CB211sl - Larger-format shallow subwoofer system

  • Single 21” extended-excursion woofer with 4 ohms impedance
  • Lowest usable frequency 19Hz.
  • Signal Integrity Sensing™ pre-wired cable compensation
  • Space-economic design for easy wall / behind-screen positioning
  • larger-format shallow subwoofer system Also available in “Front-Vent” version for baffle-wall mounting

Product description

The CB211sl is a direct-radiating slim subwoofer system for demanding cinema applications, delivering tight and accurate bass and sub response with very low distortion.
It is designed to meet all requirements of current and future (Digital) Cinema sound formats.

The direct-radiating 21” extended excursion woofer with large, 4.5” voice-coil is mounted in an optimally vented chamber, with a large bass reflex port for excellent breathing capacity, increasing overall output while minimising port-compression. Specific attention has been paid to obtain a linear response in the operating bandwidth, while handling low frequency transients with maximum control.
The 4 ohms impedance offers maximum amplifier efficiency.

Although the CB211sl has a slightly lower sensitivity than the 18” version (due to the higher mass), it has around 6 dB more excursion capability, greatly increasing the excursion-limited output performance.

The slim enclosure design provides for stacking, flying or wall-mounting. The side-oriented reflex vent enables the cabinet to be closely mounted behind the screen without chance of screen resonance. The CB211sl is also available with front-venting for in-wall baffle mounting (“FV” version).

For full system performance, the CB211sl is to be driven and controlled by the ALC amplified loudspeaker controller; Driven by the ALC, the CB211sl delivers maximum sound quality and output power with long-term operation reliability. The integrated factory presets in the drive processor of the ALC offer gain, phase and filtering matching.

The Signal Integrity Sensing™ pre-wiring ensures complete cable/connector compensation between the CB211sl and the ALC amplified loudspeaker controller, significantly increasing response accuracy, regardless of cable length and system impedance. Especially with the cinema-typical long speaker cable runs and the subwoofer system’s possible low impedance, the effect is remarkable, resulting in really tight and accurate reproduction for even the lowest octaves.

Due to its form factor, the CB211sl is designed as low frequency extension in medium-to-large cinema systems, as well as Rear LFE subwoofer channel in large immersive surround systems.

Dimensional drawing

Technical specifications

Frequency response 24 Hz -     (+/- 3 dB)
19 Hz -    (+/-10 dB)
Sensitivity nominal 95 dB (40 Hz – 100 Hz)
Nominal impedance 4 ohms
Recommended drive     Sentinel3 min., max. 1 pce. per channel (4 ohms)
Nominal SPL peak 124 dB (Sentinel3 40 Hz – 100 Hz)
129 dB (Sentinel10 40 Hz – 100 Hz)
Dispersion H x V omni

Physical specifications

System subwoofer, front loaded
Drivers LF 1x AW21.45-4 21”, side-vented
Connectors 2x Speakon NL4 input
Physical dimensions      
Height 1200 mm / 47,2 inch
Width 1000 mm / 39,4 inch
Depth 330 mm / 13
Weight (approx.) 82 kg/ 181 lb
Warranty 6 years limited

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