Quick spaced pair question.

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Dark Imagery

Dark Imagery

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When using the 3:1 rule, does the distance from the kit (or source) mean how far back the mics are or how high the mics are? For example, the mics are a foot in front of the kit so they need to be three feet apart? Or the mics are three feet above the highest cymbal they need to be nine feet apart? Cause I could run out of room really fast!
 
The 3:1 rule does not apply to spaced pairs at all. It only applies to two microphones miking two individual sources.

G.
 
Dark Imagery said:
Um... with respect I think it does.
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With equal respet, I can guarantee you it does not.

The 3:1 "rule" is one of the single most misunderstood and misrepresented concepts in this racket. And yet it's reality is sooooo simple. It's formal description is that the distance from Source B to Mic A should be at least three times the distance as the distance from Source B to Mic B:
3to1.jpg

All it's about is to use as a general reminder/guideline for cutting the amount of bleed from another instrument because that bleed can cause phasing issues in the mix otherwise.

It does NOT apply to any intentional pairs meant to mic a single compound source such as a drum kit. If that were the case, X/Y and ORTF pairs would be invalid, and spaced pairs would be impossible to calculate because you wouldn't know which part of the kit to measure from.

Just don't worry about 3:1 and set your mics at the proper distance to get the optimum sound with the optimum resulting stereo image.

G.
 
Yeah, let's get down to it (again ;)
I think the confuse' comes with the meaning of 'two sources' and the point at which you feel the need to see (sonically) the micing concerns of a single instrument's cross-width time delay phase effect as overriding other sound priorities.
Very often you'll see the spread on piano sound board given as an example. Might be valid there (don't know). But just as often –as a rule on acoustic guitar for example? Phooey.
You have plenty of choices, just try to keep in mind the variables and consider the phase effects on spaced pairs don't have to be an overriding issue to be avoided at all, and in some cases simply play well into the sound and mic position choices.
Equal time to the center point of interest trumps (big time IMHO) '3:1 very often. (still talking stereo here)
There's plenty of cases where '3:1 doesn't necessarily fix your 'phase concerns anyway.
Your kit makes almost the perfect test case.. What is reality of the sound of a multi mic'd kit?
:p
There's coincident XY and no close mics if you like.
But a soon as you introduce time as a variable, there is no 'real but rather various flavors on your time game. But then the cool thing is some of these phase tones sound pretty cool don't they?
XY- phase accurate. ORTIF and other near coincident- not only break 3:1' but add phase effect to good use.

I use omnis one either side, arm height and to the rear slightly as my primaries -but equal time to the snare (ah la 'Recorderman and others. (kick can be slightly secondary IMO)
(And/but.. That 'equal time to the snare' is not just a phase tone thing. Snare tone' was a wide acceptable variable. It also has a strong Haas pan consideration. 6-8" (= .8ms) will do it.

My omno spread is just about worst case as far as wide cross-time differences. But the picture can go from very wide with plenty of good solid tones anywhere all the way down into mono and near mono. None of them are real of course. The sound to the snare follows 3:1 –but then it doesn't need to does it, it's equal time. Other things on the kit (mounted tom?) smash 3:1 – but don't give damn. ... hell you were gona 'scoop' the mids or something anyway! :D

Here's a good one.
http://www.tufts.edu/programs/mma/mrap/StereoMicTechniques.pdf
 
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mixsit said:
Very often you'll see the spread on piano sound board given as an example. Might be valid there (don't know).
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Depends entirely upon how you mic it; there's about as many different ways to mic a piano as there are ways to play it.

But assuming we're talking a spaced pair on the harp, it's kind of a question of semantics; itcan be valid to argue that the lower half of the harp and the upper half of the harp are two different sources.

But then again, rarely is the 3:1 rule going to be much of a concern there anyway, because rarely is one mic in such a spaced pair going to be any more than maybe a few inches off the strings. Let's say they are 6" up; this means that to follow the 3:1 rule, the two mics would have to be a good 17" apart, which would be pretty darn close; probably closer than your average piano harp spaced pair anyway.

G.
 
SouthSIDE Glen said:
The 3:1 rule does not apply to spaced pairs at all. It only applies to two microphones miking two individual sources.
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Glen is correct.

The 3:1 rule is used when micing two sources with two mics.

Mic 1 is X1 distance from source 1 S1

Mic 2 is X2 distance from source 2 S2

To minimize bleeding on each mic from the other source

... the distance X1 to S2 should be at least 3 X1

... the distance X2 to S1 should be at least 3 X2
 
Sonixx said:
Glen is correct.

The 3:1 rule is used when micing two sources with two mics.

