Franc Zabkar wrote:

On Mon, 03 Oct 2005 14:05:55 +0100, Terry Pinnell
put finger to keyboard and
composed:

It may be coincidence, but I've only become aware of this since
installing a third HD - a 200GB Maxtor Diamond, 7200 rpm, in addition
to my two 60GB Maxtors.

I would think it unlikely that your two identical drives would spin at
a speed that is different enough to produce a 1Hz beat. That's a
difference of 1:120, or 1:360 if you consider a possible harmonic
effect of the motor's three windings. AFAIK, the speed is crystal
locked. Your observation in respect of the 200GB drive sounds more
plausible since it could involve different crystal frequencies.


Thanks, makes sense. Just under 1% is probably acceptable tolerance
for an advertised speed of '7200 rpm'. Mind you, given that this new
one is Maxtor too, and broadly same 'Diamond' range, I'd have expected
the same crystal to be used.

--
Terry Pinnell
Hobbyist, West Sussex, UK