One might think that loudspeakers have long been so technically mature that innovation is no longer possible. But there are always clever developers who discover interesting innovations in other areas of technology and use them successfully in loudspeaker construction.
The latest example of this is the recently introduced metamaterial absorption technology from KEF. Under the direction of their head of development, Jack Oclee-Brown, the British conduct constant basic research. They recently took up metamaterials for the acoustic optimization of loudspeakers.
Metamaterials are synthetically produced substances that can be given specific properties in the laboratory that do not occur naturally. Under the leadership of the developer Dr. In a multi-year program, Sebastien Degraeve, together with the Asian company Acoustic Metamaterials Group, has developed a material that, in conjunction with a special shape, has previously unimagined acoustic absorption capabilities.
Background: Each loudspeaker chassis not only radiates sound forwards towards the listener, but also generates sound when it swings back, which is then emitted into the housing. It is important to dampen this unwanted sound as much as possible, otherwise it could cause the cabinet of the speaker to vibrate or hinder the chassis in its work.
So far, KEF has researched the technology called MAT (Metamaterial Absorption Technology) for use with tweeters. The result is a disc made of the new metamaterial, only 11 mm thick, which has been provided with precisely calculated labyrinth-like channels. Coupled acoustically directly to the tweeter via a short pipe, this MAT absorber should absorb up to 99% of the sound energy in the relevant frequency range. That would be an absolutely fabulous value, with currently available technologies only absorption rates of around 60% are possible.
In the following short video, the developers explain the new technology and compare it to an "acoustic black hole". For those who are particularly curious (and those with the appropriate knowledge) , there is also a technical white paper with which the technology was presented at the Audio Engineering Society convention in June 2020.
At the moment, KEF's MAT technology is still in the development stage. Jack Oclee-Brown is confident, however, that it will soon find its way onto the market in the first KEF loudspeakers - we will keep you informed.
