KEF R11 Loudspeaker

hfnoutstandingThe flagship of KEF's new R-series combines the 12th generation of Uni-Q with 'aluminium skinned' woofers

Inspired by KEF's flagship Reference range, its recently updated and more affordable R series was heralded by the standmount R3 [HFN Dec '18] – a speaker that caused sufficient stir here at HFN that we were keen to explore what its tallest floorstander, the R11, had to offer. And here it is, selling for a surprisingly modest £3999 a pair, and looking impressive in a choice of three finishes – black gloss, white gloss or walnut.

As with the R3 speakers, the R11 takes the whole idea of a choice of finishes further than most, for rather than adopting a 'one size fits all' approach, in which only the colour of the main woodwork changes, KEF colour-keys both the grilles and the drivers to suit each cabinet. This aesthetic works very well to shrink the apparent size of the speakers because they're certainly not small, at a smidge under 1.3m tall and just over 31cm wide in fighting trim, while the unashamedly rectangular boxes forgo any clever shaping to make them more 'interesting'. However the clever use of colour, and the acoustic design of the speakers, makes them remarkably room-friendly. Even these, the largest speakers in the range, won't dominate quite modest spaces.

The Big Four
The configuration here echoes that of the R3, which has a dedicated 16.5cm bass driver backing up the latest generation of the company's celebrated Uni-Q coaxial driver array. This places a 25mm vented aluminium dome tweeter at the centre of a 12.5cm midrange cone. But where the R3 uses a single bass unit, the R11 deploys no fewer than four – two above the Uni-Q and two below – which does have the effect of mounting the treble/mid driver somewhat low for such a lofty speaker.

Agreed, this is better than having the treble source way above the seated listener's ears, which might encourage you to crane your head to discover how the balance changes with height, and it seems the design of the Uni-Q driver lends it suitable dispersion for this low-slung position. Certainly there's never any sense of trying to 'listen through the bass' to hear the detail, despite the substantial radiating area in action below 400Hz.

Yes, like the R3 – and in fact in common with all the R Series speakers – the R11 sets its crossover points at 2.9kHz (between the two drivers within the Uni-Q) and 400Hz, demonstrating just how much of the audio band the company's coaxial driver covers, and indeed how dedicated to a single task is that quartet of drivers. And, as we'll discover when it comes to listening, that simplicity of purpose pays dividends in the sheer musical involvement these speakers deliver.

The 12th-generation Uni-Q driver here is, as KEF's Head of Acoustics Jack Oclee-Brown explains, a long way from the original version launched more than 30 years ago. This driver ensemble is now the mainstay of the company's speaker range all the way from the LS50 [HFN Jul '12] – which just uses a single Uni-Q driver and has since spawned the LS50 Wireless [HFN Oct '17] and LSX active 'system in a speaker' designs – to the Reference line, Blade Two [HFN Jul '15] and the huge Muon [HFN May '08].

The original R series was first introduced in 2011 to fit in between the company's Q series and the Reference range, and despite superficial similarities this new collection is nothing short of a complete ground-up rethink, with no fewer than 1043 components being changed, says KEF. Indeed, thanks to the trickle-down of technology, the new R design puts more distance between it and the Q-series, while moving its performance closer to that of the Reference models. This includes the use of the company's Shadow Flare surround on the Uni-Q driver, designed to extend the unit's waveguide effect, improving dispersion and 'microdynamics' such as the strike of finger on string.

Pin-Up Grilles
The new bass unit uses an unusual construction comprising an aluminium skin over a paper cone and, like the Uni-Q, this is anodised in a range of colours to match the cabinet choices. Asked whether this also represents an acoustic enhancement, Oclee-Brown is entirely candid – 'The anodised coating is extremely thin and we don't see any measured or audible change to the drivers,' he says, 'so we've allowed our design team to have free rein over the colours'.

The effect is striking – the black speakers come with black drivers, white ones with silver-grey, and walnut with a light copper colour, giving the speakers a fully 'of a piece' look. Such colour flexibility should come as no surprise to those familiar with other KEF products, which has seen anodised drivers in everything from the little LS50 speakers to the Blade, and in the Reference series Kent Engineering and Foundry Editions. However, in these R models the impression is subtler, though still eye-catching.

The same is true of the grilles, with their microperforations over each driver. Oclee-Brown explained that the frame of the grille has the most effect on the sound of a speaker, scattering and reflecting the output of the drivers. As a result, the new design not only has a lower profile, but is also more open in front of the drivers. As he puts it, 'It looks much more interesting, and has around half the acoustic effect of a normal grille'.

So, a lot of innovation even in what looks like a very conventional speaker. The enclosure has also been substantially enhanced with a combination of internal bracing, which also divides up the space into separate compartments for each driver section, plus constrained layer damping in the form of a lossy material within the joints. And the rear-venting ports – one each for the upper and lower bass sections – are KEF's usual flexible type, shaped to reduce turbulence and resonances within the tube. Two-part foam bungs, which can be used as an outer ring or with the centre also filled, are supplied to tailor the bass according to the R11's in-room response.

GP Acoustics (UK) Ltd
Maidstone, Kent
Supplied by: GP Acoustics (UK) Ltd
01622 672 261