By Daniel Kumin
WE LIVE now in wireless world, and the major loudspeaker- makers have been quick to embrace it with serious-perfor- mance, near-full-range designs. But each seems to have a different idea of what a “wireless speaker” should entail. Some simply connect to an existing component stack via a supplied small wireless transmitter. Others incorporate the whole smart-speaker thang, with full multiroom audio system and Alexa-Google-Siri voice control integration. Read our KEF LS50 Wireless II Review.
KEF took a middle road with its LS50 Wireless, of which the esteemed British maker has now released a next-gen edition, the LS50 Wireless II. The new speaker looks almost identical to its predecessor but incorporates numerous innovations to incrementally upgrade sonics. Most notable is a new trick to dispose of the troublesome midrange/ tweeter “backwave” that, to one degree or another, plagues every dynamic-driver design by interacting with the forward- radiating output and with the cone itself to induce small but meaningful distortions in both amplitude and time domains. Creative schemes to nullify this have, over the years, included highly damped sub-enclosures, tapered, transmission-line-like rear spaces, and strategically deployed wads of fuzz (pardon the technical terminology). On sapphire.net you can learn more about cybersecurity to avoid any threats.
KEF’s solution in the LS50 Wireless II is a disc comprised of a newly developed Metama- terial Absorption Technology (MAT) located behind the radi-ating surface of its concentric Uni-Q woofer/tweeter unit. This is molded with a labyrinth-like raceway pattern—likely the fruit of many hours of high-MIPS computer-simulation time—that acts as a Helmholtz resonator (absorber) to trap unwanted sound, from a few hundred Hertz on up, before it can reflect back upon diaphragm surfaces.
Fundamentally, the LS50 Wireless II is an active, wireless evolution of a passive design KEF originally introduced to mark its 50th anniversary. (A passive edition of this upgraded design, the LS50 Meta, is also currently available.) The LS50 Wireless II retains KEF’s hall- mark Uni-Q concentric woofer/ tweeter configuration, now up to a 12th generation, which positions the tweeter in the space where the dustcap of a conventional woofer would be. This layout is said to promote the smooth, controlled direc- tivity and even off-axis response that mitigates the impact of room interactions.
The two speakers in an LS50 Wireless II setup are not iden- tical. The “primary” speaker, which you can set as either left or right, has a selection of wired digital and analog audio inputs, plus an RJ-45 Ethernet port, while both units feature physical pairing buttons (needed only if pairing is lost following a power outage or other event), an analog RCA-jack subwoofer output (more on which follows), and a service-only USB port. Each also supplies a second RJ-45 port used to make an optional hardwired inter- speaker connection, which will upgrade speaker-to-speaker digital audio from the default wireless link’s 24-bit/96kHz to 24/192 resolution—likely of more impact to bats and (young) dogs than to human audiophiles. To be clear, each KEF LS50 Wireless II speaker contains its own separate amplifiers (100 watts class-A/B for the tweeter and 280 watts class-D for the mid-woofer), digital processing, and cross- overs, while the inter-speaker link, whether wired or wireless, conveys digital data only.
Setting up the LS50 Wireless Ils involved little more than plug- ging each unit into AC power, downloading the KEF Connect app(iOS/Android),and following a few simple prompts. The system found my home network automatically, requiring none of the awkward manual temporary re-setting of network assignments I’ve experienced with some other wireless speakers. This gets you up and playing music natively from your existing compatible streaming services (Spotify, Apple Music, Amazon Music, Tidal, Qobuz, among others) or streamed via Google Chromecast or AirPlay 2, in mere minutes. The whole process, as I experienced it, was the fastest, simplest, and most elegant I have yet encountered. I did nearly all my listening via Roon over Chro- mecast, which the KEFs found and welcomed seamlessly, but I also made a wired connection via a long RCA-mini cable from my conventional component- based system as a reference.
