KEF R11 Review
As the saying goes, good things take time, and they are usually right about that. On the occasion of a visit to Hegel in Norway, I had the pleasure of hearing the Hegel top amplifier H590 and the new KEF R11. I was very impressed and immediately ordered a pair of these slim top boxes. But I was probably a bit premature because there were problems with bent front panels initially. They consist of 13 individual layers produced in a new manufacturing process. So fine adjustments had to be made, and the delivery of larger quantities was postponed to spring 2019. And more than seven years had passed since the introduction of the predecessor R series.
Anyone who has the pleasure of experiencing the KEF R11 can understand that these nicknames have now been eliminated in the new R line. I’m not understating “enjoyment” as the right expression. The processing quality alone, if you let your fingers walk on the paintwork of the R11, you won’t feel any bumps, no matter how fine. There are no gaps or edges where the fingertips could get caught. And, of course, no screw anywhere (except on the connection panel) disturbs the aesthetics and the outstanding paint finish. You won’t find that any better in much more expensive speakers.
As far as the exterior is concerned, nobody can fool the British under the umbrella of the Hong Kong-Chinese Gold Peak Group. The design department (still based in Maidstone, UK) has developed a wonderfully “urban” design language (other examples are the Blade, the LS 50, or the LSX ), which fits in well with the times and with the KEF other manufacturers seems to be one step ahead. Even the drivers become an integral part of the visual appearance.
- Sovereign sound with impressive bass and vivid imaging
- High-level reserves, high impedance linearity
- Excellent quality
- Outstanding price/performance ratio
Conception & assembly of the KEF R11
For example, the woofers, four of these basses with hybrid aluminum cones, are distributed symmetrically on the front. But do they look like classic basses? No. But like elegant applications.
Four of these new woofers work in the R11. Each of them has an area of about 120 square centimeters. Four times that add up to almost 500 square centimeters – a 30 cm woofer area. You can move some air with it.
The four are distributed over the entire height of 1.25 meters. Suppose you add the two bass reflex ports on the back. In that case, the low-frequency resonances in the room are stimulated at six different points – which is an advantage in terms of homogeneous stimulation of the room modes (compared to intensive stimulation by just one bass).
Compared to the 2011 R line, the new series doesn’t appear all that spectacularly new – and yet 1,043 new parts are said to be used for the 2018 R line. KEF slogan “The only thing that remains is the name.” OK, that’s marketing. Because, of course, the conception of the R series remained about the same. However, the R series from 2011 did not have such a large flagship model as the R11 – in this respect, I try to compare it here (and later) with Reference 5, which is almost the same size and has a similar configuration.
The housing of the KEF Reference 5 must demand respect from the connoisseur. Nothing wobbles in the completely stiffened column weighing over 60 kilos. And yet, even at KEF, the realization has prevailed that a rigid connection of the large, often vibrating housing surfaces – as almost all manufacturers worldwide do and as it was also implemented with Reference 5 – is not acoustically beneficial. Instead, the stiffening elements of the R11 only have contact with the walls at a few points via elastic dampers. This prevents the vibrations of one of the housing walls from being transmitted to the others.
The special element of the R11 is – as with all KEF loudspeakers – the coaxial mid-high driver called Uni-Q. The British have been working and researching on this topic since 1988 and certainly have an advantage over most other coax suppliers. The 12th generation Uni-Q installed here has shed any nasality and sharpness. Instead, it offers all the advantages of a point sound source and sounds open, free, and natural.
For this, however, the Uni-Q had to go to the research laboratory again. Because with all the advantages that well-made coax drivers bring with them (point sound source, time-coherent playback), they also have inherent weaknesses.
An Achilles’ heel is the transition between cone membrane and dome tweeter. If the membrane moves, a gap is created – larger or smaller depending on the level. This gap creates resonances. The 12th generation Uni-Q also has this gap, but it also has a tricky dissipation of this sound energy.
The R11 in action
Typically, using four woofers results in ugly impedance swings and dips. Not so with the R11 only in the area of the bass reflex tuning (30 Hertz) and in the transition between the midrange and tweeter (2,800 Hertz) are there minor overshoots. Otherwise, this loudspeaker measures itself almost like a measuring resistor.
This is particularly important for the connected amplifiers. If you have unlimited power and stability, the impedance is almost irrelevant. However, with weaker amplifiers, a wavy and low-impedance always negatively affects the playback. The R11 is visually and electrically capable of winning a majority in this respect.
