KEF LSX Wireless Music System
What a pleasure to find an inexpensive component that excites a high-end reviewer. And a product from KEF! KEF Chorales were the first decent speakers I owned. Modestly priced, high performance, utterly reliable, what's not to like? I owned them fresh out of university until I traded them in for the even more remarkable Spendor BC1 - more extended, lively and open, but with a habit of eating through woofers at the volume level I preferred.
Chorale (1970-79) According To
First Time Reviewing KEF
Uni-Q According To KEF
What I Like About...
The LS50 Wireless appeared in 2016, with the addition of two amplifiers, DACs and wireless streaming. Digital inputs arrive at one speaker, which is linked to the second by an Ethernet cable. Wireless, USB and TosLink optical inputs are available in addition to Bluetooth 4. Tidal, Qobuz and Spotify support is built right in. There's even an analog input, which is immediately converted to a 24-bit/192kHz bitstream. The woofer is directly driven by a 200 Wpc Class D amp, and the tweeter by a 30 Wpc Class A/B amp. The DSP based crossover works before the amplification stage and can compensate for the natural response curve of each driver in the box, so the LS50 Wireless can gain the full benefits of active amplification in terms of direct connection of amps to drivers and superior bass output compared to the standard LS50. How they ultimately compare depends on what amps you use to drive the standard LS50, what speaker cable you use to connect them and the quality of your DAC. Press reviews have been very favorable. The weight is up a little over the LS50 with 22.5 lbs for the primary speaker and 20 lbs. for the secondary, while the depth of each speaker increases to 12". the LS50 Wireless is specified at 45Hz to 28kHz (+/-3dB), with a maximum SPL of 106dB. Note the significant bandwidth extension achieved by active amplification and DSP. The price is a very reasonable $2,199.99.
So now KEF has shrunk the LS50 Wireless to create the LSX. The new box measures just 9.5" x 6.1" x 7.1 (HxWxD), the weight drops to under 8 lbs., while the price drops to $1099.99, just half the price of its bigger brother. There are other changes too. The woofer is now 4.5", the tweeter 0.75", while the woofer amp outputs 70 Watts to the tweeter amp's 30watts. Both amps now operate in Class D, a move necessary to avoid the need for bulky heatsinks. The frequency range is now specified at 54Hz to 28kHz (+/-3dB) and the max SPL is 102dB. To make sure it fits into your décor, you can choose between Gloss White, Maroon, Olive, Blue and Black finishes. The test units are Gloss White.
We can see from the specs that the diminutive LSX has superb bass reach for its size, easily beating the original LS50 and approaching the LS50 Wireless. As an audiophile, the combination of a metal dome tweeter and Class D amplification raises questions – would the treble be harsh and fatiguing, or has KEF perfected its secret sauce?
The LSX comes with a simple eight-button remote control, but I rarely used it. Instead I controlled the speakers from my iPhone. KEF provides two apps – KEF Control and KEF Stream. You can stream from your PC or smart phone to the LSX over Bluetooth, but the preferred path is to use your home Wi-Fi, which enables you to control the speakers from any room in your house. I did most of my listening through Tidal HiFi, since KEF provides a free six-month subscription. But I also used the LSX pair, to excellent effect, as speakers for my flat screen TV, and they performed very well in this role, connected by an optical cable. I never felt the need for a subwoofer.
You use KEF Control to setup the connection and to configure the LSX for the best sound in your room. You can use BASIC or EXPERT mode for sound shaping. BASIC asks if your speaker is on a stand or a desk. Then you enter the distance to the wall, and if you are using a desk you also give the distance from the front edge. Then you tell it how lively your room is, and how large. You can also configure a subwoofer. Then you can save that as a named configuration and set up more configurations that you can switch between on the fly.
For more control you can select the EXPERT mode. It offers independent selection of desk mode and wall mode, with a slider for each allowing 6dB of adjustment, plus a 4dB range for treble trim. You can select Phase correction (on, off), bass extension (less, standard, extra). If you are using a subwoofer (which I wasn't) you can select high pass mode and frequency, sub out low-pass frequency, sub gain and sub polarity.
The settings tab allows you to select Cable mode or Wireless mode for passing the signal from the Master to the Slave speaker, and you can also select whether the Master should sit on the right or the left. I tried both and couldn't tell the difference. There are options for when to switch into Standby (20m, 60m, never), volume setting (turn on and off the hardware buttons, volume button sensitivity, maximum volume limitation and a balance control. The CONTROL app also allows you to update the firmware in the speaker.
