KEF R500 Loudspeakers

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Note: Measurements taken in the anechoic chamber at Canada's National Research Council can be found through this link.

KEF R500Reviewers' ChoiceKEF’s R loudspeakers comprise an affordably priced line of nine models: three floorstanders (R500, R700, R900), two stand-mounts (R100, R300), two center-channels (R200c, R600c), one surround (R800ds), and one subwoofer (R400b). The R series followed the release of the Blade, launched in 2011 for $29,999 USD per pair. The Blade is a unique loudspeaker that not only showcases KEF’s newest technologies and latest thinking about how a speaker should be made; I believe it to be a groundbreaking design. Its cabinet’s shape, its Uni-Q driver, and the way its four woofers surround the Uni-Q to create what KEF calls a Single Apparent Source (a configuration that allows the speaker to act as a point source at all frequencies), are just a few examples of the original thinking that went into this technological triumph.

The subject of this review is the R500 ($2599.98/pair). I suspect that a speaker at this price from most manufacturers would likely have been rather ordinary, given the cost constraints. But coming from the company that created the Blade, and containing some of that speaker’s advanced features, what might have been ordinary is instead something extraordinary.

Description

By a large margin, the R500 is KEF’s smallest, least-expensive R-series floorstander (in the US, the R700 and R900 respectively sell for $3599.98 and $4999.98/pair), but that doesn’t make it a "lesser" speaker. All R-series cabinets are made of MDF and are built to the same high standard -- one much higher than is indicated by the R500’s modest price. One reason KEF can offer such quality at a reasonable price is simple: the R speakers are designed in the UK but built in China.

The Rs are available in four finishes: Walnut and Rosewood real-wood veneers, and Piano Black and Piano White high-gloss lacquer; the review samples’ Walnut finish was superb. KEF has included some other nice touches, the most obvious of which is the metal trim around all the drivers, to conceal unsightly screws and bolts, and the solid-aluminum outrigger feet with adjustable carpet spikes. Around back are fantastic binding posts that allow for single- or biwiring without any need for jumpers -- a dial labeled Link, between each pair of upper and lower posts, turns to join or separate the posts internally. Clever. One thing I didn’t like: the grille, which is quite plain and brings down the look of the entire speaker. With its grille off, the R500 looks high-tech and sharp; with the grille on, it’s humdrum to the point of being lame. That’s the one nit I had to pick.

KEF R500 binding posts

Performance-wise, the differences among the R floorstanders appear to have mostly to do with the bass, something that’s affected mainly by cabinet and woofer size. KEF’s measurements for the R700 and R900 are, respectively, 42.1"H x 8.3"W x 13.6"D and 44.5"H x 9.4"W x 14.4"D (sans outrigger feet), vs. 40"H x 7.1"W x 12"D for the R500. The R700’s and R900’s woofers are 6.5" and 8", respectively, vs. 5.25" for the R500. The larger cabinets and bigger woofers allow the R700 and R900 to reach deeper in the bass and have higher output capability in that range. Essentially, you pick the speaker based on your room size, and the importance you place on bass depth and output capability. But that doesn’t mean the R500 is lightweight -- KEF specs the R500’s -6dB point in the bass as a deep 39Hz, which is believable, based on its performance in my room. (KEF says 37Hz and 35Hz for the R700 and R900, which doesn’t sound like much of a difference, but I suspect they have far greater SPL capability in that region, something that simply stating the frequency limits doesn’t show.)

All three R floorstanders have two front-mounted woofers, each operating in its own internal enclosure, and each with a port on the rear to increase its output. If the overall bass output proves too much for your room, foam plugs are supplied to reduce the ports’ contribution (I listened to the R500 without plugs). The woofers’ aluminum cones have an interesting profile: a shallow depression obviously inspired by the Blade’s transducers. I have no idea if the shape is performance-oriented, or if KEF made them that way to make the speaker look cooler with its grille off -- or both.

KEF R500 Uni-Q

Mounted between the woofers is KEF’s newest, Blade-inspired Uni-Q coaxial driver: a 1" aluminum-dome tweeter at the center of a 5" aluminum-cone midrange driver. Coaxial drivers aren’t unique to KEF, but for decades now the company has made it their mission to perfect the technology. A coaxial’s main strength is the uniform wave launch made possible by having the tweeter in the center of the midrange cone -- something that separate tweeter and midrange drivers can’t do, no matter how expensive the speaker. The main downside of coaxials is that because the tweeter works inside the midrange, its behavior is affected by it -- mostly negatively. As a result, the shape of the Uni-Q’s midrange cone, the fins surrounding the tweeter, and the seemingly nonexistent midrange surround all serve to eliminate the deleterious effects the midrange cone can have on the tweeter’s output. The R500’s tweeter crosses over to the midrange at 2.8kHz, and the midrange to the woofers at 500Hz.

