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
Thank you for all your suggestions! I’ve double checked the suspension. And it appeared that the right tonearm side needed a stiffer spring as the aluminum housing was so low that it touched the base. It was simply sitting on the turnable instead of "floating in air". I have replaced the spring with the stiffer one and viola! The effect was instant. The footsteps rattle is gone. Even with the maximum subwoofer volume it is dead silent. It doesn’t even respond to me jumping in a room or shutting the door. It feels like I’ve got a free upgrade as it appears it sounds better!
If your floor boards run east/west, put the TT on either the north or south wall. Or vice versa. Worked for me.
I don’t use powerful subwoofers. I use a full-range speaker system that is essentially flat in-room to below 20 hZ.


No sub here too, don’t know why people use sub at home for vinyl listening, and what is the speakers if they can’t reproduce bass? Sub is for cinema (digital) or as a competition for small bookshelf speakers that can’t reproduce bass at all. 

I’m with Tannoy System 15 mkII , don’t need any sub and life is good.