don't know where this belongs, mod feel free to move it around


i'm recording instruments in a room and i have some noise coming from the vents.

if i place a mic near the vent during recording is it possible with use of hardware or software to use that (polarizes?inverts?) to cancel the offending sound out of the instrument line (even if i can't do it live w/o a unit i'd still like to do it in mixing)
I can't comment on the efficacy of what you're attempting, but it might yield better results to keep the mic in the same place as the instrument recording. Then record without the instrument in the same place so that the two signals will contain identical noise, and then invert the isolated noise.
thanks man. just saw this. i'll give it a shot then next time i mic up.
Quote by sysD
thanks man. just saw this. i'll give it a shot then next time i mic up.

To be honest, I really doubt it would result how you want. When recording the instrument, your instrument will drown out the noise that was present in the original signal.
Noise cancellation or filtering can sometimes help but always takes some of the music out with it. Always best to get a clean recording first because once noise is printed on the track, it will never be completely clean again.
Last edited by Cajundaddy at Nov 8, 2014,
This should be posted in the recording forum. You'll get more replies and better advice there. With that said, there are several programs that can get rid of background noise to some extent, but generally, if you use them it will also mess with the quality of the recording a little as well. Your best bet for this would simply be to shut the vents, or turn off your furnace for a couple minutes while recording.
If you have adobe audition, there is noise reduction feature. You just need to record only the vents before you record, or after, and then you can capture a noise profile from that, and remove it from the whole recording. It is really impressive how good it is, but it's not perfect. The louder the noise, the less perfect it is.

Really, you need a quiet room. Inverting phase only works for identical or near identical waveforms. mic placement changes the waveforms.

In recording you want to capture as best you can, you don't want to be fixing stuff really. Like the old saying, "You can't polish a turd".
Last edited by fingrpikingood at Nov 10, 2014,
There are plugins that listen to the noise and build up a profile, then subtract that from the instrument signal.

But you'd be better off stuffing a blanket into the vent while recording.
You need to record in a better room - noise reduction plugins work, but they kill the tone, especially on guitar.