Tom Fine:

> If a record sits loosely on the turntable, it resonates
> more and wobbles, all of which increases noise and rumble
> transmitted through the cartridge. The idea of the clamp is
> to hold the record center to the platter. I find it works
> well with thin LPs, I can hear and measure less rumble and
> if the warpage extends all the way to the center, sometimes
> it smooths out warps a bit.

To add to the excellent description above think "Anything that makes there
be less difference, movement, between cartridge and disk to be played
becomes less added unwanted, mostly LF, garbage"

The stylish brush on Stanton and Shure cartridges are there to lessen this

It also lessens the Q of the LF cartridge/tonearm resonance thus giving a
more stable and clean LF end.

Also lessens static electricity discharge generation, ticks, in the replayed
disk audio.

> I should point out that pro-grade cutting lathes from the 50's
> onward had vacuum-suction systems to hold the laquer tight to
> the platter, in order to prevent vibrations and resonances that
> would "bake in" rumble.

To clarify the cutting head, while movable up/down is heavy and under the
actual cutter depth control system that controls how deep into the laquer
the sapphire is cutting.

So unless the laquer is held very tightly to be as flat over the whole
cutting area then any up/down movement will produce an added LF, Low
Frequency, component not in the original recording being cut by the cutting

This is the same mechanism as when replaying any pressed disk as above top.

Also the cutting depth would not be constant if the laquer were allowed to
move up/down so you could get the cutting saphire out of the laquer or into
the aluminium substrate if not dead flat.

Best regards,

Goran Finnberg
The Mastering Room AB

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Learn from the mistakes of others, you can never live long enough to
make them all yourself.    -   John Luther