SMPTE slop

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I'm one of those dinosaurs still recording on an analog reel-to-reel recorder, striping track 8 with SMPTE time code. I'd like to be able to make a copy of my recording-in-progress along with time code to another machine, to avoid wearing out the master tape while I work on the midi sequence. What I've been doing is copying the mix onto tracks 1 & 2 of my cassette 4 track, and the SMPTE onto track 4, first running it thru my JLCooper PPS-2 to regenerate the time code (apparently SMPTE doesn't hold up well when copying directly from one tape to another). The problem I'm having is by the time I get to the end of the song, my analog tracks and my midi tracks aren't in perfect sync anymore. There seems to be some slop. It's slight, but it's enough to be annoying when you're going over and over a song. The problem doesn't exist on the reel-to-reel master tape, just on the cassette copy. Does anyone else have any experience with this, or can you recommend some other method to accomplish what I want to do?

Thanks,

Tom Cahoon

-- Tom Cahoon (analogtc@aol.com), June 01, 1998

Answers

Since you are experiencing drift, it sounds like your machines are not running with Direct Time Lock (DTL). They may be starting at the same point, and then happen to run together for a while, but it doesn't appear that they are locked in sync while playing back. The only other thing that might cause this is a discrepancy betwwen the SMPTE rates on the two machines. Make sure that one is not striped with 30 fps and the other with 29.97 fps. Since you are doing everything "in house," this is most likely not the case.

Lynn Fuston

-- Lynn Fuston (go3daudio@mindspring.com), June 01, 1998.


Don't worry Tom, your not a dinosor yet. I run an analog 16 track and I don't know anything about midi (and I went to college for this) so your ahead of me there. Anyway, on your 4-track, did you turn off the NR on track four? I've never had a problem with leaving it on on my E-16 (only once so far) but the combination of copying the smpte from one machine to another and NR might be the cause of the slop.

I know a guy who runs an A-800 and a MTR-90III without DTL. That's really kind of scary.

-- Jay Kahrs (BrownSnd14@aol.com), June 03, 1998.


Thanks for your responses.

I called JLCooper and they recommended transfering the SMPTE to the second machine without running it back thru the PPS-2 synchronizer to regenerate a "fresh" copy. They said since it would be a first generation copy anyway, I shouldn't need to go thru the extra step.

Sure enough, it worked. Now my analog and midi tracks are playing back in perfect sync on the second recorder.

For what it's worth, I also left the dolby C on my second recorder (to see what would happen), and it's working fine.

Tom Cahoon

-- Tom Cahoon (analogtc@aol.com), June 04, 1998.


I e-mailed AKAI the following: <>

<>

NEW QUESTION FOR SSS TEMP: From where is WORDCLOCK sent?

-- Angelo Natalie (buonhead@aol.com), June 22, 1998.


>>NEW QUESTION FOR SSS TEMP: From where is WORDCLOCK sent?<< Wordclock originates at whatever unit you decide is the Master Clock. It is the source to which all other clocks are slaved. If you are using a BRC/ADAT setup, then it comes from the BRC. If you are slaving your BRC/ADAT setup to a digital source, you must hand it wordclock, typically on a BNC connector, to the back of the BRC and tell it to sync to external wordclock. Or you can tell it to slave to video sync, or to SMPTE. But the clock source is whatever you decide it is. The important thing is that they must all be sourced from the same place, or synced to the same clock.

Lynn Fuston

-- go3daudio@aol.com (go3daudio@mindspring.com), June 23, 1998.



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