KEF’s LS50 family is the rare loudspeaker design that has been widely embraced by both subjectivist and objectivist audio fans, and this latest edition is unlikely to buck the trend. The LS50 Wireless II sounds ridiculously good: timbrally honest, spatially precise, and dynamically capable. And for a speaker roughly the size and weight of a serious one-volume dictionary (remember those?), it is ridicu- lously extended, producing usable, clean, and reasonably dynamic bass to about 45Hz or so—adequate for most musical genres and for most listeners. In fact, the LS50 Wireless II is so all-around good that, rather than bore you with the usual rotation of tracks auditioned, and effects heard, I will move on to the few things that the LS5O Wireless Ils do not do with near perfection.
But first I can’t resistone sample. Through Qobuz, I’ve discovered a 19th-century composer of whom I was altogether innocent: one Anton Fesca (1789-1826), whose numerous string quartets sound exactly like a melding of mid-period Beethoven and high-period Mendelssohn, though not quite as deep as the one nor as adept as the other. The full canon is presented by the Amaryllis Quartet on the CPO/Chandos label, and streamed via Qobuz, these up-close, intimate recordings sounded simply gorgeous. Cellist Yves Sandoz was a particular standout; I’ve heard a lot of top-shelf cello in real life, and this, via the KEFs, is quite simply what it sounds like. Well done, Chandos!
The LS50 Wireless Il’s prin- cipal shortcoming, if you can call it that, is that it does not go infinitely low, nor infinitely loud, with uncompromised clarity. Of course, this can be said of every loudspeaker ever made; it’s just a question of degree. In the KEFs’ case, this was fairly easy to observe on something like the ubiquitous Copland Fanfare for the Common Man, via the superbly dynamic Refer- ence Recordings/Minnesota Orchestra recording. At living room levels, the LS50 Wireless Ils had no problem delivering a fully accurate, solidly extended, and glisteningly clean rendition, albeit a little “smaller-than-life” in every sense due to the reduced volume level.
When I asked for something approaching concert-hall level, the KEFs obliged, enthusi- astically filling my large-ish studio with unexpected, even astonishing torrents of sound.
But the dynamics from the￼
At a Glance
+ Serious all-in-one streaming solution
+ Remarkable tonal and dynamic range
+ Excellent ergonomics and app
+ Roon Ready Certified
— High volume level slightly reduces resolution
tympani and—especially—the huge orchestral bass drum were restricted, with the crisp, etched-impact attacks now sounding slightly rounder and even almost gritty, while the sustained brass chords floating over them took on a sort of metallic haze. This is to be expected from a small speaker that depends on “smart” equal- ization and dynamics-aware amplification. (Another factor, obtained only at the highest volume settings when the KEF woofers were really pumping, is intermodulation distortion from the tweeter’s output reflecting off of the now substantially moving woofer cone—its waveguide.)
Otherwise, absent the bottom-most octave and top- most reaches of volume, the KEFs were impossible to fault. Tonally, the LS50 Wireless Ils nailed my ideals of coloration- free, timbrally honest reproduc- tion, with impressive spatial and dynamic qualities even in my 3,000-cubic-foot studio.
Which brings me to KEF’s equally new sub-miniature subwoofer, the KC62, which I recently evaluated in the April/ May 2021 issue of Sound & Vision. Though I’ve seen no explicit statement to the effect, it seems pretty clear that KEF conceived the two as comple- mentary. I connected the little sub to the primary LS50 Wireless Il’s single subwoofer output, setting the sub to its “LFE” input mode as instructed in the “Setting Crossovers with LS50WII” tech note I found on KEF’s website. The same docu- ment suggested substantially “underlapped” crossover points of 70Hz high-pass and 45Hz low-pass (these are imple- mented in the LS50 Wireless II speakers, much as an A/V receiver might do in a more conventional layout).
