If you’re in the market for a new subwoofer, you should consider these new KEF KC62 Subwoofer Review. Unlike other subs, these new subs have a built-in amplifier that handles truly low frequencies with ease, for high levels of power with great noise control. Keep reading KEF KC62 Subwoofer to get more information about this outstanding product.
KEF KC62 Subwoofer Reviews
KEF sub launched the KC62 earlier this year with considerable excitement, evidently believing it was on to a winner. According to the blurb, there was a subwoofer for everyone. We’re informed that the KC62, which is small and compact and packs patent-pending technology around its two driver implementation, ensures that ‘deep and powerful bass is no longer just the territory of big-shouldered, huge subwoofers.’
EVER SINCE THE FIRST Neolithic audiophile blew through a conch shell and thought, “Damn, I wish this thing went lower, louder!” MANKIND HAS CONSTANTLY SOUGHT TO PRODUCE MORE AND DEEPER BASS FROM SMALLER AND SMALLER ENVIRONMENTS.
KEF’s KC62, which is a little larger than a bowling ball, starts, like other “small” subwoofers, by exchanging woofer diameter for excursion: in-and-out capability. (According to the company, a unique innovative pleated surround boosts Uni-linear Core’s throw.)
This drastically reduces efficiency (in the physics sense), which designers respond to by applying more power: in the case of the KEF KC62, 500 class-D watts for each driver—err, voice coil dimensions. Smart DSP equalization and low-frequency dynamic management take care of the rest, thanks to another Uni-Core innovation: a current-sensing feedback loop from the actual voice coils that transmits information about impending distortion to the digital processing “brain.”
Finally, the one-piece extruded aluminum enclosure of the KC62 sub’s thinner walls resists cabinet resonance and results in higher internal volume than exterior size.
- Type: Active subwoofer
- Woofer: 2 x 165 mm
- Amplifier: 2 x 500 W class D
- Frequency range: 11-200 Hz
- Dimensions and weight: 246 x 256 x 248 mm/14 kg
- Finish: Carbon black/mineral white
- Other: Wireless audio via adapter (KEF KW1)
- KEF KC62 subwoofer is small and easy to place. It has a deep, precise bass that is proportional to its size. A perfect partner for the LS50 speakers.
- Even a powerful sub like the KEF KC62 is not perfect. If you want to play louder or have a larger listening room, there are subwoofers that can be even more powerful.
This tiny bass cube is only 25x25x25cms, and it’s actually smaller than a regular compact speaker. KEF claims they can achieve deep bass as low as 11 Hz. They had to think again in order to achieve this.
It is difficult to fit two active woofers into such a small cabinet. Engineers have found a clever way to make it work. They have allowed the two active woofers to share the same magnet system. This means that one element’s voice coil is placed on top of the other. KEF sub calls this technology Uni Core incorporates.
This has a number of benefits, such as the fact that the woofers push each other in the opposite direction and reduce unwanted resonances. Two active woofers, driven by two 500-watt amplifiers, provide significantly higher sound pressure than an active-passive variant. This results in a deeper, more powerful, and cleaner sounding deep bass.
The KC62 includes line-level (RCA) and speaker-level inputs (Phoenix connector) and a variable (40Hz-60Hz) high-pass filter (HPF) line-level (RCA) output. The main speakers can then be driven directly (full range) or the KC62 via line-level inputs, and outputs, and roll off the low-end to blend with the sub.
Four panel-mounted DIP switches allow you to set the high-pass turnover frequencies between 40Hz and120Hz (or bypass) Matching, calibrated knobs can be used to adjust the woofer’s output and low frequencies. A phase-inversion switch (0deg/180deg) and an expansion port that accept KEF’s optional KW1 wireless adapter ($200) are also available.
The KC62’s bipole radiations can double the radiating area of a single woofer without requiring a larger box. According to KEF’s website, the KC62’s magnetically unified drivers employ a current-sensing feedback loop that counteracts voice-coil nonlinearities, “distortion reducing” P-Flex folded-cone-surrounds, and a variation on their new, much-discussed Meta-material Absorption Technology.
The KC62 is available in Carbon Black or Mineral White, both with matte finishes, just like the LS50 Metas from KEF.
