Sturdy Turntable Stand

Right. That is pretty much what I did. DIY.
Next step up from what uberwaltz built, incorporate a sand bed into the shelf the turntable will sit on. Next step up from that would be what I did, cast the shelves from concrete with a sand bed cast into them. With a granite machinists plate on top its massive and stable and near impervious to footfalls and other vibrations. http://www.theanalogdept.com/images/spp6_pics/C_miller_web/TTstand_1.jpg Mine isn’t adjustable but it is modular. The legs are ABS filled with concrete and bolted together with the shelves so it can be moved one piece at a time. Altogether its near 700 lbs and, you might say, rock solid.
This is kind of old but you get the idea http://www.theanalogdept.com/c_miller.htm

@uberwaltz
I've just started looking for an audio rack for my son, I'm giving him my RP 3 and some other pieces. I like your DIY rack and wondering what did you use for feet? 
Eric

Ironically the best approach is actually a stand that allows the turntable to move freely in all directions, I.e., an isolation stand. The best isolation is achieved when the component can move easiest in all directions, all six of them! There used to be the Flexy Rack that achieved some degree of isolation by being the opposite of rigid. Rigidity and mass are the enemies of high performance. 

Way to go millercarbon:)

@ericsch 
Feet are something I really need to try a few more of!
Not that so far they seem to have made too much difference but you never know.
Right now I am just using rubber boots over the ends of the all thread rod which then sit on steel pucks on my tiled floor with felt cushioning them.
Not fancy but the rack is solid and sturdy and I perceive no vibrations at my TT.
obviously Millers effort dwarfs whatever mine achieved in solidity!