3 to 1 rule - Best Explanation

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mattkw80

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I have read dozen's of articles and books explaining phase and the 3 to 1 rule.... but this one turned the light bulb in my head on......

http://www.independentrecording.net/irn/columns/jwal/

QUOTE : The 3 to 1 rule is about isolation, not phase. The 3 to 1 rule can make it easier to avoid phase problems, but only because it isolates one mic from the other. It's the isolation (the lack of bleed) that keeps the phase problems in check, not because it's some magic point in space where all the frequencies become time-aligned. (that can't happen)

WOW !!! - I had that wrong all this time. I did think that there was a point in which all frequencies would sync. I did not consider the basis of the 3 to 1 rule was simply isolation!! That's probably why, many times I did get phase problems in my drum overheads. I was searching for a "magic" position that did not exist, versus - good old isolation using distance, and the proper polar patterns.

Many of the other articles I've read never flat out said that.

Great article !
 
Matt,

Jay will probably read this thread himself, but just in case, you may want to drop him an e-mail via the I/O page on that website just to let him know. I happen to agree with you, but Jay has expressed some self-doubts that he's a very good writer/explainer. Maybe some positive reinforcement form his readers will help convince him otherwise :).

As far as the 3:1, he and you are absolutely correct, there is nothing magical about 3:1 as far as phase whatsoever. Think about it for a minute: every frequency has it's own individual wavelength. It's impossible for any distance to be related to every wavelength at the same time.

G.
 
The snare mic needs to be at least 3 times closer to the snare than the tom mic.
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Not to be nitpicky, but I might suggest the author re-word this. Shouldn't it be:
The snare needs to be at least 3 times closer to the snare mic than the tom mic.
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(At least as I understand it....)
 
andyhix said:
Not to be nitpicky, but I might suggest the author re-word this.
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Yeah, I can see where the way you phrase it is a bit less ambiguous. I know that what Jay meant was the same thing as what you describe, but the way it is written, it can be misinterpreted in a slightly different way.

The important thing here is the relationship of the distances between the mics and their respective sources, not necessarily between the mics themselves. The way it is written can be misinterpreted to mean the latter.

I do have editor capability (and responsibility). As such, that is just as much my fault for not catching it as anybody else's. I can make that change, but let me just run it by Jay first as it is his article.

G.
 
Ok, it's settled then. The re-wording has been made. Thanks Andy and Matt.

G.
 
No problem - I am pumped now.....

...I know it maybe a no brainer to other people, but the "isolation" part of the 3 to 1 rule takes alot of confusion out of it for me.

I just read "mixing with your mind" which is a $70+ book..... even it did not explain it that clearly.

Can't wait to grab a couple of mics, and setup up some drum overheads -- now that I understand the basics of what I'm supposed to be doing with them.
 
mattkw80 said:
I have read dozen's of articles and books explaining phase and the 3 to 1 rule.... but this one turned the light bulb in my head on......

http://www.independentrecording.net/irn/columns/jwal/

QUOTE : The 3 to 1 rule is about isolation, not phase. The 3 to 1 rule can make it easier to avoid phase problems, but only because it isolates one mic from the other. It's the isolation (the lack of bleed) that keeps the phase problems in check, not because it's some magic point in space where all the frequencies become time-aligned. (that can't happen)

WOW !!! - I had that wrong all this time. I did think that there was a point in which all frequencies would sync. I did not consider the basis of the 3 to 1 rule was simply isolation!! That's probably why, many times I did get phase problems in my drum overheads. I was searching for a "magic" position that did not exist, versus - good old isolation using distance, and the proper polar patterns.

Many of the other articles I've read never flat out said that.

Great article !
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I belive there is some magic point in space. Sue me.
 
Technically, there is a magic point in space where all the wavelengths will line up. It's fairly simple arithmetic to find the least common multiple of all your wavelengths; just multiply them all together.

i.e. if you've got 3 drums with wavelengths of 3, 4, and 5 meters, you'd want to put your mike 60 m away. Magic point found!
 
VomitHatSteve said:
Technically, there is a magic point in space where all the wavelengths will line up. It's fairly simple arithmetic to find the least common multiple of all your wavelengths; just multiply them all together.

i.e. if you've got 3 drums with wavelengths of 3, 4, and 5 meters, you'd want to put your mike 60 m away. Magic point found!
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That's fine as long as you're working with a finite series of numbers. The problem is the frequency spectrum is a continuum; there are an infinite number of frequencies between 20 and 20k. This would mean that the "magic point" would be infinitely far away.

This would also mean that the volume at the source would have to be infinitely loud. Only a handful of drummers can do that :D.

G.
 
mattkw80 said:
No problem - I am pumped now.....

...I know it maybe a no brainer to other people, but the "isolation" part of the 3 to 1 rule takes alot of confusion out of it for me.

