What Does Metamaterial Absorption Technology (MAT) Do?

Metamaterial Absorption Technology (MAT™) has been a hugely significant KEF innovation in recent years. Utilising some of the latest developments in the field of practical applications of acoustic metamaterial, it was even honoured with What Hi-Fi?'s Innovation of the Year Award 2020. In this feature, we look at the technology, how it’s applied, and most importantly, what it means for you, the listener.

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 of solving distortion caused by sound from the rear of the tweeter.

First, 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 towards listeners, and from the back of the driver unit to the inside of the enclosure.  If untreated, some of this sound energy is reflected in 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

Most loudspeakers rely on porous materials, such as foam or wool, to dampen internal reflections. In fact, KEF was one of the pioneers of this method back in the mid-1960s. However, the drawback of this technique is the inconsistency of the material and the acoustic volume it takes. An alternative solution is to extend the enclosure to direct the sound energy away from the driver. But this requires a very long enclosure in order 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. This is thanks to a circular, maze-like disk that sits at the back of the Uni-Q driver array. The 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’s true that if the tweeter is listened to on its own without the contribution of the bass/midrange driver - and here we’re speaking 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, and it gets harder to distinguish the different instruments and voices, meaning that the sense of space is lost. This is because our hearing relies on these high-frequency sounds to give us detail. All the  detail comes from the tweeter, and the better the tweeter, the more enjoyable it is to listen to  music, watch a film, or become immersed in a video game.

Thanks to MAT, sound is cleaner, especially at higher frequencies, and you experience 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 LS Wireless Collection.