As usual, we tried the KEF with many different amps, including even the small Cambridge Audio AX35. That went surprisingly well. But it sounded great with powerful full-value amplifiers like that Atoll In 400 ES or the big Cambridge Audio Edge A. So even if these amps are about as expensive as the KEF, that wouldn’t be an unusual combination – simply because the R11 could also be in a higher price league.
The new R flagship is probably also good because its construction with the newly developed drivers is extremely low distortion. Such good-natured distortion behavior as our measurements at 94 decibels is very rare in classic hi-fi loudspeakers.
But even at high levels – we’re talking about peak values of up to 115 decibels – the distortion values remain moderate – see measurement below. This underscores the statement made by KEF development manager Dr. Jack Oclee-Brown that the R11 would also play very confidently in larger rooms. For example, the 70 square meter LowBeats listening room didn’t show any weaknesses in terms of volume either.
A word about the lineup, the R11 is a typical KEF with a rich bass foundation. Setting up near a wall or corner is therefore out of the question with such a precious piece. The fact is you have to try something around because of the many bass sources, but you usually get a good result.
That’s what the R11 sounds like
I was lucky enough to get an R11 that was already broken in, so after some back-and-forth, it kicked off with incredible confidence. First, to warm you up, the extremely dynamic “Crying” by James Blood Ulmer. How far did the KEF expand the live recording space but then come pretty close to the microphone again during the vocal passages? The bass drum hits didn’t quite have the brute drive of the recently tested Heco Celan Revolution 9, but more depth and almost felt just as live-like. And then Ulmer’s voice was smoky, robust, rousing.
The recording is sometimes quite snappy. And yet nothing was disturbing about the KEF. There is something incredibly natural about this speaker. With the KEF Reference series, I found the basses a bit too chubby overall, the R1 quite good, the R3 still good, the R5 only recommended in exceptional cases. The R11 comes with very similar equipment as Reference 5 mentioned and simply does it much better in the bass. The bass range doesn’t look like a subwoofer connected too loudly but is part of a natural whole.
The basses of the R11 also go far down and provide a rich foundation. But they are simply a lot more gripping and precise than those of the great Reference. A kick by the drummer on the bass drum goes like a fist in the pit of the stomach. Measured against the somewhat “softer” bass performance of many other KEF loudspeakers in recent times, this is enormous progress – towards more realism and more fun.
Boris Blank, the musical mastermind behind the Swiss electro-pop duo Yello, once dubbed an uncompressed special version of “The Expert” for me during a visit to his Zurich villa and took the opportunity to point out some of the effects of this recording to me. Some sounds lie one behind the other, like discs. I have heard this imaging accuracy in-depth in the last few weeks from exactly three loudspeakers:
- Finkteam Audio Borg,
- TAD Evolution One TX
- The KEF R11
However, the KEF costs only a fifth of the other two top speakers.
What you can also hear well are the qualities of the new coax. The mid-high range is not as transparent and delicate as the Dynaudio Evoke 50. But it is free of artifacts and sounds wonderfully powerful, homogeneous, and plastic. In any case, it has completely discarded the nasal aspect of the earlier Uni-Qs – that makes the playback even of strings and wind instruments so authentic.
But classical music also sounds overwhelming with this speaker. LowBeats author and classical music fan Andreas Günther had left his favorite recording of Mahler’s 8th symphony (“the symphony of 1,000”) in the listening room, and I was amazed at the sovereignty, joy of playing, and joy of timbre with which the R11 mastered this dynamic feat of strength.
The R11 manages to create a magical pull with its homogeneous and seamless way of playing; it inevitably draws the listener into the recording. I didn’t have much time the day I found the record in the listening room – and ended up listening to most of the recording. Because it is such great work, and because the KEF sounds so unspectacularly rousing how well the individual groups of instruments can be heard.
Unfortunately, I didn’t have the opportunity to hear a Reference 5 directly against the R11, but I found the Reference 5 to be significantly more inhomogeneous in the test. Or, to put it the other way around, the Reference would never have come home to me, the R11 immediately.
I don’t want to beat around the bush here, but this speaker is great. I didn’t find any weak points. On the contrary, its homogeneity, depth of reproduction, and variety of tones are fantastic, as are its overall technical qualities.