I just read "mixing with your mind" which is a $70+ book..... even it did not explain it that clearly.

Can't wait to grab a couple of mics, and setup up some drum overheads -- now that I understand the basics of what I'm supposed to be doing with them.
Click to expand...
The 3 to 1 rule has nothing to do with stereo mic techniques, if that's what you are talking about. Otherwise XY, ORTF, etc... wouldn't work.
 
Farview said:
How could that be? Can you explain it, I will add it to my article.
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I would contend that it is only possible in theory with perfect sine waves in a completely non-reflective environment and in a non-absorbant medium. You won't find those things in a studio.

To the OP,
This is a very nice article that helps clear things up, but IMHO the 3:1 rule is really not something people need to spend much time thinking about. Unless you're doing something really weird with microphones it really doesn't come into play.

I also can't think of how this is applicable to overhead mics.

Sorry to burst bubbles, but I just don't think that understanding 3:1 is going to instantly improve your recordings. I'd look into topics more focused on overhead micing if that's what you're looking to improve. Things like X-Y placement and the "Recorderman" method are more practical.
 
I use the recorderman - almost every time.

Some times - it works.

Other times - I get phase issues.

I try to measure the same way everytime, and try to pan the 2 tracks the same way every time.

One thing is constant : When I do have phase issues, the drums sound limp. When I don't have phase issues - the drums sound so good, that I can't believe that I recorded them. I have a plugin that tells me when tracks are out of phase with each other.

I've got a few songs where I really wish I would have taken a picture of the setup, as they drum tracks are great. Always the same room, and the same kit, and the same mic. The only thing that could be different - is the placement measurements.

What does drum overheads have to do with the 3 to 1 rule - you ask ?

Drum Overheads and Drums in general are pretty much the only multiple mic situation in my home studio - and it's the only area where I have a phase problem.... so I am researching the 3 to 1 rule to try to resolve the issue.
 
mattkw80 said:
What does drum overheads have to do with the 3 to 1 rule - you ask ?

Drum Overheads and Drums in general are pretty much the only multiple mic situation in my home studio - and it's the only area where I have a phase problem.... so I am researching the 3 to 1 rule to try to resolve the issue.
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But the 3 to 1 rule works by isolating the mics. Stereo mic techniques work because of the interaction between the mics. The 3 to 1 rule doesn't apply to stereo mic techniques.
 
PhiloBeddoe said:
...I also can't think of how this is applicable to overhead mics.

Sorry to burst bubbles, but I just don't think that understanding 3:1 is going to instantly improve your recordings. I'd look into topics more focused on overhead micing if that's what you're looking to improve. Things like X-Y placement and the "Recorderman" method are more practical.
Click to expand...
...Nah I think you missed the whole point (if I may presume for the Mattman' :) -It clearly got 3:1 out of the equation and free to move on to what does count. ;)
3:1 has been tossed around in and along side the context of 'phase' as if they are connected, in some cases with incorrect or just about as bad, no clear 'how, why' and why nots'.
 
mixsit - be my guest, please presume all you want !!

I am confused though....

...so..... I throw my 2 recorderman mics up, but I shouldn't worry about 3 to 1 because now it's irrelevant ?

Why does "stereo drum overheads" make 3 to 1 irrelevant?
 
MCI2424 said:
I belive there is some magic point in space. Sue me.
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And why not. Multiple mics, multiple distances- That would be those spots where yeah, some tones are in', some out' -as they must be -But it sounds just fine. ;) Imagin that. :D
 
mattkw80 said:
mixsit - be my guest, please presume all you want !!

I am confused though....

...so..... I throw my 2 recorderman mics up, but I shouldn't worry about 3 to 1 because now it's irrelevant ?

Why does "stereo drum overheads" make 3 to 1 irrelevant?
Click to expand...
Oops. Ok. :D Back up again. It doesn't relate because the only thing worth a damn remember 3:1 does is to attenuate the 'other mic' so you don't here cross-feed of the same source from two different times from two different mics. The kit you're micing is 3 or 4 feet wide. There is no point (let alone two points) that will have all the kit line up in time. (Oops, there is one, it's call XY' -but it ain't the sound of 'spaced pair'.
You keep both mics the same distance (time) from the center focus of the kit (snare and kick) then pick that height to sound nice (tones partly in' and partly out') with the close mics and/or room reflections if that's a factor. The rest is candy.
Look up ORTF'. That is a slightly 'expanded xy- Lows, mids in phase, candy' smear on the top.

Distance attenuates. Time' is the frequency choices, relative volume is the 'in-out of phase' depth control.

Try this. One O/H, one snare at 4" from the side- There is no point (with in the direct field) where when you blend the two the tone of the snare does not change. There are many 'points' where flipping the snare polarity are but equally usefull tasty 'versions'. None are in phase at all frequencies.
 
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