Quad was founded in 1936 in the U.K. by Peter Walker. The brand name stemmed from "Quality Unit Amplified Domestic". In the period from 1957 to 1966 Quad developed the world’s first ever full range electrostatic loudspeaker, the ESL-57. After a series of articles published in 1999, spotlighting the truly important milestones in the development of audio, Hi-Fi News Magazine pronounced the ESL-57 "The greatest hi-fi product in history".

In the early 1980s, Quad launched the ESL63. The ESL-63 took the concept of electrostatic speakers to a whole new level using, for the first time ever, delay lines and concentric annular electrodes to create an almost perfect theoretical point source. The patented system of concentric electrodes has been maintained and improved within the new ESL-988/989 range with the addition of extra bass panels. www.quad-hifi.co.uk/esl.htm. Locate a dealer (UK) Locate a Dealer (USA)