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SMPTE to MTC / Word Clock in ProTools LE? What is What?

Discussion in 'Pro Tools' started by tonystl, Mar 20, 2005.

  1. tonystl

    tonystl Guest

    Heres the scenario: I am trying to transfer 8 tracks of analog (one with SMPTE) into my computer using a SMPTE to MTC (JL Cooper) box into a Midi to USB cable (sync) through a pair of nice converters. This forces me to dump tracks two at a time and line them up by hand in PT. I don't currently have all the parts involved yet and am trying to figure out if this is the best way to go about it. Does anyone know how well this method holds sync throughout a 5 minute song?

    Also, does anyone know if there is another way to get external word clock into ProTools LE (AMIII card, 1 spdif in only) while also using the spdif in for audio? Is there a way to run word clock (BNC or AES) through midi or is there a BNC adapter that would allow word clock to go into LE through a serial or usb port? I am in word clock hell.
    thanks
     
  2. tomtom

    tomtom Guest

    Well, I can help you answer the first part of your post.
    If I were you, I would try to find someone who can dump the 8 tracks at once in your PT system. Here is why: Using a smpte to MTC converter is a good idea providing that you can trust your source machine. You need to make sure that your tape machine is not going to drift in terms of speed from one take to the next one. Analogue tape needs to be pinched on the transport mechanism in order to move and be played or recorded on. So it can, and it will slip a little over time hence speed variations. (I think it's called wow and flutter) That's why pro multitrack recorders have a device (forgot it's name, english not my main language) that constantly adjust tape speed to make it as steady as possible. I assume that your 8 track machine probably doesn't have it. That's why it would be safer to do it all at once, because then, micro speed variations will be the same on all 8 tracks and you will be less concerned with timing problems.

    If you can't get help, if phase between tracks isn't a big issue in you case, here's what I would try:

    We are gonna make sure that your MTR does not suffer from major speed variations.
    Arm all 8 tracks on you MTR and record a single click before the song start. Do the same thing after the song's end.
    Do your transfer in sync with SMPTE two tracks at a time. Now, check that your start click is in phase on all the pro tools transfered tracks. Then go to the end of the song and check the end clicks as well. If they are all pefectly time aligned you are fine!
    Do copy phase sensitive signals (stereo takes) on a same pass.

    I hope this helps...
     
  3. Steve Halko

    Steve Halko Guest

    tomtom,

    Yes all tape machines will vary in speed to some extent - but isn't that what SMPTE is for?

    If you use a SMPTE to MTC converter, you should be able to transfer the tracks one at a time, and they'll still be in sync with each other.

    Steve
     
  4. tonystl

    tonystl Guest

    thanks a lot to both of you. I just bought a smpte generator and smtpe to MTC converter and will soon have a soundcard that will take midi in... hopefully by running the wordclock out of my apogee converters while transferring the tape signals from my otari mx5050 8 track with smpte to mtc, I should have a consistent tranfer into protools. I'll know in a few days when everything arrives.
     
  5. tomtom

    tomtom Guest

    Well, I did study this at the audio school, but it has been more than 10 years. So forgive me if I'm not 100% correct...

    It all depends on how "closely" you need to sync...

    I would think that since you guys in the US run SMPTE at 30 fr/sec (we run at 25 fr/sec in Europe), it means that the time lapse between two frames of code is about 30ms. It means that your smpte to mtc device is only chasing every 30 ms. I would assume that it is okay to chase a steady master, like a betacam video player or a high quality multitrack machine synced to an external clock that generates tach.
    It would certainly be good enough to sync your midi sequencer or DAW, should you use all the tracks from your 8 tracks machine at the SAME time. For transfering track by track, I think it won't sync closely enough to garantee a good result.

    Could anybody with some more experience please help us on this subject?

    Thomas
     
  6. tomtom

    tomtom Guest

    OK,

    I was not 100% correct with what I said on my previous posts.
    Tachs are not used for close sync, but they are used for hi-speed syncing of machines.
    Let's say you slaved two multitrack machines. Once at the end of the song, you rewind the master to the beginning to continue to work.
    The slave machine cannot read the smpte information at that speed, so it stays where it is. Once the master gets to the start locator, it reads some smpte and parks. The slave machine will now move accordingly to the same smpte time code location. the problem is that rewinding of two tape machines is very time consuming. Especially now that we are used to Hard Disk work. So, using tach informations from the master, the slave machine can get a rough idea of where the master is and will move accordingly. You save about half the rewinding time... Once in play, they can sync precisely.

    Now regarding PT.
    A simple PT system using a SMPTE to MTC converter will only trigger to the incoming time code and might drift over time. If you really want to stay in close sync, you need the digidesign SYNC I/O that will remain sample accurate using smpte, tach, bi phase, all the "standard" means of syncing.

    I know that it is not going to help you in your transfer, but I wanted to make sure I would not mislead anyone and wanted to share what I found out.

    Good luck.

    Thomas
     
  7. iznogood

    iznogood Member

    tonystl....

    the setup you discribed WILL NOT WORK! don't buy all that stuff.... it' will not give you accurate sync!

    what you need is a soundcard with wordclock in.... none of the protools LE cards have!!!

    then you can just buy the rosendahl WIF.... and go... it generates wordclock that varies in speed according to the unavoidable speed variation in analog recorders!

    and i'm not talking small unhearable things here.... if you have bassdrum and snare on one transfer and overheads on another things will go very wrong.... you will have flanging on your drums!!

    or

    you need someting that can read smpte and generate what is called spdif nullsync.... that's a spdif signal with no audio just clock... (but then you have to take in the sound analog as you can't sync your system to two sources!!)

    i use a combination of a rosendahl WIF and nanosyncs... the WIF reads smpte and generates wordclock... the nanosyncs then generates nullclock (spdif and aes) and distributes wordclock to all the machines..

    as this is a very expensive solution it would be far cheaper to find a studio equipped with the right equipment and let them do it!

    or

    just get the digi 002 instead and transfer all 8 tracks at once.... far better solution than any kind of sync!!
     

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