I have that book ("Mastering Audio - the art and the science" by Bob Katz) and in it he does
indeed make a better job of explaining jitter, although it's not brilliant.
A better explanation is given here [1].
[1] http://www.jitter.de/english/engc_navfr.html
This was the first link I considered using as a reference. Rather, the original German version at
http://www.jitter.de/german/ger_navfr.html
but it seemed far from reputable. They try to sell you something. When I read stuff such as (my numbering)
--------------------
1 Why do different clamps on a top loading CD transport lead to different hearing results?
2 Why do some manufacturers of CD-transports use belt drives?
3 Why does a CD-R sound different, although bit-identical?
4 Why do different CD-transports sound different?
5 Why do some manufacturer use stray light inside the CD-player?
6 Why do products that "demagnetize etc..." the CD seem to work?
7 Why do different recording media sound different although they are all digital?
The answer to these questions is mainly:
Clock jitter due to power supply noise. -----------------
I have a hard time believing anything in the same document. 6 in particular is a screamer. Sorry, but I don't buy into green stickers on my speakers either. :) Show me proof, show me you can ABX it reliably. Next:
--------
1 Why do different digital interfaces sound different, although they carry exactly the same information?
2 Why do different cable lenghts sound different?
3 Why do some coaxial cables of the same lenght but different manufacturers sound different?
-------
Either the bit stream is tranmitted intact or it is not. There is no in-between. Sure, the waveform is distorted but there would have to be in insane lot of this "line induced jitter" to actually flip bits. Everything else can be fixed by reclocking and hinges on the quality of the reclocking.
The rest of the article is about recording, which is, espacially with multiple sources, a whole different thing.
Last not least, from that very site:
QUOTE Dual stage Clock recovery can also be combined with a data buffer memory.
The first PLL writes to the buffer, and the second PLL reads from the buffer and tries to keep it always half filled.
If we use a FIFO (first in first out) memory as a data buffer, we have more time to react to clock variations of the input signal and thus are able to attenuate lower jitter frequencies. The larger the buffer, the lower the jitter frequency that can be attenuated.
The disadvantage of the FIFO memory solution is (beside its higher price) that the output data will be delayed (the buffer has to be half filled before data is output).
UNQUOTE
Higher price: What higher price? $150 would buffer you a CD. Even SRAM is not prohibitively expensive. It's true that buffers delay the output but they shift it CONSTANTLY meaning you don't want to use this technique for recording but for playback it's just fine.
Show me scientific proof that using the above quoted jitter reduction method directly before the DAC (on the same circuit board) the jitter at the DACs output is influenced by the jitter at the input. Till then I suggest reading up on "placebo" :)
C.
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