PCX 4000 High Precision Stereo 2/3-Way Mono 4-Way Crossover World-class performance 24dB per octave Linkwitz-Riley filters Absolutely flat summed amplitude response, zero phase difference Switchable 25Hz subsonic filter on each input for low frequency driver protection Individual limiter on each output for optimal loudspeaker protection “Low Sum” function provides low-level mono output for subwoofer operation Adjustable time delay for phase alignment between drivers CD horn equalization for constant directivity horn compensation Individual output level controls for all bands Individual output mutes for easy band adjustment Individual phase reverse switches for instant phase correction Servo-balanced, XLR connectors for all inputs and outputs Precision potentiometers for ultimate accuracy and repeatability Low-noise audio operational pre-amplifiers for outstanding sound performance