I’ve struggled with working out precisely how to classify the KEF LS50 Wireless. It’s a loudspeaker. It’s an active loudspeaker. It’s a complete system. It’s audio’s tomorrow, today. It’s damn clever, and extendable and flexible enough to keep up with damn clever for the next few years at least. That doesn’t exactly make for a pithy headline, however, so we went with ‘system’.
We went with ‘system’ because that’s precisely how KEF envisaged the LS50 Wireless. It’s the 2017 interpretation of a system, or at least, it’s one interpretation, and one of the more exciting interpretations going forward. The LS50 Wireless effectively replaces bi-amped monoblocks, wireless streaming DAC preamplifier (with wired options), and includes a DSP preamplifier inside the loudspeaker itself. It even adds provision for a powered external subwoofer, should the LS50 itself not provide quite enough bottom end for your room. All of the electronics adds about an inch to the depth of an original passive LS50, itself one of the most popular and successfully received loudspeakers of the decade, and one of the spiritual heirs to the LS3/5a throne.
As you might expect, the LS50 Wireless draws heavily from KEF’s own LS50, from 2013. The Uni-Q drive unit – with a 25mm vented aluminium dome tweeter in the acoustic centre of a 130mm magnesium/aluminium alloy midbass cone. The dome has a dispersion-increasing ‘Tangerine waveguide’ while the midbass unit has radial ribs running along the cone. The unique (as opposed to Uni-Q) curved polyester resin front baffle, flexible elliptical port, and the constrained layer damping bracing of the original passive LS50 is retained in the active wireless version.
On the active side of the LS50 Wireless, both the master and slave loudspeakers use a 30W Class A/B amplifier for the high frequencies, and a 200W Class D amplifier for the mid-bass unit, the logic to this being the HF is all about refinement, the LF is all about heft, and the active crossover takes care of the balancing act (and in the process ensures the loudspeaker doesn’t self-destruct if played at party levels for too long). This also means the amplifier modules can sit inside an only slightly deeper version of the original LS50 cabinet with minimal need for heatsinking; the same would not apply were it a 200W Class A/B design, or a 30W pure Class A on the tweeter.
Where the active loudspeaker ends and the future takes off is in two related places. First, the LS50 Wireless includes built in DSP, both in terms of hard-button aspects (adjustments for desk or standmount use, wall or free space installation), and bass alignment control. Second is how that bass alignment is controlled, through a sophisticated app. This – along with a top panel and a remote control for backup – can allow the LS50 Wireless to connect to music sources through wired (UPnP and DNLA compliant) or wireless (dual band, 5GHz) networks, direct from a computer through a USB-B connector, from a traditional digital audio source through Toslink, and even a single stereo set of analogue RCA inputs (which are digitized at source). The app drives all this perfectly, and more on that later. The slaved left loudspeaker simply has a RJ45 connector to the right channel master speaker and a rear balance control. Both loudspeakers are powered from the wall directly and have a three-pin IEC socket (for giggles, we hooked this at first to a pair of Nordost Odin 2 cables, to hear what a pair of power cords that cost 12× the cost of the system do, but this was an exercise in lily gilding and unnecessary).