Out of Phase Guitar Tracks?

[mixsit]

The 3to1 rule is a starting point to isolate two mics on two different sources in the same room. It gets mistakenly applied to other situations where multiple mics are involved, like this one. It doesn't apply to any stereo micing technique and generally doesn't apply to any situation where two mics are on the same source.

Interesting your saying that about stereo on a single source. The one example (of an exception perhaps?) I would wonder about and since I've never recored one, is close micing a piano boad. Would that be a situation because it is so spread out?
Thanks

 

[mixsit]

WTF are you talking about?

Jest ramblin

 

[Steenamaroo]

Interesting your saying that about stereo on a single source. The one example (of an exception perhaps?) I would wonder about and since I've never recored one, is close micing a piano boad. Would that be a situation because it is so spread out?
Thanks

The entire point of stereo micing is to capture phase differences. That's largely what makes up the stereo image.
Things reach each mic at different times and with different volumes, which makes them sound to the left, or right.

3-1 rule should be applied (if you want) where two or more sources are being independently miced up.
For example, if you have two singers each with a mic a foot in front of them, make sure they/their mics are 3 or more feet apart.

I think most people would just consider this common sense with regard to bleed. There's not a lot of need for a 'rule', but I suppose if you're in a tight spot, 3-1 is probably a good minimum guideline to observe.

 

[bouldersoundguy]

The entire point of stereo micing is to capture phase differences.

We're getting a little off course here, but...

Phase (timing) differences are secondary. Amplitude (volume) differences are the main way of creating a stereo image. M-S and X-Y are both stereo micing techniques that don't capture any timing differences between left and right because the mics are placed together. Pan controls also change only the volume of left vs. right. 98% of stereo is done without shifting phase.

 

[mixsit]

The entire point of stereo micing is to capture phase differences. That's largely what makes up the stereo image.
Things reach each mic at different times and with different volumes, which makes them sound to the left, or right.

3-1 rule should be applied (if you want) where two or more sources are being independently miced up.
For example, if you have two singers each with a mic a foot in front of them, make sure they/their mics are 3 or more feet apart.

I think most people would just consider this common sense with regard to bleed. There's not a lot of need for a 'rule', but I suppose if you're in a tight spot, 3-1 is probably a good minimum guideline to observe.

Agreed, I totally understand. I was just bringing up a possible example where the term stereo' micing of piano board might simply blur the notion of a single source. Perhaps unlike over a kit, on an ac guitar, the conditions are a bit exaggerated.
It’s about the only example I can think of like that.

 

[Greg_L]

I think 3:1 as a "rule" is silly because it can be disproven over and over. Look at a drum kit. What's ground-zero on a drum kit? The kick? The snare? What are you gonna reference as the base point from which you start measuring mic distances? What about toms? Hats? Cowbell! For me personally, I couldn't care less about 3:1 over a kit. For me, the snare is the base point because I want it centered, and as long as the two overheads are equidistant from the snare, I couldn't care less if they're 3 feet or 3 miles apart. What about a guitar cab? One close mic, and one mic out somewhere else. Blend to taste. Even if you do go exactly 3 feet out, are you just gonna leave that track as-is? Probably not. You might drop it in the mix, you might pan it, you might do all sorts of things than essentially "move" the sound closer or farther than the original 3 feet. Fuck it. I'm not suggesting anyone just throw mics wherever, but it can be 2:1, 3:1, 5:1, 100:1. Whatever.

 

[Steenamaroo]

We're getting a little off course here, but...

Phase (timing) differences are secondary. Amplitude (volume) differences are the main way of creating a stereo image. M-S and X-Y are both stereo micing techniques that don't capture any timing differences between left and right because the mics are placed together. Pan controls also change only the volume of left vs. right. 98% of stereo is done without shifting phase.

Yeah, point taken. I had a spaced pair in my head and ran with it!

I was just bringing up a possible example where the term stereo' micing of piano board might simply blur the notion of a single source.

Well that's really where it usually goes wrong.
There's nothing wrong with what Greg is saying, but I'd consider a kit to be a single source and not even think about 3-1.

