Phase & Proximity Effect

What is phase?

Checking the phase is especially important when recording a multi-mic’ed instrument e.g. a drum kit because the more mics used on a session, the more difficult it is to keep them in phase.

Why must the phase be checked?

Because of a phenomenon known as phase cancellation when the peaks and valleys do not occur at the same time, cancelling each other out at certain frequencies. This results in a weak overall sound when mixed together.

What do In Phase waves look like?

Peaks and troughs happen at same time, no frequencies are cancelled out, they reinforce each other, and it sounds loud and full.

What do In Partially Out of Phase waves look like?

The peak and troughs happen at different times, certain frequencies are cancelled out, and it sounds weak/thin/hollow.

What do In Completely Out of Phase waves look like?

The peaks and troughs happen at opposite times, every frequency is cancelled out, and there’s silence.

How can you keep two microphones in phase using a tape measure whilst recording an instrument?

Check distance from mic 1 is similar to distance from mic 2, ensure mics are equidistant.

How can you keep two microphones in phase using mic distance whilst recording an instrument?

Ensure any two mics are not too close together.

How can you keep two microphones in phase using the three to one principal whilst recording an instrument?

The distance between the mics should be 3x the distance from the sound source to reduce the effect of phase cancellation.

How can phase cancellation be fixed in post-production?

By pressing the polarity switch which flips the phase of the audio wave, but stick with a position that sounds good.

What is Proximity Effect

a phenomenon that occurs when a mic is very close to a sound source. Due to the close proximity, bass frequencies are enhanced.

Is proximity effect positive or negative?

can create a warm, intimate sound. But too much bass build up can make a mix sound muddy.

How is proximity effect reduced?

Move the mic off the axis so it is not facing the sound source directly. Simply moving the mic further away from the sound source would increase room ambience.