Rane AC22 Active Crossover

Features
• Stereo 2-Way or Mono 3-Way
• Linkwitz-Riley Alignment with 24 dB per Octave Slopes
• Adjustable Delays
• Mono Subwoofer Switch and Output
• Infrasonic, Ultrasonic, and RFI Filters
• Low Output Muting (2-Way)
• Input & Output Level Controls
• UL/CSA/CE and 100/120/230 VAC Remote Power Supplies
• ¼" TRS Inputs & ¼" TS Outputs
• Active Balanced/Unbalanced Inputs & Unbalanced Outputs

From the Rane Data Sheet:
General Description
The Rane AC 22 and AC 22B Active Crossovers are Stereo 2-Way with mono subwoofer option, or can be used as a Mono 3-Way. They employ state-variable 4th-order Linkwitz-Riley filter alignments to minimize phase difficulties in the critical crossover region. The model AC 22 utilizes ¼" TRS connectors with balanced/unbalanced inputs and unbalanced outputs. The new AC 22B 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 22 and AC 22B, adjustable Delay circuits appear on the Low (& 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.