In another thread, I've seen it described like this: the string forms an inverted "V", with the 1st mic at the top and the 2 drums (kick & snare) at the base.
Now you can move the top of the V to a whole lot (infinity, actually) of points that are all at the same distance from both drums as mic #1.
The trick lies in finding the 2 spots that'll sound the best.
