Selvage / damping material

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Anyone ever try this for damping? If you are unfamiliar, this is heavy (90 lb+?) tarpaper (bituminous felt) which has small rocks pressed into one side. Sort of like shingles on a roll. About 2.5mm thick.

It seems like this should have good damping and mass-loading properties, but the exposed rocks could present a problem because they are a hard (if very uneven) surface, and because they can easily come off the surface.

I'm going to try lining the enclosure with this, then applying a thick layer of rubberized car body undercoat. I've tested this on scraps and it effectively seals and damps the "rocky" side.

Any comments on this combo? Anyone tried it in a loudspeaker?
 
Maybe you could use the undercoating as glue to attatch the "rocky" side to the box and leave the other side exposed. You could also use roof cement. It is about the same as undercoating except thicker. This sounds like it may be cheap and effective. Be careful which undercoating you get because some get brittle and flake off after a few years. I replaced some brake lines on a bus a few weeks ago and the undercoating would fall off whenever I touched it. I swept up a big pile of the stuff when I got done.

Darrell Harmon
 
Pinkmouse: I considered that, and I also considered turning the stone side inward, but I didn't want to have two hard surfaces in contact with each other. I figured that could be a recipe for resonance at some freqencies.

Of course using some adhesive or epoxy might mitigate this to the point where it was not worrying about, but I didn't want to take the chance.
 
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