KEF KS50 Wireless loudspeaker review
I would expect most reading this to be pretty familiar with KEF's critically acclaimed LS50 speakers by now. They've amassed a multitude of awards and excellent reviews, and deservedly so - this flexible and compact bookshelf speaker is a real tour de force of technical excellence, lending themselves equally well to home theatre as as they do for the reproduction of music. They were the speaker of choice for the Technical University of Denmark when they created their Audio Visual Immersion Lab - a collection of 64 LS50 speakers arranged spherically to totally encompass a central listening position - testing various aspects of human hearing. They've also been a hot topic on numerous forums with regards to partnering amplification, producing a wide scope of heated opinions! Whilst some of us relish the challenge of experimenting and finding the perfect combination, KEF have stepped in and done the hard work those who just want to plug and play, and introduced the LS50 Wireless.
externally
To look at, the LS50 Wireless are identical to their passive counterpart, but under the hood is a host of technology to allow them to act as a standalone solution for those who use phones and tablets to access their music, or stream music from their PC or NAS drive. The rear panel sports an ethernet connection, allowing phones and tablets to access the dedicated IOS or Android control apps, which includes a flexible set up menu (which we'll come to shortly), an asynchronous Type B USB input, a digital optical input, a pair of analogue inputs, and a subwoofer output. Whilst not an abundance of inputs, the typical prospective LS50 Wireless owner isn't likely to have a rack of source components. If more inputs are needed, there are plenty of compact solutions on the market that will allow this for a very small outlay.
On the back panel there are two small "speaker EQ" buttons, which allow simple 'out of the box' set up without the need for networking. One chooses placement - on dedicated stands or desktop use, which alters their output accordingly. The other chooses wall proximity - near wall or free space options, and again, adjusts the speaker's output.
As well as the supplied remote for basic control purposes there is a very discreet row of soft touch controls (even more so on the gloss black version) on the top face of the right hand speaker, allowing
power on/off, input choice, and volume control. A nice feature that keeps the smooth looks of the Wireless LS50 'button free' and unspoiled.
internally
Each LS50 cabinet contains two amplifiers - a 200 watt Class D amplifier for the
mid/bass driver, and a 30 watt Class A/B amplifier for the HF unit - the heatsinking for which accounts for the majority of the extra 30mm depth over the passive version. These bespoke amplifiers are wired directly to their associated drive units - the electronic crossover has already played its part by this point and separated out the higher frequencies from the bass before entering these amplifiers, so they only have to deal with the designated frequency range of the driver it is supplying. This increases efficiency and reduces distortions that are common in conventional passive crossovers.
The aforementioned crossover is part of the powerful DSP processing that takes place within
the speaker. This controls all aspects of the pre-amplifier and power amplifier sections, as well as performing timing and phasing correctional duties, ensuring the signal reaching you is as true as possible to the incoming signal it has received from your chosen source - this is something no conventional passive loudspeaker can achieve.
setup
Having a DSP processor on board extends the LS50 Wireless a few other luxuries. The
subwoofer output on the back of the master (right hand speaker) allows connection of an external subwoofer if you wish to extend bass depth, and using the control app you are able to choose your favoured crossover point (anywhere from 40Hz-250Hz) to the sub, as well as a +/-10dB sub level setting, and also reverse polarity. This enables you to pretty much place your subwoofer anywhere you like and be able to get the best out of it.
In the setup menu of the app, there are two setup options - EXPERT and BASIC.
The BASIC setup menu is very simple and straightforward, and designed for those who have no idea what they're doing - a 10 year old could set these up. First up, you choose whether your LS50s are on a stand or on a desk, after which the on board DSP processing will tailor the LS50's output to suit. Choosing the stand option takes you straight to choosing the distance from the speaker to the wall using a simple slider. Choosing the desk option gives you an extra sliding control to select how far the front of the speaker is from the edge of the desk they're sitting on (to counteract high frequency reflections).
The next option tells the LS50s what type of acoustic space they're in - DAMPED, MODERATE, or LIVELY, and again, the output will adapt to suit. You're asked what size your room is, and given three options to choose from - this sets the bass response accordingly. Finally, the touch of a button tells the LS50s if you have a subwoofer or not - if this option is chosen, you're then given two controls, a sliding volume for the subwoofer, and also a sliding balance control to choose between whether the sub or speaker handles more of the bass.
The EXPERT setup menu gives a number of extra options, ideal for those who have a little more understanding of a room's interaction with a loudspeaker. Even if you're not, it is still relatively simple, anything you're not sure of can be explained by your dealer.
DESK MODE allows a reduction of higher frequencies by up to 6db in 0.5dB steps.
WALL MODE allows a reduction of low frequencies by up to 6dB in 0.5dB steps.
TREBLE TRIM allows a 2dB increase or decrease in high frequency content.
PHASE CORRECTION allows phase correction to be turned on or off.
BASS EXTENSION gives the option of STANDARD, LESS, or EXTRA bass extension.
HIGH PASS MODE can be switched in or out. This can be switched in when using the LS50 Wireless with a subwoofer. You then have control of the crossover point between the LS50s and the subwoofer anywhere between 40Hz and 250Hz in 5Hz steps. There's also SUB GAIN which allows an increase or decrease in the subwoofer level of up to 10dB in 1dB steps. You can also choose the polarity of the sub to correct the phase of the subwoofer based on its placement in relation to the LS50Ws.
All of the above can be changed at any time using the dedicated app from the comfort of your armchair, despite being a 'set and forget' affair, and should allow the LS50 Wireless to sound great in virtually every type of room you care to place it in. Of course, the expert option could also be used to tailor the speaker's output to suit your own tonal preferences, so whether you like a little more bass, a generally smooth overall sound, or a much leaner sounding presentation, you no longer have to buy a system that sounds the way you want it to - the LS50 Wireless can allow you to make the system sound just how you want it.
