KEF

KC62 Subwoofer

£1,399

Subwoofers. Everyone knows about subwoofers. They have to be big. And heavy. It’s unavoidable. Laws of Physics, and all that. Only massive drive units deliver deep bass. Everyone knows that. Everyone but KEF, it seems, as they never saw the memo – and duly built an amazing sub that was tiny. Textbook!

With 1,000W – yes, that’s 1kW – of power from two 500W Class D amplifiers, the new KC62 boasts impressive horsepower. At 14kg, the magnesium cabinet is unexpectedly heavy – despite this metal being known for its lightness, so there must be lead inside or something. The KEF can deliver a surprisingly loud 105dB SPL without audible buzzes or rattles, so the enclosure had to be dense and well-damped – and obviously is.

Two long-throw 6.5in drivers with a common magnet are placed back-to-back in what is described as a ‘force cancellation’ chamber. Claimed frequency range is 11Hz to 200Hz (-3dB), and the output is DSP controlled to maintain optimum operation. You connect the KC62 at line level via RCA phono plugs, or your amp’s loudspeaker terminals, or wirelessly via an optional adapter. Power requirements are 100 to 240V, 50 or 60Hz. Consumption is just 100W. The variable low-pass filter is adjustable between 40Hz and 140Hz. On paper, at least, it all looks great…

Yet honestly, can a subwoofer that measures just 246x256x248mm really deliver deep bass? I mean, surely size matters? When I checked the KC62’s spec sheet and saw a claimed response down to 11Hz, I was astonished. Few subs, regardless of size or price, go down that far. One that did was REL’s original Studio. I reviewed one back in the mid-nineteen nineties, and to this day, it remains a benchmark. Alas, it was also absurdly big and ridiculously heavy. It weighed so much that I had to remove the drive units, amplifier, and brass feet from the cabinet to make installation manageable.

Even with all the guts removed, it took three of us to lift the cabinet down my stairs – it was that heavy and awkward. Sure, the Studio was a great sub. It produced the deepest bass I’ve ever heard. Yet, at the same time, it was borderline impractical, being too large, weighty and expensive. Why mention this? Well, because KEF’s little KC62 goes as deep as that mighty REL, at a fraction of the size and price.

I confirmed this by playing a certain recording released around the time I reviewed the Studio. It was a 1994 Compact Disc of Schumann piano works played by Maria Joao Pires on Deutsche Gramophon. Twenty-five years ago, while listening to Faschingsschwank aus Wein using the Studio, I noticed some incredibly deep wafts of bass, which I believe were created by Mz Pires operating the piano’s foot pedals.

The microphones must have been on floor stands, mounted without a decoupling cradle. This meant they could pick up subsonic vibrations through the floor. Such frequencies are so deep that most subs – let alone loudspeakers – would be incapable of reproducing them. So typically, you’d hear nothing. But the REL had enough deep bass extension to reveal what was there. No sub I’ve since used could reproduce these noises. When I played the Pires/Schumann disc using the KC62, for the first time in a quarter of a century, I heard all those dastardly low-frequency noises again…

If memory serves me correctly, the REL Studio made the noises slightly more audible. But no matter, because KEF’s new KC62 operates in the same ballpark. For something so tiny, this is an incredible achievement. I would never have believed a sub so small could reproduce frequencies so low.

THE LISTENING

KEF’s LS50 compact loudspeaker is the obvious partner for the KC62. The LS50 offers a bass response to about 47Hz (-6dB), which is very respectable for such a small enclosure, but adding a sub like the KC62 will greatly extend the low frequencies and improve the overall sound.

My regular speakers are full-range Impulse H1 horns which extend to about 30Hz. I partner them with a Klipsch RW-10D sub I’ve had for about fifteen years. The Klipsch is pretty good, and I regularly look on eBay, hoping to find a second RW-10D so I can run two subs in stereo. Now I’ve heard what the KC62 can do, I’m not sure I’ll bother. The KEF is vastly better than my old Klipsch sub in terms of bass depth.

Also – for someone like me, using big speakers with a full bottom end – it seems easier to adjust the KC62 to come in ‘under’ my main speakers. With most subs, it always seemed like they strayed a bit too ‘high’ into the 60Hz-80Hz range. I just want a sub to provide some nice deep grunt without adding too much above 50Hz. The KEF KC62 appears to do that very well, thank you very much.

Back in the early eighties, when I still used active Linn Isobariks, a favourite demo disc was the 12-inch 45rpm single of Ian Dury’s Hit Me with your Rhythm Stick. On Isobariks at a suitable volume, the drumming bit halfway through (1m 56s) made the windows rattle and my chest vibrate. Nice!

While I get a better overall sound today than I did in the eighties, I’ve never owned a speaker that quite matches the Isobariks for window-rattling, chest-vibrating, bass. Trying Rhythm Stick with the KC62 produced Isobarik-esque weight and breadth – impressively big and holographic. Hit Me!

Another old favourite from 1985 was a Philips recording of Saint-Saens Organ Symphony with Edo de Waart and the San Francisco Symphony – 412 619-2. The deep pedals from the mighty Ruffati organ in the slow movement have exceptional weight and power, and the KC62 did them full justice. The music is quiet and contemplative, then suddenly, as if from nowhere, subterranean bass-notes from the organ billow into the room. You feel rather than hear them. They enter smoothly yet powerfully, without modulating the orchestra. The sound was beautifully clear, natural and very true to life. The sheer depth of the organ pedals was awesome yet utterly effortless. Only a good sub, or speakers capable of exceptionally deep bass, can do this.

