How does Metamaterial Absorption Technology benefit KEF speakers?

As part of our ongoing mission to deliver sound with as little intervention as possible, from treble to bass, and everything in between, our team of engineers took on the challenge to solve the problem of distortion caused by sound from the rear of the tweeter.

Firstly, we need to talk about the sound generated by a loudspeaker driver unit. Put simply when the diaphragm of a drive unit vibrates, it generates sound. When a loudspeaker is in operation, an equal amount of sound energy comes from the front of the driver unit toward you - the listener, and from the back of the driver unit to the inside of the enclosure.  If untreated, some of this sound energy is reflected to the diaphragm of the drive unit which causes distortion.

We want to absorb the sound behind the drivers because we want to hear the music, not the artifacts created by the driver or the cabinet itself."

Dr Sébastien Degraeve, Senior R&D Engineer 

This has been a problem in speaker design for many years. In fact, up to now, most loudspeakers still rely on the use of porous materials, such as foam or wool, to dampen these internal reflections. KEF was one of the pioneers in the use of this technique back in the mid-1960s. The drawback of this technique however is the inconsistency of the material (the material itself or the application) and the acoustic volume it is taking. Another solution is to extend the enclosure to direct the sound energy away from the driver unit. However, with this method, a very long enclosure is needed behind the driver unit to achieve a meaningful effect.

With the latest developments in acoustic metamaterial, KEF engineers identified a possible way to reach near-perfect absorption in a very small space thanks to a circular maze-like disk that sits at the back of the Uni-Q driver array. This disk is made up of a total of 30 tubes of different lengths and sizes each mathematically optimised to a  different frequency to absorb a wide bandwidth of sound with extremely high efficiency.

It is true that if the tweeter is listened to on its own without the contribution of the bass/midrange driver - and here we are talking of frequencies above about 3kHz - very little seems to come out of it. 

However, if you were to listen to any loudspeaker without the tweeter connected, you would certainly notice that the sound is muffled, it gets harder to distinguish the different instruments and voices, and the sense of space is lost. It is because our hearing relies on these high-frequency sounds to give us the detail. This detail comes from the tweeter and the better the tweeter, the more the enjoyment of listening to music, watching a film, or becoming immersed in a video game.

Thanks to our MAT Technology, sound is cleaner, especially at higher frequencies, and you hear a purer, more natural performance with almost no distortion.   

Now applied to many of our leading ranges, our award-winning MAT Technology features in BLADE Meta, The Reference, R Meta HiFi Speakers, LS60 Wireless, and the LS50 Collection.