Center channel phase question.

The front speakers should all be the same distance from the seating position. If the Center speaker is closer, the processor can delay the timing. Typically its 1 millisecond per foot. If you can set them equidistant with no adjustment, that is ideal.

Here is a great way to test phase, if you have any THX movie DVD's there are Optimizer menus where you can test for phase, if it is in phase it will sound properly anchored to its position, if it is out of phase it will be hard to place where the sound is coming from, if you dont have a THX disc try and rent one, the color tracks can be fun for casual TV tuing aswell.

Steuspeed is commenting on time alignment more than phase. I think the OP means is his center channel woofer moving out when the others are, and vice versa. There are a number of multichannel test discs, but my favorite (cuz it tests phase for all 5.1 speaker combinations) is MDG's Breakthrough Into a New Dimension DVD-Audio disc. It checks relative phase for l/r, l-center, r-center, etc. It's $19-25 at CD Universe, Acoustic Sounds, etc.