Support table or shelf for turntable

Took a quick look, I find it fascinating that since you feel the oak is causing the "pick up" of vibrations that you use marble slabs under your TT footers?

In my experience this is a double negative. Marble adds mass but acts as a microphone.

What material isolates the oak shelf from the rack? What are you using as the rack legs interface to floor?

"Taut and rigid" seems like a good approach but actually this approach allows structural vibration to be transmitted *more easily* than "flexible and wobbly." This was the idea behind the Flexy Rack of yore. It’s also the idea behind isolation (decoupling) per se since the best isolation is obtained when the object being isolated is *free to move* in the directions of interest. I would like to see the object be able to undulate and wobbly slowly up and down and back and forth when manually pushed a little bit. Thus, roller bearings and springs ALLOW motion rather than CONSTRAIN it. Marble and granite are good materials as top plates for isolation stands due to their stiffness and mass. The quick fix the set up at hand would be to place low profile compression springs under the components on the table. The required spring rate of the springs and number of springs are not difficult to calculate. Problem solved!

I double what geoffkait just said.

It depends on your approach and your budget.

If you are dead set on keeping what you have, here goes...

Invest in a slightly larger Maple platform of 3" thick and slightly wider than your current rack dimensions. Install (3) Brass feet (into) this platform. Then add another maple platform on top of that decoupled by load rated springs, (hopefully you have the ability to or will have someone line these platforms up and recess the springs by 1’8" inch into the bottom/top.

This will add 5"? to your current set-up? I assume this won’t matter since your components are already in the "line of fire", so to speak.

This will completely decouple your rack from the floor.

Now that your rack/system is decoupled from the floor...you can begin to address your components as geoffkait mentioned.

To mention your marble again.. most materials are not perfectly level. While it may seem the oak platform or the marble mates well, most likely there is a big void in how these items mate, (in audio isolation terms) that compounds the very problem you are trying to avoid. So, most of the time a ball bearing type of interface or a spike is the best way to transfer vibrations. Not always though.

The basics first, is the best approach.

I can appreciate your current set-up.

Upon reconsideration, I believe you could now see improvements from a total isolation/sonic perspective? Right?

Good luck!

You may find this helpful in explaining the benefits and pitfalls of different solutions: http://symposiumusa.com/UltraAnalog.html

I like the idea of both "isolating" the rig from external vibration while simultaneously draining the plinth and bearing of vibration through transmission to the constrained layer platform.

I am in the process of installing an Ultra Platform under my TNT with a separate custom Super Plus mini-platform underneath the motor/flywheel assembly, all on top of my existing BrightStar Big Rock/Sound Anchors stand. Hoping to complete the project this week.

Dave