumen-backed jute under the carpet. Dashboard and windows were the only hard spots. Vinyl and leather interiors didn't act the same.
My whole car is leather interior. Dash included. Although comfy...and hot in the summer. When i added seat covers and a dash mat. I heard a huge difference.
 
You really can’t absorb much in a small car environment other than focusing the speakers directly at you at the mid/high frequencies and that means placing them higher up in the interior.

You are really operating in a bad surrounding arena, and at best if you can aim the speakers at the center of the interior, it will lessen the delayed arrival times as much as possible Giving the best compromise. And I do mean compromised sound in a vehicle. All you can do is minimize the damage to the sound field.



Bass frequencies should be in small sealed enclosures letting the small space environment it’s operating in give a natural boost to the deep end giving you deep tight bass overall.



The one eyed cat looks cool..



Regards

David
Haha! Noted. I actually heard an increase in SQ when i added that fur. Just saying.

And no. I refuse to cover the whole car in fur...but the fur does oscillate about 3inches at 28hz.

It does a 142 at 28hz.
 
I had a small car and placed the 8” drivers in small sealed boxes up under the dash, facing downward. The 4” mids, and tweeters were under factory grills on top of the dash, and were carefully aimed at the windshield such that the reflection for each speaker was trained on the opposite side ear.
This provided a nice full image from the front, and the imaging effect was incredible. The car was all glass it seemed, yet the sound was great from a 30w+30w amp. The key likely was that the distances between the drivers and the listeners were consistent.

Inside doors, you can use a closed-cell foam product that is made for use inside hvac ducting/plenums to reduce noise.
 
So I've been reading up on absorption and diffusion in regards to car audio and there is precious little out there. I've seen some people say its really important to treat the first reflection and others say it's best to leave first reflections alone.

I've also seen people say that you shouldn't treat more than 20% of a room.

In a car though. I think most practiced theory goes out the window. We're not talking a square room and most rooms aren't going to have a TON of initial reflections within a foot of the speaker.

Im curious of what treating the car with significant amounts of foam would accomplish. I know in home theaters, you don't want to "take the life out of the room" with too much deadener but in a vehicle. There is always going to be a significant amount of reflections that you can never treat because..glass..glass everywhere.

Im thinking of this.

Foam under the dash, like behind it where you can't see without getting on your knees and looking behind it.

Rebuilding the center console to be alot smaller and have less initial reflections from the speakers crossfiring.

Lowering the center console as well as putting dense or perhaps wedge shaped foam where the center console was. Ill probably use a strong material to create a shape but put a ton of holes in it and foam behind it.

1-2in of pyramid foam on the dash, sew it to my existing dash mat.

And 3in wedge foam in the lower panels.

As well as most likely thick foam on the back deck for any long wavelength interactions.

Some would argue that you don't put foam in a car because you can't get enough to actually have an impact but i disagree.

Since a car is so tremendously reflective. Even 1/2in of foam is going to have a large impact. Sound has to go into the foam, then exit it. Effectively making it worth 1", plus bounce around the cabin and into/out of the foam how many times before it reaches the listener??

In a car though, I've noticed that you actually get width and depth from reflections. If you were blind folded and put into a room or theater or amphitheatre and someone played music. You could tell exactly how big an area was, not from the direct sound but from the echos of reflective sound.

Im worried that i may end up having an extremely tonally pleasing system that are either stuck to the dimensions of the vehicle width wise, or make it so each speaker is super locatable because they aren't playing as one soundfield but instead multiple.
 
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