Franklin’s lightning bells
Delaborde’s Clavecin életcrique (1759): http://120years.net/clavecin-electrique-1759/
Helmholtz’s Klang Synthesizer (1863)
More information: https://120years.net/helmholtz-sound-synthesiser-max-kohl-germany-1905/
Elisha Gray’s Musical Telegraph (1874): https://120years.net/the-musical-telegraphelisha-greyusa1876/
A (poor-sounding) demonstration of the basic mechanism:
Thaddeus Cahill’s Telharmonium (1897; note: no audio recordings of the Telharmonium exist)
Choralcelo (1907) with sound recording: https://120years.net/the-choralcelomelvin-severyusa1909/
Clara Rockmore playing the theremin
Jörg Mager’s synthesizers, including the sphärophon
An example of acoustic quarter-tone music from Jörg Mager’s time
Oskar Sala demonstrating the Trautonium (1928, video from 1986)
https://www.youtube.com/watch?v=uaWrdbvhg1Q#t=95
Paul Hindemith’s Konzertstück for Trautonium and strings (1931, recorded 1978)
Hindemith’s Des kleinen Elektromusikers Lieblinge for 3 Trautoniums (1930; recorded in 1963)
Ondes Martenot (1928)https://www.youtube.com/watch?v=V8qAZQnkbkA
https://www.youtube.com/watch?v=V8qAZQnkbkA
Olivier Messiaen, Fête des belles aux for six ondes Martenot (1937; recorded 2015)
Messiaen, Turangalila symphony, including ondes Martenot (1948, recorded 2008)
Rossiné’s Optophonic Piano (1916): https://120years.net/the-optophonic-pianovladimir-rossinesoviet-union1916/
Hardy-Goldthwaite organ (1931): https://120years.net/the-hardy-goldthwaite-organ-hardy-goldthwaite-usa-1930/
Frederick Sammis’s Singing Keyboard (1934): https://120years.net/the-singing-keyboard-fredrick-minturn-sammis-james-nuthall-usa-1934/
Hand-drawn sound by Arseny Avraamaov (1930s)
Hammond organ (1935—this is a digital recreation, but this video demonstrates the timbral range well, especially the ending at 2:43)
Hammond Novachord (1939)