Question about the 3:1 principle

[Audio~Geek]

This weekend the 3:1 rule has become a huge topic of controversy and now I need some professionals to put this argument to rest.

Does the 3:1 rule apply to stereo miking techniques?

The argument started over these photos: http://www.audiogeekzine.com/?p=525

I can't find a text that specifically says it does or does not apply.
this Tape Op thread made me rethink the 3:1 rule this week
http://messageboard.tapeop.com/viewtopic.php?t=55703

There is also the Recording Engineers Handbook as evidence.
http://books.google.ca/books?id=Emke...esult#PPA77,M1

and this:
http://www.recordingeq.com/articles/321eq.html

Ethan?
Bob Olhsson?
Mixerman?
Saint?
Anyone?!!!

[Ethan Winer]

Originally Posted by Audio~Geek

Does the 3:1 rule apply to stereo miking techniques?

Beats me. I imagine it will not affect stereo microphones if you have the microphones at an angle with the tips touching each other. Regardless, stereo micing usually implies that the microphones are much closer to each other than to the sound source. So you'd inherently have more than 3 to 1 distance.

--Ethan

[Audio~Geek]

Can I just quote you saying I'm right?

So lets say you want the mics 1ft away from the source, and want it in stereo, the rule would be to have the two mics at least 3 ft apart. Which rules out M-S, XY, and Blumlein.

:shrug:

[otek]

Rules Schmules.


They are good for winning internet debates though.

Here's how I do it:

I like to pan my stereo setups hard left and right. If the image is too wide or lacks center, I move the mics.


otek

[archtop]

Stereo micing should have the mics panned hard right and hard left, so no.

I believe the 3:1 rule should be observed if the mics are to be combined

[dwoz]

read this:

http://www.thewombforums.com/showpos...06&postcount=6


The (in)famous 3:1 rule refers to things like mic'ing chorus, orchestra, etc., with widely spaced mics. It has nothing to do with ORTF, Blumlein, x/y, etc etc.

dwoz

[qharley]

3:1 rule is mostly used in spaced techniques, usually using omni microphones. I have used this technique many time with success but:

• Needs to be a full acoustic ensemble (instruments, choirs etc)
• Room needs to be either anechoic, or with a complimentary reverb - avoid in rooms that does not sound good
• Normally works in a principal of what you hear is what you get. - The act needs to be good.

[malice]

Originally Posted by archtop

Stereo micing should have the mics panned hard right and hard left, so no.

I believe the 3:1 rule should be observed if the mics are to be combined

Well, it has to do with phase issue. So, yes, you have to be able to "combine them into a mono signal. But you could say for any stereo signal. It has to be compatible in mono.

Back to the original question.

The 3:1 rule is there for you to help dealing with multi miking technique. Especially when you have bleed between several mikes recording several different instruments.

If Mic A is one meter from the Bass, and the violin is 2 meters from the Mic A and picked by Mike B, 30 cm from the instrument: you might have phase issue with the Bass because of the bleed with the vilin Mike.

1 meters for Mic A from the source means that Mic B is to close, it should be either at 3 meters, or you have to get Mic A closer to the Bass (following me ?)

Violin miking respects the 3:1 rule, so there will be no or less issues.

As for stereo miking techniques : the 3:1 rule doesn't apply since the techniques are supposed to deal precisely with phase issues. See them as exceptions to the rules. Be sloppy at positioning the mikes in a stereo couple, and you'll hear problems comming. But note that all stereo miking techniques are not exempted of phase anomalies for that matter. Some are minimising them such as X/Y, but others are subjected to incoherencies, such as ORTF or A/B couple or Blumein (especialy if your sources are outside the 90° angle).

I'm always amazed about the confusion over the 3:1 rule, even with seasoned AEs. Some of the post I read from your link are quite staggering.

And don't ask Mixerman, he's clueless about these things

malice

[archtop]

uuuhhhmmmm

I don't think ANYBODY has ever recorded anything in an anechoic chamber, except data gathering for science
and mic/speaker specs.

and it does not need to be an acoustic ensemble either

many times you might want a room mic along with your close mic

Phasey shit is enough of a problem as it is, observing the 3:1 rule will not cure it, but directly disobeying it is probably not going to help you either.

just sayin'



Of coarse (course?) there are no rules

just some good guidelines


I personally observe the 3:1 rule if at all possible

[qharley]

Originally Posted by archtop

Of coarse (course?) there are no rules

Amen. If it sounds good... who the hell cares

[malice]

That is what I'm saying, for instance :

Violin miking respects the 3:1 rule, so there will be no or less issues.

