constant "throm" on old cassette Audacity 2.0.5 Win7 SP1

I have several OLD cassettes that I’m attempting to recover to CD. Most have the 60hz hum and the cassette hiss but I have one that has a steady “thrum” or pulse that renders it almost useless.

I’ve been able to make the 60hz hum tolerable with this:
300 10)
240 8)
180 4)
120 2)
60 1)

and the hiss is reduced with a low pass filter but this thrum thing is not going away!

If anyone can tell me how to remove or at least reduce this to a tolerable level so I can save this recording I’d be very VERY grateful!

Also if anyone has some really good settings for eliminating cassette hiss I’d be really grateful.

Audacity 2.0.5 Win7 SP1

Try posting a short audio sample that has the thrum noise on its own followed by the thrum mixed in with the speech or song. See How to post an audio sample .

Generally, try using a noise sample near the beginning of the cassette rather than the end.


Gale, Thank you for your reply. Thought I added samples??? Must have had another senior moment… anyway here’s the thrum and the thrum + vocal. These are both raw. I have not done any filtering on either of these samples.

I must say I’m new to Audacity when it comes to cassette to CD transfer. I mostly do direct to CD recording and those seldom need filtering or any post production work.

One thing should be mentioned and that is these are cassettes made from reel-to-reel masters created in 1950/51. The cassettes themselves are probably 15-20 years old. I’m trying to preserve as much as I can and cleanup enough of the garbage to make them listenable. I’m not expecting perfect recovery. Any help would be greatly appreciated!

Another sample from a different cassette. this is the beginning of the tape.

Re:“thrum and vocal 2.wav” see …
for hum-removal plugin [and suggested settings].

Thanks Trebor, that worked, the recordings are the definitely usable now!