The Record Producer
Page 68
Chapter 5
Omni-Phase
The all encompassing reality of wave relationships.
When the drum head is struck, it naturally begins to vibrate creating
wave energy that travels 340.29 m/s away from the drum. As the
distance of each microphone from the drum varies, the precise
moment that the signal is received will also vary. When your
speakers then reproduce the sound; the two signals will generate
wave energy that will vary in degrees of phase distortion, when the
waves reach mix position. So, when you listen to the recording you
should notice the sound change each time your microphone was
moved.

There are an infinite number of phase degrees, just as
unfortunately, an infinite number of variables will alter the
effectiveness of this experiment. At mix position, when the snare hit
sounds the quietest; the distortion is closest to 180 degrees out of
phase. You will have to use your ears and judge the approximate
changes in degrees.

Microphone phase is impossible to control. Gravity pulling on the
microphone stands can alter the distance of a microphone from an
instrument enough to change the degree of phase distortion. Thus,
professional mixing consoles are equipped with a phase button on
each channel. This button changes each of your nodes to
anti-nodes, and vise-versa.