R11 is the flagship of the new R Series range. Boasting four 165mm (6 in.) hybrid aluminium bass drivers, R11 digs deep and retrieves an exceptionally clean and musical low-end performance. Nestled in the centre of these lies the new 12th generation Uni-Q driver array. The 125mm (5 in.) midrange driver and 25mm (1 in.) aluminium dome tweeter combine to deliver an even more natural midrange and treble than believed possible at this price point. The result is a speaker that can pick out the softest details with grace and refinement, as well as deliver raw power and strength.
Developed by KEF in 1988, the Uni-Q driver array acts as a single point source, providing pristine sound across a wider area. The R Series benefits from a new incarnation of this driver array, with advantages over its predecessors that include a new midrange motor system that drastically reduces distortion.
Air moving across the minute gaps between Uni-Q’s separate elements creates tiny resonances, but KEF engineers have reduced the impact of these necessary gaps by opening a cavity behind the drivers and adding resonance-absorbing damping material for more precise, purer treble.
Derived from the Reference Series, the Shadow Flare reduces harmful cabinet diffraction and allows the Uni-Q to work at its highest level.
More than just a trim ring, Shadow flare is a precision-designed surface that extends the waveguide effect of Uni-Q. The tweeter no longer has line of sight of the cabinet edges, creating a ‘shadow region’ at the points where the potential for diffraction is highest, minimising the acoustic impact to negligible levels.
The result is improved clarity, particularly when it comes to the subtle nuances of plucked strings and percussive sounds.
The R Series’ dedicated low-frequency drivers have a two-part structure, where a shallow concave aluminium skin sits atop a paper cone. This adds stiffness, while the cone’s unique geometry reduces resonances and delivers the pistonic movement that makes these drivers time so well.
The new drivers also have a completely redesigned magnet system that creates a more even magnetic field, and a design of spider that reduces harmonic distortion for a cleaner, more precise sound.
The R Series benefits from Constrained Layer Damping bracing originally developed for the multiple award-winning LS50, and a new internal bracing layout. This combination brings the R Series closer to the internal structure of the Reference Series, and helps it deliver music as it is supposed to sound, without any unwanted extras.
KEF engineers computer-modeled the ideal crossover networks before exhaustively auditioning every high grade component, individually and together, to select those with the lowest distortion and the smoothest response. Perfectionism takes time, but the difference is plain to hear. Nothing is overlooked - Reference crossovers are even mounted on separate boards and decoupled from the cabinet walls to minimize vibration and crosstalk.
|Design||Three-way bass reflex|
Uni-Q Driver Array:
HF: 25mm (1in.) vented aluminium dome
MF: 125mm (5in.) aluminium cone
LF: 4 x 165mm (6.5in.) hybrid aluminium
|Crossover frequency||400Hz, 2.9kHz|
Frequency range (-6dB)
Typical in-room bass response (-6dB)
30Hz - 50kHz
|Frequency response (±3dB)||46Hz - 28kHz|
|Harmonic distortion (90dB, 1m)z||<0.3% 0.3% 120Hz - 20kHz|
|Amplifier power (recommended)||15 - 300W|
|Nominal Impedance||8Ω (min.3.2Ω)|
|Weight *||37.7 kg (83.1 lbs.)|
Dimension (H x W x D)
with terminal *
1249 x 200 x 383.5 mm
(49.2 x 7.9 x 15.1 in.)
Dimension (H x W x D)
with terminal with Plinth *
1295.5 x 310.6 x 383.5 mm
(51 x 12.2 x 15.1 in.)
|Finishes||Black Gloss / White Gloss / Walnut|