KEF LS50 Meta Loudspeaker
KEF's iconic LS50 compact Monitor has been updated after nearly a decade of production. This comparison shows the original and the latest "Meta" variant.
Although it isn't a curse, it is still a huge challenge for manufacturers to improve upon a hit. It doesn't matter if you are talking about cars, cameras, or cookers, the sequel is often referred to metaphorically as "that difficult second album". KEF had to face this problem with the LS50, which will (terrifyingly!) be ten years older in 2022. There have been wireless and active versions of the speaker in the interim. However, the beloved default purchase [ HFN Jul'12] has been a popular choice for those who don't want to pay more than 1000. KEF's The Godfather Part II is the new LS50 with Meta suffix (PS999). It's that good.
Original LS50 had a 130mm UniQ array in rose gold with a 25mm tweeter at the centre.
In preparation for the test, I put the standard LS50s into a system with components that were relative to their values. After that, I lived with the speakers for a week before receiving the review samples for the LS50 Meta. Although I didn't forget how great they were, it was a while since I had used the LS50s to review them. Uni-Q's concentric driver is a special thing.
Since the Tannoy and later Thiel designs, dual- and tri-concentric units have been available for many years. KEF's first release of its version was in 1988. Laurie Fincham, THX's long-serving chief engineering, said, "When you made a regular 2- or 3-way speaker, there was always a spacing among the drivers. This meant that you had to compromise either vertically, or horizontally. The problem was with bookshelf speakers. Were they standing on their sides or up? They only worked well in one orientation.
Forming a Q
Fincham attributes the development of rare-earth magnet tech as the enabler. This is crucial because KEF wasn't considering coaxial speakers as large as Tannoy’s drivers. "A dealer informed me about this new magnetic substance... made of neodymium and iron. It was tiny and held ten times as much energy so I was fascinated. I replied, "It is so small that we could make a coaxial speakers."
But size wasn't the only advantage. "I discovered that the Uni-Q allowed me to make a loudspeaker systems that didn't require a box. The crossover was located on the driver's back, so that you could test it separately. It's also very easy to put the crossover into a cabinet. All you have to do is connect it with four screws. It doesn't take long to install a crossover - you can do it all at once.
The LS50 Meta is equipped with a 12th generation Uni-Q. This includes changes to the motor, suspension, surround, and cone of midrange driver. As a 'waveguide,' the rear tweeter duct was also enlarged to provide a better connection with the metamaterial absorber.
KEF has used Uni-Q drivers in a variety of loudspeakers including the Egg Lifestyle mini-speaker. However, one insider told me that Uni-Q's evolution into the tangerine drivers was first seen in models such as the Blade (2009). The LS50 Meta has seen extensive revisions to both the drive unit and the cabinet, despite the fact that much attention has been paid to the meta-material disc.
This is the '12th generation' UniQ in just over thirty years.
It's nearly impossible to distinguish the differences between the two vehicles side-by-side. The only exception is the colour change from orange/copper to more muted. This is my preference, although the LS50 Black would be mine. This is where you can see the interior changes and revisions.
To reduce turbulence further, the port opening has been made flush and the corners have been redesigned to accommodate the baffle retention bolts. These changes may have an impact on the sound. The rear surface has been slightly rounded, and a step has been added between the cabinet sides and the rear panel.
Rise and Shine
Although I did notice a slight difference in sensitivity when switching between the two models, it was not noticeable so I was able treat the LS50 Meta and the LS50 Meta in this respect equally. The stands were 24in high and fired straight ahead. I tried toe-in, which I found had its merits. However, for the comments that follow, I stayed with KEF's preferred method.