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Plug-in to change 15ips to 7.5ips

Discussion in 'Recording' started by Reggie, Jul 11, 2005.

  1. Reggie

    Reggie Well-Known Member

    Here is the deal. I need to transfer some 1/2" reels recorded at 7 1/2 ips into a DAW, but the playback machine only does 15ips it seems. I was wondering if there is some kind of plugin that can be used to slow down the 2xspeed audio to where it sounds normal without losing much quality. It is pretty much just voice I believe, anyway. But most of the time-stretch plugins nowdays are so fancy that they don't change pitch as would happen when playing a reel at half speed. Is there a plugin that can do what I need, or is there some kind of time-stretch, pitch shift trick I will have to do? Using Cubase.
  2. David French

    David French Well-Known Member

    Record at 88.2 and play back at 44.1?
  3. Reggie

    Reggie Well-Known Member

    Hmmm, didn't think about that....
    Just might be crazy enough to work.
    Taking up extra HD space will suck though, because I don't know how much these there will be.

    So would it work like this?: record in at 88.2k, change project setup to 44.1k, export audio mixdown?
    I'll try fooling around with this idea.
  4. David French

    David French Well-Known Member

    Should work. Just so long as you set the rate only, i.e., do not resample.
  5. Randyman...

    Randyman... Well-Known Member

    Good thinking, David! If you are recording at 2x speed, then you are actually not using any more HD space than you would be at 44.1 at 1x speed :wink:

    You may run into frequency resoponse issues from improper playback speed (the 20KHz signals are now 40KHz, and the unit's frequency response will likely attenuate these frequencies), but at least you wil have the files on disc...

  6. Reggie

    Reggie Well-Known Member

    Yeah, good point on HD space. I was already thinking it would be a cool way to do the transfer in half the time. :cool:
    However, I am wondering about the frequency response issue you present. I don't know if the playback heads will be able to properly pass a 40k signal into the Daw to be stretched out to 20k afterwards. Probably will lose something along the way. Perhaps it won't really matter since it is primarily voice. And since it is going to be duped on cassette in the end. Weird, huh?
  7. Haven't actually done this but I believe in theory the doubling of the sample rate should provide the same freq. resp. as realtime. The only other issues would be playback set up on the analog multitrack machine and the transferrence of any speed inconsistancies. On a good multitrack though that shouldn't be an issue.

    Let us know if it works for you.
  8. Reggie

    Reggie Well-Known Member

    Ha Ha, looks like I might be getting the masters on DAT after all. Folks probably don't trust their master tapes for the long haul, so hopefully this is a sign that most people have already made a transfer to digital already.
  9. Randyman...

    Randyman... Well-Known Member

    The issue is not the digital conversion, but the Tape is now playing at 2x speed. This means the tape's original 20KHz waveforms are now trying to play at 40KHz, and the tape machine's circuitry and heads may not have a flat response to 40KHz. If 40KHz is attenuated at 2x speed during the "Bounce", then 20KHz will be affected at normal speed once you slow the digital file down to 44.1.

    Hope you can get the DAT's. That would be cake (assuming they are still playable)!


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