cliveb;153833 Wrote: 
> An interesting point made in this paper is the claim that asynchronous
> sample rate conversion (ASRC) embeds incoming jitter into the signal,
> and that low jitter sources with short cable runs should be used when
> the receiver employs ASRC.
> 
> Contrast this to Benchmark's claim (and published measurements) that
> the DAC1 (which uses ASRC) is immune to incoming jitter - to the extent
> that you can stick it on the end of a thousand feet of digital
> interconnect with no ill effects.
> 
> There are precious few companies around whose literature I would be
> inclined to accept on good faith, but dCS and Benchmark are two of
> them. And yet they appear to have diametrically opposed views regarding
> ASRC. Which leaves me in a bit of a quandry.
> 
> Anyone care to shed some light on this?

Hi Clive,

I understand what he is saying there.  He says:

> 
> DATA JITTER AND ASYNCHRONOUS SAMPLE RATE CONVERTERS
> Asynchronous sample rate converters can respond to data jitter and
> process it into the signal, 
> irrevocably.  For this reason they should be used with care, and if
> they have to be used, 
> should be used with low data jitter sources with short cable runs. 
> 

The point is that ASRC embeds some jitter into the digital sequence
itself.  So you start with something which, when represented as a
string of digits, is identical to the track on the CD.  Jitter
manifests itself only as small variations in the time at which those
bits arrive.  But after ASRC you have embedded those timing variations,
to some small degree, into the digital sequence representing the sound
samples themselves. 

It's like doing D->A->D', so the jitter in D gets into D' and can never
be removed.

Of course if you then immediately play out to a DAC that's not a bad
thing, but if you stored the digital sequence for later use, or did
multiple such conversions, you might run into problems.


-- 
opaqueice
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