The AC 22S from Rane is an active crossover that can be used as a stereo 2-way with a mono subwoofer option, or configured for mono 3-way operation. It employs state-variable 4th-order Linkwitz-Riley filter alignments to minimize phase difficulties in the critical crossover region.
The Linkwitz-Riley alignment consists of 2 cascaded 2nd-order Butterworth filters exhibiting identical phase characteristics on their low- and high-pass outputs, guaranteeing in-phase outputs at all frequencies.
An added benefit of this topology is steep 24dB per octave roll-off slopes. Because of the steep slopes, drivers designed to produce a specific range of frequencies, and no more, will not be driven past their limits, thereby minimizing distortion and driver fatigue.
Adjustable delay circuits are included on the low output of each channel (and mid output when used in 3-way mode) to compensate for any physical misalignment of the drivers. Time correction ensures the mechanical phase alignment of adjacent drivers will be acoustically correct, thus providing transparent operation.
CD horn equalization is also possible with an internal modification.