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Sandbox Design Advice

I understand the recommended design is to build an open wooden box plus a loose lid (possibly granite) which is slightly smaller than the internal perimeter.

Fill the box with kiln dried sand, float the lid on top of the sand and then component on top.

Heavy duty sorbothane feet for the box.

There were a few design details i couldn’t find on the forum and so pl can anyone advise on:

  1. what size should the gap be between the lid and the perimeter?
  2. how deep the sand should be for a 52 kg power amp (114lbs in old money 😀)?
  3. i am going to use a carpenter to make it for me (pine?) and would like a professional finish in black - any suggestions? 

thanks very much - advice is much appreciated.


soma70
geoffkait's avatar
geoffkait
23,365 posts
 
My Woody the Woodpecker iso stand employs a bed of perfectly round smooth glass micro beads, much slipperier than sand for greater ease of motion, plus viscoelastic feet and hardwood (bamboo) box to simulate the physiological characteristics of the head of a woodpecker, which is able to undergo rapid and extremely high negative g forces 1200 g without injury.
soma70 OP
153 posts
 
😂 - The craziest thing about the WTWP is that you are now making me wonder if glass micro beads would be better than sand!
soma70 OP
153 posts
 
I have read that Silica can release fine airborn particles, which can be harmful to lungs.

the glass micro beads look interesting - Geoff are you TTP or is there a grain (!) of truth in your post?
dgarretson
2,593 posts
 
I elevated the heavy sandbox on five large, relatively soft springs from McMaster Carr. If you find the correct spring rate for the mass of the sandbox platform, the sandbox oscillates at around 1-3hz resonance when touched. This insulates the turntable system from the rack and any earth-borne vibrations. The sandbox then acts solely as a dump for vibration propagated from the turntable. It’s a bit eerie to give the box a visible push while a record is playing, or furiously jump up and down on a sprung floor, and experience absolutely no mistracking or skipping.
So far I've only used this approach with unsprung turntables.
millercarbon's avatar
millercarbon
12,531 posts
 
That is a good point and what I meant about understanding the details of your particular situation. Since there is no such thing as isolation its all controlling/tuning instead its important to understand that is what suspended tables are doing as well. All you're really doing is tuning or controlling the vibration down into a less bothersome range, like your 1-3 Hz. This is in other words the resonant frequency of your rack or box or whatever. If that also happens to be the resonant frequency of your arm, or your suspended turntable, oops, problems!

One more reason in favor of unsprung tables.
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