Carpet-backing (damping?)

[redfish]

I have a roll of carpet backing (the kind with different colored foam chunks glued together)and was wondering if this would be good to use as damping (line inner walls) in speaker boxes?

Thanks

[jtaylor]

> I have a roll of carpet backing (the kind
> with different colored foam chunks glued
> together)and was wondering if this would be
> good to use as damping (line inner walls) in
> speaker boxes?

> Thanks

Many people talk about using carpet padding as a dampening material. Depends on the cabinet size, you may have to use many layers, or bundle it up and stuff the cabinet full of it, for best results. This is where DIY experimentation comes in handy. Or some actual guidance from someone who uses carpet padding and actually knows what their talking about. LOL Some times you just have to be honest and tell the truth, I'm using hear say.

J. Taylor

[billfitzmaurice]

> I have a roll of carpet backing (the kind
> with different colored foam chunks glued
> together)and was wondering if this would be
> good to use as damping (line inner walls) in
> speaker boxes?

It works just fine, but runs a little thin so double it up for midbasses, triple layer it for woofers/subs.

[redfish]

> Many people talk about using carpet padding
> as a dampening material. Depends on the
> cabinet size, you may have to use many
> layers, or bundle it up and stuff the
> cabinet full of it, for best results. This
> is where DIY experimentation comes in handy.
> Or some actual guidance from someone who
> uses carpet padding and actually knows what
> their talking about. LOL Some times you just
> have to be honest and tell the truth, I'm
> using hear say.

> J. Taylor

I know what you mean. I figured I'd ask.. for some reason I was thinking someone said it was not a good damping material (Zaph maybe?). It SEEMS like it would work well, being foam and about 1/4" thick. Plus it's free!

Thanks for the reply..

[redfish]

> It works just fine, but runs a little thin
> so double it up for midbasses, triple layer
> it for woofers/subs.

Thanks for the advice.. I will try it out..

[Æ]

Actually, it is called carpet "padding."
The type you have is called re-bond padding.
It will damp sheet metal, car doors, body, quite well. Not so effective on thick MDF. Better for thin materials. Damps plastic computer type of loudspeaker enclosures well.

Backing is the back side of the carpet that holds the loops of yarn in place.

[marvin]

I used the best grade padding I could find at the local carpet store. It seemed to be the "quietest" when placing my ear close to it.

I used it to line my wall stud space behind the RS180s. It seems to be effective--sounds very dead in there when listening at the wall opening before drivers were mounted.

I did not experiment with two or more layers. There is not a lot of space in a 3.5" wall. One layer seemed to do the job, but that is only an assumption until more layers are tested.

Marvin

> I have a roll of carpet backing (the kind
> with different colored foam chunks glued
> together)and was wondering if this would be
> good to use as damping (line inner walls) in
> speaker boxes?

> Thanks

[savantstrike]

How'd it stack up to say, fiberglass insulation?

> I used the best grade padding I could find
> at the local carpet store. It seemed to be
> the "quietest" when placing my ear
> close to it.

> I used it to line my wall stud space behind
> the RS180s. It seems to be effective--sounds
> very dead in there when listening at the
> wall opening before drivers were mounted.

> I did not experiment with two or more
> layers. There is not a lot of space in a
> 3.5" wall. One layer seemed to do the
> job, but that is only an assumption until
> more layers are tested.

> Marvin

[Deward Hastings]

> How'd it stack up to say, fiberglass
> insulation?

Depends on "what kind?" and "for what?".

Fiberglass, especially the "rigid" panels, is *far* more effective at absorbing the speaker back wave. Closed cell padding (doesn't absorb water) is more effective (if it is well bonded to the box) at damping panel resonance. It is not much use for sound absorbtion. Where a proper absorber makes the box behave as if larger, closed cell padding makes it smaller. Open cell padding (like a sponge) absorbs sound better than nothing, but doesn't damp panel resonance well at all.

Bottom line is, if you've got nothing else, use it. Otherwise use it under carpet (where it belongs) and use a more suitable material in your loudspeakers.

[jonpike]

> I know what you mean. I figured I'd ask..
> for some reason I was thinking someone said
> it was not a good damping material (Zaph
> maybe?). It SEEMS like it would work well,
> being foam and about 1/4" thick. Plus
> it's free!

I had read Zaph's comment that some have very little effect, others do a pretty good job. He said you could hold some up near your ear to get a feel for how much effect it would have.

Armed with that info, I went to a few carpet stores and "listened" to several types. It did seem that some were better than others. I bought some of the better one. Of course, layering it up improves things.

This is just a relative comparison between carpet pad.. harder to say how it stacks up against other foam types, fiberglass, more dedicated damping pads...

Reading in Dickenson and others, would suggest that fiberglass is one of the better materiels, although it has its itchy and hard to use drawbacks.

[savantstrike]

Sounds like I'm staying with fiberglass for sealed and egg crate for vented (or fiberglass if I'm feeling particularly stingy). Cheap and effective. Acousta stuff is intriguing, but also expensive (especially for larger boxes!).

> Depends on "what kind?" and
> "for what?".

> Fiberglass, especially the "rigid"
> panels, is *far* more effective at absorbing
> the speaker back wave. Closed cell padding
> (doesn't absorb water) is more effective (if
> it is well bonded to the box) at damping
> panel resonance. It is not much use for
> sound absorbtion. Where a proper absorber
> makes the box behave as if larger, closed
> cell padding makes it smaller. Open cell
> padding (like a sponge) absorbs sound better
> than nothing, but doesn't damp panel
> resonance well at all.

> Bottom line is, if you've got nothing else,
> use it. Otherwise use it under carpet (where
> it belongs) and use a more suitable material
> in your loudspeakers.