Phase Cancellation

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shreddist

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I have found plenty of information on what phase cancellation is, im just not sure how to get rid of it. heres my deal, im micing an amp with both a condenser and dynamic mic, when i pan one the the right and the other one to the left there is no cancellation, but if they are both centered they start cancelling, is there a way to fix this?
 
Yeah, there are ways to fix it:

1) Re-record, checking phasing first.
2) Get a Little Labs phase alignment tool.
3) Pan hard left and right and hope noone ever listens to your mix in mono.
4) Invert the polarity of one of the guitar tracks, that may or may not help.
 
i always flip the phase right after i think i have the tone right... if flipping the phase doesn't make it sound horrid, i obviously haven't got it good enough yet. it's always easier to hear the crappy sound than the really good.
 
Reversing polarity would only help if the mikes are completely opposite.

When you reverse polarity you want to electronically compensate for the phase difference, which in a theoretical sine wave would equal to 180°
A guitar track though is not a perfect 1 frequency sine wave. The phase (when measured in time) of a wave depends on the frequency of that wave. So you can't truly "reverse it's phase", unless you define a specific frequency which you would like to shift.

All mixers, preamps and DAW's that say "reverse phase" actually mean reverse polarity. They just reverse hot and cold on the mic input.
This button is used for MS stereo for example, or to prevent your snare's top and bottom heads from losing low end, which is indeed caused by phase cancellation, a timebased phenomenon.
There is no such thing as "reversing phase". Phase is a relative distance between multiple waves expressed in degrees 0° -> 360°
As you can see, when you combine two waves (with equal frequency and amplitude), and shift one wave 180°, you get absulote cancellation. The same results are obtained when you reverse the polarity (instead of shifting) of one of the waves. Therefore they started confusing these terms, but in complex wave forms they do not have the same effect.

Anyway, if you want to use two mikes, different in distance from the source, you'll have to search where the "flanging effect" is the least present, or you can indeed pan hard.
If the two mikes are both the same distance from your speaker(s), you can perfectly remove the flanging sound using a very effective trick:

http://www.recordingproject.com/articles/article.php?article=25&page=7
By Aaron Carey

I tried this a lot of times and it allways works. Good luck
greetings, Arno
 

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If you're editing with software, you can drag the late track back into alignment.
 
Try reversing the polarity and see if it helps. It may or may not. Dragiing the track around may or may not. Technically it will probably put it even further out of phase, but realistically it may actually sound better. When I am lining to mics up I usually start with one mic. I get it placed exactly where it sounds the best to me. That becomes my primary mic. When putting the second mic out, I reverse the polarity BEFORE placing it. Then I may it around till it sounds completely thin and cancelled with the first mic. Once I have that postion, then I switch the polarity back to the standard position. Usually that will be a pretty solid placement. If you are using a different mic on the second track than the first, the response times and curves of that mic and any other processing can really change where that nominal position is. It will never truly be in phase, but small amounts of phasing are a fact of life and are present in any and every recording out there. Completely different instruments in a song even cause phasing artifacts. Sitting closer to one speaker than another causes phasing in how we hear the material. Phasing is not a bad thing, it's just like everything else, a fact of life. Too much or the wrong kind of phasing however can be distracting, and can even be irritating. Phasing can be introduced to signals to psychacoustically trigger emotions, usually in a bad way.
 
Track Rat said:
If you're editing with software, you can drag the late track back into alignment.
Click to expand...

Bingo.
All hail digital editing!

Really makes me respect all those amazing 80's recordings.
 
xfinsterx said:
Bingo.
All hail digital editing!

Really makes me respect all those amazing 80's recordings.
Click to expand...
Or you could (and should've to begin with) pay more attention to mic placement, which is what I do, or you could get one of these
http://mercenaryaudio.com/litlabibpanp.html
Software isn't inherently evil, nor is it a panacea. It's just a tool.
 
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