Eliminating low-frequency noise

[(poco) Sforzando]

This is not exactly related to CD ripping, but those who have done LP conversions and editing may have some ideas. My problem relates to a video file in .MOV format for an original play I had produced. The video is not great but acceptable, but the audio has a persistent low-frequency hum that is very annoying.

Back when I was converting and editing LPs myself, I would use Adobe Audition to create an .FFT file consisting of only the low-frequency noise; then I could apply this file to the .WAV to mask out the rumble. And this worked surprisingly well. With my .MOV file, I found I could use Nero to separate the audio from the video, and then I could take the audio component into Audition, create the .FFT as before, and import the edited audio track into Nero.

Problem is that this time, applying the .FFT didn't eliminate the rumble very well, and if I applied a more aggressive setting, I lost a lot of the good audio material as well. So my question is whether anyone knows a tool that could perform this bit of audio surgery more successfully.

[71 dB]

Problem is that this time, applying the .FFT didn't eliminate the rumble very well, and if I applied a more aggressive setting, I lost a lot of the good audio material as well. So my question is whether anyone knows a tool that could perform this bit of audio surgery more successfully.

You need a clear sample of the noise to remove it more or less successfully. Typically the start and end of the sound file contain "noise only" sections. How long is the file? 10 minutes? Hour? You could sent it to me and I could try to clean it and sent it back to you.

[(poco) Sforzando]

You need a clear sample of the noise to remove it more or less successfully. Typically the start and end of the sound file contain "noise only" sections.

How long is the file? 10 minutes? Hour? You could sent it to me and I could try to clean it and sent it back to you.

You need a clear sample of the noise to remove it more or less successfully. Typically the start and end of the sound file contain "noise only" sections.
- That's what I thought I did.
How long is the file? 10 minutes? Hour? You could sent it to me and I could try to clean it and sent it back to you.
- A little over an hour, 676Mb .WAV. Could not email, but maybe send via Dropbox.

Very grateful for the offer, Poju.

[71 dB]

You need a clear sample of the noise to remove it more or less successfully. Typically the start and end of the sound file contain "noise only" sections.
- That's what I thought I did.
How long is the file? 10 minutes? Hour? You could sent it to me and I could try to clean it and sent it back to you.
- A little over an hour, 676Mb .WAV. Could not email, but maybe send via Dropbox.

Very grateful for the offer, Poju.

Well, if you send it via dropbox I can study what can be done with it. 

[(poco) Sforzando]

Well, if you send it via dropbox I can study what can be done with it. 

Excellent. Kiitos.

[71 dB]

Excellent. Kiitos.

You're welcome! I removed the noise as much as I could. Check your private messages. 

[millionrainbows]

I thought I would mention this: I am using Logic 7 with a Powermac G5. This program is capable of recording 24 bit/96 kHz. I also used an M-Audio interface. I had a persistent low-level hum, and it would decrease whenever I held the mouse. So when I did bounces (mixes to CD), I had to hold the mouse in.

It turns out that this was a simple ground loop. I solved the problem with an AC adaptor which lifted the ground. Ridiculously simple, and it took me 2 years to solve it.

[71 dB]

I thought I would mention this: I am using Logic 7 with a Powermac G5. This program is capable of recording 24 bit/96 kHz. I also used an M-Audio interface. I had a persistent low-level hum, and it would decrease whenever I held the mouse. So when I did bounces (mixes to CD), I had to hold the mouse in.

It turns out that this was a simple ground loop. I solved the problem with an AC adaptor which lifted the ground. Ridiculously simple, and it took me 2 years to solve it.

Low level hum problems are almost always related to ground loops and yes, AC adaptors are the easy way out in many cases. Sometimes figuring out the ground loops can be difficult and the problem may seem mystic.

[(poco) Sforzando]

I thought I would mention this: I am using Logic 7 with a Powermac G5. This program is capable of recording 24 bit/96 kHz. I also used an M-Audio interface. I had a persistent low-level hum, and it would decrease whenever I held the mouse. So when I did bounces (mixes to CD), I had to hold the mouse in.

It turns out that this was a simple ground loop. I solved the problem with an AC adaptor which lifted the ground. Ridiculously simple, and it took me 2 years to solve it.

But this was a file delivered to me from an outside source, and the hum is "built in."

I was using the M-Audio Interface to record voiceovers some years back, and the hum was easily eliminated with an .FFT file in Audition. But the circumstances there were different; it was just a single speaking voice. In the file under question here, there are so many audio components that it's difficult to isolate just the noise in order to mask it.