My thoughts on TT isolation methods.


I have done extensive research on isolation platforms and with help from the Audiogon community plus many hours of listening. Its not scientific and I did not measure results but here it goes. I have tried MDF board, Granite with both and alone and cork and or neoprene rubber and truck bed material as sandwich material. Granite and marble are beautiful and mass loading. It would probably be OK for a suspension loaded TT but not as good a choice for a mass loaded TT like mine. I finally invested in a 4 inch maple slab and 4 cork rubber sandwich supports that is common in industrial machine dampening. Its better and doesn't give the sound as much detail. With detail. =harshness. Its the best I have found. With less edginess and no harshness but more neutral detail. You can use 2 MDF boards which come close. Ok, if you want the absolute best for an expensive TT get an electron microscope isolation device which costs in the thousands. You could get one for a much cheaper TT but at that point you should just invest more in a TT for more bang for the buck. I think thats what Michael Fremers 100k plus Caliburn TT comes with. Look at one of his videos. The other very low cost option is a sand box. I heard a TT in one before and it sounded great but that was a 30k Clearaudio TT. I almost went with that. I thought about suspending it from the ceiling but mine is 80 lbs. I hope this helps!
128x128blueranger
Sorry, the MinusK is better than all of them. The reason is that it's horizontal resonance is just as low as it's vertical resonance. In other words you can hit your rack on the SIDE with a hammer and it will not bother the turntable. Yes, it is a bit more touchy to set up but once it is you can forget about it. You could always just buy a Dohmann turntable with the MinusK ready to go. The MinusK negative stiffness design is said to be better than any active device in terms of isolation. 
Millercarbon, if you want to do it right you need to start working on your hanging turntable platform as described above. If you get it right it will work better than anything you are doing now. Promise:)
Mike L, The Stacore has little if any lateral compliance plus you need to keep it pumped up. The MinusK requires none of this. Both it's horizontal and vertical resonance are less than 2 Hz. They also make a low profile version now which elevates the turntable 2-3 inches only. The only real downside I can see is that the platform is ordered based on turntable weight. If you were to change turntables it might not work. 
In thinking about it, for $5000 I would build a hanging platform. $5K buys a lot of springs. Think MC. When your not playing music you can use it as a trampoline:)