How to isolate turntable from footstep shake or vibration


Even while the Oracle turnable that I use has a built-in springs suspension by design there is a low or even sub-low frequency boom every time someone walks in a room. This becomes really bad with the subwoofer’s volume set high as the low frequency footsteps make straight to subwoofer where they are amplified shaking everything around. It seems the cartridge is picking up the footsteps very efficiently as even a lightest foot down becomes audioable. What can be done to attempt to isolate the turntable from the low frequency vibrations? Interesting, that the lower the volume of the subwoofer, the less the footstep shake is evident and with the subwoofer turned off it is a barely a problem at all. 
esputnix
The springs in the turntable are to isolate the turntable from higher frequency noise. Not footfalls and subwoofers. Typically the solution on floating floors  is to decouple it from the floor and use a wall mounted turntable shelf.
You really need to get the turntable up onto a wall shelf designed to support a turntable. I’m using an Apollo wall mount support made in the UK. It is made very well out of steel. It has options of either wood or glass for shelf material, both of which are completely isolated from the steel frame of the support via rubber bushings. I chose the wood shelf version of which I since replaced with a much thicker Butcher Block Acoustics maple slab. The support/mount itself is attached to a sheetrock Clad concrete basement wall. There are zero vibrations getting to the turntable, unless of course they are seismic, which I tend to not overly worry about.
There is discussions within the ongoing thread,
'Upper Level Vintage DD Strenghts and Weaknesses', that has information that might be useful to your inquiry,
 What can be done to attempt to isolate the turntable from the low frequency vibrations?