A term used to characterize certain loudspeakers. The word concentric indicates a common center. Loudspeakers where the woofer and tweeter share a common center point are known as dual concentric (sometimes called coaxial, though this is not as specifically precise). Dual concentric speakers have the advantage of all sound emanating from one point (they are also called “point source” monitors), which eliminates certain frequency interference problems near the crossover point that occur in monitors where a woofer and tweeter are some distance apart. These anomalies occur because around the crossover point the same frequencies are being reproduced by both drivers, however, they are generally slightly different distances from the listener’s ear (in addition to having slightly different surroundings on the face of the speaker cabinet), which creates arrival time differences and the accompanying comb filtering characteristics. The phenomenon is generally not nearly as severe as a word like “comb filter” implies, however, because at the frequencies relating to a typical crossover point the time delays involved are minute enough that the phase cancellation is somewhat minimal.