word clock/sample rate pitch problem? NEED HELP!

[jgerards]

Hey everyone,

I've come across a problem that I have never encountered before. Here are the details as best as I can describe.

I recorded a concert and we had two different recording setups that I planned to manually line up in Pro Tools later.

One was my setup which is a Digi002R with a behringer 8-ch mic pre attached to the optical I/O on the 002. I'm running PT 7.4 and to my knowledge, everything was set at 48khz.

The other setup was the main soundboard which is a Digidesign Profile, sending tracks to a different computer running PT 8, but everything was still set at 48khz so I don't think the PT version should make much of a difference.

PROBLEM: The sample rate seems to be off between the two sessions because everything in my session is a little shorter and the pitch is about a full semitone sharp from the other session. Basically I bounced my session at 24bit 48khz dual mono to keep it the same bit and sample rate and then imported them into the other session. When I imported, it didn't need to convert the files which tells me that the sample rate should be the same.

IDEAS:
1) My confusion comes from the fact that the sound guy and I were both careful to do both setups at 48khz so I don't understand why everything is off. My first instinct is to say that it has something to do with the behringer unit, but I'm pretty sure I had it at 48khz. Also, I was recording stuff with that unit as well as the inputs on my 002, so if the behringer was set at 44.1, then shouldn't those tracks be off sync with the ones from my 002? This is also not the first time I've synced this piece to my gear. I've used the same setup for several other similar concerts in the past without a problem.

2) This is the first time I've done this manual sync from two independent digital sources like this. I recorded the same concert last year, but the performance venue was still using a 52-ch analog console that I was pulling analog sources from. Is there something I don't know about the difference between my 002R and a Digi Profile? The sound guy that runs it is extremely knowledgeable and knows the board as well as other digidesign products very well so I would think that if there was some significant between the two, he would have told me what to do to make it work. We didn't have them both running from a master clock, but we did have them both set a 24-bit, 48khz.

Any feedback would be extremely appreciated. Thank you so much.


Jeff

[albee1952]

What you are describing points to a sample rate mis-match. I would lay odds that, while you session(with the 002 and Behringer) was created at 48K, the Behringer was likely set to 44.1 and it was the master clock. If you import those tracks into a new session(48K) and make sure to UNcheck the SRC button, that might fix it. Or maybe look for Rail's header investigator utility that (if I remember right) is made for this issue.

[jgerards]

Thanks for the quick response. Unfortunately no luck on your suggestions. I created a new 48khz session and imported a couple files from each session with the SRC button unchecked and they are still out of sync and off pitch. I also downloaded SoundHack which Rail said was the Mac equivalent of his investigator utility. I opened several files from each session and they all have 48000 listed as the sample rate. Is there something else in the SoundHack app that I can do or look for? Any other ideas?

[Top Jimmy]

The problem with that scenario is that if some of the files were recorded at 44.1 yet the header says 48, they wouldn't get SRC'd on import to a 48 session anyway.

What you have to do is manually SRC these files on import by declaring in the import dialog that they are 44.1 not 48. There's a pulldown menu for the source rate in the SRC section of the import window.

Now, if this fixes the major mismatch, you're probably still going to find a minor one having to do with clock mismatch inherent in two independant systems. Match the front ends of the files and you may find the back ends drifting since no two clocks are exactly the same. In this case, you can elastic varipseed one set to match the other and that's as close as it will come.

At the very least, try to run both systems from the same clock next time and you'll find the tracks match perfectly once you line them up.

[Eric Seaberg]

I also recommend that, if you ever do this again, make the Profile system MASTER CLOCK for everything. Lock all other devices to it, just in case things screw up on one system, you can import files back-n-forth and they should match exactly.