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Tips & Techniques:Noisy Guitar amp..

I learned this one from Tom Dowd,

We had the right sound for a gtr track, could not make this noise go away,
Tom had me record the noise from the amp on to a track from top to bottom and then we ahead and recorded the gtr track on another track.. when we were done He had me flip the phase on the noise track and bounce it with the gtr track at unity gain to a new track... the Noise pretty much cancelled it self out..He was a genious!

Regards and Happy 008.

Contributors: mw, elmono
Created by elmono, 9th January 2008 at 04:23 AM
Last edited by mw, 27th March 2012 at 03:05 PM
Last comment by rmorris on 24th May 2009 at 04:48 PM
10 Comments, 17,293 Views
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Old 9th January 2008
  #1
Lives for gear
 
enroper's Avatar
 

That is awesome. I'm going to try it tomorrow. Tonight I found just the right sound for a little ditty...but it was on a noisy practice amp..We'll see how it goes.
Old 9th January 2008
  #2
Strictly speaking noise won't cancel out with a phase invert because it is random. But the sample and invert technique (mentioned in the post) is one of a few techniques that modern "denoise" processors.
Old 9th January 2008
  #3
Gear Head
 
elmono's Avatar
 

Thread Starter
Quote:
Originally Posted by structuredloud View Post
Strictly speaking noise won't cancel out with a phase invert because it is random. But the sample and invert technique (mentioned in the post) is one of a few techniques that modern "denoise" processors.
Interesting, It is amazing what how much time You can save now with all these plug-ins.. Tommy Dowd was probably doing this in the 70's

regards,

C.
Old 12th January 2008
  #4
Gear nut
 
namsabnek's Avatar
 

Unhappy Didn't work for me...

Got all excited yesterday. recorded three minutes of noise at the same level as the guitar i was tracking. flipped the phase on the "noise" track and nothing happened. Absolutely no noise reduction. Could it be because the noise has variables in the sound which don't coincide exactly with the noise on the guitar track?
Old 12th January 2008
  #5
Lives for gear
 
CrankyRayHanky's Avatar
 

No luck here either- I just seemed to be adding more noise
Old 15th January 2008
  #6
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EstateMatt's Avatar
 

noise is entirely random. I'm not sure who this is that posted, but he's either lying or is missing something. Sounds kind of audio-engineering-school-ish to me. if this worked, it would be built into all analog electronics.
Old 17th January 2008
  #7
Gear interested
 
dana18237's Avatar
 

yeah this trick hasn't worked for me either. i recorded about 20 seconds of noise. then on another track i recorded 20 seconds of playing guitar. flipped the phase on the noise track and summed them. no noise reduction at all. i noticed someone post something about "sample and phase." what exactly does that mean?
Old 19th January 2008
  #8
Gear Head
 
shuld's Avatar
 

Unhappy

Tried the same thing!!! Nada!!!!
Old 31st March 2009
  #9
Gear Addict
 
echoclerk's Avatar
 

It won't work

If the Noise on the Guitar amp is true "noise" then this will not work. noise has no phase so it can't cancell out.

You may be able to get rid of rumbles or pitched hums. if you can match up the frequencies / waveforms.
Old 24th May 2009
  #10
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rmorris's Avatar
 

Quote:
Originally Posted by echoclerk View Post
If the Noise on the Guitar amp is true "noise" then this will not work. noise has no phase so it can't cancell out.

You may be able to get rid of rumbles or pitched hums. if you can match up the frequencies / waveforms.
tha's right as far as I can see. Random noise ( Gaussian / White/ pink / hiss ) is random and is as likely to add constructively as destructively.
But a noise like a 50Hz hum is repetitive and will cancel out if added in anti-phase.
Since you can't really know when you begin recording wrt the phase of the hum I'd suggest that whether playing the noise track in or out of phase gives a better result is random and the ideal phase change may be anywhere between zero and 180 degrees.
Some analogue kit ( eg up market mic pre / DI s) wil let you set this variable phase change as it's usually intended to match up DI and mic signals.
Or, of course, you can do it in a DAW.
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