To play music from your phone you select the button "Open KEF Stream", which puts you into the second KEF app. Here you select which device you want to connect to. From here you can connect to any Media Server you may have, or to TIDAL or Spotify, which stream directly from your internet provider, not through your smartphone or computer. Once connected to Tidal, KEF Stream just works as a remote control, and once you set a playlist or an album going, you can turn off your phone and the music continues through its direct streaming. If you do close the apps or turn off your phone, that's when you'll need the small remote control, so you can pause, adjust volume, switch tracks and so on.
Does all this work as advertised? Mostly yes, but not perfectly. Networking is rarely perfect. I ran into the occasional operational glitch, where the speakers would fail to respond to KEF Stream. I spoke to KEF's Jack Sharkey about this and he told me this is a known issue, and we can expect it to be addressed in a future firmware update. Until then, try turning it off and turning it on again. Worked for me. A second problem for me is the range of the remote control. Rated for 33', I had some trouble at 20'. Your mileage may vary, or your room may not be so large, so you may never run into this issue. In any event, I used the remote control so rarely this was rarely an issue. I also found the LSX would often react slowly to commands, but this is most likely TIDAL's responsibility, not KEF's.
Now I'm not thrilled about there being two apps (KEF Control and KEF Stream) that you need to use on your iPhone or Android device. But iPhone users can relax. The next firmware update (free of course) will allow you to use iTunes or whatever music app you like to speak directly to the LSX using AirPlay 2, so you won't need KEF Stream any more.
OK, OK. Enough about the logistics.
Q. How does it sound?
A. Simply remarkable.
Nothing shows the LSX in better light than a Nina Simone playlist in Tidal HiFi. There is real excitement generated by these miniature speakers, out of all proportion to their size. You can turn up the wick and it gets louder but it doesn't bloat or strain. Nina's in the room, and her voice is magical. No, you don't get the dynamic range of bigger separates, you don't get the black background or the inner detail of high-end audio, you don't get the amazing reflexes and long sustain of megabuck speakers, but it's what you do get that counts. You get a real sense of scale, a beautiful tone, a non-fatiguing treble, a punchy bass and most of all… you get amazing imaging by any standards, courtesy of the coincident drivers. Mood Indigo gives us Simone's superb pianism (streets ahead of pretty much all rivals) plus her inimitable voice. Miss Simone is in the room. Don't Smoke in Bed, Do Nothing ‘Till you Hear from me, and my all-time favorite Cotton Eyed Joe take me back decades.
The LSX tackles the concert grand piano in style. You get a good feeling for the color and weight of the instrument in the hands of Richter in Handel, or Kissin in Chopin, and you can easily distinguish the touch of each artist. The sound is consistently warm, forward and engaging with a variety of genre, folk, rock, Spanish guitar, orchestral music, jazz. The excellent imaging makes up for omissions in other areas by bringing performers into the room with you. There are no hard edges to the sound, despite the use of Class D amplifiers, but I do miss some of the transient attack and especially the massive dynamics I hear in the concert hall or through my reference system. Let's be realistic here. While they exceed my expectations and offer remarkable value for the price and performance for their size, KEF has the Blade, Muon and other models aimed directly at the audiophile. The LSX is designed to bring a new level of performance to this price range and size class, way ahead of the various smart speakers from Apple, Google, Sonos and Amazon, and competitive with similarly priced speakers that lack the wireless streaming abilities. KEF's aim is true. They have achieved just what they set out to do, and the LSX is justifiably screaming off the shelves.
The LSX has a punch and liveliness that reminds me of small speakers from Totem Acoustics. This sound is quite forward, although given the DSP options you can tame this quite a bit. I didn't find the settings in the KEF Control app to work like traditional tone controls so much as fine tuning within a limited range. This is fine by me. The sound is neutral and well balanced at its central settings, and the DSP just helps to optimize the speakers to your room and your taste. However even at the central settings, DSP is already working its magic to get an enhanced bass extension from the small woofer, with the aid of the rear port. Few conventional speakers offer any such adjustments, so they are often much more critical about room placement. The LSX can work its magic just about anywhere.
Now how does the LSX compare with its big brother, the LS50 Wireless? I don't have them here, so I can't do any AB testing, but from the specifications, I would expect the LS50 Wireless to dig deeper (3dB down at 45Hz vs 54Hz) and play louder (106dB versus 102dB). I would expect other aspects of the sound to be quite similar, given the commonality in design elements.
So pound for pound, and dollar for dollar, the LSX is a class act, beautifully constructed, attractive to look at, and glorious to audition. A winner in my book. I can't wait to see what else KEF may have up their sleeve.