RANE AC 22B Active CrossoverThe Rane AC 22B Active
Crossover is configurable as stereo 2-way or mono 3-way. It employs
state-variable 4th-order Linkwitz-Riley filter alignments to minimize
phase difficulties in the critical crossover region. The AC 22B uses XLR
connectors with active balanced inputs and outputs. The Linkwitz-Riley
alignment is two cascaded 2nd-order Butterworth filters exhibiting
identical phase characteristics on their Low pass and High pass Outputs.
This guarantees in-phase outputs at all frequencies, mandatory for
proper acoustic summing of common signals from adjacent drivers in the
crossover region. An added benefit of this topology is steep 24 dB per
octave rolloff slopes. A slope of this magnitude guarantees 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.
To further guarantee the transparent operation of
the AC 22B, adjustable time delay circuits appear on the low (and mid
when used in 3-way mode) outputs of each channel to compensate for any
physical misalignment of the drivers. Time correction ensures the
mechanical phase alignment of adjacent drivers will be acoustically
correct, thus maintaining the integrity of the electrical phase
alignment of the crossover's filters. The low delay circuit may be
internally transplanted to the high output when neccessary. CD horn
equalization is also possible with an internal modification. A mono
subwoofer switch provides the option to sum both low outputs in stereo
2-way mode.