As an example, my large listening space here is mostly bare brick walls, a thin carpet on a concrete floor, with two thirds of the wall behind the speakers being large glass panels. As you can imagine, it is a fairly lively space, so will emphasise any brightness inherent in a loudspeaker. Using the EXPERT set up I was able to make sure the end result was in no way bright, and that the speakers had enough bass presence to sound balanced, but not boomy or overpowering.
sound
Even if you're familiar with the passive LS50s, you may not be prepared to hear just how
good these active versions actually sound. In my personal opinion they sound like an altogether different (and bigger) loudspeaker, making it hard to believe that what I'm essentially listening to is the same speaker I've been used to all these years. There's a transparency and openness that as good as they are, the passive LS50s just cannot match, bringing an extra layer of realism to the table, and the listener closer to the performance. For those that have always been curious, the LS50Ws give you an idea of LS50s should sound.
I've been particularly impressed with their speed. Bass lines, regardless of how much bass they actually contain, stop and start when they should do, and are easy to follow, just adding to how natural they sound. As I'm in a larger room, I've had the bass setting on extended, which according to the specs is capable of 45Hz at -3dB. That's seriously good for such a small speaker, and obviously one reason why they sound like a much larger pair of speakers, despite the majority of my listening being spent with them sat on the top of an IKEA Besta cabinet (a more normal scenario, I thought). I could hear the IKEA cabinet adding in a little of its own coloration, but the flexibility of the control app allowed me to suppress it to a point that it was no longer a major issue.
Roger Waters' 2015 remaster and "remix" sounds absolutely stunning. This remaster loses
the roughness inherent in the original mix (which I actually quite like), and adding a few re-recorded parts overdubbed for good measure (I'll refrain from expressing my anger at Waters messing with the original mixes of the best tracks on the album). Originally recorded in Q Sound, and in typical Roger Waters fashion, there are audio 'scenarios' related to the track lyrics throughout the album, and usually abnormally way off to the left or right of the soundfield. Firstly, Q Sound comes across amazingly well on KEF UniQ based loudspeakers - testament to their imaging abilities - but I have to admit I've never heard it come across this well before, although this may partly be down to my listening room. One of my favourite tracks - The Bravery Of Being Out Of Range - I noticed something I'd never heard before. One of the verses kicks in with, "Hey bartender, over here! Two more shots and two more beers. Sir, turn on the TV sound, the war has started on the ground", and today was the first time I'd ever heard that there was actually a TV set playing in the background. It's subtle compared to many of the other effects, but it's there.
I've listened to a lot of familiar albums over the past few months, and all have impressed, with many unearthing surprises I wasn't aware of, despite thinking I knew them inside out. Listening to numerous favourites, there has been something I've struggled to put my finger on, feeling unable to describe it. The best way I can put it is that whatever album you care to put on, it just sounds "right". Everything just sounds like its in the right place and at the right level. It sounds like a performance rather than a bunch of instruments. Throughout writing this review, one thought kept springing to mind: if an active pair of LS50s can sound this good, what the hell would an active pair of Blades sound like?! Game over, man.
Whenever I'm asked, one of my audition recommendations is to take along music that you
feel isn't very well recorded. much of the time it is actually pretty well recorded - it just takes a good system to strip away the layers and unravel the mess to present it in a more intelligible manner. The LS50 Wireless is capable of doing this.
tidal
A recent software update added the TIDAL music streaming service, which seems to be the best sounding of the current streaming services, and despite the LS50 Wireless not being MQA compatible, there is still an audible benefit of the TIDAL Masters section as MQA gives you a guarantee of the origin of the master that has been used - just listen to the Red Hot Chili Pepper's Californication as a good example of this.
Of course, if you're a user of multiple music streaming services, there are a number of add-on media streamers like Sonos, and hi-res capable ones such as Bluesound you can use to achieve this, and can be hidden from view and controlled via their app.
conclusion
Whether used purely as a Bluetooth speaker for phone/tablet users, or as part of serious main system, the active KEF LS50 Wireless are a hugely capable compact loudspeaker, with all the flexibility needed to make them work in virtually any environment. Their level of performance brings into question whether separates and speakers at this price point are really worth considering from a sound quality point of view. These really are high end performance on an affordable budget.
The LS50 Wireless were tested with an Innuos ZENith II as a digital source, streaming directly to the LS50s as well as through a Bluesound Node II, which also provided Napster, Spotify, and TIDAL. The majority of my listening was done with the LS50Ws placed on an IKEA Besta cabinet using Auralex Mopads as isolation.
UPDATE
Over the course of the weekend of the 21st/22nd October, the little audio company demonstrated the LS50 Wireless loudspeakers at the Home HiFi Show in Harrogate. Using a Convert Technologies Plato as a media server for the LS50Ws (it was present to drive a pair of Q550 speakers), the newly updated app performed flawlessly over the course of the weekend. There are still one or two small issues, but KEF are obviously addressing them one by one, and properly. Not once did the app drop out or fail to connect.
Using them in the 5m x 4m hotel room, and on makeshift stands (slightly wobbly bedside tables - see above!), the active LS50s sounded fantastic, despite the right hand wall being false, the front left corner being oddly "chamfered" off at 45 degrees, and a ruddy great booming (fixed) wardrobe right behind the listening position! Using the control app, I was able to get them sounding pretty much the same as they do here at the little audio company - something you just can't do with a normal passive loudspeaker. All testament to not only how good these speakers are, but also how flexible they are in being able to be tweaked to sound very similar in different sounding rooms.
davidf @ the little audio company
the little audio company