Support table or shelf for turntable

Even if you don't have fault lines under you, even if you live on Australia, one of the most geologically dead places on the Earth, there are still seismic movements as the crust rides atop the mantel, as large trucks rumble down highways, as industry does its thing. The Earth is a noisy orb.

And Slaw, I just went back and re-read all your attacks on me after my last post. Man, you're a handful, aren't you? 
You're basically telling me that if I'm not listening to my system at every opportunity, if I'm not trying everything I suggest, then I shouldn't contribute..
You are rather aggressive with me, no? 

What exactly did I suggest that was incorrect? Am I leading people astray?
Doubtful.

You seem to have a chip on your shoulder that I didn't thank you endlessly in the first thread we interacted on. If I have slighted you in some real way, please let me know and I'd be happy to apologize. I'm not a big fan of animosity.

I believe that isolation from the environment is important in audio, (as it is in engineering / photography / quantum physics etc). 

With turntables you can also get all kinds of internal resonances generated by the deck itself.  We/the manufacturer can try to damp down resonant peaks generated mostly by the bearing, motor and the stylus / vinyl interface. This is why springs (damped/undamped) are often preferred to sorbothane in decks where isolation seems critical in high performance. Springs can isolate further (< 10 HZ ) than sorbothane. As can air bladder systems.

With loudspeakers we can often get massive internal pressures in the box itself (big smile from the open baffle fans). These pressures do nothing to help the cone do its job. No matter how much we tighten everything down, or increase the panel thickness we seem to merely add to the problem by shuffling the resonances around. Usually into the critical midband where these resonances can be most annoying. This noise often gets worse and worse at high volumes where its is almost as loud as the music. 

Its encouraging to see more and more manufacturers starting to tackle these issues, and not just the high end stuff. Even a no nonsense company like ATC acknowledged these issues by changing the shape of their cabinets.

I've had good success cheaply using springs under my components if they have a very rigid/flat chassis. Otherwise, I've been using cutting boards and putting the component on the board. 

Getting the spring ratings correct is the hardest part and it's not that difficult. Plus, springs cost approximately $1 each, so I just purchase a few load ranges/sizes each time I order.

Next, I'd like to try platforms combining two different materials, such as wood and granite. Or two layers of granite...  

I used the Townshend Isolation Bars under my subs that killed the mechanical feedback coming through my floor and up my rack into my turntable. Before, a loud oscillating wobble sound, but after the Bars, nothing. I am pretty sure that the mechanical feedback, plus whatever other seismic pollution is also coming up my front wall as shown in the video link above.

Putting your turntable on a wall is definitely going to be an improvement over suspended floors. My daughter who's an architect with zero audio experience, told me that there is a lot going on in my front (bearing) wall. This was after I had the idea to tie my rack to the front wall for extra stability.

This makes, placing your turntable in another room on another wall a reasonable solution if that's what you can do. For me, I'm working towards adding isolation pods to my TT, amps, line stage, and phono stage.
Kenny