Some of KEF’s claimed specs for the R500 are typical -- a sensitivity of 88dB (2.83V/m), an 8-ohm impedance with a 3.2-ohm minimum, recommended amplification of 25-150W, and a frequency response of 46Hz-28kHz, +/-3dB -- but some are not. KEF says that the R500’s distortion at 90dB output when measured at 1m is less than 0.4% from 120Hz to 20kHz (you can assume the distortion is higher in the bass, which is typical). That’s not only very low for a loudspeaker, it’s a spec that manufacturers seldom state, for two reasons: 1) few manufacturers have the facilities and abilities to measure distortion (we do measure distortion as part of our battery of tests in the NRC’s anechoic chamber, where we tested KEF’s claim; it’s true); and 2) even if they can measure distortion, their figures are rarely so low, so it’s better not to mention it at all. Also, KEF claims that the R500 can generate SPLs of 111dB, though they don’t give the frequency range and measuring distance for this spec. Still, that kind of output, combined with the claim of exceedingly low distortion, indicate that the moderately sized R500 was designed to play loud and clean -- which it did in my room, to a shocking degree, with every kind of music I played.

Sound

Loud and clean weren’t the only things the KEF R500 did exceedingly well. The moment I hooked them up to the Eximus S1 amplifier I have in for review (125Wpc into 8 ohms), I heard a sound so full, pure, and refined that I knew in an instant that this $2600 pair of speakers was special. When I pressed on, and drove the R500s with the Bryston 4B SST2 (300Wpc into 8 ohms), I knew that what I was hearing could set a new standard for performance at this price. It wasn’t only that the R500s could use all the power the Bryston could provide, but that the 4B SST2’s world-class sound allowed the R500s to fulfill their potential -- which I found to be sky high.

What did the R500 do so well to win such praise? Many things -- but what jumped to the fore was the entire midrange region, which had amazing clarity and dazzling transparency at all volume levels. Whether I was playing an ultra-pure-sounding recording of a female voice such as Mariza’s on her Transparente (16/44.1 FLAC, Times Square), or Leonard Cohen’s deep, raspy baritone on his latest release, Old Ideas (16/44.1 FLAC, Columbia), what came out of the R500s was so utterly clean, composed, refined, and realistic that I knew that, at least in this regard, the KEFs could hold their own against the best speakers out there -- even against my reference Revel Ultima Salon2s, which sell for $21,998/pair.

However, it’s important to know that this kind of ultrasmooth, extremely natural midrange sound in a cost-effective speaker isn’t unique to the R500, and it’s not something I haven’t written about recently -- PSB’s overachieving Imagine T2 ($3500/pair), which I reviewed a few months ago, sounds almost the same through the mids. Likewise, PSB’s Synchrony One ($5500/pair) has a midrange clarity and neutrality incredible enough to shame the most expensive, cost-no-object designs. But it’s been over a year since the Ones were in my room, so I couldn’t directly compare the R500s with them. But I could directly compare the KEFs with the PSB Imagine T2s. As I said, the speakers were similar through the mids -- but where the R500 stepped ahead of the T2 was in the former’s ability to deliver this kind of midrange purity at far higher SPLs. The T2, while impressive, crapped out a little earlier; the R500 played every bit as loud as my Revels while keeping their composure. Shockingly good performance for the price.

As remarkable as was the R500s’ midrange, the solidity of their center imaging and the way they positioned the performers so precisely on the soundstage, from left to right and from front to back, was better than the T2s and the Salon2s -- something I attribute to the acoustic benefits of that Uni-Q driver. This, to me, is not insignificant -- the clarity and rock-solid focus that result from placing the tweeter at the center of the midrange is something you can’t get from a discrete tweeter and midrange at any price -- and once you’ve experienced it, it’s tough to live without it.

Moving up into the topmost frequencies, I wasn’t disappointed in the least, which surprised me -- I’ve been spoiled the last few years by having a pair of Salon2s as a reference, and by having reviewed what I believe to be one of the very best speakers on the planet: Vivid Audio’s Giya G2 ($50,000/pair). Once you hear the fantastically clean sound that both models' tweeters provide, most "typical" speakers’ tweeters are a letdown. Not so with the KEF. Where the R500’s tweeter takes over from its midrange sounded absolutely seamless -- no telltale shifts in sound. And while the R500 couldn’t quite match the effortlessness and the airy, open quality of the G2’s or the Salon2’s top end, it did sound every bit as clean, extended, and refined, which I certainly didn’t expect for the price. KEF’s designers have done some remarkable things with their latest Uni-Q drivers.

