"Dick Pierce" wrote in message
...
"Harry Lavo" wrote in message
news:yjasb.173953$Fm2.151953@attbi_s04...
It depends. I'm more concerned about the first ten years. I've got
original
cd's of "The King and I" and "Pineapple Poll" from '82 that are
completely
unlistenable...unless a jitter buster is put in the cirucit...that's how
much jitter is on the cd.

Harry, please do not think I am claiming you are nit hearing
something, but your statement needs correction.

Despite a LOT of strident claims to the contrary, CD's CAN'T have
jitter. The CD has NO explicit timing information on it other
than the fact that it has a 44.1 kHz sample rate. There is NOTHING
in the data that says when a sample has to show up. The data, as
read off the CD, is pretty scrambled up as part of the error
detection and correction algorithm: it is NOT read off in sample
order because it's not put on in sample order to begin with.

Now, there could well be problems that might cause a poorly
designed or marginal performing transport to screw up the
reconstructed data stream when it's sending it out, but that's
a player issue.

Further, if the original digital data recorded on to the CD had a
lot of jitter, say, that the A/D converter or some intermediate
process had a bad clock, there's NOTHING a "jitter buster" could
do to correct it: a "jitter buster" can ONLY correct timing skews
in the serial data stream AFTER it is read off the CD. That timing
error does NOT come from the CD, indeed, there is no timing stream
ON the CD to begin with. The serial data stream timing and any
errors in it are due to the transport, which is what's generating
the clock. If a jitter buster helps, it's basically providing a
function that is missing in the D/A converter.

Once again, the principle bears repeating: the ONLY time when jitter
has ANY relevance to audio quality is at the moment of conversion
between the analog domain and the digital domain and vice versa.
EVERYWHERE in between, it's irrelevant. Just consider the fact that
the Reed-Solomon encoding on the CDs is: if you want to talk about
timing, it's the "ultimate" in jitter, since the data scrambled out
of order when put on the disk, thus pretty much destroying ANY
sample-to-sample time relationship. The data, when it's read off the
disk, CANNOT and IS NOT sent off to the DAC as it's read: it MUST
be accumulated into a buffer until a complete block is read, then
the inverse Reed-Solomon decoding is applied to that buffer and
only then can the transport, using it's OWN clock, hand out the
result, sample by sample, to the output, at a rate determined NOT
by the CD, but by the transport's own internal clock. Indeed, the
CD is speed up or clowed down to match that transports clock, the
transport does NOT speed up or slow down the output to match the
CD.

Thank you for correcting me, Dick. So let me explain the phenomenon. The
system was a Phillips 880, fed through either a toslink to an AA DTI Pro set
for 18 bit, on via balanced cable to a Proceed PDP. The jitterbuster was
absolutely needed for the Proceed PDP to sound "musical" as opposed to "grey
and sterile" on all disks. From your posts here, I understand you consider
its jitter handling terrible, and from what I heard I would concur.
However, the DTI in the system it became a very fine DAC indeed...it was
this combo that finally wooed my into buying cd's instead of (for the most
part) LP's about 1990.

However, with the two disks in question, when fed without the DTI in the
system they sounded like they were put through a comb filter. With the DTI
in the system they sounded fine. In the Phillips 880 alone they sound fine
(not with huge resolution, but no comb filter). In a more modern player in
they also sound fine.

So, the question is, what could cause this disk-related phenomenon. To push
the intrigue still further, these were "not for resale" demo release cd's
put out by RCA for evaluation purposes (by reviewers, I would suspect) at
the dawn of the CD era. Not coincidentally, I picked them up at a use
record/bookstore in Great Barrington, MA where High Fidelity magazine used
to be published. Not a coincidence, I would guess.

Any light you could through would be appreciated. I always assumed it was
jitter related somehow.