Should I use external A/D for sync, or soundcard internal crystal?

  • Thread starter Thread starter Bigus Dickus
  • Start date Start date
B

Bigus Dickus

New member
I have an M-audio Delta DiO 2496, and I'm using a coaxial S/PDIF input from an external A/D converter. Since my soundcard doesn't output wordclock, then I have to either sync the soundcard to the A/D converter, or let each use their own internal clock.

I'm thinking syncing the soundcard to the input coming from the A/D converter might help reduce jitter, in that even if the soundcard has a better clock (I doubt it), at least the two would be in sync. Unless using PLL's to sync to a coaxial S/PDIF input isn't a very good way to use an external clock (since the soundcard has no wordclock input either), and results would be better using the two independent clocks.

I'm using 24 bit 88.1kHz sampling, and the A/D converter is part of the dbx 386.
 
Last edited:
If you are going to use the spdif and you have no wordclock, you HAVE to sync the card to the ad. You have no choice. The ad needs to have a clock, as it does not have an external wordclock it has to use its own internal clock. Now there can only be 1 master clock in a system, so the card has to slave to the incoming spdif stream.

Set the driver of the card to slave to spdif.

Using 2 independant clocks does not work, the frequency will never be the same and they will drift apart, giving you missed samples and glitches.
 
Havoc said:
Using 2 independant clocks does not work, the frequency will never be the same and they will drift apart, giving you missed samples and glitches.
Click to expand...

That was my thought, but I hadn't really seen that in writing anywhere (yes, I'm holding you liable now :) ), and I'm hesistant to make assumptions.

Thanks for clarifying.
 
When using digital input on the Delta 1010- (quite a popular card in these here parts) you have to use the external clock supplied by the digital source. No separate clock required even though the Delta has a BNC word-clock connection, just set the input clock source to S/PDIF or get ready for trouble.
 
Even if you had the choice, you generally want the a/d (or d/a for final playback) to be the master, as the digital transfer (spdif) is not where jitter comes into play.
Or so we are taught.:D
Wayne
 
So I might could generate some interesting sonic effects by using two separate clocks? :D
 
Jitter is the sound effect used in B-Movies when no helicopters are handy.
 
You must log in or register to reply here.
Back
Top