The AC 23S Crossover is back in production and available to order!
The Rane AC 23S Active Crossover can be configured as a stereo 2- or 3-way, or a mono 4- or 5-way. It employs 4th-order Linkwitz-Riley filter alignments to minimize phase difficulties in the critical crossover region. The AC 23S uses XLR connectors with active balanced Inputs and Outputs.
Simply put, a Linkwitz-Riley alignment is two cascaded 2nd-order Butterworth filters exhibiting identical phase characteristics on their low-pass and high-pass outputs. This characteristic guarantees in-phase outputs at all frequencies. In-phase outputs are 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 23S, adjustable Delay circuits appear on the Low & Mid 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.
In 2- or 3-way stereo mode, the low outputs may be mono'ed by moving an internal jumper. Constant directivity (CD) horn equalization is possible with an internal modification. See the manual for details.
How can I get my AC 23S crossover point below 190 Hz in 2-way stereo mode?
The AC 23S is not designed for 2-way operation below 190 Hz. You can "fake it" by using a summing Y-cable (check out Why Not Wye?) on the mids and highs in 3-Way mode. This allows you to use the Low/Mid (70 - 1 khz) filter for the lows.
My AC 23 doesn't have the 2-way / 3-way switches on the rear panel, how can I run it in 2-way mode?
Earliest (ancient, circa 1985) AC 23 units did not offer 2-way mode operation. They run 3-way stereo, 4-way mono and 5-way mono only. Externally combining a pair of signals -- mids and highs or mids and lows -- provides a means to achieve 2-way functionality. As above, the summing Y-cable is used to mix two signals together, (see Why Not Wye?).