Phase Checking

My main objective for recording this track was to experiment with miking up an electric guitar through an amplifier. I decided to use 4 various different mics to mic up the amp so I could assess how each mic sounds. I positioned the AKG 414 and the 57 Beta A in front of the two speaker cones on the front, I positioned the sm57 off-axis and miked to the side of the amp and used the sm58 to mic the amp from behind, to capture a 'boomy' low end texture from the amp.

As I was multi-miking the amp, I had to carry out phase checks for the four mics, to make sure they were all in phase with each other to get the best guitar sound I could.

I decided to use the AKG 414 as a reference mic and position the other mics to be in relative phase to it.

On ProTools, I used Trim to phase invert the three mics I was to position. I then turned the amp up loud, but turned the guitar right down on the guitar itself, so that the amp was generating a loud buzz. I used this loud buzz as noise for the mics to pick up and sent what was being picked up down a headphone mix, so I could listen to see what position was best for the mics to be in phase.

When you are phase checking, you are looking for the spots in which the diaphragms of each mic are picking up the sound waves of the amp in phase with one another to void possible destructive interference and generating a really strong electric guitar sound.

I have used trim to phase invert the three mic channels, as it is easier for the ear to pick up amplitude changes between smaller amplitudes than it is to tell the difference with very loud volumes, so when I am phase checking I am soloing the reference mic and each of the positioning mics' one by one, moving around the mic until the what is being heard through the headphones is at its quietest, this will mean the mics are out of phase to the reference mic, but when you use trim to phase invert the mics back, they will all be in phase with one another.