The IHL pavilion rear-loaded tweeter

As part of the development of the Sopra project, the need for compactness meant that the maximum volume of the cabinet had to be used for the bass. Focal engineers had to find a new system for loading the tweeter.

MAKING THE MOST OF THE BERYLLIUM TWEETER

Our Beryllium tweeter has an incredibly light and rigid dome. Its main limitation is air compression in the rear cavity. Ideally, to overcome this limitation, an almost infinite volume would be required.

THE IHL (INFINITE HORN LOADING) SYSTEM

The rear of the Beryllium tweeter is loaded by a small cavity that communicates with the outside of the cabinet via a horn. The inside of the horn is filled with a damping material. The tweeter's rear wave is thus gently and progressively absorbed. Its acoustic impedance tends towards zero, so there's no resistance to dome movement. Definition is pushed to the limit. This device is patented.

The advantage of this geometry is that it only slightly affects the internal volume of the cabinet.

This means we can make the most of the woofers to maximize bass performance, with ideal positioning of the tweeter, all in a reasonably-sized loudspeaker.

We also had to isolate the tweeter from any parasitic vibrations. The tweeter mounting is made from a single-piece injected polyurethane part, optimizing mass and damping in a controlled volume.

Comparison of multitone/Klippel distortion between our IAL 1 version in red and the new IHL device in blue .

A 30% reduction is achieved between 1.5 and 4 kHz.