Don Pearce said...

Hold an LP up balanced on two fingers at opposite edges - you will see
how much it sags quite easily. Obviously it doesn't sag as much as
that with six suspension points, but it sags much more than enough to
generate a huge signal.

The Hydraulic was designed for the thick'n sturdy pre 73 oil crisis
discs which are a totally different animal to the later floppies.

I got a couple of lp's last week, a Decca ffrr from 1965 and a bog
standard EMI Columbia from 1966 and neither droops on your finger tip
test, on the contrary significant pressure has to be applied to deform
them.

--
Ken O'Meara
http://www.btinternet.com/~unsteadyken/