Concrete Slabs

@dogberry - It would appear that you have no problem, so pouring concrete would provide no improvement

But for those of us that do not have a 400lb chest to sit our TT’s on...

My TT is on a metal rack with 1/2" mdf shelves, but to isolate the TT from air-borne vibrarions I did the following

• between the rack and the shelf I placed small pieces of sorbothane
• on top of the shelf is a layer of thin foamed rubber
  • the kind used for lining drawers that can be bought from the $ store for $2 a roll
• on top of the foamed rubber is a 1/2" grante tile cut to size
• the turntable sits on that using large 2" bronze cone feet

The net effect of this "sandwhich" is stunningly quiet playback. I am unable induce vibrations into the turntable

• even hitting the turntable deck with my knuckle only results in a very small thud.
• hitting the rack in a similar manner produces only the very faintest sound

The "sandwhich" approach works because of the different densities of the materials used, so the vibrations have a hard job of transcending those boundaries.

The trick is NOT to make any one layer exceptionally thick, because then you can get vibrations occuring in that layer of material e.g.

• if too thick, a granite tile/block will ring - 1/2 -3/4 inch works nicely
• if too thick, sorbothane will reduce dynamics - 1/10" thick is ample
• NOTE: I d onot use butcher blocks because I have found they have a sonic signature
• MDF for shelves is excellent - it does not ring and has no sonic signature
• see: this link Isolation Tips

Regards - Steve

At the present, I am convinced that Phenolic Resin Densified Wood offers a performance due to its properties, that is proving the most suitable for use in a structure.

A TT Plinth or Chassis, Sub Plinth, Speaker Cabinet Baffle or PCB are all today being produced using this type of material.

I have over a period of time had Birch Plywood, Compressed MU25 Birch Plywood and Panzerholz demo'd on same TT > Tonearm as the TT's Plinth. The Densified Wood as the Brand Panzerholz has shown to be the most attractive in use.

I have also been demo'd TT's and CDT's in use with a Panzerholz Sub Plinth Structure and again the noticeable attraction when the material is used is notable.

My in system testing is in the early stages, but there is already enough evidence discovered and attraction created to leave me of the opinion, that selected materials over the years are now most likely to be superseded. 

The following links will show where the Densified Wood such as Panzerholz and Permali are showing their differences in properties for damping and dissipation to other more commonly selected materials.

 https://qualia.webs.com/newdampingfactors.htm 

https://www.lessloss.com/page.html?id=80

Dear @dogberry  : As mijostyn said: you have not or are in trouble down there. 

So let it as it's, there is no reasons to change what's in rigth/good operation. Makes no sense to change it.

Regards and enjoy the MUSIC NOT DISTORTIONS,

R.

next level stuff

I had my speakers on spikes which were on solid brass cups to protect the floor which is the ground floor of the house.  I substituted Vandersteen "vandershoes" under the speakers and chucked the protectors.  My wife in the next room said the difference was dramatically improved...so do I