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meggiegardener
New Participant
October 23, 2017
Question

Converting 33 recording to 78 how

  • October 23, 2017
  • 1 reply
  • 2718 views

How do I record at 33 rpm and convert to 78 rpm? I know about different grooves and stylii.

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    1 reply

    Charles VW
    Inspiring
    October 23, 2017

    I'm glad you know about different grooves and stylii. You're ahead of the crowd. Just to check, however, are you familiar with the different reproduction curves used in the preamps for 78 vs 33&1/3rd or are you transferring flat?

    The way I've done it is to calculate the ratio between 78 and 33&1/3rd.

    78/3 * 100 = 2.34.  So, you'll simply want to use that ratio when using the Edit > Interpret Sample Rate function. So if you recorded at a hardware sample rate of 44100 Hz, and the turntable was at 33.3 RPM then I'd enter in a sample rate of 44100 * 2.34 = 103194 Hz.  This will effectively speed up the recording, and we'll automatically resample to your playback sample rate (likely still at 44100 Hz).  However, it would be a good idea to resample to a common sample rate when you save the file. So you may want to perform Edit > Convert Sample Type and try whatever settings you wish and listen to it ​before ​saving to the new sample rate.

    SteveG_AudioMasters_
    Community Expert
    October 23, 2017

    You may also wish to consider the final pitch of your recording as being a better arbiter of the sample rate conversion numbers. The reason for this is that virtually NO 78's were ever cut at exactly 78 rpm! It was all mechanical back then, and speed regulation was appallingly poor.

    You might want to read this article, and be prepared to be a little surprised by the potential extent of the variations...

    Speeds and pitching of 78rpm gramophone records