KEF R400b Subwoofer


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KEF R400b subwoofer

The R400b subwoofer is the final step to achieving a truly immersive home cinema audio experience at an accessible price. The R400b is simply seductive, offering a superlative performance of liquid-like bass, complete with the same level of control and sophistication that one would expect from any product made from KEF. Its cabinet is just 31 inches square, meaning that this punchy and dynamically capable subwoofer is not only pleasing to the ears, but also aesthetically, offering a non-obtrusive option that's easily integrated with existing decor.

The R400b's twin 9-inch LF drivers are powered by two dedicated 250 Class-D amplifier, housed within a reinforced and braced sealed cabinet. The drivers of the R400b are mounted back to back from each other, this arrangement forms what KEF call a 'force cancelling' system, resulting in the opposing reactive forces to be invalidated, completely eradicating cabinet agitation and drastically reducing unwanted resonance. This unit is designed to match the other models within the R series flawlessly, and adds a new depth of dynamic superiority to what is already a superb set of loudspeakers. 


 Model R400b 
Design  Powered Subwoofer (Sealed)
 Drive Units Bass units:
LF: 2 x 225mm (9in.)
 Frequency Response ±3dB 26Hz - 140Hz
Amplifier 2 x 250W (500W)
built-in Class-D
Maximum output (SPL) 111dB
Low pass filter variable 40Hz - 140Hz, 4th-order
Low level signal inputs  RCA phono sockets
Speaker level inputs
Internal volume   22 litres
Power requirements  100V - 120V / 220V - 240V
~ 50 / 60Hz
 Power consumption 600VA
Weight  21.5kg (47.4lbs.)
(H x W x D)
365 x 330 x 351 mm
(14.4 x 13 x 13.8 in.)

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Providing your item is in stock, the order is usually dispatched within 24 hours. Please remember that postage and packing is completely free for orders over £50*. Out of stock items will be dispatched as soon as they become available, out of stock items can take between 4 to 21 days for dispatch.

Deliveries usually take 1-3 working days. The majority of orders are sent via our couriers'; Interlink Express on a next-day-delivery service. Smaller, low value or light-weight items are normally posted using Royal Mail Recorded or Royal Mail Special Delivery.

Once your product has been dispatched, you will be notified via email and sent a unique consignment number, you can use this number at to check the status of your delivery. If you have provided a mobile telephone number, Interlink's Predict service will notify you by text (and email) of a one-hour delivery window. If the window they suggest is inconvenient, you can change the date of delivery to a later one via text or email.

*We ship free of charge to mainland UK addresses, excluding the Scottish Highlands or 'Out-Of-Reach' Scottish locations. Please consult the post-codes below to see if your location falls within this category. If you are still unsure, please contact us on 01432 354921. We also ship to Northern Ireland, Channel Islands, Scilly Isles, Scottish Isles and Scottish Highlands, however delivery to these locations will incur a charge and can only be sent via a 2-day service.

Shipping CostsMainland UK (Next-Day)Offshore/Out-of-reach (2-day)Northern Ireland, Channel Islands, Isle of Man, Scottish Islands, Scilly IslandsRepublic of Ireland (2-day)
Under £50 Orders £7.50 £12.50 £15.00
Over £50 Orders FREE £19.99 £29.99
Surcharge Orders £50.00 £69.99 £79.99
Saturday Delivery £12.99 N/A N/A
Sunday Delivery £12.99 N/A N/A
Saturday by 12 Delivery £35 N/A N/A


Post codes exempt from the free delivery service include:

Scottish Highlands Post Codes: AB30-38, AB41-42, AB44-56, FK17-99, G83, IV1-28, IV30-39, IV52-54, IV63, KW1-14, PA21-33, PA34-40, PH15-26, PH31-41, PH49-50
Islands Post Codes: HS1-9, IV40-51, IV55-56, KA27-28, KW15-17, PA20, PA41-49, PA60-78, PH42-44, ZE1-3
Northern Ireland: All BT postcodes
Channel Islands Post Codes: JE, GY
Scilly Isles Post Codes: TR21, TR22, TR23, TR24, TR25

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