Speaker featuring speaker drivers on two opposite sides of a speaker enclosure and wired to operate out of phase (as one driver moves in the other moves out) creating a null to the sides of the speaker (very little sound emanating to the sides) and a broad, spread-out sound in general. Dipolar speakers contrast to bipolar speakers that also feature pairs of drivers on opposite sides of a speaker cabinet but which feature drivers that are in phase (they move in and out at the same time). ipolar speakers are used most commonly as surround channel speakers and are the only form of speaker certified by THX for use as surround channel speakers. They create a wide-open sound field that makes the individual speakers difficult to localize by their sound. Instead, the sound seems to come from all around thus enhancing the realistic effect of being in a different acoustic environment. Dipolar speakers offer a broad, enveloping sound with less directivity and pin-point imaging than direct radiating or even bipolar speakers.