Having very low frequencies reproduced by a separate sub means the main speaker isn’t being asked to deliver deep bass that may affect midrange/treble clarity due to transmitted vibration. It ensures the overall sound has a cleaner, more effortless quality.

A good sub also gives the treble a sweet airiness that enhances the sense of spatial depth and holographic three-dimensionality. The overall sound grows bigger and fuller but also smoother and sweeter. If you’ve never tried a sub, you may find the overall improvement surprising.

The superiority of the little KEF KC62 over my old Klipsch sub was immediately apparent. Not just in terms of massively deeper and more authoritative bass, but also in the way it created an increased sense of air and space around voices and instruments. It also improved the stereo imaging…

Playing David Bowie’s instrumental album All Saints, the KC62 aided the vividness of the recording and enhanced the holographic soundstaging. Without the KC62, the sound was still good, but I noted a loss of depth and front/back spatial clarity; the recording seemed ‘flat’ and less three-dimensional.

Alas, when you reproduce ultra-low frequencies, any information below about 20Hz might not be music but noise. So you may hear infra-bass disturbances previously unnoticed, even in recordings you thought you knew well…

The KC62’s extreme bass depth can be reduced using the Apartment setting. With this engaged, the low frequencies are attenuated by about 12dB at 20Hz. On the Pires/Schumann CD, it definitely helped lower those irksome low-frequency noises, but they were not totally eliminated. Also, room size affects deep bass reproduction. I have a 30ft long room, and I sit about 25ft from the speakers, which helps reproduce the lowest frequencies. However, if I change listening chairs and sit closer, deep bass is noticeably reduced – both in terms of loudness and depth.

I’d say you’re more likely to hear unwanted infra-bass sounds on classical recordings than studio-produced pop or rock, but you never know! Certain synthesiser pop records have very deep bass, but for the most-part, most are not that deep – often, there’s nothing much below about 25Hz. Trying a CD of The Eurythmics’ greatest hits, I liked the improvement produced by the KC62. It made the recording sound more holographic and dimensional and gave the bass more attack and weight. But playing the sub solo confirmed there was very little deep bass of the trouser-flapping kind…

Getting the sub set to the correct volume level and crossover cut-off frequency is key to obtaining convincing results. I did it by ear, though there are measurement options too. To ensure we’re getting our full money’s worth, we may set the sub a little too loud to begin with. After extended use, most listeners usually rein-back the sub a bit, reducing its volume level. Basically, you shouldn’t really notice the sub until there’s deep bass present. Not having the volume set too loudly applies with a vengeance to the KC62, due to its extreme bass extension.

As the ear cannot detect directionality at bass frequencies, there’s no need for two subs from a stereo perspective – one will do perfectly well. However, when a two-channel stereo recording is reduced to single-channel mono, you often get cancellation of the very lowest frequencies. This takes away some tonal richness, bloom, and ambience. That’s why mono recordings usually have a drier, less tonally rich sound than stereo recordings. So, adding a second sub in stereo will reproduce information that would otherwise be cancelled.

For this review, KEF kindly supplied a second KC62 enabling me to experiment with a twin-sub stereo set-up. Adding a second unit certainly made a difference. It further enhanced the spatial/ambient qualities of certain recordings, resulting in an even more holographic, out-of-the-box sound. The effect is subtle yet very noticeable on the right recording. If having a good sub increases the sense of ‘being there’ realism, adding a second sub enhances the effect. I even read of one keen KC62 enthusiast who claimed to have a three-sub set-up. KEF must love him…

On the debit side, having two subs tends to make low-frequency disturbances slightly more audible. A surprising number of classical recordings suffer from background rumble – perhaps from distant road traffic or air conditioning? There’s an increased risk of reproducing unwanted structure-borne low-frequency noise transmitted to microphones mounted on floor stands. For example, on certain piano recordings, I detect a slight infra-bass ‘shudder’ during strenuous forte passages as the keys are pressed hard.

Playing vinyl, I wondered if using stereo subs might reveal lashings of motor or bearing noise, but using a 1966 idler-driven Thorens TD-124, I heard very little bearing noise to speak of – just a faint, barely-audible low-frequency background rumble. This noise reduced using one sub. This reproduction of unwanted low-frequency noise is not a criticism of the KC62 – it’s only showing us what’s there, revealing all the things that lesser subwoofers cannot. With recordings made under controlled studio conditions, you probably won’t hear too many low-frequency disturbances.

THE VERDICT

There is no doubt in my mind that KEF’s new KC62 is a breakthrough product, one that redefines what is expected from a small subwoofer. It’s not inexpensive, but when you consider what it does and how it compares to bigger more expensive designs, it actually offers very good value.

Indeed I would call it a bargain, no less. This really is one instance where you get what you pay for. While the small size is a huge benefit, the KC62 is also superbly made, beautifully styled, and very pleasing to look at in both its Mineral White and Carbon Black finish options. Me? I’m totally smitten. No question, the KC62 vastly exceeded my expectations.

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