old thread, but im bored, as usualy, lol.

they key eliment to what audiophyl was talking about is relative phse when two or more speakers are interacting. if you had a mono system with just one speaker, there would be no reason to talk about phase becuase its just one speaker. its always perfectly in phase (well, of course you do get reflected sound waves, but assume you were in an anechoic chamber for this example). its like dropping one rock into a pond. it produces perfectly concentric circles of waves around it. imagine those as the sound waves.

now you add a second speaker, or for our example, a second rock dropped into the water. depending on the physical location of the new speaker, its amplitude, and several other factors, you run into situations where the waves interact, either causing positive re-enforcment or cancellation. cancellation occurs when two waves that are 180 degrees out of phase with each other meet. the pressure wave is then nullified, resulting in no sound (although its rare for two waves to completely cancel each other out). positive re-enforcment occurs when the two waves are in phase with each other, and they sort of "add" up.

so the whole point is this: by reversing the mechanical polarity of the mid speaker on the passengers side, you are effecting the way the sound from that speaker interacts with all the other waves produced by the rest of the system. this could result in better or worse sound, and may make a certain song that sounded good before sound terrible, while a terrible sounding soung sounds great. you might wind up wiith a huge peak at 500hz and a huge valley at 2khz. theres a lot of experimentation involved in creating the perfect sound enviroment.