On Friday 30 November 2007 18:18, Bill Unruh wrote:
> > Nevertheless, from a "perceptual" point of view, reasonable amounts
> > of "analogue artifacts" (modulation) seems to be much more "benign"
> > to our ears (brain, actually) than most currently common levels of
> > "digital artifacts".
>
> Your evidence for this is what?
obviously listening experiences, what else?
Would you choose which wine you prefer to drink based on your own taste
or on some chemical analysis whose results tells you little (if anything)
about the taste of the wines?
Analogously, when it comes to judge audio quality, what I can ear is the
only thing that eventually matters to me.
Incidentally, as in this case my personal "taste" happened to match that
of so many other people, I have concluded that perhaps it should be some
sort of a general "rule", likely dictated by how human earing "reacts" to
different forms of sound "distorsion" (here this term is used in a much
general sense, not just to mean HD).
To avoid misunderstandings, what I'm saying (and have said) was not meant
to argue the relative merits of analogue vs. digital in general.
Quite obviously, a good digital system is much better than a bad analogue
one... as much as a good analogue system is better than a bad digital one.
If we really want to argue about relative merits, my personal opinion is
that, as of today, for what regards audio quality the best digital systems
(based on "high resolution" media such as SACD or DVD-A) are more or less
"on par" with the current best analogue systems. Of course if the source
record material is of an adequate quality in both cases.
(actually, in the last few years I've "seen" -eard- an obvious progress on
the digital side. While the first SACDs were not able to compete with more
or less standard LPs, today the best ones are able to come close -tough not
yet equal- the best vinyls recorded at 45rpm).
Then we may argue than a state of the art analogue system may cost an order
of magnitude more than a corresponding state of the art digital system, but
that's another story. As is another story the many obvious advantages of the
digital systems in terms of "comfort" of use, versatility, etc.
I was just screaming against the ubiquitous "digital = perfect" message which
in the last ~20 years appeared and still appears in mass-market advertisement
of just about anything, from CD players to... microwave ovens! 8-)
But perfection does not exists in this world, and digital systems are no
exception.
Since I care about improving my own audio system (which is digital based),
I do care to try to discover, point out and hopefully address the problems
of digital systems... at least the few ones I can do something about on my
own. 'Cause I know there are some problems, if I can clearly ear them!
Quite obviously, I get irritated when someone rather answer with some
marketing nonsense like "digital is perfect, there are no problems to
speak of".
If people stop believing on "digital perfection" and rather keep working
to improve it, we would all be enjoying better digital audio. ;-)
(needless to say, the same would stand for sooo many other things, too! 8-)
> > of nasty, correlated jitter resulting from so doing afterwards...
>
> No idea what this means.
you have no idea of what signal correlation does means or what?
If you know what correlation means, than what I say is that listening
tests have shown clear evidence that (from a perceptual point of view)
jitter correlated to the signal is much worse than purely random one.
And I would say not quite surprisingly, since the correlated jitter
produces more "correlated noise" than random jitter does and, as is
well known, our earing system is most sensible to correlated sounds
rather than to "more random" noise.
Thus, if you care about sound quality rather than crude spec-sheet
numbers, it's better to have a somewhat higher level of uncorrelated
(random) jitter rather than a lower level of jitter which is somehow
correlated to the audio data stream and/or to the analogue signal.
That's why S/PDIF (and AES/EBU for that matter) are so bad; embedding
the clock in the signal stream at the source and recovering it at the
other side generates large amounts of highly correlated jitter on the
reconstructed clock, which no PLL can ever completely get rid of.
A colleague and friend of mine have done several tests about this on
his own... I have heard the results and have been shocked by them.
> Exactly what hype is that? The hype appears to me to be coming from the
> other end-- the analog junkies.
claiming that something is perfect is pure hype by definition.
Or you do believe in a perfect world? 8-)
Ciao,
Paolo.
--
Skype: Paolo.Saggese
http://borex.lngs.infn.it/saggese
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