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Fulcrum CSP121

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 CSP121 is a portable, subcardioid subwoofer module intended for a wide range of venues. It includes a single, high power 21 inch direct-radiating woofer in a compact enclosure. An M20-threaded connector plate is centered on the CSP121’s top panel for use with the optional, height-adjustable SP1 Speaker Pole. This pole’s M20 threaded bolt screws securely into the connector plate and is used to mount loudspeakers equipped with a 35 mm / 1.38 inch pole socket directly above the CSP121. Four vibration isolation feet prevent spurious vibrations and “walking”. When stacking enclosures, the vibration isolators nest in recesses in the enclosure below.

The CSP121 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.

Fulcrum Acoustic’s TQ™ processing is an integral part of the CSP121 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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