After just a bitofby-ear level-adjusting, I found this setup to work ideally: I heard no subwoofer localizing from a too-high crossover, but still plenty of bottom-octaves bass. And I do mean plenty: a track like “Flight of the Cosmic Hippo,” Bela Fleck’s acrostic on Duke Ellington’s “East St. Louis Toodl-Oo,” which features Victor Wooten’s powerful elec- tric bass sliding downward from notes in the 30-40Hz octave, was fully realized, with no loss
DRIVERS: 5.25-in aluminum-cone woofers, 1-in aluminum-dome tweeter in Uni-Q (coaxial) arrangement
ENCLOSURE TYPE: vented rated power: 280 watts class-D (woofer), 100 watts class-A/B (tweeter)
Connections: HDMI (eARC), optical and coaxial digital, analog-stereo mini-jack, RJ45 Ethernet; RCA subwoofer output; USB type-B (service-only); RJ45 wired inter-speaker port; I EC AC-power
OTHER: Wi-Fi: IEEE 802.11a/b/g/n/ac dual-band 2.4/5GHz
HIGH-RES AUDIO: 24-bit/384kHz via wired network, 24/192 via wireless; MQA-compatible; up to DSD256 (via network)
DIMENSIONS: (WxHxD) 12 x 7.9 x 12.2 in
WEIGHT: 44.3 lb (per set)
of content right down into the 20Hz zone, even at window- rattling loudness.
But adding the KC62 introduced benefits that, while less obvious than more-and-deeper bass, were no less important. Replaying the Copland Fanfare, I now heard the full measure of this unusually dynamic recording. A welcome extra octave of bass-drum and tympani foundation was present, but the sound of the remaining nine octaves became clearer and more depth-perceptible. Also, the marginal grain, or haze, or whatever it was that I’d heard on sustained brass notes when the big percussion strikes came along, was gone. Most impor- tant, the full degree of dynamics was restored on the “whomp- whomps,” even at concert hall levels, for a clear and valued step-up in realism.
Even music that did not necessarily require the subwoofer benefitted from its presence, especially at more substantial volume levels. A track like Tracy Chapman’s iconic “Fast Car” sounded just that little bit more transparent both dynamically and tonally, with the sub relieving the LS50 Wireless Ils of the 40-80 Hz load—not too surprising given the little KEFs’ diminutive woofers. With the sub onboard, I could no longer visibly see these displacing on strong bass notes at higher volumes, and the enhanced clarity made it easier to tease out the individual voices of guitar and mandolin (dulcimer?) on the repeated unison lines.
THE OTHER STUFF
Ergonomically, the LS50 Wire- less II story is a bit too involved to unpack fully in my remaining space. The KEF Connect app, which gives access to all the speakers’ features, adjustments, and setup options, is perfectly straightforward and a pleasure to use. It also gives direct access to the major streaming services once you enter your login details, so in theory it’s all you need. That said, as mentioned I mostly used Roon, but this was only via Google Chromecast discovery since the LS50 Wire- less II was not yet Roon Ready certified during my testing. [Editor’s note: As we were going to print, KEF informed us that the LS50 Wireless II had been Roon Ready certified—AG]
KEF supplies the LS50 Wire- less Ils with a nice little remote featuring volume/mute, source select step-through, and track forward/reverse buttons. A set of capacitive touch buttons on the speaker’s top surface also enable basic controls, but since the KEF connect app duplicates these functions and more, I found both to be of limited utility. As mentioned, I also auditioned the LS50 Wireless Ils via their analog-stereo inputs, observing no difference whatsoever in sonic performance. It’s worth noting that while the original edition of the KEF LS50 Wire- less speakers included a USB type-B port for wired streaming from a desktop or laptop computer or other source, the LS50 Wireless II has dropped this feature, presumably since its on-board streaming abilities (and other connectivity options) deemed it redundant.
The recent spate of serious- performance, all-in-one streamer/amplifiers has impressed upon me a new era of “just add speakers” integra- tion. With its LS50 Wireless II, KEF has gone one better: “just add music.” Assuming you have a suitable streaming service— and who doesn’t these days?— all you need for certifiably audiophile-grade playback is an AC outlet and suitable stands or shelves. The LS50 Wireless Ils are that good, and when paired with KEF’s KC62 subwoofer, they are even better. It’s true, the speakers/sub combo will set you back four large, but many an audiophile has spent as much or more on cables alone, and received far less sonic satisfac- tion in return.
KEF’s wireless speaker package is an ergonomic marvel that delivers tme audiophile perfor- mance—especially when paired with the company’s complemen- tary KC62 subwoofer.
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