Recorded audio from tape is distorted. How to fix?

Audacity Help Forum Windows
1

Hi,

As stated in the title, (this) recorded audio from tape is distorted. This is caused by recording, I think. The recording was too loud.

My questions are rather simple. Is there a name for this distortion? And, is there a way to correct this?
A sample is added. The sample is made mono. There is no difference in stereo or mono for the distortion.

It would be nice when this 40 years old recording could be “repaired”.

Regards

Rob

2

It seems I didn’t understand how to attach the wav file.
Here is a new try. I hope this will work.
https://forum.audacityteam.org/download/file.php?mode=view&id=35427
Rob

3

I think it’s analog [u]clipping[/u], like it was recorded too loud and the tape was saturated. Digitally, it’s not “too loud”. You’ve got more than 1dB of headroom.*

Audacity has a [u]clip fix[/u] effect but the thing about clipping is, it’s impossible to know the original-unclipped wave height or shape. Tape (or vinyl) clipping has another issue of recording/playback equalization which changes the wave shape and sort-of “hides” the clipping (that also makes it sound less-bad). Something similar happens when digital recordings are dynamically-compressed and limited to “win” the loudness war. The processing is complex and it can’t be un-done. Clip Fix can make the wave look better but when I tried it, it didn’t actually sound better.

You can also play-around with the [u]Graphic EQ[/u] effect to see if you can improve the sound. Note that when you boost with EQ you run the risk of boosting the levels into digital clipping. But, Audacity itself won’t clip so you’ll be OK if you run the Amplify or Normalize effect before exporting. With the default settings either of these effects will bring the levels up, or down for “maximized” 0dB peaks (actually -1dB for the Normalize effect.)

Your recording doesn’t sound “terrible” to me… I’ve heard worse… But in general, there is only so-much you can do with software. Even with the latest pro-software, pro recordings are still done in soundproof studios with good equipment and good mic placement, etc.



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  • There is a correlation but no calibration between analog and digital levels. 0dB on the tape may be higher or lower than 0dB on your analog-to-digital converter, and there may be a recording-level adustment in-between, etc.

If you are old enough to remember analog recording, you wanted a “hot” signal to overcome the tape hiss. And it’s OK to occasionally go over 0dB where the tape begins to soft-clip. And the tape playback equalization tends to further “smooth” the clipped waveform.

With digital, there is no tape noise and pros usually record at very-low levels to leave headroom room for unexpected peaks. Then levels can be boosted after recording. And, analog-to-digital converters (and digital-to-analog converters) are hard-limited to 0dB and the will “hard clip” if you try to go over. So, digital recording levels are not critical except you should always avoid clipping.

4

overload distortion (like you say: too loud)

Cutting back the frequencies above 8kHz makes it sound less harsh, at the expense of treble …

5

DVDdoug’s answer was very informative.

Trebor’s answer was very practical. I’ll experiment with those settings, and it seems it works. I just have to find the settings I like the most.

Thanks

Rob