Chris,
On 04/28/2014 04:16 PM, Chris Albertson wrote:
On Sun, Apr 27, 2014 at 11:41 PM, sg sg <[email protected]> wrote:
Thanks very much for your responses!
..
The source is an AK4114 AES/EBU audio receiver, which has both master
clock (24.576 MHz) and "word select" rate (48-192 kHz) outputs. Perhaps it
is better to run the PLL at the latter? Any disadvantages from this?
So this is for clock distribution in a studio? While our eras don't care
about nano seconds or even micro seconds we do care that long of the same
length have exactly the same number of samples. In other words at a given
times into a track, all tracks have the same number of samples. I think
what matters in this application is long term stability over days, weeks
and even years. So the first step is always to figure out your
requirements and USE NUMBERS.
Next. It is not "either/or" you can put the PPL at 24..5MHz or 48K or you
can divide by 10 and put the PPL at 2.45Mhz. or any place in between.
One question: Why use the receiver as a clock source? Most use something
independent like an OX or even Rb then use that to drive a DDS chip.
Rb is way overkill. Beyond keeping things in sync to ensure same sample
rate, what is important is jitter but not ppm level wander.
Jitter can kill your listening experience by to ways, one is bit error
rate, causing bits to be incorrect. The second is that it creates
side-bands, which causes issues when you try to achieve 24 bit
resolution, or for that matter 130 dB dynamics. Do read what Julian Dunn
had to discuss on that matter, since he look at what sidebands would do,
considering masking effects of psycho-acoustics etc.
Then again, we being time-nuts, overkill is easy to achieve.
We need to be careful about jitter as we re-synthesize and lock things
up. Jitter-peaking as a cause of jitter accumulation, and that leads
to... bit errors and side-bands.
Cheers,
Magnus
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