KEF's journey into wireless

KEF’s active speaker revolution began with the LS50, created to celebrate 50 years of loudspeaker engineering. Nearly 10 years on from that, the addition of wireless has made KEF’s LS50W and latest LSX wireless speakers simple but spectacular hi-fi system solutions.

It started with a mass-produced polystyrene cup, the kind used for hot drinks, made by vacuum-forming a foamed plastic over a shaping tool. These were patented in the USA back in 1957, at which time one Raymond Cooke (pictured above right) was designing loudspeaker drive units as Technical Director of Wharfedale, a position he’d taken after working for the BBC’s Designs Department. By 1960 the humble polystyrene cup had made its way across the Atlantic, and when Cooke first saw one, the proverbial light bulb illuminated above his head.

At the time his loudspeaker driver cones were made from paper pulp, using a process that was expensive, time-consuming and difficult to achieve consistency. But suddenly, here was a new technique, a new material, and one capable of mass production. Could drive units be formed in the same way?

A very short history of KEF. Click for larger view.

His Wharfedale masters being unresponsive to his excitement, in 1961 Cooke left the company and set up his own at the Kent Engineering and Foundry. KEF Electronics was born.

Over the decades that followed, KEF’s success spoke for itself. From its first ‘slimline’ speakers to its reference designs and on to wildly-successful midrange hi-fi with the likes of the long-running Coda series, Cooke’s engineering focus and materials research paid dividends in delivering both state-of-the-art technologies applicable to both the heights of loudspeaker design, and value-for-money core hi-fi products. Others also used KEF’s revolutionary drive units. At Cooke’s old BBC stomping ground, the now-legendary LS3/5A studio monitor used KEF drive units made from Bextrene, a lightweight acetate plastic sheet derived from wood pulp. The LS3/5A set the ‘BBC Standard for Loudspeakers’, and remains a respected design to this day.

THE ORIGINAL LS50
So when KEF celebrated its anniversary in 2011, 50 years after its founding and 15 years on from Cooke’s passing, it was more than appropriate to honour the occasion with a new loudspeaker that took design inspiration from that classic BBC/KEF collaboration, the LS3/5A studio monitor.

The result, KEF’s LS50 ‘Anniversary’ speaker, was a gorgeously-designed and surprisingly diminutively-proportioned standmount in a gloss piano black finish, with a curved baffle covered in a low-diffraction ‘rubber-like’ material. This small monitor, aimed squarely at the high-end market, also featured a new copper-coloured 130mm version of KEF’s Uni-Q driver, which here leveraged trickle-down technology from the recent mighty Blade, KEF’s flagship.

The Uni-Q driver concept, which sits the tweeter within the midrange driver in a deviation from the standard coaxial, has long set KEF apart from the crowd. This point source driver array, where all sound is aligned as if originating from a single point in space, has claims to outstanding acoustic clarity and off-axis dispersion in particular. The normal arrangement of separate drivers causes different amounts of interference with each other depending on the listening position (hence the notion of a central ‘sweet-spot’). With the coaxial Uni-Q, the sweet spot becomes far less crucial. KEF has continuously developed the concept for more than 20 years.

In the LS50 Anniversary speaker, it delivered not only exceptional clarity of sound, but remarkable frequency response. When Newport Test Labs measured its performance for Australian Hi-Fi magazine, it reported results that were “simply outstanding for all measurements, particularly the incredible flatness and uniformity of the frequency response and the almost unheard-of bass extension from such a small speaker”.The Uni-Q driver concept, which sits the tweeter within the midrange driver in a deviation from the standard coaxial, has long set KEF apart from the crowd. This point source driver array, where all sound is aligned as if originating from a single point in space, has claims to outstanding acoustic clarity and off-axis dispersion in particular. The normal arrangement of separate drivers causes different amounts of interference with each other depending on the listening position (hence the notion of a central ‘sweet-spot’). With the coaxial Uni-Q, the sweet spot becomes far less crucial. KEF has continuously developed the concept for more than 20 years.

As a relatively small monitor speaker, the LS50 did not defy the laws of physics by digging into the deepest depths of bass, but what it did above a perceived 50Hz was reported in Australian Hi-Fi as “well-controlled, detailed and pleasingly visceral.... I needed to remind myself the LS50 is a small speaker with a 130mm driver with reduced surface area due to the inclusion of the tweeter assembly within it, while the use of a Uni-Q driver in a monitor with a relatively narrow and rounded baffle translates to extraordinarily exacting focus with images precisely placed within a wide and extremely deep soundstage, and a dynamic range that is very impressive, irrespective of speaker size.”

GOING WIRELESS – LS50W
By 2017, times were a-changing in hi-fi, with traditional sources being replaced by streaming from the internet and the smartphone, and traditional systems being replaced by standalone wireless speakers. So KEF delivered the LS50 Wireless, one of the first active wireless loudspeakers to deliver hi-fi levels of performance from such an all-in-one solution. By building inside the LS50 Wireless twin power amplifiers and a digital input stage including DACs, the LS50 Wireless reduced the traditional hi-fi system to just the speakers. The right-hand speaker had both Wi-Fi and Bluetooth, able to stream from smart devices or from computer or NAS drive files across the network, while the difficult sychronisation of data to the left speaker was achieved by having an Ethernet cable linking the two.

It was a huge and immediate success, winning awards globally including What Hi-Fi?’s All-in-One System of the Year award for both 2017 and 2018, and an entry into its Hall of Fame. The current LS50 Wireless packs a full 240W of internal power, and offers analogue, optical and USB computer inputs in addition to Wi-Fi and Bluetooth streaming, all under the control of two KEF apps for iOS and Android.

