KEF R400b Subwoofer


Trade-in available

R400b is a twin 9-inch driver "force-cancelling" subwoofer in the R Series range, by KEF Audio.

Only 14 inches high, but with twin bass drivers and a solid 500W of power amplification, R400b is perfectly made for serious home theatre systems.

Available in Black Gloss or White Gloss finishes.




Featuring a reinforced, braced cabinet housing twin 9-inch low frequency drivers, R400b is ably powered by 2x 250W class-D amplifiers. These drivers are mounted in a "force-cancelling" arrangement for fast, powerful bass.

Force-cancelling drivers avoid cabinet agitation – opposing reactive forces are nullified by rigidly mounting the low frequency drivers back-to-back.

Dynamic, uncompressed and undistorted bass of heart-pounding clarity will envelop you, striking deep emotional chords. KEF promise your soul will awaken and the earth will move!

Massive vented magnet assemblies and large aluminium voice coils drive the lightweight yet stiff, strong hybrid cones. Bass output is faster, cleaner and more accurate.

Satin anodised elements contribute to the unit’s elegance, while the diameter of the trim ring accentuates a visual sophistication that belies this subwoofers awesome power.


  • Design: Powered Subwoofer (Sealed)
  • Weight: 21.5kg (47.4lbs)
  • Frequency Range: 26Hz-140Hz (-6dB)
  • Power Consumption: 600VA
  • Power Requirements: 100V-120V / 220V-240V ~ 50/60Hz
  • Low-Level Signal Inputs: RCA phono sockets, Speaker level inputs
  • Maximum Output: 111dB
  • Recommended Amplifier Power: 2x 250W (500W) built-in Class-D
  • Variable Low-Pass Filter: 40Hz-140Hz, 4th-order
  • Drive Units: LF 2x 225mm (9")
  • Crossover Frequencies: 400Hz / 2.9kHz

R Series

KEF R Series Loudspeakers | Unilet Sound & Vision

The KEF R Series offers a choice of three floorstanding speakers, a stand mount for more compact spaces and two accompanying matching theatre models. Each one offers the finest sound KEF has ever delivered in its category, whatever the dimensions of the room or system configuration.

Contact Unilet Sound & Vision today and come experience the KEF range for yourself.

More Information



Founded in 1961 by ex-BBC electrical engineer Raymond Cooke OBE, KEF was initially headquartered in a Nissen Hut on the premises of Kent Engineering & Foundry (from where the name KEF is derived), a metal-working company on the banks of the River Medway, near Maidstone in Kent.

From the very beginning, the pioneering inventiveness of KEF loudspeakers was undeniable and now for several decades, audiophiles around the world have revered KEF for their innovative, high-performance, beautiful loudspeakers.

KEF | Unilet Sound & Vision

Additional information

Weight 21.5 kg
Dimensions 35.1 × 33.0 × 36.5 cm

Gloss Black, Gloss White

Purchase Options

Click & Collect, Trade-In Available


There are no reviews yet.

Only logged in customers who have purchased this product may leave a review.