Editing Optigan (section)

==The optical disc format==

[[File:OptiganProgramDisc.jpg|thumb|right|An Optigan Program Disc]]
[[File:OptiganChristmasMusic.jpg|thumb|right|Cover art of box containing Program Discs]]
The Optigan's playback system functioned much like the [[optical sound|storage and reading of an optical soundtrack]] as was used in motion pictures, using a light bulb to energize a row of [[photodiode]]s on the opposite side of spinning, 12" diameter clear plastic film discs (officially referred to as "Program Discs") encoded with fifty-seven [[concentric]] [[optical]] tracks. The system then translated the [[analog signal|analog waveforms]] on the disc to an audio signal.  A flip-down door beneath the keyboard allowed access to the disc's loading area to the left of the unit and a disc storage area to the right. Program discs were loaded by simply sliding them onto the felt-covered platform; a V-shaped notch on the front of the panel aided in alignment.  When power was applied and the front cover closed, a spindle engaged the center hole of the disc and a motor-driven [[Idler-wheel|idler wheel]] spun the disc on the spindle.  The power switch itself was mechanically linked to the disc's drive system; lowering the front panel dropped the spindle and disconnected power to the instrument, allowing the program discs to be changed without the need to fully power down.  A broad, flat, white plastic cleaning tool with a purple, simulated velvet cleaning surface was supplied with each Optigan to allow periodic cleaning of the photoelectric cell, located near the rear of the instrument.

Thirty-seven tracks were sustained or repeatedly percussive notes in the [[timbre]] of a particular instrument and were played through a standard three-octave [[piano]]-style [[musical keyboard|keyboard]] with the right hand; twenty-one were of a live band or [[Solo (music)|soloist]] playing [[Chord (music)|chords]] in different [[key (music)|keys]] arranged per the [[circle of fifths]], specifically B-flat, F, C, G, D, A and E [[Major chord|major]], [[Minor chord|minor]], and [[diminished triad|diminished]] and were played with the left hand in much the style of a chord organ or [[accordion]]. The remaining five were assigned to rocker switches above the chord buttons and featured (depending on the disc in question) [[percussion instrument|percussion]], [[sound effect]]s, introductions, vamps, and endings synchronized with the chord buttons.  Pushing upward on the rocker switches locked them in place for use with percussion; pushing downward allowed momentary use for vamps, introductions and endings.

[[Image:Optiganmanual.jpg|thumb|left|150px|Cover of the beginner's music book shipped with each new Optigan. Despite the mention on the cover, no disc with the sound of a [[sitar]] was ever offered]]

Not all of the chord buttons had their own track assignments, the result being only fifty-seven sounds on sixty-three buttons, keys and switches. There was also an optical [[metronome]] incorporated into the discs which showed as a red flashing light for the downbeat and white for the upbeats inside the Optigan badge above the keyboard. The advantages of this unique optical playback system were that the Optigan's range of timbres was infinitely expandable and that there was no limit on the duration of a note as there was on the Optigan's professional-grade counterpart, the [[magnetic tape]]-based [[Chamberlin]] or its successor the [[Mellotron]]. The disadvantage was that notes could have neither [[envelope (music)|attack]] nor decay, as the tracks had no specific beginning or end.

The "Starter Set" sold with the Optigan contained discs with fairly self-explanatory titles:  "Big Organ & Drums", "Pop Piano Plus Guitar", "Latin Fever", and "Guitar in 3/4 Time".  More modern styles were represented by titles such as "Movin'!", which was a [[rhythm and blues]] disc and "Hear and Now", with a sound clearly based on the hit single "Sweet Seasons" by [[Carole King]] (and cover art evocative of that of her ''[[Tapestry (Carole King album)|Tapestry]]'' (1971) album). Other discs were marketed individually and packaged much like long-playing [[phonograph]] [[Gramophone record|records]]. These individual titles were also bundled in much the same way as the "Starter Set" and sold as six-disc "Entertainment Folios".  Some discs were available only as part of a two-disc "Style Pak" with titles such as "The Joyous Sounds of Christmas", "Country Style Pak.", "Polka" and "Songs of Praise" - these last two being produced towards the end of production and in very low quantities. Music books of various styles and even arrangements intended for individual disks were also available and sometimes packaged with the different bundles.

The initial run of musical tracks were recorded by Southern California studio musicians in [[Hollywood, Los Angeles|Hollywood]] and [[Torrance, California|Torrance]]. However, a musicians' union strike meant that some of the later discs were recorded in Germany. One disc is of particular note. The instrumental tracks for "Bluegrass Banjo" were recorded by members of the [[Nitty Gritty Dirt Band]]. The Vox Humana disc keyboard sound was used for the "Vocal Choir" Orchestron disc.

For the benefit of those unable to read music, the notes in the books were numbered in correspondence to a numbered and color-coded foil strip above the keyboard. The Optigan's songbooks were written and arranged by Optigan Corporation's music director, [[Johnny Largo]]. Largo, an accordionist and session musician, was a contemporary of [[Johnny Marks]], a composer best known for his popular mid-20th century Christmas melodies. As such, many of the songs in the Christmas books were Marks compositions.