The Optigan is an electronic keyboard instrument designed for the consumer market. The name stems from the instrument's reliance on pre-recorded optical soundtracks to reproduce sound. Later versions were sold under the name Orchestron.
Keyboard overview of a model 35002 Optigan. The coded strip above the main keyboard corresponded to numbers in the music books for those unable to read music.
Detail of the Optigan's chord buttons, special effect rocker switches, power switch, tempo adjustment wheel and stereo balance wheel. The adhesive-backed metal "Stereophonic" trim plate covers the unused reverb control opening on this example
An Optigan Program Disc
Cover art of box containing Program Discs
Optical sound is a means of storing sound recordings on transparent film. Originally developed for military purposes, the technology first saw widespread use in the 1920s as a sound-on-film format for motion pictures. Optical sound eventually superseded all other sound film technologies until the advent of digital sound became the standard in cinema projection booths. Optical sound has also been used for multitrack recording and for creating effects in some musical synthesizers.
Edge of a 35 mm film print showing four types of soundtrack. The stereo optical sound strip is located on the right, with waveforms for left and right channels. To the far left is the SDDS digital track (blue area to the left of the sprocket holes), then the Dolby Digital (grey area between the sprocket holes labelled with the Dolby "Double-D" logo in the middle), and to the right of the analog optical sound is the DTS time code (the dashed line to the far right.)
A transparent program disc imprinted with concentric optical sound tracks, used for the Optigan musical organ
Example of a variable-area sound track on the right side of the frames on this strip of 16mm film. The width of the white area is proportional to the amplitude of the audio signal at each instant.
Newspaper ad for a 1925 presentation of De Forest Phonofilms shorts, touting their technological distinction: no phonograph.
