3:1 Rule of Thumb Illustrated

[jimmys69]

View attachment 81388

Sorry if this doesnt belong in this thread, but I was pretty surprized when I saw this picture of Van Halen recording at Sunset Sound. Is it a common thing to record a band playing that loud without any isolation?

It sure looks like David lee Roth is planted for the picture, but the rest looks real.

Sunset Sound & Sound Factory

They put them in studio 2 to decide if they were worth putting in the main one. And then decided how much deposit to demand, based upon the beer cans, cigarettes, demands for brown M&M's, and combined ego. I'm sure it was around $25,000. lol

From hearing the raw tracks from Diamond Dave, there is no way that they recorded in the same room. Just a photo opp... Likely of a rehearsal.

 

[mixsit]

Hmmmm. This discussion about the 3:1 rule differs from my understanding. I thought the guideline applies to the difference between two mics being used on one source, not the distance of each mic from the sound source. For example, when micing a choir, if two mics are placed ~ 3 feet in front of the vocalists, they should be ~ 9 feet apart. Is this outdated? If so, there is a lot of misinformation on the internet because a quick google search pulls up numerous references consistent with what I described. And they state that the main objective is to minimize comb filtering.

A few things then- When one says a 'guideline applies to the difference between two mics being used on one source... Let's tart there. That (not your fault..) again on it's own w/o clarification is useless.
Now, one source, two mics.. we're getting closer..

Ordering from the menu today sir!
Will that be the Near + far mic combo, or I hear the 'Stereo pair is excellent today!
Ah! And for a main course, we have the Guitar Cab special, or 40' Wide Choir?

..So it's not simply a matter of placing the second mic farther from the source such that the recording level is diminished and thereby reduces phase problems. This explanation doesn't actually make sense to me, so I'm not defending it.

The rule' is exactly that -attenuating bleed you don't want to have effecting your mix of signals.
Latch on to that, it takes about -9dB apparently in general. How you get there ..turn it down, separation matters not...
Relative level is like your wet/dry mix on your 'phase shifter.
Time difference is your phase tone' frequencies.
So 'mic distances are playing with both.

 

[Farview]

Hmmmm. This discussion about the 3:1 rule differs from my understanding. I thought the guideline applies to the difference between two mics being used on one source, not the distance of each mic from the sound source. For example, when micing a choir, if two mics are placed ~ 3 feet in front of the vocalists, they should be ~ 9 feet apart. Is this outdated? If so, there is a lot of misinformation on the internet because a quick google search pulls up numerous references consistent with what I described. And they state that the main objective is to minimize comb filtering. So it's not simply a matter of placing the second mic farther from the source such that the recording level is diminished and thereby reduces phase problems. This explanation doesn't actually make sense to me, so I'm not defending it.

Its not outdated, it was never accurate in the first place. Think about it, if you put a Mic.five feet from a guitar amp, you would have to have the mics 15 feet apart, with your understanding.

The 3-1 rule has nothing to do with stereo Mic technique.

Anyway, when would you put the mics only 3 feet from a choir? (unless its a very small choir) In order to get a cardioid to cover half a a large choir, it would need ti be back 10 feet or so...which would force you to have the mics 30 feet apart. If it were true, it would get ot of hand very quickly. Good thing it isn't.

 

[Steenamaroo]

Hmmmm. This discussion about the 3:1 rule differs from my understanding. I thought the guideline applies to the difference between two mics being used on one source, not the distance of each mic from the sound source. For example, when micing a choir, if two mics are placed ~ 3 feet in front of the vocalists, they should be ~ 9 feet apart. Is this outdated? If so, there is a lot of misinformation on the internet because a quick google search pulls up numerous references consistent with what I described. And they state that the main objective is to minimize comb filtering. So it's not simply a matter of placing the second mic farther from the source such that the recording level is diminished and thereby reduces phase problems. This explanation doesn't actually make sense to me, so I'm not defending it.

There's a muddle of different circumstances here.
Single source, two mics, combined sound.
Single source, two mics, stereo image.
Two sources, two mics, isolation required.


Traditionally the 3-1 rule applies where there are 2 sources, 2 mics and isolation is required.

Putting a 57 and a 421 on a cab is not the same. You've moved those mics until you like what you heard.
The 'problem' created by <3-1 with 2 mics 2 sources is the goal with a cab and 2 mics!


With a choir you're dealing with stereo image.
If you take the very first image on the page, those two loudspeakers could represent altos and sopranos.
Depending on the size of the choir, you could get 3-1 on the extreme l+r of the choir, 1-1 on the people bang in the middle, and the rest is the best of a bad job.
If you're trying to create a stereo image, that's not a bad setup, right?

Idk, the choir example you gave is probably a tried a tested happy medium or whatever, but if someone said "tell me about 3-1 rule", I wouldn't start talking about choirs.

Thinking about it, I observe 3-1 rule when stereo micing an acoustic.
Not because I read it somewhere and think it's a rule that I should follow in that context, but because that's what I've found to sound the best through trial and error.

Basically it happens to fit, kinda, but it's not what the rule is for.

 

[bouldersoundguy]

Hmmmm. This discussion about the 3:1 rule differs from my understanding. I thought the guideline applies to the difference between two mics being used on one source, not the distance of each mic from the sound source. For example, when micing a choir, if two mics are placed ~ 3 feet in front of the vocalists, they should be ~ 9 feet apart. Is this outdated? If so, there is a lot of misinformation on the internet because a quick google search pulls up numerous references consistent with what I described. And they state that the main objective is to minimize comb filtering. So it's not simply a matter of placing the second mic farther from the source such that the recording level is diminished and thereby reduces phase problems. This explanation doesn't actually make sense to me, so I'm not defending it.

Think of the different parts of the choir or any large group as different sources and then it fits my explanation. You're still going to get some interaction from parts of the group that are more or less equidistant from the two mics, but most of the signals from each mic will be sufficiently isolated that it will sound okay overall.

 

[Greg_L]

There's a muddle of different circumstances here.
Single source, two mics, combined sound.
Single source, two mics, stereo image.
Two sources, two mics, isolation required.


Traditionally the 3-1 rule applies where there are 2 sources, 2 mics and isolation is required.

Putting a 57 and a 421 on a cab is not the same. You've moved those mics until you like what you heard.
The 'problem' created by <3-1 with 2 mics 2 sources is the goal with a cab and 2 mics!


With a choir you're dealing with stereo image.
If you take the very first image on the page, those two loudspeakers could represent altos and sopranos.
Depending on the size of the choir, you could get 3-1 on the extreme l+r of the choir, 1-1 on the people bang in the middle, and the rest is the best of a bad job.
If you're trying to create a stereo image, that's not a bad setup, right?

Idk, the choir example you gave is probably a tried a tested happy medium or whatever, but if someone said "tell me about 3-1 rule", I wouldn't start talking about choirs.

Thinking about it, I observe 3-1 rule when stereo micing an acoustic.
Not because I read it somewhere and think it's a rule that I should follow in that context, but because that's what I've found to sound the best through trial and error.

Basically it happens to fit, kinda, but it's not what the rule is for.

All this ^^^^^

For every 3 bad posts on this subject, there's one good one. This is one of them.