User-friendly Bass With (partial) App Control
KEF KC62 can be used in almost any sound system. However, it is well-suited for use with the LS50 models. You can connect it to the blade and muon speakers using a standard RCA signal cable or speaker cables from the amplifier via a small and awkward adapter. KEF offers a USB dongle KW1 for wireless connections. This is the most flexible option, as you can place the subwoofer almost anywhere.
The KEF KC62 is a dual 6.5” driver subwoofer in a tiny cube of around 10” on each side that makes your bookshelf speakers sound like a full-range system.
If you use the KC62 with the LS50 Wireless, there are additional benefits. KEF Connect is an app that allows you to tune and optimize your sound. You can adjust the crossover low frequency dynamic management and double bass level, as well as save your EQ settings. The KEF connect app also lets you decide when the subwoofer should take over and roll off.
The app doesn’t allow you to remotely manage the sub’s manual settings. You will still need to adjust the EQ settings on the back.
The app will automatically choose the best settings if you indicate that you are connecting a KC62. You can also add a subwoofer to each speaker or run stereo bass.
KEF KC62 is open about the fact that the KC62 was designed to work well with the LS50 Wireless II. We trusted them and used them in conjunction with our test. We began listening to the KEFs without a subwoofer. However, we know from experience that they thrive close to the back wall (approximately 50 cm) so that they can receive a little boost of deep bass from the surrounding. They sound great in these conditions and can play a large variety of music.
However, it quickly becomes apparent that they lack weight in the lower octaves. They sound very slim when they are pulled out from the floor. Although they have a better soundscape and focus, they also lose the deep bass. A subwoofer can be added to make the deepest bass sound. This allows you more freedom in positioning the speakers and creates a larger sound image.
Naturally, we were excited by how KEF managed to integrate and time the LS50 speakers. It works! The bass projections are perfectly matched with the speaker’s low bass reproduction. It doesn’t sound like we have connected any subwoofers. The LS50 speakers sound several times larger!
The KEF sub was challenged with long, challenging, bass-heavy music. We were impressed at how much bass it managed to squeeze out. It seems solid. The cabinet boom is solid even when the elements are vibrating at maximum speed.
A good bass will make even the most groovy tracks, such as Lemonade, more engaging and entertaining. This is also true for the deep, rhythmic synth-bass that DeadMau5 has used to create some of their best songs. Double bass and acoustic guitar are also available.
A subwoofer can make the double bass sound even better. You can see the improvements in the midrange. The soundscape becomes larger and instruments have a better anchorage. The music is more synchronized and has a greater presence and size. This brings us closer to the real feeling of live music!
You can expect to gain more weight if you use the KEF LS50 for TV speakers via the HDMI input. This solution was tested with a Samsung TV. The movie sound is as expected much more powerful when a subwoofer is added to the bottom.
A separate sub reproduces very low frequencies, so the main speaker doesn’t have to produce deep bass. This could affect midrange/treble clarity from transmitted vibration. This ensures that the overall sound is cleaner and more natural.
The pair of line-level outputs noted previously in this study are located to the right of the LFE/Smart-Connect inputs. These may be configured such that the audio signals that emerge there are simply a ‘loop-through’ from the line-level inputs, or they can be routed via a high-pass filter (controlled by the DIP switch) to eliminate low frequencies before they show at this output.
The main power switch is designed to make sense to owners in the United States since pushing the top inwards turns on the subwoofer (the exact opposite of mains power switch operation here in Australia and the UK). Above the switch is a tiny dual-color LED that illuminates red when the subwoofer is turned off, but power is present and green when it is turned on.
The KEF KC62 is available in two colors: carbon black and mineral white. It will weigh 14kg, which is very hefty considering its size of 246256248mm. That’s just slightly larger than a shoebox!
The KC62 could inspire the word “cute” if not for its denseness– it is three times heavier than the bowling ball it immediately recalls. It is beautifully finished with great attention to detail, textures, and tones, just like every KEF product that I have encountered. Two sides culminate in the opposing driver cones, while the bottom large vibrating surface moving a footing of some vibration-absorbing, woofer-walk-resisting stuff.
