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Clicking using ADAT (in Pro Tools)

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Stephen Pritchard
Clicking using ADAT (in Pro Tools)
on May 20, 2011 at 6:23:57 pm

Hi
I've a new variation on the common ADAT clicking problem.
We have a digital mixer (Fostex) outputting the mic channels via ADAT optical to a Digi002 rack running Pro Tools (8LE Mac). All at 44.1.
Clock set to ADAT optical in Pro Tools rather than internal - this has dealt with clicking issues in the past.

However today I had set up a Denon minidisc as a backup recorder. This connects via SPDIF in and out (our outbound gear runs via a Fostex optical patch bay). The desk is set so its SPDIF inputs are the output from the patchbay. The stereo buss/master out from the desk is then fed to Protools via its SPDIF input (on coax). This gives us a stereo mix which 9/10 times is fine - the direct inputs are only used if someone taps a mic etc.

Usually this works fine. However, today we had the ADAT clicking back when the Denon MD was switched on but not recording (we forgot about it). Switching the Denon off again and running the same test removed the clicking. The Denon is not a pro unit, but a high end hifi one, and it's been in use for about 10 years without fault.

Any ideas welcome - of course we can work without the MD recorder but it would be good to work out the root cause of the issue.

A Tascam DAT doesn't do this, when set to either 44.1 or 48 (as long as the PT session matches the sample rate).

Thanks!


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Ty Ford
Re: Clicking using ADAT (in Pro Tools)
on May 22, 2011 at 2:27:01 pm

Hello Stephen and welcome to the Cow Audio Forum.

As you know, clicking is frequently caused by sample rate discrepancies. The Denon. Is it possible that it operates at several different sample rates and that it has been altered by accident to conflict?

Is it possible that it was used in analog mode before? Some of the prosumer ports combine optical and wire in the same jack.

Maybe the Denon is old and has slipped out of spec.

Regards,

Ty Ford

Want better production audio?: Ty Ford's Audio Bootcamp Field Guide





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Stephen Pritchard
Re: Clicking using ADAT (in Pro Tools)
on May 22, 2011 at 3:13:27 pm

Hi Ty

slipping out of sync is possible - the unit is about 12 years old now. It only has a 44.1 sample rate (which is what the rest of the gear was clocked to during the session but your suggestion's prompted me to run further tests this week, as we sometimes record in 48, and under that scenario we don't use the Denon but an even older Tascam DAT as a backup (but that's a pro unit which is switchable 44.1/48). So it does seem to be the Denon deck. The test I will run later should confirm that.

thanks for the pointers!

Steve


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