If you're close mixing a little jazz group or something, it's definitely worth keeping in mind.
If they called it the bleed rule, there wouldn't be a problem.

I suppose with a kit it might become relevant if you were putting your tom mics 2 feet away or something.

 

[Greg_L]

There's nothing wrong with what Greg is saying, but I'd consider a kit to be a single source and not even think about 3-1.

A kit isn't a single source though. It certainly can be treated as such, but it naturally isn't.

 

[Steenamaroo]

A kit isn't a single source though. It certainly can be treated as such, but it naturally isn't.

If you view it as multiple sources then your gripe with the 3-1 rule is well founded, in my opinion.

 

[Greg_L]

All of my gripes are well founded! And my grapes are well rounded!

 

[bouldersoundguy]

I think 3:1 as a "rule" is silly because it can be disproven over and over. Look at a drum kit. What's ground-zero on a drum kit? The kick? The snare? What are you gonna reference as the base point from which you start measuring mic distances? What about toms? Hats? Cowbell! For me personally, I couldn't care less about 3:1 over a kit. For me, the snare is the base point because I want it centered, and as long as the two overheads are equidistant from the snare, I couldn't care less if they're 3 feet or 3 miles apart. What about a guitar cab? One close mic, and one mic out somewhere else. Blend to taste. Even if you do go exactly 3 feet out, are you just gonna leave that track as-is? Probably not. You might drop it in the mix, you might pan it, you might do all sorts of things than essentially "move" the sound closer or farther than the original 3 feet. Fuck it. I'm not suggesting anyone just throw mics wherever, but it can be 2:1, 3:1, 5:1, 100:1. Whatever.

Most of what you're describing is for a single source. The 3:1 guide doesn't apply to that. Like you say, the ratio of close to far mics is irrelevant. Putting the two far mics the same distance from a source is a good thing.

It does apply to the close mics. Each one should capture just the drum it's closest to (and aimed at).

 

[Steenamaroo]

All of my gripes are well founded! And my grapes are well rounded!

LOL. Good stuff.

Just thinking though, you probably apply it on a kit just through common sense.
If you're taking each tom to be a separate source and your mics are say, 1" from each skin, they're bound to be at least 3" apart right?

The drum kit is a mix from the perspective of microphones.
They overheads 'see' a single source, but the close mics see multiple sources.

I'm not fighting a side here though. I totally wouldn't even think about it with a kit. You just kinda…mic it up.

 

[Farview]

Interesting your saying that about stereo on a single source. The one example (of an exception perhaps?) I would wonder about and since I've never recored one, is close micing a piano boad. Would that be a situation because it is so spread out?
Thanks

The rule is about isolation, not phase. (the only reason people think it is about phase is because when you get enough isolation, you don't have phase problems) Since a piano is so big, close micing it can turn into a phase nightmare, so you would use that rule to isolate what the two mics are hearing. you are essentially isolating the highs from the lows. In a bigger room without any other instruments playing, you would probably Mic the piano from farther away and not use the 3to1 rule at all.

 

[Farview]

I think 3:1 as a "rule" is silly because it can be disproven over and over. Look at a drum kit. What's ground-zero on a drum kit? The kick? The snare? What are you gonna reference as the base point from which you start measuring mic distances? What about toms? Hats? Cowbell! For me personally, I couldn't care less about 3:1 over a kit. For me, the snare is the base point because I want it centered, and as long as the two overheads are equidistant from the snare, I couldn't care less if they're 3 feet or 3 miles apart. What about a guitar cab? One close mic, and one mic out somewhere else. Blend to taste. Even if you do go exactly 3 feet out, are you just gonna leave that track as-is? Probably not. You might drop it in the mix, you might pan it, you might do all sorts of things than essentially "move" the sound closer or farther than the original 3 feet. Fuck it. I'm not suggesting anyone just throw mics wherever, but it can be 2:1, 3:1, 5:1, 100:1. Whatever.

The only way the 3to1 rule would be used on a drum kit would be to isolate the individual mics on the individual drums. But, if you are close micing, you almost can't help getting the Mic on tom 2 more than 3 times farther away fromtom1 than the Mic on tom1, or the Mic on the snare.