Nor did the R500’s performance lower in the audioband disappoint, although here there were some indicators of the speaker’s modest size and price. Like the midrange-to-tweeter handoff, the outputs of the R500’s woofers blended seamlessly with the midrange to produce rich, voluminous bass that easily extended below 40Hz in my room with surprising weight and fullness, even at high volume levels. Granted, that’s still not 20Hz terrain, which is what’s considered "full-range" performance, but I don’t think anyone expects a speaker of this size or price to go that low. In fact, the PSB Imagine T2’s bass performance sounded largely the same as the R500’s.

KEF R500 woofer

When I played through the R500s "Misguided Angel," from the Cowboy Junkies’ The Trinity Session (16/44.1 FLAC, RCA), the bass surged like a wave about to engulf me. Ola Gjeilo’s robust-sounding acoustic piano in "North Country II," from our high-resolution 2L-TWBAS 2012 Sampler (24/176.4 FLAC, 2L/SoundStageRecordings.com), was incredibly rich and remarkably well controlled. The piano is notoriously tough for a pair of speakers to re-create, but the R500s aced it. Øystein Baadsvik’s tuba in Erlend Skomsvoll’s Prince Igor: Fantasy on a Theme by A. Borodin, from Baadsvik’s Ferry Tales (16/48 FLAC, BIS), sounded forceful and full, as it should. The R500’s bass depth, fullness, and control were excellent for a smallish loudspeaker.

Where the R500 fell back in the bass mirrored the same deficiency in the Imagine T2: detail. In short, the R500’s bass lacked the awe-inspiring low-frequency definition that speakers like the Revel Ultima Salon2 and Vivid Giya G2 can provide. As a result, the rich bass textures present in the recordings I’ve mentioned were somewhat obscured, meaning the bass in the R500 sounded a touch more loose than tight.

Is that a problem? If a pair of R500s cost as much as, say, Vivid’s B1, which I consider to be close to the state of the art for a moderate-size floorstander, it would be. But those speakers cost $15,000/pair -- for that much cash, you expect to get everything. The R500s cost less than 20% of that -- so, no, no problem at all.

Conclusions

When KEF told me they’d ship me a box speaker costing just $2599.98/pair, it never occurred to me that I’d have for it the same sort of admiration or enthusiasm that I’ve felt for their Blade since that speaker’s debut. But I have to give the R500 equal praise -- not for its build and styling, which are simply very good for the price, but for its sound, which is nothing short of extraordinary, and sets a new standard for what can be expected at this price.

The R500’s sultry-smooth, extraordinarily clean, natural-sounding midrange allows this small floorstander to compete with speakers at any price. Its highs approach what the best speakers offer, and its soundstaging and imaging are beyond reproach. The R500’s bass is deep and robust, and what it lacks in definition it makes up for in a fullness and heft that allow this moderate-size speaker to sound big -- really big. Then there’s the transparent, seamless coherence of its drivers’ outputs: The R500 sounds as if it has only a single driver.

The result is a loudspeaker that sounds remarkably complete and uncompromised, despite its low price. In fact, calling the R500 a great-sounding speaker for the price doesn’t tell the whole story -- the KEF R500 is a great-sounding loudspeaker by any measure. The fact that its price is so low simply makes it all that much better.

. . . Doug Schneider
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Associated Equipment

  • Speakers -- PSB Imagine T2, Revel Ultima Salon2
  • Amplifiers -- Eximus S1, Bryston 4B SST2
  • Preamplifier-DAC -- Eximus DP1
  • Computer -- Sony Vaio laptop running Windows Vista and JRiver Media Center 17
  • Digital interconnect -- AudioQuest Carbon USB
  • Analog interconnects -- Nordost Valhalla
  • Speaker cables -- Nirvana S-L, AudioQuest Comet

KEF R500 Loudspeakers
Price: $2599.98 USD per pair.
Warranty: Five years parts and labor.

KEF
Eccleston Road, Tovil, Maidstone
Kent, England ME15 6QP
UK
Phone: +44 (0)1622-672261
Fax: +44 (0)1622-750653

Website: www.kef.com

North America:
KEF America / KEF Canada, Inc.
10 Timber Lane
Marlboro, NJ 07746
Phone: (732) 683-2356

E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

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