KEF R7 (DEMO)
Mid-sized three-way floorstander
The R7 is the mid-sized floorstander in KEF’s new R Series, very powerful yet not too large it brings music and movies to life.
With a pair of 165mm (6.5 in.) hybrid aluminium bass drivers and a Uni-Q combining a 125mm (5 in.) midrange driver and 25mm (1 in.) aluminium dome tweeter, R7 outperforms all expectations.
In KEF tradition, the R7 is a tour-de-force in engineering. The drive units are all designed in-house, notable amongst them being the central Uni-Q drive unit with its ‘tangerine’ waveguides (fins). This is two drive units in one. At centre is an aluminium dome 25mm (1in) tweeter. It is surrounded by an aluminium cone mid-range unit in what KEF term a co-axial arrangement.
The point they’re keen to make here is that the acoustic centres of the two units are aligned axially (front to back) to eliminate acoustic phase error between them. Putting tweeter at centre means there’s no vertical distance (gap) between the two units either, as with conventional three-way loudspeakers, so you get a totally cohesive launch of the sound wave into the room. Typically, this sort of drive unit is described as a “point-source”.
Being a technical loudspeaker, as it were, I am being a little technical here, but as KEF have ruefully told me in the past, some people think that what appears to be a single drive unit can’t be as good as two of ‘em! The Uni-Q is two drive units carefully arranged into one space.
Why do this? Because notionally sound is meant to come from one point and you do get a sense of focus and coherence I’ve found, especially noticeable when moving around: the sound stays the same.
How to describe a large shiny black cabinet? Bit like something from ‘2001 a Space Odyssey’. That dates me rather than the loudspeaker, but because the R7s stand 1062mm tall, are 200mm wide and deep at 383.5mm, they loom large, unless the lights are out. This is a big loudspeaker trying not to look it. And the reason for big is to get deep bass. If you want to go low cleanly then it’s a large drive unit to move volumes of air without distortion, and a cabinet to cope. And that’s what the R7 offers whilst trying to disguise the fact. Alternative finishes are white and a walnut veneer.
The woodwork and drivers add up to 31.4kgs (69.2lbs) per loudspeaker, so not an easy lift. KEF supply four bolt-on stabilising feet, plus adjustable spikes. No foam bungs for the ports, to damp bass down in a boomy room. These are easily obtainable and cheap – better than using a pair of old socks!
For bass duties KEF again use aluminium fronted drivers, two of them here. The all-aluminium driver array keeps character consistent; there’s no change in tonal colour, as happens when drive unit materials differ. Aluminium comes across as fast and vivid, suggesting the R7 will not sound dark or damped.
The rear panel carries ports for the upper and lower chambers and they are stagger-tuned our measurements showed, to give smoother low bass output. This also improves the loudspeaker as an amplifier load, again shown by measurement (see Measured Performance). There’s a sturdy connection panel that allows single or bi-wiring, with an unusual screw switch to choose between these modes, rather than removable links.
Build quality and finish are immaculate. The front grilles can be removed easily, being held by magnets.
|Design||Three-way bass reflex|
|Drive Units||Uni-Q Driver Array:
HF: 25mm (1in.) vented aluminium dome
MF: 125mm (5in.) aluminium cone
LF: 2 x 165mm (6.5in.) hybrid aluminium
|Crossover frequency||400Hz, 2.9kHz|
|Frequency range (-6dB)
Typical in-room bass response (-6dB)
|33Hz – 50kHz
|Frequency response (±3dB)||48Hz – 28kHz|
|Harmonic distortion (90dB, 1m)||<0.3% 100Hz – 20kHz|
|Amplifier power (recommended)||15 – 250W|
|Nominal Impedance||8Ω (min.3.2Ω)|
|Weight *||31.4 kg (69.2 lbs.)|
|Dimension (H x W x D)
with terminal *
|1062 x 200 x 383.5 mm
(41.8 x 7.9 x 15.1 in.)
|Dimension (H x W x D)
with terminal with Plinth *
|1108.9 x 310.6 x 383.5 mm
(43.7 x 12.2 x 15.1 in.)
|Finishes||Black Gloss / White Gloss / Walnut|
* Measurement per unit