The 311 crossover from ART may be used as a stereo 2-way crossover network and has the addition of the subwoofer output for low-end frequency reinforcement. It employs 24dB/octave state-variable, Fourth-order Linkwitz-Riley filters that guarantee properly phased outputs at all frequencies. Each channel features independent high and low output level controls and a crossover frequency rotary control which covers a wide range of 250Hz to 6kHz. All three outputs have a 30 cycle low cut switch to eliminate low-end rumble. The subwoofer features an independent output level and rotary control for frequencies in the 50Hz to 250Hz range.