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Fulcrum CS121

21″ Subcardioid Subwoofer

Key Features.

  • Operating Mode: Single-amplified w/ DSP

  • Operating Range: 29 Hz to 143 Hz

  • LF Transducers: 21.0″ woofer, 6.0″ voice coil; ceramic magnet

  • Power Handling at Nominal Impedance: 2000 W @ 8 Ω

  • Equalized Maximum SPL (peak / continuous): 138 dB / 132 dB (half space)



The CS121 is a subcardioid subwoofer module intended for permanent installation in a wide range of venues. It includes a single, high power 21 inch direct-radiating woofer in a compact enclosure. A variety of mounting points facilitate suspension via shoulder eye bolts or a yoke bracket.

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.

The subcardioid behavior is produced by a meticulously conceived acoustical circuit which balances the position of the low frequency driver, the enclosure depth and volume, and specially constructed rear-mounted ports which include a calibrated resistive element. By opting for a subcardioid pattern as opposed to a pure, hyper or super cardioid pattern, the rear rejection increases when the modules are deployed in a subwoofer array.

Fulcrum Acoustic’s TQ™ processing is an integral part of the CS121 design. Sound, innovative acoustical design combined with state of the art digital processing leads to exceptional clarity and precise transient response, even at very high sound pressure levels. The required digital signal processing can be provided by one of many supported platforms.


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