 

[Greg_L]

Most of what you're describing is for a single source. The 3:1 guide doesn't apply to that. Like you say, the ratio of close to far mics is irrelevant. Putting the two far mics the same distance from a source is a good thing.

It does apply to the close mics. Each one should capture just the drum it's closest to (and aimed at).

That's what I'm saying....in the realm of home recording. Realistically, where does 3:1 as a rule apply for home recording? I'm not talking about a symphony in a concert hall. I'm talking about guys in a spare bedroom miking their shit. Where would one have to really worry about it?

 

[Greg_L]

They overheads 'see' a single source, but the close mics see multiple sources.
.

This must be semantics, because if overheads only saw a single source, there would be no stereo spread.

 

[mixsit]

Thanks Jay, that sums it up nicely.
And Greg I totally agree with this-

Look at a drum kit. What's ground-zero on a drum kit? The kick? The snare? What are you gonna reference as the base point from which you start measuring mic distances? What about toms? Hats? Cowbell! For me personally, I couldn't care less about 3:1 over a kit. For me, the snare is the base point because I want it centered, and as long as the two overheads are equidistant from the snare, I couldn't care less if they're 3 feet or 3 miles apart.

And add is a terrific case/example; 'The kit' It has multiple sources, arriving at different times not only from different directions but different depths as well.
Short of the coincident pair there is no where-no way to get that 'in phase’ - other than your few selected equal distance targets (snare, maybe kick and snare.
Equal distance from your target' or whatever you care to have 'in phase, the rest is differnt candy to play with.

 

[Steenamaroo]

This must be semantics, because if overheads only saw a single source, there would be no stereo spread.

I suppose it is semantics. I mean the overheads intend to catch all elements of the kit.

The way I'm looking at it is this.
The overheads are meant to catch the whole kit, so there's no attempt at isolation and 3-1 doesn't apply.
The close mics are meant to isolate certain elements so 3-1 does apply.

You don't need to consciously observe it because it's just common sense….Don't put the snare mic 2 foot away! Or if you do, expect massive bleed.

I know there'll be exceptions in all of this. I'm talking about your average spaced pair overheads and close mics on toms/snare.

 

[mixsit]

This must be semantics, because if overheads only saw a single source, there would be no stereo spread.

Yeah. I see what he is saying, but it's ...slippery

 

[ashcat_lt]

Oh, back on this dead end street? Against my better judgement, I will try one more time...

3:1 rule is about volume difference, period. It technically can be applied any time you've got the same sound hitting at two different times on two different channels and need to mix them together. This is, in fact, true whether that same sound is on two different channels "on purpose" or not.

If there's a delay on that one sound between the two sources, there will be phase-induced comb filtering when they are mixed together. This comb filtering will be strongest when the two signals are exactly the same volume. As one gets louder than the other, the depth of the peaks and dips gets smaller. Somebody somewhere along the line determined that a difference of 9db between the two signals will make those peaks and dips small enough to be barely (if at all) noticeable. (This is true no matter what the actual delay between the two signals). If you put a mic in a spot in front of a source you'll measure one level. If you move it to where it is three times as far away as the first spot, it will measure 9db down from that first measurement. It really is that simple. It's the same thing that you would have demonstrated for yourself if you'd played along with my post back toward the beginning of the thread.

If you use a different mic for the distant mic (with different sensitivity), or change the gain on the preamp, or try to move the fader to blend in more of the distant mic, or pretty much do anything at all other than leave them at unity, then the volume difference changes. When it gets to be less than 9db difference, you'll hear the comb filter. If that's a problem, you have to look at what can be done about that. You could just turn one of them down till there is a difference >9db again (even if that means turning down the close mic), or you can start nudging, or play with one of those "phase correction" tools, or whatever.

And that is why folks are saying it doesn't apply to the OP's situation. It is probably more likely than not that he will want those two mics mixed at closer than 9db difference from one another, so even if it was set up at 3:1 distance-wise, it won't help.

It's all about relative volume. Period.