Motivated by the experience in the construction of the ESL63.2 QA and "driven" by the demands of our customers, Quad Musikwiedergabe would like to deal with the conception of an interesting electrostatic special solution. Besides the acoustic point source, which Peter Walker successfully used as the heart of his electrostatic decades ago, there is another approach reproducing music in rooms: The cylindrical wave.
Correctly applied, it is possible to avoid the unwanted ceiling and floor reflections which occur and at the same time making use of wall reflections in an intentional way, while reproducing music in a living room. The result is amazingly close to the sound perception of the original and lets the listener completely forget about the loudspeakers presence. The listening zone, i.e., the area in which the original event can be experienced, is increased considerably in width and height. This way the music can be played in any room but allows the listener the experience of being in a concert.
This is by no means new! Peter Walker was already thinking about this before he launched the ESL57. Together with Mr. Williamson (with whom Peter also developed the circuit for the QUAD tube amplifiers at the time) Peter worked on electrostatic solutions for installation in walls and on comparatively large omnidirectional radiators. In the USA, Harold Beveridge later worked on this concept as well and integrated the idea in a modified way into a small number of handmade music systems.
The implementation is not quite that simple. They are large systems that take up space like large works of art such as paintings. If you want something like this, in addition to the the financial resources you will need the appropriate room. Cylindrical waves are created when the corresponding frequency range emanates from a kind of "line source" whose height approximately corresponds to the height of the room. The crucial point here is that the frequency range above a few hundred hearts up to the high frequencies are generated in this way.
Dealing with such special solutions, Quad Musikwiedergabe is always aiming for understanding more. Sometimes such experiments result not only in valuable insights about the matter itself, but also in knowledge that Quad Musikwiedergabe incorporates into existing products.