acoustical foam???

[bbcmp1979]

I had some foam laying around in the garage and couldn't really tell if this have any acoustical damping property.

They are home insulation foam.

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thanks all...

[Jed]

You want open cell foam for dampening. I wouldn't recommend that for inside a speaker.

[bbcmp1979]

Jed,

how is this?

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[Kal Rubinson]

Nope. Also closed cell.

[evilskillit]

Think "something you could breathe through". If you want some bottom dollar stuff I used these items and they seemed to be pretty good.

Ultra Touch

Polyester Batting

Also you can get acoustic foam on the cheap from these guys.

The Foam Factory (Open Cell Foam)

[john trials]

Also unfaced fiberglass insulation (~2" thick). Very inexpensive. Easy to find locally. You can even get a tax credit (consult with a qualified tax consultant... :W ).

[bbcmp1979]

got it.... I have too many types of foam around the house. hence the question. but yeah, i do have r13 still that I can use.

[fbov]

With loose fiberglass, there are 2 caveats:
- you want it along the walls to absorb reflections, not in the volume.
- many like to fix the surface with spray glue to preven the escape of fibers.

Fiberglass boards are what you really want, Owens Corning 700-series, as the are already properly compacted and fibers don't escape. I personally use carpet padding unless I find some scrap accoustic insulation lying around here at work.
Frank

[Bastek]

In a sealed box does it matter if fiberglass is loose or on the walls?
I would guess it would behave as loose polyfill. My sealed Infinities have 3" fiberglass on all walls, with a big void in the middle of the box.
Boston Acoustics uses many 5x6x2" loose pieces to fill the box.
Who is right?

[fbov]

There are two uses for "fiberglass" in a speaker.
- to line the walls and prevent internal reflections
- to fill the volume and modify its compression response

In a sealed box, I like to have a dense layer on the walls, to absorb reflections, and a sparse layer filling the volume of the box. In ported, I only line the walls, with fill used sparingly if at all. I also prefer foams and fiber fill over glass.

Bastek, are your Infinities and BA's ported or sealed? What's optimal depends on the configuration; both may be right for their respective designs.

Frank