Three to One Rule

Robert Katz Leave a Comment

From: “Knut Erling Johnsen”

Hello

Is there somthing which I have misunderstood…?

In an article called “The Properties of Sound Part 4”, written by Kevin Becka About.com Guide to Home Recording http://homerecording.about.com it’s beeing said…:

The Three to One Rule

The other situation we talked about was if the two mics were equidistant from the source. This is a very common way of miking an acoustic guitar or a piano for instance. In this case you can follow what is known as the Three-to-One rule. This rule states that for every unit of distance away from the sound source, your mics should be at least three units apart. For instance, if your mics are six inches away from the source then they should be eighteen inches apart. If they’re 1 foot from the source they should be three feet apart. This will keep you out of phase problems when close miking.

In another article on your website the 3 to 1 rule is described the following way…:

When a sound source is picked up by one microphone and also”leaking” into another microphone that is mixed to the same channel, make sure the second microphone is at least 3 times the distance from the sound source as the first.

To me it seems like the first def is talking about moving the microphones apart from each other on the x-axis and the other def is talking about moving the microphones away from each other on the y-axis. Am I wrong? Is someone else wrong?

What is correct, then…?

With regards

Knut Erling Johnsen

Norway

Hello, Knut.

Good catch. I just checked in the original Burroughs text dated 1974.

Looks like you’re right! I’ll have to correct it. The “interfering” microphone must be at least 3 x the distance from the “main” microphone as the “main” microphone is from the musician.

Note that this is primarily for a mono situation, and in stereo, the distances may be more tolerable.

Sorry for the confusion,

Bob

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