KEF Updates Flagship Blade and Reference Speakers With Metamaterial Absorption Technology

Back in 2020, KEF announced that its loudspeaker designers had been working with an organization called Acoustic Metamaterials Group on a new engineering tool called Metamaterial Absorption Technology, or MAT. The company explained that it would be using metamaterial — in this case, an intricately-designed acoustical device to work as a sound absorber inside a speaker cabinet — on an upcoming product. KEF described MAT as “a highly complex maze-like structure, where each of the intricate channels efficiently absorbs a range of specific frequencies. When combined, the channels act as an acoustic black hole, absorbing 99% of the unwanted sound, eliminating the resulting distortion and providing a purer, more natural acoustic performance.” At the time of this announcement, no hint was given as to which KEF product would first be employing this breakthrough tech, but I assumed it would be the company’s Blade speaker, which is a technological tour de force, and serves as KEF’s de facto flagship design (even if the $225,000 Muon technically holds the top spot). Or perhaps, I thought, KEF’s venerable Reference series would be first to get the metamaterial treatment. Instead, the diminutive and wildly popular KEF LS50, along with its active, wireless/streaming counterpart, became the world’s first speaker to employ metamaterial. While I was surprised that a relatively affordable speaker was chosen over KEF’s top offerings to receive such a cutting-edge update first, I can understand why the decision was made. The original LS50 was such a ubiquitous, well-known speaker that it would be very easy for audio reviewers and potential customers to do a side-by-side comparison and hear for themselves the difference that metamaterial could make. Now that reviews of the LS50 Meta are plentiful (and overwhelmingly positive), the audio world knows that Metamaterial Absorption Technology isn’t just a gimmick; it’s a real step forward for loudspeaker engineering. With that established, the folks at KEF are ready to launch the latest update to their high-end Blade and Reference speakers.

The new Blade and Reference lines have also been updated with KEF’s other recent acoustic innovations, including a new high-end version of the brand’s 12th-generation concentric Uni-Q driver, which places a 1-inch aluminum dome tweeter (with MAT, and KEF’s proprietary tangerine waveguide) in the center of a 5-inch aluminum midrange driver. For both series, the crossover has been fully reworked with new, low distortion components, according to the company. KEF says that “the result of these innovations and developments for both Blade and The Reference is that the Uni-Q with MAT reproduces more transparent and life-like sound than previously possible.” KEF’s less expensive speakers, including the LS50 range, are made in China, but the Blade and Reference ranges are assembled by hand in the company’s Maidstone, England production facility, by “master craftsmen.” Impressively, each pair is measured to ensure that the speakers match — both to each other, and to the laboratory-maintained line standard — within 0.5dB.

The Blade One Meta and Blade Two Meta

The Blade began as a concept back in 2006, but wasn’t revealed to the public until 2009. The final, market-ready Blade launched in 2011. The smaller Blade 2, which was scaled down in size but not in performance, came out in 2014. Now, just over a decade since the first Blade was released, KEF’s engineers have managed to improve upon a design that was still considered state-of-the-art. The original Blade has been replaced by the Blade One Meta ($35,000/pair), which looks nearly identical, standing the same 62.5 inches tall, and weighing in at the same 126 pounds as its predecessor. (The slightly smaller Blade Two Meta costs $28,000 per pair.) At $35K, The Blade One Meta is competing with the top offerings from fellow British brands Bowers & Wilkins and Monitor Audio, newcomers like PerListen and PS Audio, and the usual suspects from Wilson, Magico, YG, and many others. To some people, this might sound like an absurd sum to spend on a pair of speakers, but it’s a popular and crowded segment of the high-end audio market. What sets the Blade One Meta apart from its rivals? At its heart, the Blade One is the most complete realization of KEF’s Single Apparent Source technology, which extends the inherent point-source characteristics of the Uni-Q driver all the way down to the deepest bass frequencies, while delivering immense dynamic output. As KEF’s Head of Acoustics Jack Oclee-Brown puts it, “the whole audio spectrum appears to emanate from a single point in space.”

