In article , Paul

wrote:


Personally I would not have said any of the above means the system is
'broken'. Just that as with any real engineered system, it has
imperfections and limitations that stem from its design. Any analog
system has equivalent limitations

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Perhaps you are correct when you say it isn't 'broken'. After all,
assuming no other problems, is should perform exactly as physics
predicts. Unfortunately, *that* is the problem. Physics does predict
that said performance will always be inadequate for the job that the
mechanical method is trying to achieve (assuming that it is trying to
achieve High Fidelity).

Yes and no. :-)

I would put the 'problem' slightly differently, It is that any 'analog'
system which has no accompanying error detection and correction mechanisms
tends to end up with a level of performance which strongly depends on how
well each specific instance was designed and made.

Thus there are some LPs and LP playing systems which can deliver better
results than others simply as a result of being made and used with
particular care and skill.

On this basis the advantage of 'digital' systems is that their ability to
carry information is not so linearily dependent on avoiding small
imperfections. One example has already been mentioned. That an otherwise
well made CD can have a 1mm hole in it, yet reproduce the same waveforms as
if the hole hadn'y been made. Whereas I doubt many people would have the
courage to even try playing an LP with a 1mm hole drilled into the playing
area of the disc. :-)

In principle, we could have made 'better' analog systems. e.g. used a
higher playing rotation rate, etc. But this would sacrifice playing time
for other factors. i.e. a trade-off of the kind familiar to engineers.

My experience is that I have some LPs that actually sound very good. These
are the ones that were well made, and have remained undamaged, and where
the recording didn't 'push the limits' of the system. But with CDs the
situation I experience is that I rarely encounter quality problems due to
the physical CD. Any problems tend to be because the orginal recording made
onto the CD was deficient in some way. So, for example, if I hear
background noise or distortion when playing a CD I tend to suspect that
this was what was placed onto it, and isn't due to a physical imperfection
of the CD itself. Whereas if I hear background noise on an LP I suspect
that EMI had decided it was cheaper to pop the LP out of the press before
the surface had properly formed. :-)


Clearly, the level achieved is satisfactory for many. It isn't for me,
especially as other methods are demonstrably better. I would disagree
with you when you state '...imperfections and limitations that stem from
design'. I would guess that any half reasonable design would, through
necessity, have been conceived only after careful consideration of known
principles and material properties.

Indeed, but the primary purpose of most music carriers isn't actually
'superb fidelity'. It is to make units that sell in large enough numbers
for the owners of the record companies to be able to buy large cigars. :-)

The engineers involved would have pointed out that, say, 33 rpm would mean
more of a problem with inner groove distortion and HF limits than 45 rpm.
But the decision was made that 33 rpm for an LP gave a longer playing time
than 45 rpm, all else being equal. Hence engineers design to the specs they
are given, and the results reflect that.


With that in mind, I would imagine that many mechanical systems do in
fact operate within the specifications the designer intended. I suspect
the designer of such a device, being aware of the principles etc and the
impact that they would have on his masterpiece, would not hang a label
stating 'High Fidelity' on it. That would be left to the marketing boys
who undoubtedly would!! In my opinion, the problem is one of methodology
rather than design.

Indeed.

I have never said, or implied, that other systems don't have limitation
(although I'm not sure I can agree that they are equivalent). If I had
said that (and believed it) perhaps my quest for High Fidelity would be
at and end. That is where I need help

FWIW My personal concerns for some years have been mainly with areas like
the design and use of speakers. Compared with the problems in that area, I
have no real worries about CD-A that are on a similar scale. Nice that
DVD-V's of concerts tend to have 48 ks/sec LPCM, though.

Slainte,

Jim

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