Description

Dual 9-inch force-canceling drivers

The R400b stands just 14 inches tall, but with twin woofers and 500 watts of power, it's built for serious home theater systems. The R400b's reinforced and reinforced cabinet houses two 9-inch LF drivers powered by two 250-watt Class D amplifiers. The drivers are mounted in a force-cancelling arrangement for fast, powerful bass.

Design: Amplified Subwoofer
Weight: 21,5 kg (47,4 lbs)
Frequency range: 26Hz-140Hz (-6dB)
Power consumption: 600VA
Power Requirements: 100V-120V / 220V-240V ~ 50/60Hz
Low level signal inputs: RCA phono jacks, speaker level inputs
Maximum Output: 111dB
Recommended amplifier power: 2x 250W (500W) integrated class D
Variable low pass filter: 40Hz-140Hz, 4th order
Trans unitmissione: LF 2x 225 mm (9")
Crossover frequencies: 400Hz / 2,9kHz

Specifications

Diffuser type	active
Frequency response	26 140-Hz
Cabinet type	bass reflex
Weight	21.5 kg
Trim	Piano Black
Electricity consumption	600 W
Alimentazione	100-120V / 220-240V ~ 50/60Hz
RMS power per channel	250 W
Amplification type	class D
Maximum sound pressure (1m)	111 dB
Woofer	2x 225mm (9 inches)
Analog inputs	RCA, speaker level inputs
Crossover frequency	40-140 Hz

About the brand

KEF is a British brand of high-end loudspeakers, founded in 1961 by Raymond Cooke in Tovil, near Maidstone, Kent, England. The name itself—an acronym for Kent Engineering & Foundry—recalls the company's origins, which began within the premises of a metallurgical foundry. KEF positions itself in the premium segment of the hi-fi market, targeting discerning audiophiles seeking faithful, natural, and technologically advanced sound reproduction.

KEF's corporate philosophy is rooted in the education of its founder. Raymond Cooke, an engineer from the BBC laboratories, brought a rigorously scientific approach to the world of loudspeakers: KEF was among the first manufacturers to experiment with new synthetic materials and advanced measurement and design tools, with a single goal: to bring listening as close as possible to the live musical event.

The innovation that made KEF famous worldwide is the Uni-Q driver, introduced in 1988. In this system, the tweeter is placed precisely at the acoustic center of the mid-woofer, creating a single point source: the result is extraordinarily coherent sound, a wide and stable soundstage, and optimal listening even off the central axis, from any position in the room. Constantly refined over the years, Uni-Q technology has become the brand's unmistakable signature.

KEF research has never stopped. With Metamaterial Absorption Technology (MAT), the company has developed a special acoustic labyrinth capable of absorbing almost all the sounds.missionthe rear of the tweeter, reducing distortion and delivering exceptionally pure sound. It is the heart of the celebrated LS50 Meta, an evolution of the legendary LS50: one of the most awarded and beloved bookshelf speakers of all time.

The KEF catalog ranges from compact bookshelf monitors to large reference floorstanding systems: from the historic LS3/5A—a mini-monitor associated with BBC studios—to the highly acclaimed Q and R series, all the way to the flagship Reference and Blade, true acoustic sculptures. The result of a constant dialogue between engineering and design, KEF speakers combine top-level performance with a refined and instantly recognizable aesthetic.

Choosing KEF means bringing home over sixty years of British innovation and the promise of faithful, detailed, and emotionally resonant sound. Discover the KEF range available from Audiocostruzioni and let yourself be won over by the coherence and naturalness of the Uni-Q sound.

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