KEF Products | Technology | History

Developing Concept Blade - The World's First Single Apparent Source Loudspeaker

With the release of Muon in 2007, KEF changed the 21st Century paradigm of audio excellence and visual aesthetics. With a statement as bold as Muon, and with the world-wide accolades they received, it would have been completely understandable if KEF had sat back and rested on their laurels for a few years, but Concept Blade was well underway at the time of Muon’s introduction.


Gold Peak and KEF CEO Victor Lo explains, “the original purpose of the Concept Blade project was to look for a new future direction for our Reference Series.”



Another surprising thing was learned from the Muon and its $235,000 price tag: a lot of consumers – even non-audiophiles – were not bothered by the price tag but found the sheer size of the Muon intimidating. Concept Blade then became a combination of the things we learned during Muon’s development, and the idea of making a flagship product like Muon only smaller. According to Lo, “we were looking for a product that had, if you looked at it from the front, a narrower footprint. It could be deeper, but it should be narrower, so if you looked straight on to the loudspeakers, they shouldn’t look bulky.”


The original concept was going to be made from wood but that was simply not possible, so a carbon fiber material was used although the original prototypes used a carbon fiber/balsa wood sandwich material.

KEF engineer Mark Dodd had been toying with the idea of a single apparent source side-firing design with the Uni-Q firing forward and the bass drivers firing to the sides. Concept Blade also needed to go as low as the venerable Reference 207 – a speaker universally praised for its low-frequency response. The Uni-Q would also have to be redesigned to suit the performance requirements of the new speaker – a speaker that was not originally meant to be designed for consumer release.


Dr. Jack Oclee-Brown explains, “there is a lot of new stuff in the Blade Uni-Q. We took the kind of approach on the computer of doing as much of it as we could and putting as much detail into the model as possible, because we’d been … bitten before: if you leave out a detail, then the final thing might not be a little worse, it might be completely different from what you’d expect.” A lot of the technology in the new Uni-Q was taken from the development of the KHT 3005 mid-range driver and Uni-Q, so this was a case where some exciting new knowledge from a product design trickled up to a high-end product.


The force produced by the four 10-inch LF drivers was so strong that the rear-magnets had to be bonded to each other in order to reach the full benefit of the side-firing technology. Force-cancelling technology – first employed in Reference models from the early 1990s – was also used to get the most out of the side-firing design and the sheer power of the drivers. Concept Blade was starting to look like a major advance in loudspeaker design.


Introduced at the Munich High-End show, Concept Blade was a 62½” tall carbon fiber/balsa wood sandwich tower that revealed its name through a shape reminiscent of a propeller. A beauty to behold – both visually and aurally – Concept Blade looked more like a fully-developed market-ready product than the one-off prototype it actually was. The response was overwhelming, but KEF staff remained steadfast in their assertion that Concept Blade was a showcase for new ideas only and not a design that would ever go into production.


The biggest obstacle to a commercial release of the concept was producing the enclosure. There needed to be an alternative material that did not compromise the design of the original but that was also capable of being manufactured in commercial quantities. Oclee-Brown explained, “[We’d been] examining different possibilities, but it [was] quite difficult to find something to get the complex shape, that [would] work acoustically and that we [could] launch at a price that people want to pay. We already had one really expensive monolithic product.”


Eventually a carbon-fiber cabinet was developed that allowed for commercial production and Concept Blade found its way to the market as world’s first single apparent source loudspeaker – the soundstage is as detailed and three-dimensional as the original performance, with all elements coming from their own unique space within the soundstage.

If you haven’t heard Blade or Blade Two for yourself, it’s something to behold and well worth the trip to a dealer near you who is displaying them – and of course, the technology found in Blade found its way to our Reference, R, Q, and LS series. So regardless of your budget you can enjoy the magic of the technology for yourself.  

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