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date: 22 November 2019


  • Hugh Davies


Electronic keyboard instrument developed by George Secor and Hermann Pedtke and manufactured in Chicago by Motorola for a brief period during the early 1970s (about 12 were constructed). It has two five-octave manuals. Each note can be independently tuned and the tunings are selected and fixed before a performance begins; the frequency (about 3.5 MHz) of a master oscillator is divided by the operation of ten binary switches for each note, giving 1024 pitch possibilities per key, accurate to within less than half a cent. A second version, constructed in 1979–81 under the direction of Richard Harasek, features Secor’s design for the ‘Generalized Keyboard’, which has up to 56 notes per octave, controlled from 294 colour-coded oval keys (white naturals, red flats, black sharps). The keyboard can be electronically divided to provide two-manual effects. The system memory can store 17 switch-selected tunings. The Scalatron offers traditional organ sounds as well as synthesizer capabilities such as synthetic wave shapes, filters, and a white noise source. Outputs can be fed to a multi-track tape deck or to multiple channels for live performance. The Scalatron was used by Easley Blackwood at the University of Chicago in the late 1970s in the composition of his 12 Microtonal Etudes, each one of which explores an equal-tempered system having between 13 and 24 notes to the octave. Secor himself composed works in the 31-note system and in unequal temperaments using the Scalatron. A Scalatron electronic tuner was also marketed, in which stroboscopic patterns are aligned on a television screen....

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