I was asked to post a Lissajou graph of one of my recordings, to show the stereo separation. This is from Cantus performing "Lux Aurumque" from their "While You Are Alive" CD that I recorded in 2007. The 9 singers are arranged in an arc around the microphone array and can be heard to be equally spaced form 3/4 left to 3/4 right. In this kind of graph a vertical line is a signal at hard left, a horizontal line a signal at hard right, and a line at 45 degrees slopping upward from left to right a dual-mono, in-phase signal.
Cantus Recording Phase Response