I've been assisting another engineer on a harp CD project and he's been using an interesting trick that is new to me. The trick is inverting the polarity on one side of a stereo ambient pair in order to move the reverb away from the center. In this particular setup, he was using a coincident pair of cardioids with a 180 degree included angle. The mics were at least 40' from the close pair and the two were not time aligned. I had him do some AB-ing for me, turning the polarity shitch on and off, and it was very cool to hear the reverb move from a mass in the center to a huge, beyond the speakers inveloping effect. I understand the idea of antiphase and how all this works, but what I was wondering is this: Have you heard of or done this, and is it a good idea?