Phase. What exactly is it?

[Bigduggieface]

Keep in mind that the 3 to 1 principle is not a RULE. It is a basic guideline in order for the engineer to visualize the movement of sound through the atmosphere and into your microphones.

darrylm mentioned reversing the phase of one of the microphones. This can be done to help align the phase of an phase-offending microphone. If you have 2 mics that cancel each other, 'flip' the phase on ONE of the microphones, and this may often help align the phase of the two mics.

For instance, many times engineers will place a mic 1/2" from the top of a snare drum, while also placing a mic under the snare as well. Often it may be helpful to invert (flip) the phase on the bottom mic.

Most quality microphone preamplifiers have a phase-invert button on them. It's often designated by a symbol that looks like an "O" with a diagonal line through it. You can try flipping the phase or moving one of the mics a couple of inches and it usually clears up any phase problems.

There are many useful visual phase meters which let you "see" the phase relationship of 2 or more mics. Meters such as the Waves Dorrough Meter. It's often better to use your ears, especially if you're just starting out.

Be careful recording acoustic guitar or a guitar cabinet with 2 mics. Also, if you're recording a bass amp while taking a direct signal at the same time, you almost always will need to reverse the phase on one of these signals.

[zildjohn01]

Yeah, for the most part. Of course, let your ears be the final judge. And always try your mixes in mono.

Do you know what kind of sounds you're trying to avoid, or is this all "hear-say" for you so far? If not, I can post some clips of what you're trying to avoid, or instructions on how to make your own. The only way you'll learn to avoid phase issues is to know what to listen for

[ajcarson1]

Originally Posted by zildjohn01

Yeah, for the most part. Of course, let your ears be the final judge. And always try your mixes in mono.

Do you know what kind of sounds you're trying to avoid, or is this all "hear-say" for you so far? If not, I can post some clips of what you're trying to avoid, or instructions on how to make your own. The only way you'll learn to avoid phase issues is to know what to listen for

That'd be great if you could post some clips ZildJohn, I don't believe I have too many phase issues yet, but I wasn't really sure what to look for.

I'd just heard the term "phase" quite a bit, and wondered exactly what I needed to do to avoid problems with it. With a new set of mics for drums and guitar cabinets coming in, I figured now was the best time to learn.

After all, i'm basically just starting out.

Thanks for all your help

[zildjohn01]

Hey sorry I didn't forget about you, I don't have access to clips at the moment, but here's how to hear it on your own.

Take a raw instrument recording (drums, guitar, doesn't matter) and delay it 1 or 2 ms, then mix it with the original. That's about what you're trying to avoid with real mics. Hear it?

[Denim N Leather]

Hi everyone,

First post on this forum.

The only thing I have to add to this discussion is to remember that the signals produced by musical instruments are very complex and impossible to predict. As a result, you can can have two microphones that are not exactly "perfectly" out of phase with each other.

Phase invert swaps the phase of the signal 180 degrees and the sound may not be substantially improved if they microphone capsules are not 180 degrees out of phase to begin with.

Something like this is invaluable when using more than one microphone Radial Phazer™ phase adjustment tool - introduction

Hope you find this helpful!

[Creedasaurus]

any time you have more than one mic recording something, you will be dealing with phase. 3 to 1 rule or no 3 to 1 rule.

I've been recording a drumset with about 10 mics for the past two weeks. i've been very careful about where i put them all so as to minimize phasing and whatnot. But no matter how well that advice is followed you will hit phasing issues. in your DAW, zoom in on the waveforms close enough and you will see most of them are skewed a few milliseconds from the closest mic. if you want, you can drag the track over and flip the phase if needed.

you dont have to buy a $350 phase alignment box if you want to correct phase issues.

[fortyseven]

Two waves that are in phase with each other will combine and amplify.
Two waves that are out of phase will combine and cancel each other out resulting in a null wave.

[ryry]

Somebody once mentioned a somewhat simple technique for making sure the phase is correct. If you are using a mixer with a phase reverse switch you put the phase of one of them backwards. Then adjust the second mic so that the sound is as out of phase as possible. Flip the phase switch back to normal again. Rinse repeat.

[brandondrury]

Two waves that are out of phase will combine and cancel each other out resulting in a null wave.

In "laboratory" situations. In real life if you toss an SM57 on the cone of a guitar amp and a Ribbon mic dead center and blend them you'll end up with a nasally mess (unless you just hit the jackpot!)

If you are using a mixer with a phase reverse switch you put the phase of one of them backwards. Then adjust the second mic so that the sound is as out of phase as possible. Flip the phase switch back to normal again. Rinse repeat.
Back when I was a proponent of multiple close mics (I have not been for some time) I used this method often. It's often more difficult than I thought it should have been.

I could often cancel out everything but the top end air. Of course, the second I flipped the polarity back this meant I was losing the end air.

I consider my extreme fear of comb filtering to be a gigantic contributing factor to my improvement as an audio engineer.

Brandon

[Electriclight]

In "laboratory" situations.

Exactly,
that's why some arbitrary 3:1 rule makes no sense.

With all the various frequencies being emitted, how can you find an actual sweet spot? After creation, I don't think a 440 Hz wave will ever be in phase with a 12360 Hz wave except on rare, essentially random occasions.

It will always and necessarily be a compromise between frequencies you find in phase and those you find out of phase.