The CS121 incorporates Fulcrum’s patent-pending Passive Cardioid Technology™ to overcome one of the major challenges of many loudspeakers: excessive rear LF radiation. Unlike active cardioid loudspeakers, Fulcrum’s passive cardioid technology does not require an additional amplifier channel or additional transducer to achieve its impressive low frequency directional control: 10 dB of rear rejection over the subwoofer’s operating range.