KEF LS50 Speaker Review
Is this a baby Blade for less than a grand?
What is the LS50?Most speakers you can buy today are part of a wider range of products. The reasoning is simple enough- if you are going to tool up to make a new speaker, you would be foolish not to make as much use of the key parts like drivers, crossover components and dozens of other parts that make up a modern loudspeaker. This does mean that while there are ranges of speakers where every model is fantastic, there are (more commonly) line-ups where one model is the star of the show. This approach means that at one level or another, the models are a compromise where the components are designed to work as well in other speakers rather than for a single model.
This means that one off models where the components have been designed to work with one speaker and one speaker alone ought to be superior to their range based rivals. The problem is that developing a one off speaker is almost as costly as designing a range of them and the costs have to be recouped from a single model. This means that for the most part, one off models tend to occupy the higher price points where higher retail prices and longer lifespans help to ease this cost issue.
These considerations make the LS50 from KEF something of an outlier. Built to commemorate, KEF's 50th anniversary, it is a one-off model that shares elements of the KEF design philosophy but is not a member of the Q or R Series. KEF also lists the LS50 in the 'Flagship Hi-Fi speakers' section of their website in the company of the Blade and Muon which is a pretty big space to fill for a speaker with an asking price of £800. Does the LS50 deliver?
DesignThe LS50 is a two way standmount speaker which is a normal enough sounding device, but thanks to KEF's long standing interest in the use of dual concentric drivers, it takes on a different concept and appearance than most rivals. KEF's Uni-Q driver places the tweeter in the 'throat' of the main driver and this has become a trademark of their products for many years now. The benefits of doing this are two fold. The first is that the dispersion and phase characteristics of the combined driver are better than having two separate drivers. There should be a larger and more convincing 'sweet spot' where both drivers are delivering their best than when the two drivers are on a different horizontal or vertical axis.
The second advantage is one that the LS50 really takes to its logical conclusion. With both drivers built into the same assembly, the speaker only needs one hole in the baffle for the driver. As the more perforations a front panel has in it, the harder it is to make the baffle inert, this is a considerable bonus. When you then add the one off nature of the LS50's design, the baffle can be created with the view to housing this one driver. This means that the KEF is built around a baffle that is made from a heavyweight ABS and curved in such a fashion as to aid sound dispersion from the single driver. This is an immensely solid piece of engineering that gives the LS50 a noticeable weight bias towards the front. It extends backwards about half an inch from the front panel before meeting the cabinet which is more conventional MDF. Conventional or not, it is still very heavily damped and the LS50 feels extremely inert thanks to bracing and stiffening shared with the Blade.
Around the back of the cabinet, there is another design innovation. The LS50 is rear ported but the port itself is unusual. Rather than make it from a stiff lined plastic, it is soft and deformable- and something of a surprise if you haul it out of the box using it as a finger hold. The reason for this is that KEF's own studies have found that by making the port this way, it is more focused on low frequencies as higher ones are generally radiated back into the cabinet. The only connections are a single pair of hefty speaker terminals.
The driver itself is a 5.25 inch unit with a 1 inch tweeter. Although this concept is used in almost all KEF speakers, the one for the LS50 is specific to this speaker. It is the latest spec version of the type and features design elements like the 'Tangerine' waveguide and the Z Flex surround. In my opinion, it looks fantastic- like an intricate mechanical movement but one visitor to the house noted it reminded them of a lamprey, which is a little hard to unsee after it has been pointed out.
As a piece of design though, the LS50 is a little bit special. It looks and feels different to the competition and more like a concept than anything else. As taking such a piece of equipment and then wrapping it in 'wood'- real or otherwise would undo much of the good work, KEF has gone for a painted finish with a choice of black with a rose gold driver or- in the case of the review samples- white with a blue driver. The review samples have seen a bit of life prior to coming here but they still look and feel impressive.
What's good about the LS50?In audio terms £800 is on the kindergarten slopes of speaker pricing so to be able to buy a speaker that is priced at this point that borrows from vastly more expensive models and is full of unique design features is unusual and exciting. Furthermore, the end product feels like a finished article and not an escaped technology demonstrator. It is also not a difficult speaker to live with. They are 30 centimetres tall, not terribly picky about placement and while the impedance can dip momentarily to 3.2 Ohms, they don't need huge amounts of power in practise.
As a piece of design though, the LS50 is a little bit special
What's not so good?Against this positivity, there is little to complain about. It might have been nice for KEF to have offered a stand to complement the LS50 and if you live in a house full of traditional fittings and fabrics, they might not blend in perfectly but aesthetics is always a balancing act in this regard. I would also note that after their busy life, the review samples are starting to show some of the limitations of the white finish, with marks appearing on the lower edge of the baffle. The black is likely to be more hard wearing in this regard.
