THE THEREMIN WAS invented by Leon Theremin of Leningrad, Russia in 1924 and it represented a revolutionary change in thinking about how music could be produced, challenging traditional stringed, brass and percussion musical instruments.

Comprising electronic oscillators, it allowed control over both pitch and amplitude by moving the hands over sensor plates. Its design eventually led to the development of the Moog Synthesiser and electronically synthesised music in general.

Fig.1: the Theremin circuit involves three virtually identical oscillators, two to generate the tone and one to control the volume.

But the invention was not only instrumental in the development of electronic music, it also had an impact on a free-form style of playing music. The free gesture hand control afforded by the Theremin pre-empted the modern Sensor Chair synthesiser controller where the whole body is a part of the musical generation process.

Before this, Jimi Hendrix was creating new sounds by generating feedback between his guitar and the amplified sound and then moving his body to modulate the amplitude. It freed him from the restriction of generating music solely by plucking the guitar strings.

The Theremin was commercially manufactured by the Radio-victor Corporation of America (RCA) around 1929. It comprised a large box to which were attached an antenna and wire loop. The antenna provided the control for the pitch while the loop enabled the volume to be adjusted. Moving the right hand toward the antenna would reduce the pitch while moving the hand away from the antenna would increase the pitch.