Issue with glitches when recording into Pro Tools with ADAT

Hello all.

Simple question here. Whenever I try and record from the ADAT out to Pro Tools I get random glitches in the recording. I am using a DIGI 002 to record in and Pro Tools 8. This doesn't happen when using the analog outs. The sample rate is the same 44K. I have also tried with 96 and seem to have the same problem. The ADAT cable I am using is of a high quality and I have tried a couple of the.

Does anyone else have experience with this issue and if so were you able to resolve it? Any help is appreciated as using ADAT is really convenient in terms of tracking out.

Thanks

Whenever you connect any devices with a digital audio connection, you have to synchronise their wordclocks, so that they run at exactly the same sample rate as each other, and so that the sample rate is synced with each other, otherwise you will get clicks/pops in the audio.

You have to sync the wordclock (sample rate) of Pro Tools to the MPC, or the wordclock of the MPC to Pro Tools.

Go into Pro Tools Setup/Hardware, or Setup/Playback Engine, can't remember which, and set the digital wordclock source from Internal to the ADAT connection coming from the MPC, or to an SPDIF coaxial/RCA connection coming from the MPC.

Or do the same, setting the Pro Tools digital clock source to Internal, and syncing the MPC wordclock to an ADAT or SPDIF connection coming from the 002.

Sometimes I find that syncing wordclock over coaxial SPDIF, and sending the digital audio over Toslink/ADAT Lightpipe, can be more stable than both syncing and sending audio over Lightpipe.

Keep any bends in the ADAT Lightpipe cable as large a radius as possible, don't have sharp bends in the cable.

Brilliant, thanks for you help Simon. I'll try all you recommended and report back.

It worked a treat. For some reason I got the message that there was an invalid clock source when I tried with 96k even though both the MPC and Digi 002 support it. Perhaps it's because I'm using Pro Tools LE?

I opted for 44.1 as it's so common and worked perfectly. 48k seemed to also. There were no pops and glitches in the recording.

For the record the options to set the clock are under the Hardware menu in Pro Tools. I set the MPC's clock to 'Internal'.

Thanks again Simon.

Make sure that the Pro Tools Session is set to the same sample rate that you are externally clocking Pro Tools to, when creating the Session.

Did you have a 96kHz Pro Tools Session open, when trying to set the Pro Tools digital clock to the external 96kHz digital audio coming from the MPC?

You can get into trouble down the line if the Pro Tools Session sample rate does not match the external sample rate you are syncing it to.

I think I did but I could be wrong, I'll have to check/test.