It was this combination of connectivity with the sonic strengths of the KEF LS50 design which made these wireless speakers unique; others had released active speakers with bolt-on wireless options, but none had delivered such an integrated standalone solution which achieved the dream of high fidelity made so simple. They looked thoroughly modern as well, especially in their gloss white finish (shown above), and even more so when renowned design studio Marcel Wanders was let loose on the externalities, delivering a Nocturne edition (pictured above) in which “the inherently circular nature of KEF’s Uni-Q driver and musical notation symbols subtly blend with unique architectural and rhythmic elements, a vibrant luminous visual quality and magical atmosphere...”

Or something. We rather liked that the Wanders version glowed in the dark, and even more, that the sound was as good as ever.

LSX – BRINGING IT HOME
If there was one impediment to the KEF LS50 Wireless speakers invading more homes with their convenience and quality, it was price. Despite replacing most of a conventional hi-fi system with a single pair of speakers, the LS50W’s price (currently $3495) still seemed high to some. Last year KEF unveiled its answer — the LSX — bringing the same ideas in a new design which roughly halves both the size and price.

But it is “not simply a baby LS50W”, as KEF’s Ben Hagens made clear at the Australian launch of the LSX. This is about KEF changing what hi-fi can be — a product for the 95%, not the 5%, he said, noting wisely that, “You shouldn’t have to spend more time learning about a product than using it.” In a similar nod towards ease of use, the LSX has the ability to tailor its sound using DSP, meaning these are “speakers you can put where you want them, not where you’re
told to put them.”

Ease of use is one thing; performance is another. KEF kept its key technologies in the LSX speakers: they use a smaller version of KEF’s coaxial Uni-Q driver, with a 19mm aluminium-dome tweeter within a 115mm magnesium/aluminium-alloy mid/bass cone (compared with the 25mm/130mm combo in the LS50W).

In addition to a smaller UniQ module, the cabinets are 24cm high rather than 30cm, and the width is more than halved, making it slightly slimmer from the front. The effect on the overall cabinet volume is significant, reduced to around a third that of the LS50W.

Yet KEF’s specs indicate remarkably little loss of low-end extension from the shrinkage — a quoted -6dB figure of 49Hz for the LSX, compared with 43Hz for the LS50W.

One very useful change is the banishing of the connecting cable, the LSX speakers able to pair wirelessly and share music up to 24-bit/48kHz, while adding an Ethernet link between them raises this to 24-bit/96kHz. Their internal amplifiers deliver a quoted 30W to the tweeter and 70W to the woofer; this compares with 30W and 200W in the LS50W.

The same two apps can stream from Tidal directly, and play files from home shares (computers or NAS drives) via DLNA, but the speakers will also make themselves available to your Spotify app on any device, and have Apple’s AirPlay 2 in addition to their Bluetooth streaming, which includes the aptX codec. And there are physical inputs too — optical digital (very handy for TV audio), and an analogue minijack. There’s a wired subwoofer output if you want more bass.

The white LSX has a full gloss finish, while black, blue, red and green have their contoured front baffle in a matte finish like the LS50W, while the sides are wrapped with fabric from Danish textile manufacturer Kvadrat.

And the LSX sound? We loved it. Their bass response is significantly loaded by the use of digital signal processing (KEF refers to it as a ‘Music Integrity Engine’) so that their frequency balance is especially impressive at casual listening levels. Most systems lose relative bass strength as level drops, but the LSX keeps the balance tilted for a powerful and musical presentation. They energised the room even at medium listening levels, but didn’t then overly drown vocals when we turned things up.

They also showed the benefit of streaming via Wi-Fi rather than Bluetooth, the limited quality of the latter reducing slightly the joys that the LSX can bring with a higher quality signal. And crucially, compared to so many standalone wireless speakers, these deliver true separate stereo sound with a wide soundstage assisted by the imaging powers of that Uni-Q array. In this we applaud KEF’s marketing slogan for the LSX — ‘Give your music the space it deserves.’

The true stereo LSXs deliver a higher level of hi-fi, effective at medium listening levels from Bluetooth, but far better using the Wi-Fi connection, where they can be entrancingly effective music-makers from such attractive and compact cabinets.

KEF LS50W & LSX
wireless stereo speakers
+Real hi-fi speakers for the modern world
+Contain all you need for streaming hi-fi
+ Physical inputs also available

LS50W
Price: $3495 pair
Drivers: Uni-Q 25mm aluminium dome inside 130mm magnesium/aluminium-alloy cone
Amplifiers: 30W treble, 200W bass
Inputs: Optical digital, minijack analogue, USB-B, Bluetooth with AAC+aptX; Ethernet, dual-band 2.4GHz/5GHz Wi-Fi.
Outputs: Subwoofer out; master-slave link
Dimensions (whd): 300 x 200 x 308mm
Weight: 10.2kg (master), 10kg (slave)
NOTE: A special offer of $500 voucher towards the LS50W is available from Oct 1 to Nov 30 2019: details here: KEF Family fan club sign up: click here

LSX
Price: $1895 pair
Drivers: Uni-Q 19mm aluminium dome inside 115mm magnesium/aluminium-alloy cone
Amplifiers: 30W treble, 70W bass
Inputs: Optical digital, minijack analogue, Bluetooth with AAC+aptX; AirPlay 2 (coming in 2019); Ethernet, dual-band 2.4GHz/5GHz Wi-Fi.
Outputs: Subwoofer out; master-slave link
Dimensions (whd): 240 x 155 x 180mm
Weight: 3.6kg (master), 3.5kg (slave)

Contact: Advance Audio
Telephone: 02 9561 0799
Web: au.kef.com