[John Stone]

On 6/30/07 12:22 PM, in article
, "William Sommerwerck"
wrote:

I heard the effectiveness of this about 25 years ago when
James Boyk at Caltech sent a review LP with a severe warp.
The side with the warp "up", so that it could not be pressed
against the Platter Matter pad I was using, had a much different
tonal balance (brighter, thinner) from the other side.

I think this issue is better handled by improved cart technology
lowering the eq. mass of the stylus and the force it imparts on
the record than on the other side.

The point I was making had nothing to do with warps..

This brings to mind the vacuum platter turntables that were popular 20+
yrs.ago. I had a Luxman PD300 with an external auto vacuum pump. Pain in the
ass to get the record to seal properly, and the outer seal had to be kept
perfectly clean. But the audible effect was very obvious, and for the
better. It truly did remove all the warps, which was a great help for the
Dennesen air bearing tonearm I had matched to it. There were many theories
about the vacuum system permanently damaging the grooves, etc., but I never
had a problem. It was a major pain in the ass to maintain, and I ultimately
got too busy to get much use out of it. By then CD's were good enough to
justify my switching over. I still maintain a Pioneer PL 1000 linear
tracker, which is fine for the little vinyl I still play.