Turntable Isolation Platform

[heyraz]

My wife got one of these and the first thing I thought was "She Got Me A Turntable Isolation Platform".
Nope...it's a kid's trampoline
Not too expensive, less than $70 USD
20" x 24"
Amazon and Kohls

 

[Buck Rogers]

You want a platform that is heavy like Marble or Granite.

Then place rubber feet under.

This one is 15" X 12" at walmart for 25$.

 

[rothwellaudio]

You want a platform that is heavy like Marble or Granite.

Then place rubber feet under.

This one is 15" X 12" at walmart for 25$.

Mass per se doesn't provide any isolation. If the surface it sits on has movement in it, the extra mass will lower the resonant frequency of that movement.
In the case of the kids' trampoline I'd expect the resonant frequency to be on the high side with only the weight of a turntable on it, so the extra weight of a heavy slab to lower the resonant frequency would be beneficial.