kef r400b subwoofer

The introduction of the R Series in 2012 not only brought KEF's new UniQ technology designed for the Blade model to an affordable price point, but also introduced exceptional build and finish quality too.

From a tonal point of view, you can hear the R Series comes from the same family as the Blade and Reference models. Bass quantity and depth that belie their dimensions, smooth midrange reproduction, and detailed but inoffensive high frequencies - all designed around the 'apparent point source' approach of the KEF Blade loudspeakers.

This approach lends each model of the R Series equally well to both stereo music reproduction as well as the home cinema experience.

Magnetic grilles complete the clean external look, allowing the range to look just as good without grilles as with.

internal view of the KEF R400b subwoofer showing force cancelling technology,

The R400b subwoofer uses dual 9" bass drivers, derived from those designed for the KEF Blade loudspeakers. Each of these bass driver has its own dedicated 250w amplifier.

As mentioned above, these are used 'back to back' in a force cancelling arrangement to reduce distortion for cleaner bass.


Its sealed design produces a more even in-room bass response than ported subwoofers, and will be easier to integrate into the average room too.

One area where sealed subwoofers tend to excel is "punch" - the impact of a bass note or explosion is delivered with more force than a ported subwoofer, and with better speed too, conveying better definition for more accurate reproduction.

force cancelling


The sealed R400b subwoofer uses force cancelling technology, something KEF has refined over decades of loudspeaker design. This feature reduces distortion, as any force created internally by one driver is cancelled out by the other, removing cabinet vibrations and producing cleaner bass for your hi-fi or home theatre system. 

Rather than being a serious home theatre subwoofer with a suitably serious price tag, the R400b is relatively budget in comparison to many other subwoofers with similar musical qualities. The R400b has been designed to compliment the R Series loudspeakers, acting as an extension to the already ample bass they produce. Along with the clean, low disortion output, the R400b blends seamlessly with the rest of the R Series - more can be added for higher output or even more impact..

The luxurious gloss finish of the black or white finish will suit modern rooms and furniture, whereas the smooth, satin finish of the rosewood or walnut real wood veneer finishes will help blend in to more with classic looking surroundings.

KEF R400b subwoofer shown in gloss white,

The force cancelling R400b subwoofer is available in gloss white or gloss black with aluminium trim.


KEF R400b subwoofer shown in gloss black,
  • dual 9" aluminium bass units

  • force cancelling design

  • sealed cabinet

  • 2x 250watt Class D amplifiers

  • 26Hz-140Hz (+/-6dB)

  • H365mm x W330mm x D351mm

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KEF R400b subwoofer shown in gloss white