The back panel houses a complex control panel and input/output panel. It has the usual, but unusually well-detailed, system lacking crossover facility and rotary volume knobs, 0/180 degree phase, and LFE/Normal toggles as well as a five-position EQ switch with Wall, Corner, and Listening Room settings. Cabinet and Apartment are two additional settings that limit vibrational transmission and deep bass output.
A four-place “DIP” switch set can impose a high filter on the KC62’s stereo line outputs. This is useful for systems without a crossover facility in their amps or receivers.
With a subwoofer, the problems are quite straightforward. Is it able to get low enough? Is it audible enough? Is its three-octave useful range flat enough to prevent booming or hooting? Is it acceptably low distortion at useable levels (remembering that humans are far more tolerant of distortion at extremely low frequencies than higher frequencies)? Most of the rest, including my favorite oxymorons, “fast bass,” and “tuneful bass,” are nonsense.
Now that we’ve finished the digressions, let’s go back to the tiny KEF. Is it able to get low enough? True, true. I heard usable levels of clean, un-doubled output down to 25Hz and even below (caveats to follow). Is it audible enough? Yes. No. Maybe. (Of course, I’ll surprisingly elaborate control below.) Is it sufficiently flat? Particularly with its versatile EQ choices.
I began with the KC62 in my desktop setup and IK Multimedia’s tiny yet powerful MTM-powered monitors (see review on page 56). These offer their own set of versatile settings, including a 60Hz high-pass option. With this option selected and the sub connected to my DAC’s unbalanced left/right outputs and pushed under my desk out of reach of my size 11s, I was rewarded with rich, fully extended sound that required nothing more than nudging the KC62’s adequate volume and crossover controls to perfect electromagnetic balance up to near perfection.
Bassist Nathan East slaps a low E-flat-D vamp in parts on Fourplay’s smooth-jazz tune “Café l’Amour,” delving down around 35Hz. The little KEF had no trouble “keeping up” at my desktop levels—the MTMs can play clean and punchy to a solidly loud volume but a tad short of control-room-monitor level. Deep bass stayed solid, powerful, and undistorted, while the following octave had no boom, thud, or unsightly whooshing.
While re-listening to “Café l’Amour,” I pushed up the volume to the maximum the IK monitors could provide, then switched them off and auditioned the sub “naked.” I got exactly what I expected: crisp, robust bass. (Surprisingly, I discovered that the KEF’s Crossover control, which I had always tuned in by ear alone, was perfectly aligned with the 60Hz marker. That never occurs!)
Keeping to the same track, I progressively raised the sub’s volume control, as well as the output-volume control of my DAC, and observed the results. The small KEF became louder with no loss of bass content, probably 10dB louder than where I’d been at max with my desktop monitors; beyond that point, although the sub’s mid-bass continued to grow, the deep bass remained constant: bass-dynamics limitation at work, as predicted.
But, until the final measure of gain from my DAC (whose max output is well over 2 volts), with the sub’s volume wide open, there was no detectable distortion or unseemly sounds from the KC62. The small woofers then provided a faint “phut” on each note when they reached the end of their trip on powerful kickdrum-bass unisons.
How would this small tot fair in my enormous system, which supports considerably bigger, far higher-output 6.5-inch three-way active speakers and replaces an SVS cylinder subwoofer with a cubic capacity nearly 25 times that of the KC62? Let us investigate.
I hooked in power and the lengthy RCA wire from my pre-sub pro’s out into the KEF’s unfiltered LFE input and did a fast level balance using the pre-match pro’s noise and my iPhone’s SPL-meter app, muscling the SVS aside.
With the preamp’s crossover set to 80Hz, I played the identical Fourplay recording (through Roon) at a comfortable listening level, making minor changes to volume and crossover in the settings menu of my pre-pro.
The end effect was a strong, rich sound—exactly how my system normally sounded. To be sure, I switched back to the huge sub a couple of times and heard no discernible change.
This was pretty much what I anticipated, but it should be nothing short of amazing to an unjaundiced ear. At moderate listening settings (75-80dB SPL average, –ish), the KC62 had no trouble matching my huge system’s extension, weight, or musicality—this in a 22 by 16-foot room with a volume of around 2,800 cubic feet. Track after track produced the same outcomes.
