Years ago I built a sandbox isolator platform for the turntable system of an audiophile buddy. By then my turntable system was in storage (where it will remain forever, sadly), so couldn’t test the efficacy of this box. But my friend said it did wonders to cut down vibrations from footsteps, doors opening/closing, etc.
As a wood working project it was simplicity itself:
1 - Using furniture grade plywood (more layers/glued laminations than regular plywood), construct a box with bottom, 4 sides, and no top face. Dimensions in this case were 18" square with 6" sides
2 - Those 5 pieces must fit together tightly/precisely & be joined by glue + screws
3 - Carefully use a router to gently roll/bevel the upward facing edges of the 4 sides
4 - Using a separate piece of the same plywood, make a top element that is 1.5" to 2" smaller than the inside measurement (Length & Width) of the box. Use the router to smooth all 4 outside edges
5 - Situate the box in the desired location in the listening room (easy to do it now, near impossible after the next step)
6 - Fill the open-topped box with play sand, enough to come w/in 3/4" of the top of the sides
7 - Drop the top element onto the sand. Use a carpenter’s level to level the top element.
8 - Place the turntable on the top element (centered securely), then re-level.
That’s it. End of vibration reaching the TT via floors, walls
