KEF R400 2x225mm Drive Units, 2x250W Class D Amps, Active Subwoofer, Piano Black

Additional Information

Description Specification

At just 31 inches square, the KEF R400b may be compact, yet it packs an incredible punch. With a reinforced and braced sealed cabinet, the R400b houses twin 9-inch LF drivers powered by twin 250W class-D amplifiers. The drivers are mounted back-to-back, to create ‘force cancelling’. This means the opposing reactive forces are nullified, resulting in no cabinet agitation and a clean, fast, powerful bass performance – perfect for any serious home theatre system.

Model: R400b
Design: Powered Subwoofer (Sealed)
Drive Units: Bass units: LF: 2 x 225mm (9in.)
Frequency range (-6dB): 26Hz - 140Hz
Maximum output: 111dB
Amplifier: 2 x 250W (500W) built-in Class-D
Low pass filter Variable: 40Hz - 140Hz, 4th-order
Low level signal inputs: RCA phono sockets
Internal volume: 22 litres
Power requirements: 100V - 120V / 220V - 240V
~ 50 / 60Hz
Power consumption: 600VA
Weight: 21.5kg (47.4lbs.)
Dimension (H x W x D) (with terminal & plinth): 365 x 330 x 351 mm (14.4 x 13 x 13.8 in.)


  • 2 x 250W (500W) Built-in Class-D
  • Force cancelling technology
  • Compact, yet it packs an incredible punch