Concrete Slabs

I have not heard @dogberry's System or set up for his source.

I am certainly not qualified to inform him his set up is correct.

I am with experiences that the outcome has been quite beneficial, even if only assessed as subjective evaluation. There can be no harm in suggesting to the OP that a reconfiguration of the support structure in direct contact with the TT, can create a performance from the TT, that is perceived as for the better.

One advocate of this type of practice has already put the idea of suspension forward.

I have found adding Tiers to a Structure and using certain types of Separation/Isolation Footers between the tiers has proven to be a very valuable inclusion.   

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 

next level stuff

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.

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and attraction created to leave me of the opinion, that selected materials over the years are now most likely to be superseded.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

@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

@dogberry , you would gain absolutely nothing. Concrete slabs might protect you from foot fall problems, which you do not have, but they will not protect you from environmental rumble, only a well suspended turntable will do that. 

I use concrete supports and find it a solid improvement over a wooden support and a steel frame rack.

@lak Out of curiosity is there anything inside your 400lb 17th-century oak chest?

It's a cupboard chest, so rather than a hinged lid it has two doors on the front, there is a vertical divider up the middle and a shelf on each side. One side has an Ayre C5xe on the shelf, with turntable tools underneath. The other side is full of rather disreputable LPs that would not fit on my shelves (the kind one gathers from relatives and don't like to throw out, Great Western Movie Themes, Greatest Hits of 1968, Soundtrack from Dr Zhivago - that kind of thing). Certainly adds a lot of weight. I also have a large block of wood under the chest in the centre, so that it supports the bottom where the central divider is. I'm not going to make any changes to it that would damage its worth as an antique, and I don't want to know what it's worth! I had some canny grandparents that bought up all sorts of antiques in the 1950's when the exorbitant death duties of the Attlee government meant many large houses were sold up to pay the duties when the owner died. That was the intention of a deliberate policy aimed at redistribution of wealth. My grandfather, most of his life a fitter for the Crewe railway works, had a little cash from his football career, so he bought up antiques. I can't complain!

Creating a Structure to mount a sensitive item of equipment on is a Topic that will appear the more it becomes understood how the impact of the Ambient Environment on the equipment can be detrimental to it.

There is no harm trying out additional Tiers of Supporting Structure, between a TT and Table Top.

The New Addition of Materials and added levels of Isolation will bring something new to the perception of the SQ.

An assembly for a Support Structure is likely to be discovered that will surpass what is already in place.

It is the trialing of Support Materials and Isolation/Separation, that helps one determine where their objective is best served.  

Does a $4K Vibration Control Platform offer much more in control, than a well thought out structure that can be produced for a considerably less cost, or is the $4K Platform a shortcut to a Support Structure that can be mimicked using other types of Structure as a support, only Trials will assist with learning this.

As for the Oak Table a very affordable trial could be to utilise Newplast Modellers Putty. This can be used between the Oak Table Top and have a Sub Plinth Tier, seated on to it.

This as a method is now offering Two additional Materials as Tiers to create a Sub-Plinth, and can have a very valuable effect on the Damping Factor of the Structure and improve on the Dissipation of energies being transferred. 

@dogberry your system set up for your turntable is fine, enjoy your music and be grateful. Out of curiosity is there anything inside your 400lb 17th-century oak chest? If not perhaps some type of fill might be beneficial, most likely a trial-and-error experiment.

Sounds like you’ve got your turntable support reasonably well sorted. Congrats! In my experience: isolation isn’t a problem, until it’s a BIG problem. If you don’t have good enough support (combination of rigidity & mass), then footfalls and speaker energy through the floor can cause a large enough displacement (shifting the cartridge relative to platter) to excite your cartridge & tonearm’s resonance (8 - 12 Hz). This isn’t usually audible, but it can be enough to cause problems for your amp & woofers. It can even cause your amp to clip, which will send a nasty jolt to your tweeters. Absent that, it can certainly cause mis-tracking.

Concrete slab floor isn’t a complete isolation - it will transmit energy in the audible spectrum just fine - but that stuff can be handled in a number of ways, with audiophile footers or platforms. What concrete can do, is it vastly reduces the maximum displacement your cart & arm get subjected to. Because of its great mass & rigidity. Absent a concrete floor, isolating speakers and turntable are your next best bet. A properly tuned spring platform works great - Townshend podiums look interesting. SOTA’s 4-point suspension is amazing - it will absorb even large displacements QUICKLY and then dissipate the energy very SLOWLY at like 2Hz where it doesn't matter. Bigger SME’s also have very substantial elastomer suspensions, but your SME 10 appears to have a non-suspended design utilizing polymer layers.

As crazy as it might sound, one of the most significant improvements I achieved whilst going through the various permutations of materials to produce a Structure to support the TT.

Was discovered when I placed a Steel Sheet of a Dimension 1100mm x 750mm x 15mm as a Base Plinth to Build the Racks onto.

It is a 'young mans sport' getting the Steel Sheet into place, but the recollection of the change that occurred one the structure was once more assembled was quite indelible.

The Steel Sheet today is rested/attenuated on Footers, which ended up being made up of Granite with a Cork Pad as the Base and a hard foam in between the Granite and Steel Sheet.

This is not too expensive to achieve, even if the Steel Sheet was to be cosmetically finished.

Exactly where would you be pouring concrete? From my understanding, while concrete would help resonances somewhat for isolating components on your rack, the larger benefit is to get the most performance out of your speakers. Resonances from the speaker to the floor will bounce back less, and you will notice an audible improvement in imaging, clarity and speed. Of course, you can get pretty far with good isolation solutions. But I think the bigger gain would be seen from speaker performance vs improved imaging due to improved component isolation, which would be incremental in comparison.