Concrete Slabs


Here I go, perhaps stirring up some controversy.

I have two turntables, both sitting on a 400lb 17th century oak chest. The chest in question sits on a suspended wood floor in a 1985 post and beam house. I just started to play Mahler's 9th (DG/Guilini/CSO) on an SME 10 with an Ortofon Cadenza Bronze. It sounds as it should. But the point is that if I stamp as hard as I can right next to the chest, there is no interruption of the sound. Even if I take a deep breath and jump with both feet off the floor—nothing, nothing at all. So, tell me, what may I gain by pouring concrete here, there, and everywhere (as I believe someone once sang)?

Is this reverence for the ultimate solidity of a foundation the same kind of daftness as when someone says an interconnect must be as thick as their wrist, even though the component may pass the same delicate signal through a PCB trace of minuscule cross-sectional area? What are we aiming for?

dogberry

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. 

@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!

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

@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. 

@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