Removing "electrical hum" from a recording

[Chris]

I've been recording some things this morning I want to keep from some cassette tapes (sadly no longer used but they still exist; but digital recording has taken over) but I have this horrible "electrical hum" in the silent parts of my recordings. I assume this is due to the (ageing) equipment I am using to playback the tape.

Does anyone here know how I can get rid of it?

I have Adobe Audition at my disposal if that helps.

[Nick Harvey]

I have Adobe Audition at my disposal if that helps.

Assuming the menus are similar to Cool Edit Pro, and I expect they are, start at Transform/Noise Reduction and you won't go far wrong.

[marksi]

Might be better to use a notch filter, but play about in Cool Edit. Playing around with it is the only way to learn how these things work.

[Nick Harvey]

Assuming it really is electrical hum, you ought to be able to just notch out 49, 50 and 51Hz.

[Nick Harvey]

As far as I know there's still a legal requirement for the public electricity supply to be totally correct in frequency when averaged over any twenty-four hour period measured from 06:00 to 06:00.

So if it's down on 48Hz for an hour in the evening for some reason, they must run it at 52Hz for an hour before the following 06:00 to get the average correct.

It's all to do with people still being allowed to rely on electric clocks which take their time from the supply frequency.

On the Cool Edit matter, I note that their "50Hz" notch filter appears to take out about 5Hz from around 47 to 52.

[Dusty Jacket]

I suggest you turn the volume down so you can't hear the hiss.