Best building material for vibration free shelving

@skyscraper,

I was in a similar position not long ago when I bought my heavy new Transrotor turntable and had to modify my existing flimsy rack to accommodate it and create an isolation base.

Reading the many threads and forums, and soliciting info from other audiophiles was enough to make me start tearing my hair out because you encounter so many different views and advice.

I took some of the info, and then the rest in to my own hands, bought tons of isolation materials and footers, and tried them out, especially measuring with seismometer apps on my ipad/iphone.

FWIW, here’s what I ended up with:

I re-enforced the top (thin) mdf shelf of my Lovan rack with 1/8" steel. It’s quite remarkable how much solidity that steel creates when bonded to the mdf (I used a product called "wall damp" used to damp vibrations in walls, as the bond).

Isolation base:

2 1/2" Maple block
1/8" steel sheet
MDF layer of 3/4" and 1/2" sheet, bonded by wall damping
sitting on Townshend Isolation Pods (spring based pods)

(Actually, I also threw in some thin sound-damped steel discs that I had ordered to test, between the pods and the MDF, mostly because I had them to use).

As far as reducing external vibrations reaching the isolation base/turntable, nothing - sorbothane sheets, footers etc - came close to the performance of the spring-based Townshend pods. You can see in seismometer measurements, and feel, huge reductions in vibration getting through to whatever they are holding up. If I put the seismometer/ipad on top of one of my other av rack shelves and stomp the wood floor around the base, it registers huge ringing spikes on the read-out. Place it on the isolation base held up by the pods, and almost nothing at all registers stomping hard around the base, and almost nothing at all is felt with a hand on the base.

All the rest of the material below the Maple block is just there to add thickness, weight, more reduction of isolation through combining various materials, and to provide the right weight for the springs to work optimally. I have to emphasize again btw how much bang for the buck stiffness you get just throwing in even a 1/8" sheet of steel in the mix. It even made the whole base layer obviously more solid, no matter where I through it in within the layering.

Don’t ask me if all this had benefits on the sound as I don’t know. There was no practical way to do a before and after. But in terms of a peace-of-mind project, and knowing how much vibrations were reduced, I’m quite happy with the results.

Cheers.

Mike,

It turned out I found no need to actually bond the steel sheet to the base.  It seemed simply placing it between the maple block and the MDF  - no glue or damping to bond - worked fine.  Whatever type of wood I sat on to the steel sheet, the combination immediately became more solid - the wood having a slight ringing "knock, knock" tone when rapped without the steel, and a very dead, dense "thunk, thunk" sound when placed on the steel.

That was the isolation base though.  When I added the other steel sheet to the very thin MDF top shelf on my lovan rack, in that case bonding it (with all damp) made more sense, because the MDF shelf was so thin it could slide a bit over the steel if the turntable above it happened to be pushed.  But with the steel sheet in the turntable isolation base, just the natural weight of the wood placed above it (and the turntable) provided tons of friction and it's really solid.

Mike,

One more detail in case it makes any difference:

I just remembered upon looking at my turntable base:  As I said, I have the Maple Block (on which the turntable sits), sitting atop the stainless steel sheet, and then beneath that, the two layer sandwich of MDF held up by the pods.

I actually undercut the size of the steel/MDF beneath the maple block so the maple block overhangs the rest by around an inch or so.  The reason is, the Maple block is the pretty part of the whole thing and I wanted it just floating with the turntable above it.  MDF isn't exactly beautiful.  So in cutting it inset about an inch under the maple block, and painting the MDF and stainless steel with matte black paint,  they completely disappear from view under the shadow of the maple block.  So all you see above the rack, sort of floating, is the maple block and turntable.

So actually, not too long after painting the steel on both sides with the paint (it was dry), the paint also provided something of a bond-like friction to both the maple block above it, and the MDF below it.