Perlite Speaker Stand Filler

I've thought about this. To damp ringing in a metal structure, you need mass applied to the structure. Lightweight materials simply won't have much effect on this. Gravel, because of the space between granules, is lighter than sand but does very effectively damp the ringing. Hence my solution.

I like pea gravel. It is not as messy to work with as sand, is cheap, and has good damping properties.