On 22-11-07 11:10, Clemens Ladisch wrote:
> Paolo Saggese wrote:
>> Of course I plan to use the PC only to provide a "bitperfect"
>> (exact copy of the original media, normally CD) digital stream
>> to an external DAC.
>>
>> As you probably know better than me, the one major known problem
>> when you strive for the highest possible quality in digital audio
>> reproduction is jitter... and the best (if not only) way to really
>> minimize it is to use a good, clean and stable clock close to the
>> DAC chip, slaving everything else to that one.
>>
>> Thus, what I would need to do would be to "slave" the sound card
>> SPDIF output clock to the external DAC clock i.e. to make this one
>> become the "master clock" for the whole digital audio stream.
>
> An SPDIF input _always_ derives its clock from its signal.
>
> Besides, the clock for the actual DAC has to be a multiple of the bit
> clock anyway, so there must be a PLL to derive the DAC's clock from the
> input signual, i.e., the amount of DAC clock jitter depends more on the
> PLL implementation than on the input signal quality.
I don't quite understand your reply. He isn't asking to sync the S/PDIF in
to the signal, he's asking to sync the S/PDIFF _out_ to the S/PDIF in.
Ie, to have a dummy S/PDIF connection
DAC --> Card S/PDIF In
that exists only to supply a clock to the card, to which
Card S/PDIF Out --> DAC
will then be synced. This is a valid wish, isn't it? And at least the
M-Audio Audiphile cards can sync themselves to the S/PDIF In clock.
Rene.
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