KEF LS50 Wireless II

KEF takes its successful LS50 Wireless and makes cunning revisions to deliver impressive sonic improvements.

The original LS50 Wireless speakers were almost universally praised, and rightly so — they pounced on the clear need for higher levels of hi-fi in wireless audio. Taking the then-passive LS50s with their Uni-Q combined driver array, KEF added amplification, streaming and smart operation. With modern minimalist looks — and with various special editions too — they were as close to a guaranteed success as the hi-fi industry has seen.

Now comes the sequel, the LS50 Wireless II, modestly described as “the perfect all-in-one speaker system”. KEF is going here for easier integration — improving the simplicity and reliability of use without losing any performance. So the Wi-Fi networking now has mesh-network frequency-hopping abilities for improved robustness. Gone are any of the control app hiccups which sometimes occurred with the originals; the Wireless II comes with a new and improved KEF Connect app, which KEF has spent two years re-engineering from scratch, and which has some quaintly British touches — the streaming options for example, are listed as

“Music in the Cloud”. These include Tidal, Qobuz, Amazon Music, Deezer and Spotify, as well as internet radio and UPnP serving of files available on your home network. In China, TenCent’s freemium music service QQ Music will also be available.

Meanwhile peak file support here is 24-bit/384kHz, with DSD up to DSD256, and MQA decoding, including for Tidal Masters.

Indeed you might hardly need the new app considering how many ways the speakers make themselves available: the LS50 Wireless IIs support AirPlay 2, Google Chromecast and Bluetooth, and are also Roon Ready.

The streaming system was similarly revised over the same time period, KEF choosing to base it on WiSA — simply on merit, they told us, because it offered the best point-to-point high-res streaming available. Gone now, if you wish, is the cable that was required between the two speakers, though as with the LSX you can have one if you like, an included Ethernet cable which raises native playback to 24-bit/192kHz. Leave things wireless and they’ll still work at 24-bit/96kHz, which really should be enough for this level of hi-fi.

Furthermore, KEF has squeezed even more performance out of the familiar chassis and Uni-Q driver arrangement through the introduction of a new KEF innovation called Metamaterial Absorption Technology (pictured above).

Whassat then? Well a ‘metamaterial’, as KEF itself defines in its white paper, is a synthetic material with properties that cannot be found in nature. What metamaterial does KEF use here? ABS plastic which has been moulded into a shape that is an almost ideal broadband absorber. While we’d argue with

the use of the word metamaterial in this context (see comment p8), this absorber is a brilliant idea: it takes the concept used in room acoustics, where absorbers have different lengthed channels to absorb different frequencies. KEF and a partner company has designed what looks like a maze, but is actually 30 separate tubes in two layers. This goes behind the Uni-Q assembly, and KEF says it almost entirely absorbs the back energy from that driver — 98% of the energy above 680Hz. So it’s clever, innovative, and looks very cool, if slightly worryingly in its maze design for fans of the Westworld TV series.

As for socketry, the previous USB-B connection for computers has gone, but KEF has hardly shortchanged owners, replacing it with an HDMI eARC socket to make it more TV-friendly. Alongside this are coaxial (max 24-bit/192kHz), optical (max 24-bit/96kHz) and minijack analogue inputs, plus a subwoofer output — though if you’re looking to add a sub, the perfect partner might be KEF’s new and remarkably small Uni-Core KC62 subwoofer, which will make the connection wirelessly, while the main speakers have a delay switch to keep them perfectly in sync. Will KEF expand further into full surround, perhaps using an LSX-size speaker for rears? KEF will, it says, consider this based on user feedback, but with the WiSA platform being used, it’s certainly now within the existing abilities of the LS50 Wireless II.

The quoted power supplied by the built-in amplifiers, developed in-house by KEF, are 100W of Class AB for the tweeter, and 280W of Class D for the mid/bass drivers.

Outside little has changed. And why fix it if it ain’t broke? The speakers look fabulous with their Uni-Q driver array and range of finishes — Carbon Black, Titanium Grey, Mineral White and Crimson Red Special Edition. Threaded inserts in each corner of the base allow them to lock onto the new KEF S2 Floor Stands ($800/pr).

But while they look just like the previous versions, they really do sound significantly improved. The effect of that MAT absorbtion is evident in the cleanliness of the treble; indeed the difference in purity can be heard across the frequency range. Mids are cleanercut as well, and the bass more defined, their extra refinement making the originals almost sound a touch crude. The whole presentation has been opened out, with the extra space not only filled with subtler, more precise detail, but also allowing for greater instrument separation that makes music sound less congested in comparison with the originals.

So listening to Adrienne Lenker’s Symbol became a more captivating affair through the Wireless IIs. The extra space between her vocal and the strings was notable contrast to the originals, where it could sound as though they were fighting against one another for attention. That extra spaciousness isn’t at the expense of cohesiveness either; that remains a hallmark of the Uni-Q driver’s point-source tweeter-inside-the-mid design. The new KEFs laid bare more intricacies in the guitar work too, while disclosing the distinctive fragilities in her vocal.

Similar sharpness and detail were evident as we switched to Peter Broderick’s Moment, the LS50 Wireless IIs more deftly defining the start and finish of notes.

With Mac Miller’s What’s The Use? the Wireless IIs showed off improved punch and agility, as well as their enhanced subtlety. The clarity and cleanliness enlivened the tuneful baseline and cutting rap, while highlighting this track’s clinical production.

While KEF has made plenty of tweaks here besides the sound-absorbing maze behind the Uni-Q array, it’s hard not to credit the specific improvements of clarity to this clever advance. We look forward to hearing more products using the technology in the future. Meanwhile KEF has another barnstorming LS50-based product in its stable — and probably a tribe of original LS50 Wireless owners feeling like they really need to hear this new model ....