AZ Nomad wrote:

On Tue, 20 Feb 2007 15:31:37 -0000, Pete Cross wrote:


I noticed a similar effect yrs back when I got a Sony CDman , I stuck my
Alan Parsons sound check cd in and on the sweep freq test it sounded ok till
just past 5KHz when all sorts of harmonics where added, it was due to the cd
spinning at 4x for the read ahead buffer ( anti jog ),must have been sampled
at too low a freq, if you turn off the anti jog it plays fine.


It wasn't from reading the disk at 4x. Reading data at 1x or 200x is
reading the same data. As you also surmised, sampling at too low a sample
rate will cause all kinds of distortion once you get past the nyquist
frequency.

I thought that the Sony compressed the data before loading the buffer
then uncompressed it on reading from the buffer, because memory was
expensive in the second millennium. Of course, I may have got hold of
the wrong end of the stick again.

--
Eiron.