Sync Cubase to Logic Via MTC on same system - works, but..

but why?

hey there! I would like to sync CB7.5 MAC to Logic Pro X via MTC, which works seamless when I loop one of my interfaces’ midi ports (Edirol UM880 here) back to the corresponding input port via a phisical midi calbe (loopback) - but it will not work when just using the IAC bus, which should, in theory, just be the same thing, without a real midi cable in between…hmm

in the ladder case cubase just skips the playhead quickly to some imaginary bar 7120 or something the likes :wink: - really weird skip.

maybe anyone of you got a clue on to why it works over my edirol on a physical cable and not over the IAC bus?

of course I could just sync via that cable, but you know, firstly it is not an elegant solution, and more importantly, I want that extra of timing integrity when the MTC never leaves the mac/digital domain.

any suggestions what might go on? I assume it has something to do with an internal loopback leak of the mtc signals being forwarded and going round the system, why else would cubase go to bar 7000 in about 3 seconds?

I always run midi clock to sync things, that or ADAT.

Always heard about problems with MTC.

MTC sends a lot more data, might have actual transmission latency, bottleneck or something.

Or some kind of sysex filter you’re not aware of in something…

Hard to troubleshoot unless you have a lot of equipment to try things.

Try everything but only one thing at a time.

I tried about everything, thats why I came here to ask, and yes I got lots of equipment to test, I have no way of analyzing the midi stream though, I should compare the midi stream from the interface loopback to the one of the internal loopback