opaqueice;146431 Wrote: 
> So your point is, even if memory had been affordable 20 years ago there
> would have been no reason for CD players to incorporate it - they are
> already immune to jitter, or at least to jitter caused by variations in
> the optical read rate of the CD.  The only room for improvement might be
> in the DAC chip and the analogue stage.

Clive is correct, in a CD player the transport speed is driven by the
buffer being clocked out to the DAC, not the other way around. It is
not a record player. Jitter happens on a timescale of _trillionths_ of
a second and comes from noise in the clock source or the transmission
thereof. The pickup speed varies on a much coarser scale, but this
happens on the _other side_ of the buffer.

I think the point of the original question was: why weren't CD players
designed to use buffer memory as a means of re-reading data to avoid
skips. The answer is it was a bad design (not random access), so that
even as memory became cheaper this could not easily be implemented.
They did eventually make portable players with quite a lot of anti-skip
memory, but since the  format inherently lacks a robust error recovery
scheme, there is no way to recover from severe scratches, pits etc.

> 
> So all this talk about solid state players (like the SB) being superior
> because of a lack of moving parts  is just so much marketing hype. 
> That's an interesting answer to the OP.

Moving parts are bad - they are unreliable, slow, noisy, inconvenient,
etc, but they are NOT a source of clock jitter in the way that people
seem to think.


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seanadams
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