Speed issues with audio cassette tapes

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mjzee
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Joined: Sat Mar 22, 2008 5:20 pm

Speed issues with audio cassette tapes

Post by mjzee »

Back in the '70's, I recorded a number of concerts using a $40 Norelco audio cassette recorder and a microphone. Invariably, they played back a little slower than the actual performance, but consistently so (my theory is these machines were primarily designed for dictation, where a little slower playback might be beneficial for transcribing speech). I am looking for what would be the proper settings to enter under Effects>Change Pitch and Speed... to return the music to the proper speed. Is anyone here familiar with this issue? I am assuming that since the slower speed seems to be consistent from tape to tape, there should be only one correction needed to pitch and speed. Thanks in advance.

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Martin Hairer
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Re: Speed issues with audio cassette tapes

Post by Martin Hairer »

In any case, you want to make sure that "Lock" is checked, so that it is a pure speedup / slowdown and not a composition with a pitch shift. The precise value would probably depend on your specific hardware, so I would suggest using the "Preview" function to move the slider until you reach the correct pitch and to use that.

If you happen to have a sample sound with a known frequency played steadily over a long duration (say at least half a second or so), for example a long piano or flute note, then you can check its precise pitch with the Spectrum function and compute the required shift to hit the nearest note on a tempered scale...

mjzee
Posts: 30
Joined: Sat Mar 22, 2008 5:20 pm

Re: Speed issues with audio cassette tapes

Post by mjzee »

FYI, after some trial and error, and comparing a performance I had to the same one I found on a website, I believe the speed corrections should be:
Pitch: 0.67
Speed: 104.7%

IrlSmith
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Re: Speed issues with audio cassette tapes

Post by IrlSmith »

I posted an earlier question about the Spectrum window being empty (blank). How does one start the Spectrum function (OS X 10.13.6).
Irl

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Martin Hairer
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Re: Speed issues with audio cassette tapes

Post by Martin Hairer »

Make sure that
1. The sound sample is sufficiently long.
2. The color of the spectrum isn't the same as the background.

IrlSmith
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Joined: Tue Oct 14, 2008 1:45 am

Re: Speed issues with audio cassette tapes

Post by IrlSmith »

The color of the spectrum had for some reason defaulted to white, and the background was white also. Seems like an odd default, but changing the color made the spectrum visible.
Irl

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