With all the playing around that has been going in, I decided to have
a look and see how important it is to have a deck properly suspended -
I mean what does it actually do for you?

So here are three frequency plots (on one display). They show:

blue: The output of the cartridge resting in its holder
orange: The output when on the platter
green: the output when on the chassis

http://81.174.169.10/odds/seismic.gif

The platter is suspended, the chassis isn't. So even in a seismically
benign part of the world where I am, there is a ton of stuff coming up
through the ground. The suspension is effective in removing it from
20Hz up, while the unsuspended chassis obviously does nothing. I could
have shown a plot with me walking around, but the green trace would
have been off the screen.

The motor is of course not running for any of these.

So there's the moral. Even if you think things are quiet, don't
operate a deck without a decently sprung suspension. It is quite
nasty.

d

--
Pearce Consulting
http://www.pearce.uk.com