Quote:
Originally Posted by Knives&Guitars
I was wondering if you could point me to a good article on Mic- guitar Phasing. I do so understand the concept reasonably well...but get confused on why some Mic positions do not seem to cause phasing...when the distances are not equal. Like the over the shoulder for one and 12 fret for the other. Heard great sound from this technique...but seemingly no phasing problems. So I would love to learn more about this in relation to phasing.
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Try this one:
https://www.soundonsound.com/sos/apr...emystified.htm
or this one:
http://jaygraydon.net/MIC_TUTORIAL.pdf
(by THE Jay Graydon, no less...)
All just from searching on "mic phase" on google. Much more where these came from.
My 2 cents:
Phase is important, but I think people get overly worried about. It's not usually a problem, (unless it is.) Phase is one of the audible cues that give info about a sound. When you hear a sound slightly off to the right, the sound arrives at our right ear a millisecond or so before it hits our left ear -aka "out of phase". No big deal - it's useful info that our ears use to tell us location, in addition to volume. Phase isn't "bad", it's just a phenomena that exists any time you pick up the same sound from 2 different locations (even if those 2 locations are on each side of our head)
Mics work the same way. If you record in stereo, and play back in stereo, for recording acoustic guitar, then depending on your mic placement, the sound in each speaker may or may not be in phase, because both mics pick up all parts of the guitar, but may be different distances from any given spot on the guitar. If you use "co-incident" placements (X/Y mostly), then the sound will be mostly in-phase, and the stereo effect you hear is strictly due to volume differences in the sound hitting the mics. As you move the mics further apart ("spaced pairs", for example), then you get not only volume differences but phase differences. This isn't a bad thing, it's just a different way of creating the stereo effect. You choose that mic placement if you want that sound.
Why/when is phase "bad"? Well, if you record using spaced pairs, and then mix to mono, the phase differences will cause cancelation at some frequencies. That may or may not sound good. But as long as you listen in stereo, it matters a lot less. You even get some people here on AGF who, knowing full well what they're doing, record with spaced pairs, and then pan the mics partially inward. What they're doing is narrowing the stereo field by deliberately causing interaction between the mics, including phase cancelation. If it sounds good, no problem...
Also, once you get beyond just one guitar, things get more complicated. Drums is a great example, where maybe you have 6-10 mics on a drum set. Then you mix those mics down to 2 channels. So some mics are going to be combined into one side, so maybe you have a snare mic 2 inches from the snare and a cymble mic that's 2 feet from the snare. Now those are out of phase, and you get that frequency cancelation on your snare. Might sound perfect. But probably not...
You can have the same thing with guitar and voice, where you have a close vocal mic, and your guitar mic also picks up a bit of voice, and vice versa. Now when you mix, that bleed may be out of phase and again, cause some phase cancelation.
One thing that comes up here from time to time is someone who has a mic or mic cable reversed in polarity. People will call that 180 degrees out of phase, but it's actually a bit different. You can really only talk about phase in relation to a specific frequency. But with polarity reversed, *all* frequencies will be out pf phase. Record 2 identical tracks with mics in reverse polarity, and 1 of two things happen. If you listen in stereo, you get this odd, ultra-wide sound that's a bit diffused and hard to focus on, or if you mix to mono, you get total silence. Both are bad things, unless of course that's what you want - there are techniques that leverage this effect.