Coupling MAT to the Tweeter Dome
Of equal importance to the application of MAT is how the back wave is shepherded into the disc. This requires a complete redesign of the area behind the tweeter to form a waveguide with particular characteristics. Essentially, the acoustic impedance of the waveguide must match that of the opening of the MAT disc to avoid a reflection of the wave within the waveguide back intothe tweeter dome. This led KEF to designing a tapered duct, which reduces in diameter towards the disc opening with a conical profile. This inverted conical horn eliminates said reflections, but also fulfils the design requirements of allowing for easier accommodation of the absorber into the driver package and reducing the size of the MAT disc itself.
In addition, the sheer increase of acoustic volume behind the tweeter increases the venting and reduces non-linear distortion related to the spring effect of compressing this rear acoustic volume. KEF has done detailed mathematics behind MAT and the tweeter coupling technique.
The metamaterial application to the Reference and Blade series is an example in miniature of the extensive theoretical, computer simulation, design, manufacturing and testing efforts that KEF has made on many performance variables of the new Blade and Reference speakers.
I wonder how the Meta tech on the Blade 2 affect front wall placement. Can the speaker be placed closer to the front wall?
