Noise reduction - would this work?

[Bulls Hit]

My recording room is quite noisy. I mean it doesn't seem noisy to me but when I arm a track to record, the meters are bubbling away at around -55, -60dB.

I was thinking, prior to recording drums or guitar, if I reversed the phase on each mic and recorded 4 minutes or so of 'silence', then flipped the phase back again and did my normal recording with a few seconds of silence at the start. I could then blow up the wave forms and line up the silence at the start of the tracks with the reversed phase silence recording, then nudge the reversed stuff along until it was 180 degs out with my real tracks.

In theory this would/could cancel the noise. Maybe? Could this work, or is background noise to variable and I'd only end up adding even more noise?

 

[kylen]

My recording room is quite noisy. I mean it doesn't seem noisy to me but when I arm a track to record, the meters are bubbling away at around -55, -60dB.

I was thinking, prior to recording drums or guitar, if I reversed the phase on each mic and recorded 4 minutes or so of 'silence', then flipped the phase back again and did my normal recording with a few seconds of silence at the start. I could then blow up the wave forms and line up the silence at the start of the tracks with the reversed phase silence recording, then nudge the reversed stuff along until it was 180 degs out with my real tracks.

In theory this would/could cancel the noise. Maybe? Could this work, or is background noise to variable and I'd only end up adding even more noise?

Yes, I agree pushing a track into a compressor that has a -55dB noise floor won't sound pretty. You've stated that your recording room is noisy like you can't change that at all or get mics closer to the source - is that so ?

 

[bennychico11]

Could this work, or is background noise to variable and I'd only end up adding even more noise?

You can try it and see...but I think it would be too variable. You'd have to get the noise of the out of phase one to be the exact opposite of the recorded one. Which I think would be impossible since noise isnt' a perfect sine wave. However, you might be able to luck out and get a second here or a second there that it does cancel. I think you might get better results with a noise reduction plugin. The Waves restoration plugins work really well for me.

 

[Bulls Hit]

The main source of noise would be the computer fan, then traffic etc.
For guitar, the mics are right up near the grill.

The activity is more noticable on the condensor mic as its more sensitive I guess

 

[MadAudio]

Is this "noise" actually audible? Could you post a sample of it?

 

[bennychico11]

well if it's general noise from traffic or computer then i would worry about fixing those problems first. try and isolate your computer or it's components. there is a bunch of acoustic equipment you can buy to put in your computer and make it a lot quieter: http://www.quietpcusa.com/acb/webpage.cfm?WebPage_ID=1&DID=8 for a few ideas. Try and figure out what the noisiest parts of the computer are and go from there.

 

[Farview]

If the mic is right on the guitar amp speaker, and you can hear a computer fan, turn the amp up!

 

[kylen]

If the mic is right on the guitar amp speaker, and you can hear a computer fan, turn the amp up!

That's the deal ! In Bulls Hit environment it's not cool to turn the guitar amp up much louder - I'm guessing here. If that's the case a J-Station or some other DI is the way to go. You're not really loud enough to get a cool sound in the 'room' so maybe even the amp has line-outs or some other connection to DI (with a ground lift probably - just be careful if you lift a ground, they get noisy but they're also for protection).

I don't think you really want to repair the noise issue after the fact - you won't be spending much time on your music that way - you'll be editing hour after hour. Record a cleaner signal - that's what you want IMO.

 

[Bulls Hit]

If the mic is right on the guitar amp speaker, and you can hear a computer fan, turn the amp up!

Heh, yeah I've got no problems cranking it, but even so the noise is still 'there' isn't it, under the covers, muddying things up. Kylen's right, the only real solution is to remove the sources of the noise somehow

 

[xfinsterx]

Are You Running A G4 Bulls?

 

[NYMorningstar]

I agree with bennychico11. You have to tame the source of the noise. I'd move the computer to another room if possible. If not, build a sound muffler box around it, get a quieter fan or put an a/b switch on the fan to turn it off while recording. Be careful of overheating your computer.

You might also want to try out a noise gate for the traffic and other noise because the problem is going to be magnified if you're multi-tracking. The noise on each track will be added to the noise on all the tracks to the point of it being real annoying.

Another idea is to isolate the amp and mic by throw a noise deadening blanket over them.

 

[Adam P]

As a sidenote, I wouldn't put a heavy blanket that might trap heat over top of a tube amp.

 

[Farview]

Heh, yeah I've got no problems cranking it, but even so the noise is still 'there' isn't it, under the covers, muddying things up. Kylen's right, the only real solution is to remove the sources of the noise somehow

If you crank the amp, you have to turn down the mic pre (thus turning down the volume of the ambient noise) to keep the recorder from clipping. If you turn down the mic pre by 20 db, you are turning the noise down by 20db
(-60 plus -20 equals -80) the ambient noise goes down to below the noise specs for vinyl. certainly a livable situation

 

[Bulls Hit]

Are You Running A G4 Bulls?

No it's a PC. It's got 5 fans in it.

Farview yeh I see what you're saying now.

To hell with the wife & kids, I'll just turn it up

 

[kylen]

To hell with the wife & kids, I'll just turn it up

Save your marriage !

http://www.johnson-amp.com/jstation.htm

 

[MOFO Pro]

Phase polarity swap Y cable

This is a live sound trick for limiting mike bleed on vocal mikes. Two identical mikes are hooked up to a Y cable with polarity reversed to each mike. One mike was used for vocals, the other was mounted lower away from singer to capture the ambient sound from the amp stacks behind the band. The vocal mike would pick up (+vocals) & (+ambient noise), the out of phase mike would capture (-ambient noise), combined you're left with vocals only. Both signal sources are exactly 180 degrees out of phase with each other so that signals common to both cancel out.

Not ideal or practical in a studio environment, but in a pinch...

 

[crosstudio]

put the PC in the closet.

even better... put the PC in an adjacent closet. in my old house, my closet was next to the closet in the next room, so I put my PC in the next room's closet and drilled a small hole to pass the cables into my closet. I used extender cables for the mouse, keyboard, and monitor, and longer ADAT lightpipe and SPDIF cables for the audio cards.