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|In this section, you'll find some ideas I have about audio in general. It's nothing
more than my own opinion, so if you disagree, just let me know,
discussion is always interesting ...
It's not my purpose here to fire against digital sound. In fact, I strongly believe in
digital not because is better by itself but only because we've never found a truly
good way to store analog sounds (or other phenomenons). Digital is easy to store, this is
its main and probably unique advantage over analog.
Since the first introduction of the Philips/Sony CD, I felt something was wrong,
something was missing and is still missing: Emotion. I do not believe in esoterics: I work
in computers and have both the feet right on earth !
When Philips designed this standard, optical storage was only beginning and
particularly limited in capacity. They wanted their system to be:
That's the reason of this standard: 44.1KHz sampling rate with 16bits definition.
What does this mean:
We can hear up to 20'000 Hz, and with this standard, a 20KHz sound will be measured
only 2 (!) times per cycle.
Second problem, the resolution: 16bits. It's enough only for strong sounds ! In fact, you have 65'000 different levels only at the highest sound level recorded but, in the reality, all the subtle sounds (small instruments, reverberations, ...) which makes the "emotion" are much, much lower than that and you could be happy to have a hundred or two different levels to measure them !
Try to imagine how well a low 10KHz sound could be reproduced by such a standard ...
For true Hi-Fi, I don't think we should go under 24bits, which give 16mio different levels. We could also imagine a logarithmic scheme: proportionally more levels for small signals and less for high ones. This is nothing else than compression at recording (like Dolby, but this one could be frequency-linear) and expanding during the playing, but this should be only a last option: a linear system is simplest and though a better one.
Actually, the sampling circuits can't certainly achieve such a resolution and at such a high speed but that should be the main goal when you talk about Hi-Fi.
There are several other problems with CD's like the recovery system that "fills" in the blanks or the 44KHz rejection that implies strong (and bad) filtering or oversampling and other jiitter phenomenons.
The actual format of CD's is nevertheless a big step forward for the "common
soup" Hi-Fi, but certainly not for purists.