STEREO GUIDE verdict
+ natural, highly transparent sound
+ top-of-the-line focus, imaging and ambience
+ Excellent room correction via app
+ tremendous connectivity and wireless options
- Bass is deep but not as punchy
- certain limits in dynamics and SPL
Sound: Bass / Dynamics8.5
Sound: Spatial imaging10
Ease-of-use / Connectivity10
Sound: Tonal Balance / Transparency9.6
Yes this concept existed before in KEFs lineup: A pair of monitor-like active bookshelf speakers with a complete digital/analogue high end stereo system built-in at a rather high end price point. With the KEF LS 50 Wireless II, little has changed in terms of design, size and concept, but the technology inside has. This is mainly true to the new abundance of playback and connectivity options as well as the app (see p. 2), but also to the actually relevant transducer technology.
A single driver per speaker handles the entire audible frequency range. However, it is not a full-range driver, but a coaxial one. This combination of woofer and tweeter, comes close to the acoustic ideal of a true point source.
KEF LS 50 Wireless II: Fully active with coaxial driver
The Wireless II his taking advantage of the 12th generation of this so-called ´UniQ´ driver, already used in the passive ´Meta´ model. This name refers to a rear compartment of the tweeter with some kind of maze that allows rear soundwaves to completely disappear into the void. To avoid the influence of the tweeter sound by the low-midrange cone, KEF uses an elaborate waveguide placed in the center of the driver.
Both drivers are controlled by their designated power amplifier. KEF relies on a powerful and highly efficient switching amplifier for the woofer-midrange. For the treble, developers use an old-school power amplifier built in analogue MOSFET topology. This decision, motivated by sound characteristics, and the astonishing total output of 380 watts with a power supply that is generously oversized offering 760 watts also might explain the need for the huge heat sink on the back. In some kind of “chimney style” open tubes, elevating air is cooling the heat sinks, and so is the air ventilating in the embedded reflex port.
The baffle shape is fundamentally different from almost all other speakers on the market. It is merely a cutout from a spherical shape than a baffle. This means the fewest obstacles to the sound waves radiating laterally to the baffle, thereby minimizing the risk of diffraction. The same goal is achieved by the rather flat, wave-shaped surround of the cone driver.
Plenty of features, even more sources, designated app
While analogue signal input was rather the standard than the exception even with modern digital speakers, it has become obvious that it is not anymore to the KEF LS 50 II. A 3.5 mm jack connects a turntable (with line-out) or other analogue sources if needed. All other source options are digital, and more versatile than any other system we know to date.
Among the digital inputs, besides optical and coaxial, an HDMI-in is available. This is meant to connect the LS 50 Wireless II directly to a TV and synchronize its volume control via ARC (Audio Return Channel).
Streaming services supported
Plenty of wireless and streaming options are offered, among them a traditional Ethernet cable. Thus, the KEF LS 50 Wireless II not only accepts signals via the Bluetooth (4.2). It can also be connected comfortably using Apple Airplay2 or Google Chromecast. Streaming service subscribers will be pleased. Besides the common Spotify, Tidal and Qobuz, the KEF set can also be integrated in Amazon Prime and Deezer. It also acts as a playback option in an environment with the streaming software Roon, in the highest quality level “Roon Ready”.
Many of the aforementioned features, as well as traditional UPNP streaming from mass storage devices in the local network, can also be controlled using the now stable and comfortable app. KEF had a completely new released for iOS and Android for the LS 50 Wireless II which is not compatible to neither the predecessor nor the LSX. It also offers quite some practical acoustical controls. Positioning close to the wall or on a desk, for example, as well as the treble control for adapting to different reverberation characteristics of the room can easily be compensated. The icing on the cake is the built-in digital subwoofer crossover, which can be adjusted via app. It assigns the correct signal to an additionally connectable subwoofer (also from other manufacturers). At the same time, the KEF is appropriately high-pass filtered to increase its own dynamic capabilities.
Very easy to set up: the KEF LS 50 Wireless II
The KEF concept is a bit too complex for true plug-and-play; a setup via app (iOs or Android) is mandatory. This also applies to logging in via either Apple ID or Google Home. However, the new free KEF Connect app helps the user step by step even in complicated setup cases and tells the user what to do next by indicating the status trough a flashing or colored LED.
