Acoustic Foam

[Early B.]

As a tweak or upgrade, has anyone ever changed out the acoustic foam in their subwoofer or speakers? Or does it really matter what type of dampening material you use or its density, especially in a sub? I'm more interested in real world results as opposed to theory and what the "experts" say about it.

The acoustic foam that came with my Dayton Titanic kit was of much higher quality than the foam I installed in my main sub. Just wondering if this foam is worth switching out and if so, what benefit I can expect.

Thanks.

[VR3]

Dude just order that Sonic Barrier stuff from PE...

That stuff is 8-15 bucks a sheet...

And well worth it, very good stuff. You dont have to spray adhesive everywhere, its very rigid and very easy to work with...

[Early B.]

Sid -- did you use Sonic Barrier on your BP rebuilds?

[VR3]

yes.

[Early B.]

I checked it out. I would need 5 pieces @ $10.94 plus shipping and PE adds a shipping surcharge due to the size. Probably cost me about $65. I would gladly do it, but I don't know if it'll make any difference. In the product description, it says the Sonic Barrier "improves high frequency performance." Since I will be using it in a sub, I see no reason to spend that kind of loot on something that may not be more beneficial than what I already have.

[VR3]

The biggest thing I can tell you is... it is very rigid and not like the foam you sent me at all. It absorbs vibrations like crazy.

[Early B.]

OK, the acoustic foam I ordered from PE arrived today (1.5" egg crate type) and I installed in my sub. Originally, I had a cheaper quality foam, but once I changed it out, the bass got "bassier." Not sure how else to describe it. The only very minor complaint I had about my DIY sub was that it didn't sound as deep as the sub actually goes, if that makes any sense. In other words, it sounded like there was a tiny terd of treble lurking in the bowels of the bass. The new foam has corrected this issue.

The PE foam is quite dense and very good for the price. Cheap tweak. Glad I did it.

[VR3]

Yeah man...

PE's Eggcrate is great, not quite as good as the SB stuff - but still good. Its not "eggcrate' like everyone thinks, its very rigid, and very good stuff...

Congrats on the cheap upgrade!

[madmax]

My understanding is the foam stops high frequency noise (from the woofer moving) from reflecting off the wood and piercing back through the woofer to the outside (which you would hear).

The polyfil type of stuffing, although it too will help the above situation, actually works in a different way. It eats up noise by the billions of fibers vibrating. This energy is released in the form of heat rather than sound.

madmax

[Early B.]

When is it best to use polyfill vs. foam???

[burdette]

I used dense egg-crate foam for my sub. But I didn't buy it from Parts Express (although I like PE and bought a lot of the other parts from them).

I went to WalMart and bought a twin-sized egg-crate mattress pad. It even had varying 'zones' with different sized and shaped bumps. It cost something like $20 and I had enough to completely line my 5ft3 cylinder sub enclosure, used some in a center channel project, and still had a big chunk left over.

All I know is my sub operates as designed and is flat to around 15Hz.

I started out trying to use AcoustiStuff fill from PE. I'd bought a big bag a year earlier for a different speaker project. I had it on hand and didn't have to spend more money so that seemed the way to go. It had stuffed into those speakers slick enough. But it was such a pain and so messy to try to glue to the inside of that cylinder, I 'broke down' and spent the $20 on the pad.

[madmax]

Wallmart has big boxes of polyfil. Seems to work fine. I'm not sure what is best for what. I'd try each alone and then both together to find out what is best.
madmax

[VR3]

The "eggcrate" for mattresses is NOT what Parts Express sells. Just to clarify.

The "eggcrate" PE sells is a very rigid material, you wont find that stuff sold wrapped in a cylinder - its not very flexible to the extent the mattress eggcrate is.

its a "denser" material, yet its not as "heavy" - just very strong and very easy to work with...

[VR3]

Here we go!

[burdette]

http://www.partsexpress.com/pe/showd...number=260-515

http://www.partsexpress.com/pe/showd...number=260-516

It is flexible and it can be used in a cylinder. No offense, but please don't make such narrow assertions when you don't know what you're talking about.

[kejolly]

When I design my sub, should I deduct the space that the foam takes up? I know to subtract the volume displaced by bracing and the speaker/amp.

Thanks

[VR3]

No, foam isnt solid... although it will add volume you wouldnt do it the same way as bracing...

Burdette, I meant the packaged cylinder Walmart sells the bed mattress rolls in, it isnt that flexible. A cylinder like a sub cylinder, sure.

If I had some mattress egg crate around here (which I might) - Ill take some pics of that too. Its a very different material.

The mattress eggcrate is heavier, the stuff PE sells is fairly light weight and rigid and not very spongey. I dont know what makes it different...but I know it is. ;)

(And I do know what I'm talking about... I have a piece in the den... :) - heck, I have to much foam... all different kinds, thicknesses...

[Early B.]

Let's just say you and your significant other would be totally uncomfortable using PE egg crate foam as a mattress pad.

[ilikesound]

would it work if you laid a couple coats of spectrum from second skin in there? or would the foam actually be a better idea? im hearing noise from my sub, perhaps just backwaves eminating from the cabinet...it's a sealed box, and i don't want to mess with it or spend much money fixing it. have some SS left over from the install that must be used anyways..

[Lasareath]

Has anybody tried this stuff?

I'm curious to try it out but I don't want to be the first one ;)

http://www.polkaudio.com/forums/show...7&postcount=46

[shadowofnight]

Dude just order that Sonic Barrier stuff from PE...

That stuff is 8-15 bucks a sheet...

And well worth it, very good stuff. You dont have to spray adhesive everywhere, its very rigid and very easy to work with...

I agree as well...extremely sticky....rigid enough to place large panel sizes without it flopping over on you....I use it on all of my subwoofers ( The very thick http://www.partsexpress.com/pe/showd...number=260-535 ) and the next size down for anything else. Works really well....

[Lasareath]

I wonder if I can use this stuff on the walls of my listening room. It would be very easy to adhere to the walls ;)

[VR3]

Has anybody tried this stuff?

I'm curious to try it out but I don't want to be the first one ;)

http://www.polkaudio.com/forums/show...7&postcount=46

I mentioned in that other thread...

My sub uses BH 5 --- and apparently the reason Brian offers that upgrade is it goes further to dampen the cabinet walls and gets rid of resonance. Since it has that thick foam layer sandwhiched together inbetween not as dense foam --- that basically gets rids of any possible resonances...

[ilikesound]

would fibreglass insulation work too? sorry, im a broke student. haaa.