Skinny;382055 Wrote: 
> I'm with you on that. Bits will be bits.
> With you on that as well.
> 
I would have once said that bits are bits (and so they are) but without
an accurate clock bits can't be reproduced into the waveform they
represent. 

Since the S/PDIF standard doesn't provide a clock connection, unlike
some professional digital audio interfaces, the DAC is left to
reconstruct the clock as best it can from the waveform transmitted over
the coax or optical fiber link. 

If there is variability on the received waveform, due to imperfections
such as impedance mismatch, slew-rate limitations etc, then the clock
recovery will be subject to timing jitter, at least to a certain
extent. Since this same derived clock determines when a new DAC word is
available in the analog domain, it is of importance to control the
timing jitter to within reasonable bounds, otherwise it will create
side-bands in the frequency domain of sufficient magnitude to be
audible.  

A well-designed DAC may take a lot appropriate measures to combat
timing jitter on the internally derived word clock to the extent that
there is no audible difference between the two types of connection. I
don't know enough about the DacMagic to say for sure. 

At one time this was not well understood at all, but it is now. The
only real controversy is: how good is good enough? 

The following paper is a good reference for the technically minded.

http://www.scalatech.co.uk/papers/aes93.pdf

If that is way too long, you may like this one:

http://www.audiocraftersguild.com/AandE/npt.on.jitter2.htm

Best regards,

--dsdreamer


-- 
dsdreamer

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