R400B SUBWOOFER
Twin 9 inches driver 'force-cancelling' subwoofer
The R400b is just 14 inches high but with twin bass drivers and 500 Watts of power, it's made for serious home theatre systems.
The R400b's reinforced and braced cabinet houses twin 9 inches LF drivers powered by two 250 Watts class-D amplifiers. The drivers are mounted in a ‘force-cancelling’ arrangement for fast, powerful bass.
Subwoofer KEF R400b is, so to speak, a half of LF-section of Blade acoustics. Two absolutely identical emitters, the baskets of which are rigidly interconnected, are mounted in completely closed 22-litre body. Working in-phase and radiating in opposite directions, they create identical spurious vibrations, which are opposite in phase.
Model R400b
DesignPowered Subwoofer (Sealed)Drive Units
Bass units:LF: 2 x 225mm (9in.)
Frequency range (-6dB)26Hz - 140HzMaximum output111dB
Amplifier2 x 250W (500W)
built-in Class-DLow pass filter Variable40Hz - 140Hz,
4th-orderLow level signal inputsRCA phono sockets
Speaker level inputsInternal volume22 litres
Power requirements100V - 120V / 220V - 240V~ 50 / 60Hz
Power consumption600VAWeight21.5kg (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.)
Amplification is provided by two 250W modules of D class.
The crossover is regulated smoothly within wide limits; phase control is discrete. Also there is the possibility of additional equalizing of bass.
EQ control allows to locally increase the output on the frequency of 40 Hz on 6 or 12 dB.
In addition to low-level inputs there is a high-level one, which is not through and realized in the form of original connector.
We had to horse around the setting.
When we tried KEF R400b to go with satellites on the frequency higher 100 Hz, the middle and upper bass becomes to dominate, thereby masking the lower frequencies. Thus, it is preferable to use this sub with system, which is able to play low frequencies confidently up to 80 Hz.
Listening to how KEF R400b works in cinema mode, you understand that despite of quite small sizes exactly the lower bass is its native environment.
The subwoofer elaborates LFE-channel authentically and powerfully. It is not bad in music too, but sometimes I would like to add more subtle microdynamics to clarity and cleanliness of bass.
However, there is the risk to roll down to coloring and KEF can't afford it.
