KEF R400B Active Subwoofer
Featuring many of KEF’s latest innovations in premium hi-fi and home theatre loudspeaker technology, the all-new R Series makes genuine audiophile standards of entertainment more affordable than ever before. Stunningly fluent new Uni-Q driver arrays combine with potent new bass drivers and many ingenious refinements to create a rich, spacious sound image of such accuracy that it approaches the benchmark standards of KEF’s legendary Reference Series.
The new Uni-Q MF/HF driver array is a masterpiece. Midrange response is amazingly fast and clean, thanks to a braced magnesium/aluminium alloy cone, with KEF’s Z-flex surround smoothing the transition to the front panel and a sturdy die-cast aluminium chassis that prevents resonance being transferred to the cabinet. At the acoustic centre of the midrange cone is the sophisticated vented tweeter that endows KEF Blade with such startlingly pure HF response. With a large neodymium magnet and a computer-optimised dome structure so stiff that it operates pistonically over its entire working range, the upper registers are articulated with flawless precision – and to capitalise on Uni-Q’s point source characteristics, KEF’s ‘tangerine’ waveguide helps to disperse the higher frequencies evenly across a wider angle to flood the room with an intricate and refreshingly natural soundfield. Operating together as a single, perfectly integrated voice, the array as a whole delivers a sweet, accurate sound of unprecedented clarity.
The new bass driver is equally impressive. The combination of a massive vented magnet assembly and a large, lightweight aluminium voice coil driving a light, stiff and strong hybrid cone assures clean, deep and uncompressed bass output with superb dynamics and power handling.
Inside the cabinets (in a choice of classic Piano Black and real wood veneer finishes in Rosewood or Walnut) every single component confirms KEF’s technology leadership. Computer-designed crossovers allow the level of each driver to be fine-tuned for a smoother, flatter response. Constrained layer damping panels prevent cabinet vibration from muddying the mid-range and bass – even the airflow through the reflex ports is managed using computational fluid dynamics to optimise acoustic integrity.
With nine timelessly handsome models including three assertive floorstanders, two bookshelf speakers, two fully-specified centre channels, dipole surrounds and a matching subwoofer, the all-new R Series represents a decisive step forward in the enjoyment of music or film. By incorporating the high end technologies of KEF Blade in a classically elegant format, it gives serious audiophiles phenomenally accurate reproduction that neither adds to nor subtracts from the original recording: refined, spacious and exquisitely detailed. For those whose appreciation of true audio excellence outstrips their bank balance, it’s the perfect buy.
At just 14 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.
Design Powered Subwoofer (Sealed)
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.)