How was the LS50 tested?The KEFs were placed on a pair of Soundstyle ZT60 stands with blutack giving a little isolation and serving to secure them to stand more effectively. They were used with a Naim Supernait 2 integrated amp and ND5XS streamer with an XP5 XS power supply with some additional testing being undertaken with a Roksan Xerxes 20+ turntable, all of which was connected to an IsoTek Evo 3 Sigmas mains conditioner. Material used included lossless and high res FLAC, Vinyl and some internet radio services.
What does the LS50 sound like?KEF says that the design intention of the LS50 is in keeping with the classic vein of British broadcasting monitors that were made by a variety of speaker manufacturers (and which for the most part, used KEF drivers). Given that the LS50 has almost nothing in common with these speakers in a technological or design sense, this might sound a little odd - but after some time listening to them, the parallels make a great deal more sense. These older speakers are prized for their midrange- as speakers designed to monitor the human voice, they are still absolutely magnificent in this regard- and spend a little time with the LS50, there is definitely an element of this.
With the simple and elegant 'Till the Sun Turns Black by Ray LaMontagne- an album that predominates in this magic midband region, the KEF is startlingly good not simply judged by the standards of a speaker that costs £800 but as a transducer full stop. It has a real 'stop what you're doing and just listen to this' quality. The scale and positioning of the performers is totally convincing and this is partnered with tonality that is truly exceptional. There is a school of thought for many people that metal drivers can sound hard or synthetic and while I've heard plenty over the years that are anything but, this is one that most eloquently rebukes that claim.
The Uni-Q arrangement means that the integration of tweeter and midrange is effortless. It is genuinely impossible to ascertain where one driver ends and the other begins and the effect is very similar to the single driver Eclipse in terms of being a single point source. Where the KEF is rather different is that the dispersion is far more effective at filling a room than the much more focused Eclipse. The LS50 images brilliantly and more so can do this at a variety of distances and with a sweet spot that can accomodate more than one person in it.
If the LS50 was possessed of these attributes, this would be good news but the KEF takes this exceptional midrange and places it in the centre of a frequency response that is far beyond anything that a broadcast monitor of old would have been able to manage. To be clear, the LS50 is still a small speaker and the bass response needs to be judged in this context but the performance is still deeply impressive nonetheless. If you put on something totally unsuited to a small speaker like Photek's Form & Function, the LS50 simply gets stuck in. Compared to the transmission line fitted PMC twenty.21, the Kef doesn't quite go as deep, but it motors through pieces with such enthusiasm that you tend to overlook that you aren't listening to a floorstander.
The news in the upper registers is also very good. KEF claims a +/- 3dB upper frequency response of 28kHz which is largely decorative but does mean that frequencies within the threshold of human hearing are well handed and completely free of roll off. There is a sense with the KEF that if your partnering equipment is a little on the bright side, they almost certainly won't help matters. The Uni-Q driver is revealing and to this end will highlight limitations in the equipment it is connected to. By the same token it takes a lead from the partnering equipment and if that is sympathetic towards less than perfect material, the LS50 can generally be persuaded to do the same.
What then ties all this together is a sense of energy, excitement and good honest fun that lifts the KEF from monitor to brilliant home loudspeaker. One of the enduring joys of having music stored and catalogued on a NAS drive is that you'll stumble across an album you haven't listened to in years. In this case it was the eponymously titled effort from The Bravery and in the capable hands of the KEF, revisiting the album was a brilliantly experience. The LS50 hammers through the dense, punchy beats and does so with a sense of joy that is hard to top. Across multiple genres, the LS50 just wants to get to the music and this is surely what HiFi is all about?
It has a real 'stop what you're doing and just listen to this' quality
- Wonderful midrange performance
- Excellent integration
- Handsome looks
- Dependent on decent partnering equipment
- No dedicated stand
- Not terribly sensitive
KEF LS50 Speaker ReviewThe KEF LS50 has been on sale for a little while now and I have heard it in passing at various shows and events. I had never truly managed to get a complete handle on the LS50 despite being reasonably impressed with what I heard. I was also a little sceptical of the claimed tie in with the Blades at more than twenty times the price but the little KEF has made more sense in its relationship to the other flagships than I expected.
The LS50 resolves beautifully and matches this with tonal accuracy and cohesion that is truly outstanding for less than £1,000 but just as importantly, it does all this with a sense of energy life and sheer entertainment that is quite its own. This is a speaker that works across huge swathes of musical styles and satisfies with all of them. KEF has gone to the effort of making a one off speaker and I'm pleased to say that the result is truly singular.
Suggested retail price when reviewed: £800.00
Our Review Ethos
To comment on what you've read here, click the Discussion tab and post a reply.