The introduction of Prokofiev’s Romeo & Juliet scene “Dance of the Knights” featured rich, vivid orchestral bass with no trace of buzz or woodiness. The Eagles’ unplugged “Hotel California” has a high-impact, gut-punching smash with heavy bass-drum content about 40Hz and “undertones” way below.
I returned to Prokofiev for a natural-acoustic reference. In the somewhat loud settings I was listening to. The KEF performed well. This was approximately 76-78dB SPL on average, roughly equal to what you’d hear from a seat two-thirds back in Boston’s Symphony Hall, the venue I’m most acquainted with.
Adding 4 or 5dB of level—about one-third-back—made no difference: the overall balance was somewhat “lighter/brighter,” but there was still sufficient of 30-60Hz octave for full impact. Adding another 4 or 5dB, we’re now in row three, nose-to-nose with the stage. The contrast was clear here, with the considerably brighter balance forcing the question, “Where did all that rich, deep bass go?”
Of course, it didn’t go anywhere—it’s a balancing act. The small KEF ran out of lowest-octave headroom when my main speakers reached peak concert volumes, and its sophisticated dynamic circuitry limited them to avoid audible distortion.
This allows the internal volume to be reduced by one-third, and also allows longer cone excursions for higher output. The two drivers have concentric voice coils of different diameters, each operating in its own voice-coil air gaps. The Uni-Core driver requires a lot of optimization of the motor common magnet structure in order for the two separate drivers to behave the same, having different voice coils, Bosch noted.
This topology requires a balletic balancing of magnetic and electrical parameters like flux, resistance, reluctance, and inductance, such that two loudspeakers “motors” with necessarily very different voice-coil dimensions and air gaps maintain perfect electromagnetic balance over their full travels.
Meanwhile, its highest half-octave (and the remaining 8 octaves of the primary speakers) continued to amp up. Result? The ear hears “bright,” and Prokofiev’s deep cocoa Bassi/contrabassoon/tuba unisons almost disappear—even though the sub reproduces them just as forcefully as it did at my original level.
I chose the nuclear option, “Bass I Love You,” by electronica artist Bassotronics, a tune with about as much 15-30Hz bass content as you’ll find. (Of course, it’s all synthetic; you can’t get this low and loud without military-grade explosives.)
The KC62 provided almost all of the infra-bass—the super-low thump, the breathless type of decompression between pulses, and the falling flutter of sub-25Hz content—with a gratifying presence at my set “moderate” level.
Switching back to my monstrous SVS subwoofer made shockingly little effect, even though the big bruiser was stronger and more dramatic with this infra-bass stuff. In this situation, though, the KC62’s level limit was “moderate.” Even asking for 2dB more was futile: the >100 Hz things went louder, but the 60 Hz stuff didn’t.
Limited Sound Pressure
We had to verify that the bass response was as deep as KEF claims. The KC62 does indeed provide a tactile/audible response of just 11 Hz. This tiny sub has a powerful thrust and a low sound level of 25 Hz. It made the recording sound more holographic and dimensional and gave the bass more attack and weight. Although it’s not always the case that the foundation wall cracks or is visible in the floorboards, it can be felt!
All good things have a price. A small subwoofer likes this has certain limitations when compared to a full-size model. KEF’s engineers may be smart, but they cannot change the physical laws. The amplifier then compensates by lowering the level when the drivers are too small for the task. It all depends on what you like, how much space you have, and your relationship with neighbors.
The KEF subwoofer was also tested in conjunction with two larger, hi-fi floor standing speakers (Sonus Faber Olympica III). These speakers have a deeper bass than the LS50s and don’t require as much “traction” from a subwoofer. The KC62 also made a significant difference, but it could not keep up with very high listening levels. This is where a larger subwoofer or an additional KC62 will be helpful.
The KEF KC62 subwoofer is a compact, powerful subwoofer with audiophile-grade sound reproduction. Packed with space-saving features that are rarely found in affordable subwoofers, this subwoofer is an excellent choice for any sound system.