Turntable isolation for bedroom floor

infection asks

How about placing the one rack with the turntable in the sand...?

The general idea is to get your vibration control as close to the component as possible. Easy enough to experiment and determine for yourself. What you will find is putting a rack on a sand box and then putting the component on the rack is nowhere near as good as putting the rack on the floor and the sand box under the component. Turntable, CD, whatever, same deal.

The biggest misconception, and its a real common one, is that its all about isolation. This one you can disprove so easy it will make your head spin. Simply have someone go pick up your CD player or whatever while you listen. Minute they pick it up its isolated. Does it sound any better? Not on your life. Because its about vibration control. Even a turntable, most of the vibration that needs controlling is generated within the device itself. You could float the thing in orbit, couldn't get more isolated than that, still gonna need vibration control. 

The easiest change that will make the biggest improvement is to place the turntable on the floor. This is because the floor is gonna move anyway. But the higher the rack the longer the lever arm and the greater the move the higher you go. 

You can try a wall mount. But floors usually are a lot more structurally sound than walls. 

Your most fool-proof and cost-effective solution is the tried and true sand box. Dirt (heh) cheap and hard to mess up. You could if you want experiment and see for maybe $10 if that. Simply buy a bag of kids play sand, dump it in a tote. Tamp it flat. Find something flat and around 3-4" diameter, place that on the sand, place the component on that. Then when you have proven this works (and it will) you can decide how to make it look better. Build a box out of MDF for example. 

The bigger/deeper/more massive you go the more it will damp and the lower it will drive the fundamental frequency. My table for example does move when I walk up to it. But its in the range of a few hertz, and only when I'm right there. That's with over 500lbs but also on a rack over 40" high. For years before the rack mine was right on the floor. The rack is even better. But look how much mass it took to compensate for being that high. That's why more often than not the best rack is no rack.