Recorded casettes are too fast?

Audacity Help Forum Windows
1

I’ve recently started digitalising old audio tapes, using a cable from my mic out on my stereo to my audio in on my notebook.
Works fine, but I felt like the audio was just a tiny bit too fast and I compared it with some old recordings of the same tapes I still had on CD and there’s about a difference of 2 seconds on every 6 minutes (which is obvious rom the waveforms). So nothing major but it does feel like I’m not getting the audio that’s on the actual tapes this way?
Mind: these are recordings I did with friends as a kid so ‘just getting the CD’ isn’t an option :wink:

Today I also played one of my audacity recordings and the original tape at the same time and noticed even then the audacity one eventually started to get out of sync because it was just the slightest bit faster. I noticed my mic in was set to 48000hz instead of the 44100 the project mentioned but even after changing that there’s still an ever so slight difference and I’m not sure how to fix it? Is it an audacity bug, a soundcard thing, anything else?

Suggestions how to fix already recorded audio without losing much quality would be useful as well, cause I’m not looking forward to recording hours of audio again if it’s not necessary

I’m on Windows 10 and Audacity 2.4.2.

2

I noticed my mic in was set to 48000hz instead of the 44100 the project

Of course that would create a much bigger error. :wink: But when everything is working normally the hardware, drivers, and software, all communicate so resampling doesn’t cause a problem.

Suggestions how to fix already recorded audio without losing much quality would be useful as well

The Change Speed effect is fairly “simple” and you shouldn’t get any artifacts. (When you change speed or pitch independently that’s mathematically more complex and more trouble-prone.)

The speed of the tape machine may be slightly-off or the clock (oscillator) your soundcard (or other device) could be slightly-off. (i.e. the sample rate may not be exactly 48000Hz). A soundcard problem will only show-up if you record on one device and play-back on another. It usually happens when you record with a USB device and then play-back on your regular soundcard or if you record and play back on two different computers.

3

So if you do use the change speed effect, you may find it easier to specify the Selection Length, rather than try to figure out the multiplier or percent change.