KEF LS50 Wireless
KEF LS50 Wireless
If you've read from the beginning of this round-up, you’ll know a good deal about the LS50 Wireless already. As the starting-point for KEF'S LSXS (p26), these active speakers with preamplifier have established quite a reputation for themselves. A good one, that is.
The Bluetooth tech here is 4.0 with the aptx codec and, as well as having Tidal and Spotify built-in, the LS50 Wireless can also replay any music stored on a NAS unit or computer connected to your home network.
From one to the other
Few rival systems contain such a wide range of features in such an elegant two-box format. Those that offer a range of inputs often add an extra connection hub that transmits the signal wirelessly to the speakers. That’s not the case here. There are just the two fully active speaker boxes, arranged in a master and slave configuration. All sources connect to the right (master) speaker, which is then linked to the left by means of a supplied ethernet cable.
As is usually the case, 'wireless' doesn’t actually mean wireless. While these KEFS are better than most, you still have two mains leads – one for each speaker – and the connecting lead between them. Still, they remain a neater solution for getting high-quality sound into the home than traditional separates.
It will come as no surprise to any regular reader that the Award-winning passive LS50S are the basis for this design. The drive units are the same.
These speakers use a Uni-q array, where the 25mm aluminium dome tweeter sits in the centre of a 13cm magnesium/aluminium mid/bass cone.
This arrangement helps to produce an even dispersion of sound and improves integration between the two drivers. What looks like a grille in front of the tweeter is, in fact, a waveguide that improves its performance.
That beautifully built and finished enclosure is the same as the one on the passive version too, bar a couple of centimetres of additional depth to accommodate the electronics and heatsinking. There are three cabinet options: the Titanium of our review samples, gloss black and gloss white. Each option comes with a contrasting colour on the Uni-q driver array.
That curved front panel still looks unusual and is made of DMC (Dough Moulding Compound: a polyester resin combined with glass fibre and calcium carbonate). DMC was chosen for its inertness and ability to be shaped.
The rest of the enclosure is made from MDF. It’s heavily braced and strongly damped to minimise any resonances. We don’t tend to talk much about ports, but the one here is unusual in that it’s flexible in a bid to reduce distortion.
These are true active speakers where each drive unit has a dedicated power amplifier. A 30W Class A/B circuit feeds the tweeter while a 200W Class D module powers the mid/bass unit. The Class D design was chosen for its combination of high power and low heat output – heat generation is an important consideration in a product as crammed as this.
KEF has taken advantage of the internal DSP by phase-correcting the crossover and using the software to allow the speakers to play loud and true while minimising distortion.
The digital signal path is 24-bit/192khz-capable and there’s a dedicated DAC for each drive unit. Only the optical input is limited to 96khz signals, but that’s not unusual.
Take a look at the back of the right speaker and you’ll find stereo analogue, optical and USB Type B connectors. You’ll also find a subwoofer connection, in case you want to add more lowfrequency output, and an ethernet socket for connecting to your network.
Normally we’d recommend sticking to the wired network option for greater stability but we used the twin-band (2.4ghz/5ghz) wireless option for most of our test without issue.
Environmental adaptability
There are also controls for adjusting the sound for different speaker placements with options for close-to-wall or free-space positioning as well as the choice between desk or stand supports. These choices can be made from the dedicated ios/android app too.
That app looks nice, is well laid-out and easy to use. It controls the streaming (DLNA as well as Tidal/spotify) functionality and allows plenty of scope to fine-tune the speaker’s performance in a given environment. There is room for improvement, though. It’s a little glitchy and feels unresponsive at times.
We also don’t like the sliding volume control. It doesn’t change the volume until you lift your finger, so you don’t know how loud the sound is going to be until you hear it. It can shock on occasion.
It’s important to note that the app doesn’t switch between physical inputs, as it operates the KEFS only in streaming mode. To change input, you need to use the supplied remote or the touch controls on the master speaker.
This swapping around of controllers gets a little annoying if you switch
sources a lot, particularly as the app has to reconnect with the LS50S every time you switch back.
It would also be nice to be able to see an indication of the input chosen when sitting at the listening position – the only indicator is out of sight on the right speaker’s top panel. So, if you’re using the remote to change input there’s no way (apart from counting clicks) to know what input the LS50 has settled on.
None of these things is anywhere near serious enough to be a deal breaker for us, but they make living with the speakers a fussier experience than it should be. Make no mistake; you will want to live with them.
Why? To our ears they sound at least as good as the best comparably featured separates combinations available for similar money. Remember, here there are no extra electronics to house or cables to hide, just a pair of beautifully built speakers on (ideally) a pair of stands.
A deep impression
We start off with Arvo Pärt’s Tabula Rasa and are deeply impressed by what we hear. The LS50 Wirelesses sound clean and precise. They dig up so much detail and deliver it in an organised and stable manner. We’re struck by the KEFS' subtlety and their ability to generate strong dynamic shifts without stress.
These are small speakers but they manage to fill our medium-sized listening room with high volume levels. KEF claims a maximum sound pressure level of 106db, which should be loud enough for most people.
Positioned with care, a little away from the rear wall and with a touch of toe-in towards the listening position, they render a lovely, expansive soundstage that’s neatly layered and nicely defined.
We try the LS50S in less optimised positions and manage to use the app to make the results sound balanced. They’re never quite as good as the optimal position in terms of outright clarity or stereo imaging, but tonally we still get a balanced presentation.
Once it's set-up properly, we think KEF’S engineers have struck a really nice tonal balance. It’s even-handed yet refined enough to make the most of less than optimal recordings or sources.
We play Massive Attack’s Angel and the LS50’S impressive bass performance really shows. These aren’t big speakers so you won’t get really deep floor-shaking bass, but they generate low frequencies that are taut, articulate and punchy.
For a speaker that stands 30cm tall and has a mid/bass unit that’s just 13cm in diameter, it’s an impressive result. There's more good news higher up the scale with a transparent and fluid midrange and insightful highs.
Vocals are delivered with passion, while percussion comes through with bite and composure.
The LS50 Wirelesses are rhythmic too, delivering the song’s unmistakable momentum with determination. They never sound too pushy either, allowing the song’s natural flow to come through.
Overall, these speakers have the insight to unravel a recording yet never go so far as to tear the music apart. They’re informative but always musical with it.
We play a whole range of music from the heartfelt grit of Bruce Springsteen’s Terry’s Song and sparse electronica of xx’s Stars right through to large-scale symphonies from the likes of Stravinsky and Beethoven; these speakers take it all in their stride. It takes a broad range of talents for this to happen.
Turning the tables
Wireless versions of impressive wired devices usually suffer a relative drop in sound quality, but with the LS50 Wireless KEF took a step forwards. That £2000 price tag might look pretty hefty for such compact speakers, but remember that money also buys you a dedicated streamer, a Bluetooth module, 24-bit/192khz DAC, preamp and four power amplifiers with a total of 460W of output. And it's an impressive package.
“Informative yet musical, these KEFS sound at least as good as the best comparably featured separates combinations that are available for similar money”