IAC bus drift

[Dr Fletch]

It is unlikely that this is a Pro Tools issue but thought I'd post in case anyone has experienced this issue.

I sync Pro Tools 12.8.1 to Cubase 9 within the same machine (Mac Pro late 2013 10.13.1) and sync is fine until a minute or so when I detect drift. After 2 minutes, I'm 20ms out...and so on. It's the same every time so there is some mismatch somewhere.

I use Cubase for midi as it is superior to PT (sorry but it is) and track-lay everything to PT. I do this currently by internal bouncing as running in sync clearly doesn't work.

Anyone had this? solutions?

thanks

[Dr Fletch]

More info on this weird drift issue.

With frame rate and sample rates matching - Cubase drifts ahead when it's the master.

For example - at 90.000 BPM, I recorded one bar of Cubase click into PT and when you zoom in on waveform at bar 2, it's 44 samples out!! (One plug in on session - click, unused)
With Delay Compensation off in PT, it's 34 samples out.
With NO plugin's at all it's 24 samples out.

The results are IDENTICAL when Pro Tools is the master.

I just don't get it. I honestly think the tempo's don't match. If so, which one is correct?!?

Could it be to do with the interface I'm using for cubase? It's a Presonus on a USB bus. Obviously with Pro Tools, I'm using the AVID HD i/o's on loop sync.

Maybe I simply need to accept that syncing DAWs any way without a word sync is going to be inaccurate.