Distortion, Delay, Playback issues with one live set

[justinmessina]

My problem seems like one of those pain in the rear, headache kind of problems, so apologies in advance.

First, my set-up:
I have a macbook pro 2.66 ghz running os x 10.6. I use a Motu 828, an edirol pcr-1, and an apc-40. Live 8
Second, the problem:
I have a rather complex live set made up primarily of 2 audio channels, one midi instrument, and 16 returns. The set was working fine and sounding great, until the night of an informal premiere. Suddenly any sound originating from the second audio track came out heavily distorted and at a slightly slower rate than it should. This includes channels that are heavily filtered (ie, even though the LP filter cuts off at 200 hz, i still hear distortion far above that).
Other problematic symptoms include a delay between the sound happening on all channels and the master. In other words, I see the meters for channels 1-3 move and then about a second later the sound is audible through the master. The only thing that changed was that I went from working with headphones (via the CPU's built-in jack) to sending sound out the MOTU (actually, i had seen the delay happen before I plugged in the motu, but the sound was still fine).

Things I know:
It's not a CPU issue, since (even though the set is enormous) the CPU meter rarely gets above 30. It's not a sound card issue (the MOTU plays other sounds fine). It's not a live issue (other sets still sound fine). It's not a MIDI issue (the arp2600 vst in the same set still sounds fine).
Finally, and this one really sucks (for me), I have 5 versions of this set saved. The day that the last version stopped working normally, all the others also stopped working.... (Gotta get those mythbuster guys going on this one)

Is it possible the set is corrupted? If so, why are all the previous versions of the set also screwed up now? I'd just recreate the set, but it took weeks to build up and it will take another week to do it all again:(
If you got this far, thanks.
Help!

[justinmessina]

Hmmm, hope you are all drink egg nog. Anybody got any ideas?

[justinmessina]

last bump... hoping for some help please

[Pitch Black]

Hmmm... no huge help here I'm afraid... though I wonder if the "slightly slower rate" of playback you mention holds a clue. I'm thinking maybe an audio file has gotten corrupted, which could have freaked out a plugin somewhere in the chain? I wonder this because you say all your other versions of the set instantly became corrupted too.

Couple of things to try:
(make a copy of the set first) then pull all the audio content out of the set. Save, quit, re-start your mac, Repair Permissions, boot Live from the App icon (not from the Live Set) then load your audio-less Live set. If you drop a few different audio files back in, do you still get the problem?

If we were to suspect a faulty plugin, try deleting one FX return channel at a time, to see if the culprit might be there.

Also, do you have any feedback loops set up between Return channels? i.e. Return A sends to Return B, which sends to C, which goes back to A etc. If you temporarily "Disable All Sends" from the context menu in all your tracks and Return channels, do you still get the problem?

good luck! hope this is some help

[alex.the.forge]

have you contacted support about this? They will be more helpful in this situation.. This forum is now "users" help forum and I don't think other users will be able to help here.

One thing I will say though is that by using 16 returns you are basically using one core for everything (assuming you are sending to them from all 3 tracks) - so you are not making use of the multiple cores.

You also didn't mention what plug-ins were on the problem track and if there are any external ones. But again you really need to talk to support about this.

[justinmessina]

Thanks a million for your responses. I'll get to work on implementing your suggestions right away.

PitchBlack - I had the same thought about the corruption, but the audio file still sounds normal outside of Live. I suspect that the set is what's corrupted, not the audio file, but we'll see.

Alex - Contact Support--will do. Could you please elaborate or tell me where i can learn more about utilizing the two cores? I never knew how the workload was distributed. Are tracks on one core and sends on another?

Thanks again guys,
j

[alex.the.forge]

Alex - Contact Support--will do. Could you please elaborate or tell me where i can learn more about utilizing the two cores? I never knew how the workload was distributed. Are tracks on one core and sends on another?

Thanks again guys,
j

as I understand it if you use sends then the tracks are forced to use the same core, so if you have loads of send/returns and are sending from all tracks then everything is basically using the same core. You could avoid this by using FX as inserts when possible.

But even still, I would have expected your CPU to show higher if that was the problem.