Emperor MK II,
Omnidirectional Loudspeaker

Low resonance cabinet design enhances transparency

To realise the full potential of this loudspeaker, considerable effort has been put into creating a highly rigid structure in order to minimise the radiation of sound energy through the cabinet panels. The colouration this creates is one of the principle causes of degradation of a loudspeaker’s ability to resolve fine detail and thereby produce a sense of realism, as it smears and generally confuses the sound.

The Emperor Mk II’s DDD drivers solve this problem by having very small enclosures, minimising the area of any potential vibrating surface. By being cylindrical, they eliminate the resonances that can arise with a conventional rectangular or square section cabinet. Because they are made from aluminium, a comparatively soft metal, residual vibration of the enclosure is minimised. The DDD driver enclosure end-caps are made from non-resonant MDF and the enclosure is packed with damping material to dissipate any standing waves. The result is that the German Physiks Emperor Mk II has the clarity that we normally associate with electrostatic loudspeakers and for the same reason: the DDD drivers essentially have no enclosure to colour the sound.

The bass system covers the range from 180Hz downwards. This is divided into four independent cabinets, so the panels are smaller and therefore stiffer and more vibration resistant than if a single large enclosure were to be used. All the cabinet vertical surfaces are non-parallel to prevent the formation of standing waves between them. Internal bracing increases rigidity to suppress resonances. Residual vibration is minimised by applying a special damping material called Hawaphon®, to the inside surface of each panel.

Hawaphon®, consists of a polymer sheet containing a matrix of small cells filled with fine steel shot. It adds mass to the panels to reduce the resonant frequency and the ability of the balls in each cell to move against each other provides a very effective way of converting vibration energy into heat. Originally developed as an anti-surveillance measure for use in military and government buildings, Hawaphon® achieves broadband attenuation of structure-borne sound of more than 50dB, which is an exceptionally high figure.

To damp resonances of the air within the cabinet, the whole of the interior is lined with a 1cm thick layer of high-density felt. This is achieved by fitting pieces of felt that are precisely cut to fit each panel, rather than just inserting a roll of felt into the cabinet. This is a time-consuming process, but we believe it produces a superior result and is typical of the attention to detail that we lavish on all of our products.