Dan Wilson wrote in MMDigest 981104:

> Anyway, this converter gave you the choice of hearing the music sampled
> at 60 kHz (a bit faster than CD) or 120 kHz (nearly three times as
> fast).  The only conversion I found at all acceptable was the 120 kHz
> rate -- 120 thousand samples per second -- and I immediately lost and
> have never regained any enthusiasm I might have had about CDs.

Which is why recording engineers are moving rapidly toward 24-bit,
96 kHz recording and beyond.  Good dithering can, however, make the
16-bit consumer disks derived from these originals quite satisfactory;
the same applies to images -- a well dithered 16-bit image is almost
indistinguishable from the original 24-bit.

One reason the higher sample rate is needed is that the effects of
jitter are proportionately less.  Possibly on your early circuits
jitter was a problem.

Possibly there will eventually be higher spec CDs and players.

> The human ear is non-linear and creates supporting sounds from the
> ultrasonic components in music, so it's illusory to suppose the usual
> 200-20,000 Hz bandwidth is enough.  A real piano disposes of this
> problem once and for all !

If we were living in the Roman Empire we would have slaves to play real
pianos for us.  Or would we be the slaves?  As it is, perhaps it is
kinder to use digital gadgets.

Regards

Don Cox
doncox@enterprise.net


 [ Editor's note:
 [
 [ "Dithering" adds a weak wide-band noise (a "hiss") to the analog
 [ input signal before it is converted to discrete values by the
 [ analog-to-digital converter (ADC).  The hiss is inaudible, but it
 [ helps the fidelity by reducing conversion jitter.
 [
 [ Clock jitter is caused by external signals corrupting the ADC
 [ conversion clock.  A computer mother board is notoriously noisy,
 [ and so the ADC circuits for recording are usually in another
 [ cabinet, far away from the electrical noise of the computer.
 [
 [ In recent years improvements in the group-delay characteristics
 [ of the analog filter which precedes the ADC has also helped reduce
 [ the distortion of digital audio recordings.
 [
 [ -- Robbie