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Pro Tools Question (Firewire 1814) DAW Software
Old 15th August 2007
  #1
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Akoppenheffer's Avatar
 

Pro Tools Question (Firewire 1814)

I have a little problem right now. I was testing my ADAT inputs and outputs to see if I'm all good to go for an 8 channel preamp with ADAT out. Anyway, to do this test I simply ran the ADAT output into the ADAT input. Then in tools, I had two tracks. the first had a stereo track on it and the output went ADAT out 1+2 (or A 5+6). Then It returned on the new track via ADAT input 1+2. Signal passes fine, but... The track that is being recorded is like 20 samples or so early! How and why does this do this? It's like pre latency. Shouldn't they be totally synched? Here's a picture to explain a little better.
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Old 16th August 2007
  #2
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Has anyone seen this issue before? I don't think it would happen if I was using an 8 channel preamp with A/D conversion and just recording something into... Maybe some internal errors that make it early.
Old 16th August 2007
  #3
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All recording software has (or should have) built in compensation for the A/D conversion time. Some software that is capable of using different hardware sometimes gets this conversion time wrong (usually reported by the hardware it's plugged into). Some software allows you to enter in this timing bugaboo yourself - ProTools LE not being one of them. I have an MBox somewhere, and it does this round trip through the converter with perfect accuracy; as does my HD rig (depending on the ADC settings). Ableton Live failed miserably with all hardware and was unusable for overdubbing (maybe it's been fixed by now).

Sounds like you found a flaw. Perhaps you should post this at the DUC for the good of all...

Last edited by juniorhifikit; 16th August 2007 at 08:24 AM.. Reason: additional info
Old 16th August 2007
  #4
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Hmm, that's interesting. And makes some good sense. I'll ask over there. Do you think it would be different if I was using like an 8 channel preamp? Not just running a big loop from the output to the input. Thanks!
Old 17th August 2007
  #5
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Has anyone else had delay compensation work against them?
Old 17th August 2007
  #6
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I know nothing about this, this is just a guess...

But what if the Digi 002/3 always has 20 sample latency when ADAT synced to external hardware so it automatically moves it back 20 samples. Very handy. But as it's synced to itself, this isn't the case, but it still automatically compensates?

I have no idea how it works. Probably a load of **** to disregard.
Old 17th August 2007
  #7
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That's what I was thinking... It thinks it needs to be converted when in reality it already is. Therefore, making it early in time... It makes sense on paper, but I dont know if it is really doing it... Can anyone try this on their 002 or other interface? See if you get the same issue? Thanks!
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