Home grown turntable platform/base?

If your making a platform with layers, use a proper glue for the specific materials. Don't use screws, they defeat the purpose and allow the vibrations to freely travel through the platform circumventing the layer effect to reduce transmission of vibrations . The Herbies materials are better than sorbathane which around turntables will muddy the bass lines and mess with the treble frequencies where as the herbies materials are designed to avoid that specific issue. If foot falls are not a problem , a simple gluing of a couple pieces of 16 X 18 approx. void free ply with 4 herbies tall tenderfeet will do as well as what you would realistically need/want with the project table. The plywood is just an economical choice that works quite well,  other materials may be substituted that cost more, but don't always deliver the results wanted by adding vibration tone of their own. I made one like this for my daughters Rega RP6 and bought a cheap piece of leather from a fabric store and glued it to the top to dress it up and very fine sanded the sides smooth and sealed them and put 4 Herbies Tenderfoots on and done. Works great and looks quite sharp actually.

 A sand box is a cheap easy build as well if more extreme measures are wanted/needed. 

If foot falls are a problem, then isolating the table from the floor with a wall mount is the best and final method for that issue over suspended floor deflections. 


Good luck, nice to see the gift of music appreciation being joined together...……...

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Regarding has2be's statement that screwing the two pieces of birch ply together will defeat the isolation provided by the constrained layer damping placed between them, that layer of damping material is put there not to provide isolation for the turntable, but to absorb and dissipate the resonances of the plywood itself. Green Glue, ASC Wall Damp, and EAR Isodamp is too thin to provide any isolation. It is the springs, roller bearings, Herbies feet, or Seismic Pods (or even slightly inflated inner tube) placed under the shelf that provides isolation, not the constrained layer damping.

Yes that is what the layer is there for, no question. However, the screws still allow the resonance to travel straight "through" the absorbing layer from one ply to the other ply....., it stands to reason . I know the concept well, and its intended purpose and the screws will and do defeat the performance of  impeding those resonances.  There are adhesives out there that defeat the problem you create by not using an adhesive that will act as you require it to as well....