The Blade’s low end is provided by four side-firing, force-cancelling 9-inch woofers. Two woofers are placed on each side of the speaker, allowing the drivers to be braced against each other in pairs, thus cancelling out vibrations that would otherwise excite the cabinet. KEF claims that you can balance a coin on top of the Blade’s cabinet, and that it won’t fall (or even move), no matter what ear-assaulting bass you pump through the speakers. Each pair of woofers is located in its own chamber, reducing the potential for interference between the drive units, while also reducing the need for damping, which can have a deleterious effect on bass quality. The woofers are positioned symmetrically relative to the Uni-Q driver, and the crossover ensures perfect time alignment. The result of this design is that low, mid, and high frequencies all appear to radiate from one point, and all reach the listener’s ears at the same time. This makes the speaker incredibly coherent, with more precise imaging than other multi-driver speakers, according to KEF. The icing on this cake is the Metamaterial Absorption Technology behind the Uni-Q driver, which absorbs the tweeter’s backwave to prevent resonances that would otherwise color the sound. The massive, damped cabinet is formed from high-density polyurethane (which, according to KEF’s longtime brand ambassador Johan Coorg, provides a huge sonic upgrade compared the composite of carbon fiber and balsa wood used in the early prototypes of the first Blade). The speaker’s unusual, sculptural shape employs parabolic curves to minimize diffraction. Although it’s over 5 feet tall, the Blade One Meta is only moderately large compared to some super-speakers, and looks rather slender at 14.3 inches wide and 21.2 inches deep. But if those dimensions won’t work in your room (or if you’re concerned that the Blade One Meta would overload your smaller listening room with bass), you might instead choose the slightly smaller Blade Two Meta, which is designed to deliver the same experience in smaller spaces. The Blade Two Meta employs 6.5-inch woofers in place of the Blade One’s 9-inch woofers, and its cabinet is smaller, at 57.5 inches tall, 13.3 inches wide, and 18.7 inches deep. Both Blade models are available in four standard finishes: Piano Black & Grey, Arctic White & Champagne, Charcoal Grey & Bronze, and Frosted Blue & Blue. Four special-order finishes are also available: Piano Black & Copper, Frosted Blue & Bronze, Charcoal Grey & Red, and Racing Red & Grey. KEF will be offering custom finishes as well, starting in June.

The Reference Series

If the Blade is the result of KEF’s engineers’ being given a clean slate, the Reference series can be seen as the result of decades worth of audio evolution. The Reference DNA can be traced back to the Model 104, which was the first KEF speaker to carry the Reference tag back in 1973. But it was the Reference Series Model 105, which debuted in 1977, that really made waves in the loudspeaker industry, thanks to its radical-looking, form-follows-function design and its high standard of precision imaging and tonal accuracy. Not long after the first Uni-Q driver array appeared on KEF’s C35 loudspeaker in 1988, the Reference Series embraced that technology, marking the start of a new, modern era for the Reference. All of that was a bit before my time in the audio industry, but I remember very clearly reading John Atkinson’s 2008 Stereophile review of the $20,000 KEF Reference 207/2, which he said was, “to all intents and purposes, …without flaw.” These days, the Reference speakers aim to deliver as much of KEF’s engineering prowess as possible in more traditional-looking (rectangular box) designs that fit well into contemporary home environments.

As with the new Blades, the new Reference speakers feature an updated 12th-generation Uni-Q driver, with a new motor system and spider to improve linearity, and Metamaterial Absorption Technology to absorb the tweeter’s backwave. Surrounding this is what KEF calls a Shadow Flare, which the company describes as “a specially profiled trim ring” that extends the waveguide effect of Uni-Q driver array, resulting in “improved clarity, particularly when it comes to the subtle nuances of plucked strings and other percussive sounds.” It achieves this by reducing the negative effects of diffraction, “allowing Uni-Q to deliver a beautifully wide and accurate soundstage,” according to KEF. Vibration is addressed with constrained layer damping, while tuned internal chambering prevents standing waves. Adjustable, flexible ports make chuffing a thing of the past and allow the user to tweak the speaker’s bass to better fit the room. The Reference speakers use more conventional front-firing woofers, with a “massive, vented magnet assembly paired with a huge aluminum voice coil and a stiff, yet cleverly damped alloy cone (to ensure that) the Reference is fully capable of achieving pipe-organ depths.”

