Subject:Getting rid of 60 cycle hum

Posted by: Abbottfk

Date:3/8/1999 10:41:54 AM

Does anyone know a way to edit out 60hz hum? I record dance teaches to tape, and transfer
the tape into .wav files. In the course of recording, power lines sometimes cross my recording
line and I get a nasty 60 cycle hum.

Subject:Re: Getting rid of 60 cycle hum

Reply by: pauly

Date:3/24/1999 5:15:01 AM

Freeland Abbott wrote:
>>Does anyone know a way to edit out 60hz hum? I record
dance teaches
>>to tape, and transfer
>>the tape into .wav files. In the course of recording,
power lines
>>sometimes cross my recording
>>line and I get a nasty 60 cycle hum.
>>

Subject:Re: Getting rid of 60 cycle hum

Reply by: pauly

Date:3/24/1999 5:18:30 AM

The best and most obvious cure would be a balanced power
supply or a good power conditioner at the least. I had all
kinds of crap on some tracks at odd times that I have had
NO problems with after buying the Furman IT-1220(they do
make a 10 amp version) Other than that use a VERY narrow
parametric eq and there are a few denoise programs
available that work quite well! I hope this helps!

Freeland Abbott wrote:
>>Does anyone know a way to edit out 60hz hum? I record
dance teaches
>>to tape, and transfer
>>the tape into .wav files. In the course of recording,
power lines
>>sometimes cross my recording
>>line and I get a nasty 60 cycle hum.
>>

Subject:Re: Getting rid of 60 cycle hum

Reply by:

Date:3/26/1999 4:11:23 AM

> make a 10 amp version) Other than that use a VERY narrow
> parametric eq and there are a few denoise programs
> available that work quite well! I hope this helps!

Sonic Foundry's Noise Reduction plugin is perfect for this, and will do a
much better job than a parametric.

With a parametric, you'd also have to filter at 120, 240, 480, etc, to get
the overtones of the hum out. By the time you've run that many narrow bands
of EQ, your signal would be trashed. Noise Reduction will get all the
overtones in one pass, and the hiss as well.

--
Bruce A. Richardson
Purple Iguana Productions
bandmaster@sprynet.com

pauly wrote in message
news:3OceWphd#GA.250@logan...
> The best and most obvious cure would be a balanced power
> supply or a good power conditioner at the least. I had all
> kinds of crap on some tracks at odd times that I have had
> NO problems with after buying the Furman IT-1220(they do

>
> Freeland Abbott wrote:
> >>Does anyone know a way to edit out 60hz hum? I record
> dance teaches
> >>to tape, and transfer
> >>the tape into .wav files. In the course of recording,
> power lines
> >>sometimes cross my recording
> >>line and I get a nasty 60 cycle hum.
> >>

Subject:Re: Getting rid of 60 cycle hum-One other note...

Reply by: O_G_Killa

Date:3/9/2000 5:08:00 PM

One other thing worth mentioning is that when you try to get rid of
AC hum with a very narrow parametric eq, it will never seem to get
all of it no matter what you do....that is because you need several
different bands of very narrow parametric eq.

I deal with AC hum a lot within what I do for a living. One thing I
have noticed is that AC hum is usually accompanied by several
harmonics. Most notably around 120Hz, and 210Hz and up. I am not an
acoustic engineer, so I can't spout off the formula for the harmonic
(overtone) series but I am sure if you do some searching on the web
you could find some info about it and figure out exactly what
frequencies to cut.

Also try using a sonogram or spectrogram to see the harmonics in your
recordings. I know SF 4.5 has a sonogram, and a free utility like
Gram(or Spectrogram v2.2 as it is sometimes called, made by R.S.
Horne [rshorne@delphi.com]) works really well too.

Hope this helps

paul wrote:
>>The best and most obvious cure would be a balanced power
>>supply or a good power conditioner at the least. I had all
>>kinds of crap on some tracks at odd times that I have had
>>NO problems with after buying the Furman IT-1220(they do
>>make a 10 amp version) Other than that use a VERY narrow
>>parametric eq and there are a few denoise programs
>>available that work quite well! I hope this helps!
>>
>>Freeland Abbott wrote:
>>>>Does anyone know a way to edit out 60hz hum? I record
>>dance teaches
>>>>to tape, and transfer
>>>>the tape into .wav files. In the course of recording,
>>power lines
>>>>sometimes cross my recording
>>>>line and I get a nasty 60 cycle hum.
>>>>

Subject:Re: Getting rid of 60 cycle hum-One other note...

Reply by: Andonyx

Date:3/28/2000 2:56:00 PM

Try this-
Take the original file, which I'm assuming is mono, unless you have a
stereo mic, or a stereo pair of mics. Then create another file with
the exact same sampling rate and bit depth. If you can find a section
of the recording with just hum, copy a snippet of that hum and paste
it into the second file. Zoom in on the wave you have created until
you can clearly see a single cycle of the wave. Edit the file so the
first sample in the file is the first zero crossing in the wave's
cycle, and the last sample in the file is the second zero crossing in
the sample. In other words the entire sample is exactly one half of
one complete cycle of the wave. Then return to the orginal file, and
select all. Copy the entire file and paste it into the very end of the
new file with the half-wave. What you have now is a file that is
exactly 180 degrees out of phase with the hum from your original file.
If you mix the two files back together at the exact beginning point of
the original file. the hum should be drastically reduced, if not gone.



O.G. Killa wrote:
>>One other thing worth mentioning is that when you try to get rid of
>>AC hum with a very narrow parametric eq, it will never seem to get
>>all of it no matter what you do....that is because you need several
>>different bands of very narrow parametric eq.
>>
>>I deal with AC hum a lot within what I do for a living. One thing I
>>have noticed is that AC hum is usually accompanied by several
>>harmonics. Most notably around 120Hz, and 210Hz and up. I am not
an
>>acoustic engineer, so I can't spout off the formula for the harmonic
>>(overtone) series but I am sure if you do some searching on the web
>>you could find some info about it and figure out exactly what
>>frequencies to cut.
>>
>>Also try using a sonogram or spectrogram to see the harmonics in
your
>>recordings. I know SF 4.5 has a sonogram, and a free utility like
>>Gram(or Spectrogram v2.2 as it is sometimes called, made by R.S.
>>Horne [rshorne@delphi.com]) works really well too.
>>
>>Hope this helps
>>
>>paul wrote:
>>>>The best and most obvious cure would be a balanced power
>>>>supply or a good power conditioner at the least. I had all
>>>>kinds of crap on some tracks at odd times that I have had
>>>>NO problems with after buying the Furman IT-1220(they do
>>>>make a 10 amp version) Other than that use a VERY narrow
>>>>parametric eq and there are a few denoise programs
>>>>available that work quite well! I hope this helps!
>>>>
>>>>Freeland Abbott wrote:
>>>>>>Does anyone know a way to edit out 60hz hum? I record
>>>>dance teaches
>>>>>>to tape, and transfer
>>>>>>the tape into .wav files. In the course of recording,
>>>>power lines
>>>>>>sometimes cross my recording
>>>>>>line and I get a nasty 60 c