Audio power amplifier inside the chassis of the main product. The audio amplifier was invented around 1912 by Lee De Forest, made possible by his invention of the first practical amplifying electrical component, the triode vacuum tube (or "valve" in British English) in 1907. The triode was a three terminal device with a control grid that can modulate the flow of electrons from the filament to the plate. The triode vacuum amplifier was used to make the first AM radio. Early audio power amplifiers were based on vacuum tubes and some of these achieved notably high audio quality (e.g., the Williamson amplifier of
Charles Brown (engineer) Rione Amedeo, Naples, Italy. He married a Swiss woman and they had a son Charles Eugene Lancelot Brown who founded Brown, Boveri & Cie. Charles Brown died on 6 October 1905 at Basle. Charles Brown (engineer) Charles Brown (1827–1905) was a British engineer. He was born at Uxbridge on 30 June 1827 and was apprenticed to Maudslay, Sons and Field. In 1851 he moved to Switzerland to join the Sulzer company. In 1871 he left Sulzer to set up Swiss Locomotive and Machine Works (SLM). While at SLM he invented the Brown valve gear, a radial valve gear for steam