KEF KF92 Subwoofer Review

Great and Small

by Martin Dew
MSRP: £2,250.00
9
AVForumsSCORE
OUT OF
10

KEF KF92 Subwoofer Review

KEF has excelled once again with the KF92. Its force-cancelling driver architecture is capable of a detailed and room-filling soundstage from a stylish and compact cabinet. A subwoofer qualified for tremendous power and dexterity in small to mid-size rooms.

Pros

  • Excellent sonic detail
  • Deep sub-20 Hz response
  • Sometimes astounding transients
  • Controlled performance
  • Finely styled compact cabinet

Cons

  • No XLR input, 12-volt trigger or signal-activated auto turn on function
  • Can lack energy in high-output scenarios

Introduction: What is the KEF KF92?

It’s fair to say that respected British brand KEF knows a thing or two about loudspeakers. After working as an electrical engineer for the BBC, the late founder Raymond Cooke collaborated with the BBC in the development of the Corporation’s professional monitors in the early 1960s. And despite KEF’s history of producing an evolving selection of its much-praised Reference Series floor-standers over the years, it is the company’s intrinsic ability to pack loads of performance into compact designs that probably defines its output best.

In recent years, KEF has made a splash with its highly detailed and wide-dispersion Uni-Q drivers deployed across its portfolio. In 2021, KEF developed the Uni-Core technology for the KC62, an enhancement of its signature force-cancelling arrangement in subwoofers (more on that later). One of the precursors of the KC62 is the 2019 model, the KF92, which we review here. The subwoofer sits below the Reference 8b subwoofer and above the iconic Kube range. The KF92’s extraordinarily slight dimensions and stylish finish suggest that this mid-price player is targeted for use in décor-conscious environments.

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KEF announces KF92 subwoofer

KEF announces KF92 subwoofer

by Andy Bassett ·
KEF announces its new KF92 subwoofer which uses dual drivers in a force cancelling configuration.  
KEF KF92
The Kef KF92 subwoofer

Design

The KEF KF92 is one of those pleasing subwoofers which can be carried across the threshold of your front door and up the stairs without the need to call your physio. Its 20kg weight and dinky 35(H) x 33(W) x 36(D) cm housing mean it can be extracted from its packaging with relative ease. The plain front and outer housing are finished in a beautiful piano black finish.

... it is KEF’s intrinsic ability to pack loads of performance into compact designs that probably defines its output best

Both nine-inch opposing and grilleless drivers are designed to be focused towards the left and right walls of the listening room. The aluminium-reinforced paper cones with circular front discs are elegant and match the carbon fibre circular surrounds. The rear panel consists of a steel amp plate with a forged curvature covering the heat sink’s ribs. Recessed screws affix the plate to the chassis, and the tactile control knobs are fashioned from chunky black plastic. The aesthetics and modest form factor of the KF92 are great assets. The sub’s finish and slightly bevelled edges exude quality and luxury. The KEF will surely avoid arrest by the fashion police.

Connections and Control

KEF gives you a choice of response curves in the form of a manual switch on the back panel. The options are Room, Wall, Corner, Cabinet and Apartment (response below 40Hz attenuated). The included, but simplified, operation manual illustrates typical room placements to suit those selections. LFE vs Manual, Phase (0 or 180 degrees) and Ground Lift (ground loop noise reduction) also take the form of on/off slider switches fixed to the amp plate. Both the volume and crossover controls are dials with the latter topping out at 140 Hz if you wish to manually match the sub to, say, your bookshelf speakers.

KEF KF92
The Kef KF92 subwoofer - rear panel

Line level inputs support LFE and L&R. Corresponding L&R outputs sit just beneath the inputs. You can also manipulate the DIP-style high pass crossover frequency manually if you’re connecting the KF92 to your loudspeakers’ external amplifier. An on/off power switch and power cord input round out the rear plate functionality. Notable in absence are an XLR connection, 12-volt trigger input or signal-activated auto on feature.

Features and Specifications

As mentioned earlier, KEF uses a dual driver, force-cancelling configuration which the company claims will result in “lightning quick articulation and immense power”. The KF92 features two nine-inch drivers mounted into the cabinet walls, a design philosophy imported from the company’s own R Series speakers. The drivers themselves boast massive motor systems and voice coils with a vented design to reduce distortion. The two drivers are positioned in opposition to each other to cancel out reactive forces, minimising or eliminating cabinet agitation. According to KEF, this arrangement should deliver 110dB SPL from the diminutive cabinet size.

KEF KF92
The Kef KF92 subwoofer with its force cancelling 'back to back' driver arrangement

As well as promising an 11 Hz bottom-out thanks to optimized excursion characteristics, the sealed-box KF92 uses 2 x 500-watt Class D amplifiers for each driver. These should improve timing, dynamics and detail. Intelligent Bass Extension (iBX), part of KEF’s proprietary ‘Music Integrity Engine’ (MIE) analyses input signals and applies customised DSP to optimise the relationship between the amplifier, drivers and cabinet for louder playback. The sealed box construction with sculpted heat sink, along with the compact design, should also ensure better placement options and more accuracy in audio output.

