Interesting, compact design; great build, finish and spec; uncompromised performance
An app too many; predictable restrictions on scale and dynamism
Ever since KEF delivered its remarkable LS50 Wireless stereo speaker/entire system back in 2016 it’s been a fur-lined, ocean-going critical and commercial success. Everyone who’s come into contact with it admires the way it looks, the way it’s specified and the way it performs.
In fact, there are really only two realistic objections one might have to the LS50 Wireless. It’s possible to object to the amount of space it occupies (after all, we are all interior decorators now). And it’s possible to object to that £2,000 price-tag. In every other respect, the LS50 Wireless is thoroughly deserving of all the many plaudits it’s received.
So naturally enough, KEF is attempting to democratise the LS50 Wireless experience with the new LSX. It’s a considerably smaller system than LS50W, and it’s yours for half the price. And from the get-go it’s possible to enjoy those looks (and the many finishes in which they’re available).
But what about the way it’s specified? And the way it performs? Has KEF managed to preserve its integrity with LSX, or does taking 50 per cent out of the price mean halving the fun?
Design
As far as products as functional as loudspeakers go, nothing looks quite like a speaker from the KEF LS range.
The gently curved front baffle is designed to lure sound pressure variations out of the cabinet rather than back into it - it just happens to look good while it’s doing it.
And the Uni-Q driver arrangement, with the tweeter mounted in the centre of the mid/bass driver, is arranged just so to give as tight a point-source as possible in order to make music sound as realistic as it can. By happy coincidence, it just happens to look smart at the same time.
With LSX, though, the whole package is on a very compact scale. Cabinets of just 24 x 16 x 18cm are smaller than the overwhelming majority of common-or-garden stereo speakers, and it means the tweeter sitting in the throat of the titchy 11.5cm mid/bass driver is a mere 19mm. This is hi-fi viewed from the wrong end of the telescope.
The drive down to a more mainstream price means LSX is built from rather prosaic plastic rather than LS50W’s more esoteric high-tech dough (yes, such a thing really does exist). But that does at least mean LSX can be wrapped in handsome, tactile, hard-wearing and not-all-that-affordable Kvadrat fabric.
Colour-coordinated Kvadrat fabric features on each different LSX finish (blue, red, black and olive green) except white, which has a gloss finish all over. So between the petite dimensions and the number of available finishes, there should be an LSX to blend in (or contrast nicely) with your decor choices.
Features
Like LS50W, LSX is an active loudspeaker, meaning each driver has its own discrete amp on board. System power is reined in compared to LS50W, though: each LSX tweeter is driven by 30 watts of Class D amplification, while each mid/bass driver gets 70 Class D-derived watts. A total of 200 watts is not to be sniffed at, mind you.
Class D amplification is not the default choice when all things are equal. All things never are equal, though, are they? Class D power means greater efficiency, and it means LSX doesn’t need the hefty heat-sinks of LS50W - a cost saving and an aesthetic gain all at the same time.
And while there may be fewer ways of getting music out of LSX than there are with LS50W, that doesn’t mean you’re in any way short of options. Use the ethernet socket or dual-band wi-fi to stream via DLNA, Tidal or Spotify. Use aptX Bluetooth or (from early 2019) Apple AirPlay 2. The master speaker also includes a 3.5mm analogue input and a digital optical socket, too, as well as a subwoofer pre-out for those with a profound bass preoccupation.
Because they’re both powered, both speakers naturally need plugging into the mains. The option of connecting them together via the supplied ethernet cable is preferable in terms of absolute signal stability - though, unlike the LS50 Wireless, it’s possible to use LSX without the speakers being connected to each other.
It’s a trade-off between convenience and outright quality, however. Opt to connect the speakers and LSX is capable of serving up 24bit/96kHz audio - it will accept files up to 24bit/192kHz but must downsample them. Should you prefer to go down the "fully wireless" route, 24bit/48kHz is the standard LSX will downsize to.
Interface
No doubt the app development business is populated by people more intelligent than WIRED, and no doubt people in the app development business know what they’re doing. But it does seem strange to us, the humble end-user, that one product needs two apps to use it fully.
LSX requires both KEF Control (for set-up, firmware updates, source selection and EQ settings) and KEF Stream (for streaming Spotify, Tidal or DLNA-derived digital files) - it’s all the more puzzling when you consider a product like Naim’s Mu-so (which, despite its very different appearance, is probably LSX’s most obvious rival in the "real hi-fi with wireless convenience for under a grand" stakes) uses one app to do what KEF needs two for.
There’s also a more traditional remote control included in the box with LSX. It’s no great shakes, being of hard plastic and rather random button placement, but it does at least give you another control option.
Performance
Here’s where our localised moaning about the number of apps LSX needs gives way to borderline-rhapsodic prose about the sound LSX makes.
Think of an amp/speakers combination with a wireless element (Google Chromecast, maybe, or Bluetooth at the very least) costing around £1k. The system you’re thinking of is bigger and bulkier, less good-looking, requires more faffing around with set-up, and needs more mains sockets than this one. And it’s by no means a given it can outperform LSX, either - because for a product of this type and size, LSX sounds remarkably accomplished.
Dive in at the deep end with a 24bit/192kHz file of Iggy Pop’s The Idiot (which the LSX squashes to 24bit/96kHz) and it’s immediately obvious it has expression, detail and poise to spare. The rattling piano and treated drums of Nightclubbing are securely positioned on the wide-open stage, and even when they’re joined by squalling guitar every element has plenty of room to manoeuvre.
The same song displays the LSX’s well-judged tonality. Iggy’s double- (and sometimes treble-) tracked vocals overlap without getting in each other’s way, and the details of different microphones and different vocal techniques are revealed in an almost casual manner. The plodding bassline sets a monotonal undercurrent, but above it every instrument is alive with texture.
The journey from the bottom of the frequency range to the top is smooth and even, too. Autechre’s Bike is crisply punchy, with top-end attack balanced nicely by low-end authority - so unless you really crave hairstyle-disrupting bass, that subwoofer pre-out is going to go unoccupied. And in the midrange, the LSX is gloriously communicative - Aretha Franklin’s Until You Come Back to Me (That’s What I’m Gonna Do) is hair-raising in its immediacy.
The Uni-Q driver arrangement really shows its merits where timing is concerned - the apparent unity of any performance, the sense of musicians responding and reacting to each other rather than performing in isolation, is stronger here than from any other similarly priced and specified alternative.
It’s not the out-and-out loudest £1k you ever heard, mind you - if you’re interested in letting the neighbours know you have a new system, your money can be spent more anti-socially than this. It’s far from timid, but will struggle to fill bigger rooms with sound.
It’s also worth pointing out the slightly cramped dynamic range at this point, too. LSX can put some distance between the quietest and loudest passages of Cannonball Adderley’s Why Am I Treated So Bad! but not as much as is ideal. Consequently the band hurtling back into the final chorus loses some impact.
But, of course, everything’s relative. Judged on its own terms - as a compact, decorative, convenient integrated system that does more than just nod towards hi-fi performance - the KEF LSX is outstanding. It demands to be heard.
This article was originally published by WIRED UK