Once the setup process is completed, one should always take use of the acoustic correction options given by the app. This works surprisingly well despite the complexity of the functions and fine adjustments (such as treble level and wall mode for positioning close to the wall).
High resolution provided
Pairing the second speaker works like magic: wirelessly, with KEF promising Hires transmission up to 96/24 PCM resolution. Higher hires formats can be sent losslessly via an optional Ethernet cable up to 384/24, and the set also handles DSD and MQA.
How this truly futuristic high-end system is controlled is just a matter of the owner´s taste. The traditional way via IR remote control is as comfortable and easy as KEF´s own app. The can also integrate UPnP streaming, Internet radios and various streaming services. Alternatively, KEF can simply be used as a zone renderer for software like Roon which we usually recommend. Only the HDMI input has certain limitations. The ARC does not work with all TVs and connecting a bluray player is not possible.
Audiophile sound and superb room correction
As usual with active speakers, the local equalization settings in the app should first be adjusted to room acoustics and placement. A slight boost in treble (+1dB or a bit more) turns a slightly dark overall sound characteristics to “perfectly balanced” in a typical room. Likewise, it is worth activating the extra bass when placed on a stand far from the wall. For positioning close to the wall, the “Wall Mode” control helps, but this one you should dose carefully.
Optimized in such a way, the sound could only be rated as ´truly high-end by any means´. No matter which music genre the compact monitors reproduced, they mastered everything with a balance of superb transparency, unagitated silkiness and astonishing neutrality. Voices were particularly well focussed in the room, just as the imaging is one of KEF’s outstanding virtues. In this respect, it does not need to shy away from comparison with even the most expensive high-end systems.
Large orchestras, choirs, big bands – you always get an as-big-as-live imaging, superbly natural in the reverberation, so extended in width and depth, that deserved the highest praise we are capable of. Voices of all kinds were of a pronounced clarity and transparency, even suboptimal recordings sounded neither sharp nor unpleasant. The KEF did play like a monitor in the sense of ´doesn’t hide details´ However, when in doubt, it was more likely to show mercy to difficult albums.
Loves rather the quiet tones
Pop and rock with a rich bass fundament revealed an astonishing depth given the cabinet size, whereby beats were reproduced rather dry and blended unobtrusively into the overall sound without too much of punch. As much as the KEF appealed to all audiophile senses in terms of acoustical beauty and spaciousness, it was not very dynamic in terms of effects. Fine dynamic shading suited her well. However, it softened aggressive brass impulses, blaring percussion recordings, and massive orchestral sforzati somewhat. That’s perfect for those, who are paying more attention to fatigue-free long-term listening than to the ultimately explosive effects in dynamics. In general, a certain lack of dynamics set in at higher SPLs. This could make an additional subwoofer advisable, especially when listening to deep–bass material such as electronic music or action movies. At low or medium SPLs, the KEF is among the best of all.
Alternatives to the KEF LS 50 Wireless II
As an integrated concept with app, HDMI and streaming, the KEF is completely unrivaled as a complete stereo system. There are several active bookshelf speakers or monitors with fewer number of features in this price range. Those who want more bass, SPL and glittering treble will be happier with the significantly larger Nubert Nupro X-4000, for example.
If you want to combine surround suond and wireless and tend not to shy away from a fatter bass, you should look for Canton’s Smart Vento 3 or Smart A45 BS. The KEF, on the other hand, can only be used reasonably in stereo. In terms of price and concept, the Elac ARB-51 would still be a direct competitor and sounds astonishingly similar to the KEF, costing as with the (Roon and Bluetooth-enabled) wireless hub. Sonically bigger speaker, but far behind in terms of features and room correction. If it comes to the reproduction of film and electronic music, the operation with optional subwoofer KEF KC62 is recommended.
Specifications KEF LS 50 Wireless II
- Price: approx. 2,800 $
- Dimensions (W x H x D): 20 x 30.5 x 31.1 cm
- Weight: 20.1 kg (pair)
- Features: AirPlay 2, Google Chromecast, ROON Ready, UPnP, Bluetooth 4.2, HDMI (ARC), analog input jack
- More at www.kef.com