On Mon, 03 Oct 2005 20:09:28 +0100, John Woodgate wrote:

I read in sci.electronics.design that Terry Pinnell
wrote (in
) about 'PC CPU fan', on
Mon, 3 Oct 2005:

It's just resting on the carpet and underlay at the side of my desk.
Then wood flooring and plasterboard lounge ceiling below.

That's not effective sound insulation. Your wood floor will love to
vibrate at 1 Hz, even if it's not tuned to that frequency. You need a
THICK pad -- no, thicker than that!

Apropos nothing, I once was renting a guy's basement. It was always
uncomfortably cold, but there was a gas space heater, but all of the
warm air, of course, floated up to the ceiling (which was the underside
of the floor of the upstairs), so my feet would freeze, while my head
would sweat. In lieu of walking around the apartment on my hands, I
took one of those little fans - you know, the shaded-pole motor, with
about a 3" (8 cm?) aluminum fan blade - and hung it from a joist to
blow warm air downwards toward my bed and stuff. It went "THRUMMMMM!!!!"
and my roommate/landlord didn't like the noise. Well, it turns out
that he also had an old turntable (remember record players?) that he
was going to toss, so he let me salvage it, and I took a couple of
the suspension springs from the turntable, and hung my little fan
from them. The silence was golden. :-) :-)

Floors make surprisingly good sounding boards. :-)

Good Luck!
Rich