Note the "less" part.

It should be use as a rule of thumb, of course. And should be observed as much as you can.

Many other aspects of sound recording mess with phase.

As always : use your ears to make a final decision

malice

[Audio~Geek]

I think part of the debate came from whether or not the way the piano was miked was stereo or not. I say it is, she says its not.

[malice]

Of course it is. There are 2 mikes, right ?

It's just ONE way to do it if you want a stereo representation of the piano where the bass and the treble register are panned left to right.

In classical, they prefer a more natural piano where the stereo comes from resonance and natural acoustics.

Now if you ask me, take out the lower front panel and do the same miking on the other end of the strings, it's a great way to mike an upright

malice

[qharley]

It is definitely stereo, just perhaps not stereo as you would hear it when you stand next to the piano.

edit: ok so this is what happens when you get distracted and take more than an hour to write one sentence...

[malice]

Originally Posted by qharley

It is definitely stereo, just perhaps not stereo as you would hear it when you stand next to the piano.

This is precisely the point. Some representation are faithful to a listener position, some are faithful to the player's perspective, and some are artistic and somehow : more artificial.

All valid candidates for stereo recording.

In this case, you can say it is more of a performer perspective because it is a representation of what you hear if you play the upright.

It might be not a perfectly accurate representation, but if you go that path : no stereo recording technique is 100% natural

malice

[qharley]

...and this is exactly why I love recording stuff. By just moving a mic slightly, you can get something quite different, and sometimes quite interesting and beautiful.

I tend to start off with approximately 3:1, but after moving the mics by ear is it almost never a mathematical 3:1 that makes the best sound.

[magicchord]

Originally Posted by malice

Well, it has to do with phase issue. So, yes, you have to be able to "combine them into a mono signal. But you could say for any stereo signal. It has to be compatible in mono.

Back to the original question.

The 3:1 rule is there for you to help dealing with multi miking technique. Especially when you have bleed between several mikes recording several different instruments.

If Mic A is one meter from the Bass, and the violin is 2 meters from the Mic A and picked by Mike B, 30 cm from the instrument: you might have phase issue with the Bass because of the bleed with the vilin Mike.

1 meters for Mic A from the source means that Mic B is to close, it should be either at 3 meters, or you have to get Mic A closer to the Bass (following me ?)

Violin miking respects the 3:1 rule, so there will be no or less issues.

As for stereo miking techniques : the 3:1 rule doesn't apply since the techniques are supposed to deal precisely with phase issues. See them as exceptions to the rules. Be sloppy at positioning the mikes in a stereo couple, and you'll hear problems comming. But note that all stereo miking techniques are not exempted of phase anomalies for that matter. Some are minimising them such as X/Y, but others are subjected to incoherencies, such as ORTF or A/B couple or Blumein (especialy if your sources are outside the 90° angle).

I'm always amazed about the confusion over the 3:1 rule, even with seasoned AEs. Some of the post I read from your link are quite staggering.

And don't ask Mixerman, he's clueless about these things

malice

Thanks to Malice, I don't have to type a thing; he's absolutely right. So there.

[archtop]

From the pic, I can't tell if the mixer panned them hard left and right, (stereo) heck they might have put them up the middle (not stereo) neener neener

[lebouche]

I had a problem today, had a band in and they've been reading up on the net and wanted a space pair of 414's. I didn't have the wdith in my room where the drums sound best to follow the 3-1 rule unless we had the overheads really low. What part of the drums do you consider the '1' part to be anyway?
I ended up having a space pair up high in about 5 ft in front of the kit angles down at about 45 degree's. Didn't like it much but they were happy. Still felt like an idiot. Really need some help with my overhead skills. The only time I'm happy is Glyn Johns or recorder man and occasionally low spaced pairs as cymbal mics.

[Bob Olhsson]

It's all about avoiding comb filtering when the mikes combine.