Reference 1 Meta and Reference 5 Meta

The new Reference series comprises five models with easy-to-remember names: The Reference 1 Meta, The Reference 2 Meta, The Reference 3 Meta, The Reference 4 Meta, and The Reference 5 Meta. But it’s not quite as simple as it seems. The Reference 1 Meta, 3 Meta, and 5 Meta are “free-standing” speakers, meaning they are intended to be used in a stereo pair, away from room boundaries. The Reference 2 Meta and Reference 4 Meta are designed to be used as center-channel speakers in home theater environments, or as left and right speakers where bookshelf or cabinet mounting is required. Let’s look first at the free-standing speakers. The Reference 1 Meta ($9,000/pair) is a 3-way stand-mounted speaker that combines the Reference Uni-Q with a single 6.5-inch woofer in a rear-ported cabinet. It’s fairly large for a stand-mount, at 17.3 inches tall, weighing 40 pounds each. The Reference 1 is intended for use in smaller listening rooms, where they would benefit from room gain (and where larger speakers might produce an excess of bass). The new S-RF1 ($1,200/pair) is a dedicated floor stand for the Reference 1 Meta, featuring bolting points and cable management. The Reference 3 Meta ($15,000/pair) is the smaller of two floorstanders, at 47.5 inches tall, and weighing a substantial 113 pounds each. It employs a pair of 6.5-inch ported woofers, one above and one below the Uni-Q. As you might guess, it’s designed for use in medium-sized rooms. Larger spaces might be better served by the Papa Bear of the range, the Reference 5 Meta ($22,000/pair), which places a pair of 6.5-inch woofers above the Uni-Q, and another pair below it, delivering an in-room bass response reaching down to 25Hz (-6db). The Reference 5 Meta stands just over 55 inches tall, and weighs about 133 pounds each.

If you’re an old-school 2-channel audiophile, you can stop there. But the home theater crowd will surely be interested in the Reference 2 Meta ($6,000 each) and Reference 4 Meta ($8000 each), which will serve as center-channel speakers, or LCR speakers, depending on the requirements of the system and the room. The drivers in both of these models are symmetrically arranged, so that the speakers can be used either horizontally or vertically with no change to tonal balance and no undesirable effects. However they are oriented, these speakers are optimized for use either in free space or positioned close to room boundaries, such as a wall or entertainment center. They include adjustments for bass and treble balance to help compensate for changes in their sound that may result from proximity to the wall behind them, or from being mounted behind a projection screen. The Reference 2 Meta is a sealed-cabinet design, with a single 6.5-inch woofer on either side of the Uni-Q. The larger Reference 4 Meta employs a pair of woofers on either side of the Uni-Q, and is a ported design, so it does require a bit more clearance in order for the port to work properly. The Reference series is available in three standard finish options: Satin Walnut & Silver, High-Gloss White & Champagne, and High-Gloss Black & Grey. There are also two special-order options: High-Gloss White & Blue, and High-Gloss Black & Copper.

With the addition of Metamaterial Absorption Technology, new drivers, and new crossovers, this new generation of KEF’s high-end offerings packs a lot of engineering into familiar-looking packages that might easily be mistaken for the older models. That said, both the new Blades and the new Reference speakers can be had in a variety of extremely stylish color combinations, and the company’s approach to industrial design makes sense to me. If you want super-modern looks and extreme performance, go with the Blades. Meanwhile, the Reference series offers nearly the same level of technology in a wider range of sizes and configurations, all packaged in a more traditional design that will work in more living spaces. Would you choose the flashy, hardcore Blades, or the more timeless, elegant Reference speakers for your own system? Share your thoughts in the related forum thread below.  

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