Tweakers' Asylum

RE: sand or lead shot to dampen hollow metal tubes?

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Duomike

In Reply to: RE: sand or lead shot to dampen hollow metal tubes? posted by Duomike on February 19, 2009 at 19:53:18

thanks for all the responses. I live in indonesia and i guess getting sanitized sand or other fancy materials would be difficult or impossible. due to the lack of choice i will go with beach sand. using different materials seems to sound like a good idea. unclestu, are you using avantgardes as well?
Duomike

Follow Ups:

Try clay granules. - Al Sekela 10:49:16 02/20/09 (1)
This stuff is sold as cat litter and as oil absorber for auto shop and factory floors. It is lighter than lead or sand, and is an effective damper.

Consider the basic physics of a steel tube as a resonator. It will have organ-pipe modes, which filling will control. It will also have modes in which the tube resonates as a strut. Adding mass with the filling lowers the strut resonant frequency. A lower resonant frequency will be more difficult to damp with the filling material and through external means.

You might be successful in damping your tubes with tightly-packed rags torn into strips. These would add even less mass to the tubes. I've used polyester batting, sold in fabric stores as filling for quilts, etc., in tubes where granular material would have been difficult to fill and retain. It is a chore to get enough of it in through small holes and to pack it tightly enough to do any good.

If you don't mind the appearance, covering the outsides of the tubes with automobile body damping sheet, such as Dynamat X-treme, will also help quiet them. These sheets are sold to damp auto body panels, to improve after-market audio system performance.
- Pack with fiberglass insulation? - pburant 07:32:58 02/21/09 (0)
  That's what I'd do anyway. It's more dense and effective at dissipating energy than polyester while still being very light so that it does not alter the resonant frequency downward more than a trivial amount.
  
  I realize some do not like working with fibrglass, but it's actually quite easy to handle safely (just cover all your skin and wear a cheap dust mask).
  
  -Pete
River Sand - Mike B. 08:32:22 02/20/09 (0)
stay away for sea sand which will contain salt. Salt and moisture can start corrosion of your metal. See if you can get sand from the bank of a fresh water river.

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