[78-L] Turntable vibration isolation

[Michael Biel]

  On 8/3/2010 1:05 AM, Malcolm Rockwell wrote:
> I remember something about mercury isolation dampers fit as "feet" for a
> platform the table would rest in or on.

Can't be mercury.  Its generally illegal now.

> That way the room can dance a
> jig, figuratively speaking, and the table will remain rock steady. Not
> sure about audio frequency transmission, though - if you thump the shelf
> that the platform is standing on will the sound be picked up by the
> cartridge? Maybe yes, maybe no.
> Mal

The old AR turntable advertised hitting the top of the platform deck 
with a hammer and the record didn't skip.  The turntable, motor, and 
tone arm were on a spring suspended sub-chassis.  If you tapped it on 
the SIDE of the case ever so slightly it would bounce all over the 
place.  It was vertical vibrations it was immune to!  No 78 pulley for 
the belt, but it did fit a 16-inch ET, especially thin pressings.  
Shellac ETs would sink the sub chassis to the bottom, but I could play 
it by removing the outer part of the platter.

Mike Biel  mbiel at mbiel.com