Using foam inside of boxes

[z00mz00m 10+ year member]

I used to have foam egg crate inside of my box but I took it out yesterday because a friend at school said that the egg crate would probably be absorbing the bass and deadening it. I have messed around with a few subwoofers we have in our house for home audio and their enclosures are completely lined with foam of some sort inside of them.

I have always had a roll of egg crate foam inside of my closet because I once slept on it as a kid and that's why I decided to experiment with the stuff. I haven't hooked up my sub yet because I am going to be carpetting the box tomorrow and I figured I could just ask here because I'm sure some of you have experimented or heard about foam being in boxes and the effect it has on the sound.

I have a blown sub in one of the home audio boxes and I could easily pull the foam out of them and see what it does to my Kicker's box. It isn't very spongy/fluffy, its more of a home insulation type foam. I believe I've been told about fiberfill before, and I'd guess that's what its like, although I really don't know what fiberfill looks/feels like. I just know that my egg crate foam is pretty dry rotted, not to the point where its falling apart, but you could tear it pretty easy, its kind of brittle, although it still is a pretty good cushion.

What do you think different types of foam do to the overall sound of a subwoofer? I have begun to think that the smoothness and SQ of the bass is improved, while SPL is decreased.

Thanks for any comments or opinions //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

-Ryan

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[nosaj070 10+ year member]

It possibly could dampen the sound, though it depends on the material used to make the stuff. I would just go buy some polyfill, fiberfill, polyester filling, whatever you want to call it, it'l set you back about 3 bucks. the stuff that somes in a sheet rather than a giant mass of puff is usually much much easier to work with.

 

[z00mz00m 10+ year member]

It possibly could dampen the sound, though it depends on the material used to make the stuff. I would just go buy some polyfill, fiberfill, polyester filling, whatever you want to call it, it'l set you back about 3 bucks. the stuff that somes in a sheet rather than a giant mass of puff is usually much much easier to work with.

What are the purposes of the types of foam that you just mentioned though? Do they enhance SPL and/or SQ?

 

[Berry47 10+ year member]

Polyfill slows down the air molecules so that the sub thinks it is in a larger box. A larger box usually yeilds better bass.

 

[Trixter 10+ year member]

Ii's a good thing for a small box. Not usually used in a ported boxes as much as sealed, but it can be. I have noticed that it creates a smoother bass, not sure about the SPL, but I think your on the right track. And yeah, use the polyfil over the foam. Wal-Mart-bedding section-pillow stuffing.