Sirius BE
Inspired by the fascinating realism and lightness of live music, the search for this listening experience is always taking us down to new paths. We feel an the inspirational desire to try out new possibilities and materials to conjure these live emotions into your listening space.

We were interested in looking into the different materials that could be used to make the dome section of the mid-high range driver in our large speaker system – the Sirius. Diamond and ceramics had to be ruled out, as these are neither available in the necessary size nor as compression drivers. The high level of efficiency of a compression driver is essential for our omnidirectional horn loudspeakers, as we would only achieve an abysmal acoustic result with a conventional driver.

The most dimensionally stable and at the same time lightest metal which can be used for speaker membranes of this size is beryllium. Needless to say, beryllium is a welcome upgrade for any loudspeaker.

The first speakers with beryllium dome sections came out on the market as early as the late 70s. Unfortunately, their durability was limited to only a few years, as they were – and still are – manufactured using the PVD process (physical vapour deposition).

This process consists of evaporating the metal onto a carrier substance that is afterwards removed. The metal atoms do not bind with one another; they degrade after a few years of use and are therefore unsuitable for integration in long-lasting, resilient loudspeaker systems.

This changed recently: a new technique enables beryllium to be rolled into a wafer-thin foil (Truextent material). When subjected to extreme heat and high pressure, the metal atoms are forced into a compound system (highly uniform grain structure). Thanks to the tear resistance and lifespan of a dome section manufactured this way, integration in a pressure chamber driver is not only finally possible but also extremely useful for (amongst other things) minimizing various partial oscillations.

Our latest project, the Sirius BE, combines the advantages of a beryllium mid-high range compression driver with acoustically and visually unusual acrylic horns. These are milled from one massive piece, painstakingly high-gloss-polished by hand and already inspire confidence through their immense weight. Acrylic is twice as dense as e.g. wood and thus has a higher stiffness and inertia, preventing self-oscillation (opposite –> bell/sound bowl). The high internal damping guarantees that the sound of the music reaches the ear as optimally and with as little distortion as possible.

For decades now, we have invested great diligence, meticulous care and even more hours of listening into creating the perfect-phase concept, the ingenious serial crossover, the tuning for the woofer, and the perfectly designed case.

Over the last years, the Sirius has established itself as a world-class reference speaker.
This place is now taken by the Sirius BE, taking you into an even more immersive experience.
Sirius BE - Specifications
    Voice Coil Diameter:
    Neodymium ring magnet:
    Die cast chassis
    Nomex voice coil former
    4 inch pure Beryllium dome - polymer surround diaphragm

3,6 kg
150 mm
100 mm
150 mm
    Voice Coil Diameter:
    16 Neodymium magnets:
    External neodymium magnet assembly
    Die cast chassis
    Double Demodulating Rings (DDR)
    Exclusive Carbon fibre reinforced straight ribbed cone

6,2 kg
315 mm
100 mm
26 mm
  Phaselinear crossover
  Power handling:
  Beamwidth ±3dB:

6 Ohm
93 dB SPL
400 W RMS

360(430) mm
360(430) mm
1330 mm
65 kg
5 Years

     Watch this video of a laser scan of a Truextent beryllium dome compared to scans of aluminum and titanium domes.