Set-up and Operation

As with my last review here at AVForums, I used my reference system in a dedicated room with Lyngdorf MP-50 pre-amp/processor, two Parasound multi-channel amplifiers and M&K S150 satellites in a 5.1.2 configuration. The KEF KF92 was connected via the LFE input with 0 degrees phase selected, the crossover control set at max (140 Hz) and volume control set by my Lyngdorf processor. I tried out the sub in both Room (open space) and Wall (next to a wall) modes before running RoomPerfect in-room calibration in each case.

Performance

The remaster of the UB40 track Rat in Mi Kitchen MP3 from the album of the same name kicks off with a ferocious bass line which locks onto a reggae-style percussion rhythm. The KF92 resolved the bass guitar and kick drum with stunning proficiency. Startling bass transients - the like of which I have never heard from a subwoofer in this class – almost appeared to keep the song hanging for an instant at the start of each bar. The KEF gave Killing Joke’s Requiem - with its scratchy guitars and distorted, repetitive synth line – both space and a soundstage-filling breadth. It also happily eked out the bottom resonances from the pounding tom-toms at the start.

KEF KF92
KEF KF92 subwoofer

Next up, I tried out the J. S. Bach Organ Recital (CD, Samuel John Swartz, Perpetua) and the piece Wachet auf Ruft uns die Stimme. The bass pedal notes ground into the floor and walls of my listening room. The trumpet reed pipes simultaneously sent harmonics just skirting into the subwoofer’s upper range while lending the necessary ecclesiastical scale to the scene.

Startling bass transients, the like of which I have never heard from a subwoofer in this class

The KF92 revealed immense front soundstage detail in the T-Rex attack in Jurassic Park (1993, 4K UHD). My LCR speakers felt like they were suitably weighed down by the gravity of the subwoofer. Here was a sense of innate control with no hint of distortion or anything being in the wrong place. The dinosaur’s foot rendered its squelch in the mud next to the Ford Explorer with multi-layered horribleness. I did get the feeling that the KF92 was occasionally grappling to match the sheer power output of my Parasound amps and satellite speakers during loud and densely mixed movie scenes. This could sometimes leave the mid-range feeling exposed. But I also had to remind myself that the KF92 is essentially a living or gaming room subwoofer and has clearly been optimised for such environments.

KEF KF92
KEF KF92 subwoofer in situ

The opening sequence of Interstellar (2014, 4K UHD) with its transitions from Cooper’s house and into outer space was equally convincing. The KEF paid out on the raucous spacecraft engines shaking the room juxtaposed with the gently rumbling and atmospheric bedroom and porch scenes back on Earth. The KF92 clearly dipped well below that magic 20 Hz threshold on several occasions and proved its worth as a companion for a high-octane movie collection.

Conclusion

Should I buy one?

The KF92 is a thing of beauty. This piano-lacquered subwoofer will not look out of place in a luxury flat or stylish media room. The fact that the KF92 includes an ‘Apartment’ mode illustrates that this subwoofer is not primed for the dedicated cinema or large room end of the spectrum.

Although we have quoted the MSRP here in the header, it does not require much snooping around on the internet to earmark dealers slashing the KF92 by £400 or £500. If you can pick one up for £1,700 or £1,800, we believe that represents excellent value. The £2,250 MSRP as advertised by KEF feels a little top-heavy.

Whether you are a KEF loyalist or just someone who wants to take a punt, you will not be disappointed with a purchase of the KF92. What you get with this subwoofer is a living room friendly device with KEF’s signature cabinet styling, true musical finesse, and deep and resolved bass response from all sources. The KF92 delivers performance which quite simply defies its modest dimensions.

What are my alternatives?

The REL S/812 boasts an 800-watt amplifier section with both active and passive 12-inch drivers. Although described as embodying a medium-sized chassis with slightly larger dimensions and weight (34 kg) than the KF92, the S/812 also employs stunning looks. REL suggests stacking the S/812 to create two- or three-strong line arrays for extra “width, depth and height” in real world performance. The S/812 is listed presently at £2,799 but can be found for c. £2,300.

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43

REL S/812 Subwoofer Review

REL S/812 Subwoofer Review

by Steve Withers ·
The new REL S/812 is the latest subwoofer from the company and represents a complete transformation of its Serie S mid-sized range. The new model has been upgraded to incorporate elements of the high-end Reference Series, but also adds increased power and a redesigned driver for a seriously impressive performance.  
9

The Paradigm Defiance X12 supports 650 watts of power presiding over a 12-inch driver and a high-velocity and low-turbulence ported design. App control and Anthem Room Correction (ARC) are included, and Paradigm promises the delivery of massive SPLs and intense performance detail in use. The X12 carries a price tag of £1,885, comparatively compact cuboid dimensions and an unassuming design aesthetic.

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133

REL S/510 Subwoofer Review

REL S/510 Subwoofer Review

by Steve Withers ·
The REL S/510 is the smaller entry in the company's Serie S range, and like the other models it boasts increased power and a redesigned driver for an improved performance.  
9
Home AV Review

50

SVS SB16-Ultra Subwoofer Review

SVS SB16-Ultra Subwoofer Review

by Steve Withers ·
SVS's new SB16-Ultra combines a 16-inch driver and sealed box design with three key innovations to deliver their best performing subwoofer to date.  
9

Scores

Sound Quality

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9

Build Quality

10

Value For Money

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8

Verdict

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9
9
AVForumsSCORE
OUT OF
10

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