understanding phase

general questions, comments and ideas about recording, audio, music, etc.
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dirtmachine
pluggin' in mics
Posts: 33
Joined: Mon Jan 03, 2005 11:45 am
Location: Brooklyn, NY

understanding phase

Post by dirtmachine » Wed Feb 16, 2005 8:54 am

Hi y'all, i just started mixing my first serious effort at recording a band and im trying to get a handle on phase relationships. i think that some of the indistinct-ness of my sounds might be the result of phase issues. i recorded the band live in a medium room, through a mackie, onto 1/2 inch and then dumped into DP for overdubs and vocals.

i've been using the invert phase plug-in on soloed tracks to hear how it sounds, as well as dragging tracks slowly, a few samples at a time, and i can hear some of the cancellation and degradation, but i still feel like i dont really understand how the overheads affect the snare and room mic, etc. although im sure experience with micing the room is the best way, i wonder what else i could do to get a handle on this stuff.

on some analog boards ive seen phase meters. are there any plug-ins that do this?

is it possible for some parts of an instruments frequency spectrum be in phase while others are out? can be this be fixed (or made worse) by eq-ing?

any other suggestions for learning to hear this stuff?

Thanks.

thethingwiththestuff
george martin
Posts: 1296
Joined: Mon Mar 22, 2004 9:00 pm
Location: philly

Re: understanding phase

Post by thethingwiththestuff » Wed Feb 16, 2005 9:46 am

if you can hear the difference between inverted and non-inverted polarity on a soloed track, you're a better man than i. phase cancellation can only occur between two (or more) sources. (although, it can happen in the room as well, if not properly designed. even then, it is the interaction of a source with something else.)

what is a phase meter? an oscilloscope?

yes, certain frequencies can cancel out while others dont. low end is the first thing to go, usually. EQing can aggravate this, especially poorly designed hardware and software eq's.

also, if your computer isnt fast enough, the more plug-ins you put up, the more the latency of the processing can throw things out of phase.

there is SOOOOOOOOOOO much information about phase on this site (utfsf!!!) and on the web.

dirtmachine
pluggin' in mics
Posts: 33
Joined: Mon Jan 03, 2005 11:45 am
Location: Brooklyn, NY

Re: understanding phase

Post by dirtmachine » Wed Feb 16, 2005 10:58 am

thanks for the reply. yeah, i see that i wasn't clear- i meant i could hear the effect when playing the original and inverted tracks together, soloed, thus creating the maximum amount of cancellation (right?).

since putting up the post i googled for plug ins that contain phase meters and it seems to be a fairly standard part of mastering suites like waves and bias, metric halo also makes one.

oobedoob
alignin' 24-trk
Posts: 71
Joined: Wed Nov 03, 2004 9:43 pm

Re: understanding phase

Post by oobedoob » Wed Feb 16, 2005 11:22 am

it's been pointed out already that there's nothing to hear with absolute phase changes, only relative. You're not going to hear anything when you solo something and change the phase. You'll only start to hear things when you have the same sound on two tracks and you change the phase of one track relative to the other.

One way the checks are done in the rock idiom (let's just assume you're doing something close to that for the time being), is to bring up the overheads (or one overhead) and get a good sound that you're comfortable with. Don't worry about phase yet. Now bring up the kick fader. Or the snare fader, or whatever track you're concerned about.

Listen to how the different frequency ranges change. If there's a phase problem, you might hear the cymbals get boxy or tinny sounding, you might hear the kick low frequencies go away, you might hear the snare sound like a cardboard box. You may like some of this, or you may want to change some of this. Unfortunately, if your overheads sound boxy or tinny or otherwise crappy by themselves, there's not a lot you can do that doesn't involve a hammer, a few beers, and some trips to Home Depot. Or a super-duper-slam-o-pressor

I guess, the point is, use your ears as well as utfsf, etc....
"Revolution is not a dinner party." -Sun Yat-Sen

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