Sanjay Durani (user-name: sdurani) wrote:
Keep in mind how dipoles work: there is an in-phase driver that pushes out while the anti-phase driver pulls in at the same time.
Dipole surround speakers are typically labeled Left & Right so that, when you set them up at your sides, the in-phase drivers are pointing towards the front of the room. This allows them to be in phase with your front speakers and avoid cancellation problems that can occur when out of phase drivers are facing each other.
Now, if you're going to place another pair of these same surrounds on the back wall as the rear speakers of a 7.1 set-up, you'll run into a problem. The anti-phase drivers of the side speakers will be pointing towards the rear of the room; in fact they will be facing the in-phase drivers of the rear speakers. So you'll have to swap the rear Left & Right speakers, which will make sure that like-phased drivers are always facing each other in your set-up.
Text copied from this AVS forum thread
page 9 of this pdf says "Point Arrow At Screen" which effectively aligns the polarity, although the picture isn't as clear as above.
Page 2 figure 5 of this manual also agrees with the above recommendation.
Page 15 agrees and says "If dipole-type speakers are used on either the side or rear walls of the room, please note that if there are arrows on the speakers they should face the front of the room for the side speakers, or toward the center of the wall for the rear speakers."
Interesting graphs of effects of dipoles and bipoles against the wall