Mic 1 is X1 distance from source 1 S1

Mic 2 is X2 distance from source 2 S2

To minimize bleeding on each mic from the other source

... the distance X1 to S2 should be at least 3 X1

... the distance X2 to S1 should be at least 3 X2
Click to expand...

And, to add to that, the height of the mike is irrelevant. The shortest distance between two points (relativity aside) is a straight line, i.e. source to mike, and that is what you measure.
 
Hmm... I feel like I've read about the 3:1 rule pertaining to a spaced pair on a single source in a few books, and heard it mentioned in a few video tutorials. I'll have to investigate further. I do appreciate everyone's professional responses to my question when it's obvious I'm a greenhorn.
mixsit said:
... hell you were gona 'scoop' the mids or something anyway! :D
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Yeah, on the kick mic. :rolleyes:
 
Dark Imagery said:
Hmm... I feel like I've read about the 3:1 rule pertaining to a spaced pair on a single source in a few books, and heard it mentioned in a few video tutorials.
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In 2010, video tutorials on meTube and places like that are unreliable at best. Anybody can post anything without editorial review up there and it winds up being a petri dish for myth and parroted untruth.

As far as books, I wouldn't be surprised if there were a smattering of misinformation printed out there, especially from publishers anxious to cash in on the home recording age who do not have editors qualified to properly vet the content submitted by the author.

True story: A couple of years ago one of the regulars here (mixsit?) correctly questioned an article in EQ Magazine that described an incorrect application of the 3:1 rule. Craig Anderton, of all people (the editor of EQ magazine) actually came on here asking what was up. Even he had an incorrect understanding of the 3:1 rule. You can probably do a search of this BBS for "Craig Anderton" and find that thread if you're interested. I bring this up not to dump on Craig, who is a good guy, but just to show how pervasive the misunderstanding of 3:1 actually is.

The reality is that when one has a true understanding of the fundamental nature of audio - it's not rocket surgery - one can pretty easily understand that there is no way that the 3:1 rule could possibly apply to multi-miking of a single source.

The last time this subject came up - and it comes up pretty often - someone said they would like to just see the 3:1 rule disappear, because it really causes more trouble than it's worth. I would have to agree with that myself. Unfortunately that is not about to happen anytime soon.

G.
 
It will Glen but there will have to be Government sanctions that states when recording you MUST ONLY USE ONE MICROPHONE.:laughings:





:cool:
 
SouthSIDE Glen said:
In 2010, video tutorials on meTube and places like that are unreliable at best. Anybody can post anything without editorial review up there and it winds up being a petri dish for myth and parroted untruth.

As far as books, I wouldn't be surprised if there were a smattering of misinformation printed out there, especially from publishers anxious to cash in on the home recording age who do not have editors qualified to properly vet the content submitted by the author.

True story: A couple of years ago one of the regulars here (mixsit?) correctly questioned an article in EQ Magazine that described an incorrect application of the 3:1 rule. Craig Anderton, of all people (the editor of EQ magazine) actually came on here asking what was up. Even he had an incorrect understanding of the 3:1 rule. You can probably do a search of this BBS for "Craig Anderton" and find that thread if you're interested. I bring this up not to dump on Craig, who is a good guy, but just to show how pervasive the misunderstanding of 3:1 actually is.

The reality is that when one has a true understanding of the fundamental nature of audio - it's not rocket surgery - one can pretty easily understand that there is no way that the 3:1 rule could possibly apply to multi-miking of a single source.

The last time this subject came up - and it comes up pretty often - someone said they would like to just see the 3:1 rule disappear, because it really causes more trouble than it's worth. I would have to agree with that myself. Unfortunately that is not about to happen anytime soon.

G.
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Yes Glen that was me, and there was quite a little slug of flack and noses turning up over at his site at the time. Fun stuff.
You have to say though this (and other examples) shows though we can have some of this stuff completely wrong, and still make good recordings. ;)
 
moresound said:
It will Glen but there will have to be Government sanctions that states when recording you MUST ONLY USE ONE MICROPHONE.:laughings:
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Then it would be time to invest in off-shore recording studios ;) Hello? Cayman Islands Recording? :D
mixsit said:
You have to say though this (and other examples) shows though we can have some of this stuff completely wrong, and still make good recordings. ;)
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True. And it works the opposite too; one can get that stuff completely right and still make awful recordings :).

G.
 
SouthSIDE Glen said:
I think we're halfway there already. Most musicians I know are "grass" fed ;).

G.
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:laughings: HA HA HA HA HA :laughings:

Your spot on with that Glen.
Now to go out on the north forty to rope and brand a few *free range grass fed musicians*.





:cool:
 
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