The use of Electrostatic technology goes back towards the early 1900s. It was first used by a scientist from the UK - Lawrence Frederick Richardson, who was developing its use for underwater object detection. Through being used for scientific research, and then later adapted towards the 1920s for condenser microphones, it was yet to be used in loudspeaker design until Peter Walker’s curious approach to loudspeaker development led to the ESL.
The ESLs cult following and iconic status is not just because it was the first to use such technology – like all projects led by Peter Walker, this was to quench his thirst of reproducing sound originally as it was recorded.
“The first production electrostatic speaker did away with such vulgarities as cones and bulky enclosures in favour of a space-age design that virtually eliminated distortion and had near-perfect frequency response. The BBC quickly requisitioned them to use as reference monitors […] A hi-fi classic.”
-Stuff magazine, Stuff’s 100 Best Gadget’s ever (ESL-57 - Best Gadget Of 1957)
It was such an innovative design as it does away with conventional tweeter / woofer configurations and instead uses one thinly stretched electronically charged diaphraghm. This diaphraghm is stretched thinner than a human hair, which as you can imagine is extremely light. As a result there is no inertia inherent in the moving parts of the ESL and the diaphragm is able to respond to musical detail and transients with unparalleled precision and accuracy. A system of charged stator elements either side of the diaphragm control the diaphragm to vibrate and generate soundwaves.
“Listening to the original today merely confirms what many suspected: Despite its limitations, the Quad ESL delivers some of the most natural, open-sounding mid-band (especially vocals) you’re ever likely to hear.
It is a speaker which addresses certain needs, appealing to those who want their ears caressed, not battered. The speaker disappears into the room leaving you with nothing but… music […] It is stubbornly superior to modern designs in aesthetic, cultural and intellectual terms as a Leica M4 camera is to a polycarbonate SLR, as a 1950 Patek Philippe Calatrava is to a digital watch, as a vintage Vuitton trunk is to a nylon rucksack.”
– Hi-Fi News, 2000