This is a symmetric (or asymmetric) load wherein are mounted two speakers facing each other. The back side of the upper speaker looks at a fully enclosed load damped by some absorbent material while that of the lower speaker looks a bass-reflex load where the vent is located at the base of the enclosure. Each of the two speakers respectively receives the modulation from the right channel and the left channel. They are connected in parallel with crossed phases, so when one ahead the other back, and vice versa (push-pull) ... Thus they accept twice the power of a unique speaker with full compensation of non linearities.
This push-pull mount with shifted coupling allows to smooth the parasitic resonances and to down very low in frequency with excellent linearity for a reduced volume. By this principle of load, the cut is made acoustically and so there is no need of a lowpass filter, hence a better impulse response and a damping factor close to ideal.
Art & Acoustique Appliquée
3A patent filed January 13, 1988 n° 88 00 317
