The Motorola Scalatron. Herman Pedtke & George Secor. USA, 1974

The Scalatron was an unusual microtonal electronic instrument developed in the early 1970s by Motorola as a new venture into the instrument market. Promoted as the ‘first instant-performance instrument that plays in the cracks’ the Scalatron was aimed squarely at a more experimental, microtonal market – if such a market existed. The instrument itself was a rather basic synthesiser consisting of 240 square wave oscillators (one for each key) built into a wooden home-organ casing.

Scalatron with the
The Scalatron with a Secor Generalised Microtonal Keyboard

The instrument was controlled in early models by a dual manual and later using a multi-coloured ‘Bosanquet generalized keyboard’ designed by the Chicago microtonal composer George Secor.  The Secor keyboard consisted of 240 tuneable oval multicolored keys and allowed the user to create complex tunings

 “Earlier that year (1974) I had attended a demonstration of the Scalatron (digitally retunable electronic organ) prototype, and recognizing that conventional keyboards were not the best way to perform music with more than 12 tones in the octave, I unwittingly proceeded to re-invent the Bosanquet generalized keyboard and subsequently approached the Motorola Scalatron company with the proposal of employing it on their instrument.”… “Around that time several members of the xenharmonic movement had gotten in touch with Scalatron president Richard Harasek and sent him copies of the first two issues of Xenharmonikôn, which he passed on to me and which I promptly read. The second issue included Erv Wilson’s diagrams of a modification of Bosanquet’s keyboard, with hexagonal keys, at which point it became clear that my keyboard proposal was not new… For the remainder of the year I was heavily involved in the generalized (Bosanquet) keyboard Scalatron project and, after that, in using it to explore new tunings. In effect, the keyboard that I had discovered was destined to be overshadowed by the one that I had rediscovered.”

George Secor

Secor Keyboard
Secor Keyboard Diagram

Costing around  $6000-$10,000, the Scalatron was an expensive and unusual instrument. Less than 20 Scalatrons were ever made (including only 2 Secor versions). The Scalatron came with a black and white monitor to adjust each key’s pitch (using Motorola’s TV tuning technology) – a split screen showed horizontal bars representing  true pitch on the left side and the instruments variable pitch on the right side, and, for an additional $1000  a cassette interface was added with a number of tuning ‘programmes’. George Secor toured with the instrument playing works by Harry Partch (who also used the instrument towards the end of his life) and Ben Johnston.  The Scalatron is still much in favour – though very hard to find – by microtonal composers and was used on several albums by Jon Hassell, most notably ‘Vernal Equinox’.

“Finally they invented what I needed–forty years too late.”

Harry Partch via Kenneth Gaburo

A dual manual Scalatron at La Trobe University  Melbourne
A dual manual Scalatron at La Trobe University Melbourne. Each key can be tuned to one of 1024 different pitches

scalatron_02 scalatron_01


5 thoughts on “The Motorola Scalatron. Herman Pedtke & George Secor. USA, 1974”

  1. Herman Pedtke was a teacher of mine at DePaul University, back in the 70’s. He had a no-nonsense approach in the classroom that some of the students did not always appreciate. I did, though. We were aware of his invention called the scalatron..and one day he asked if I’d be interested in working with a guitar version of the instrument. (I was a major in classical guitar.) I felt quite honored by the offer and I thanked him but begged off. “Thank you, Mr. Pedtke,” I said. “But I already have enough trouble with 12 tones to the octave!” It was an unusual time for “modern music”, the beginnings of synthesizers, and performance art. Another one of our teachers, Phil Windsor, had Pauline Oliveros visit our smaller classroom. She shared a piece she had written for clucking human voices, tape recorder, slide projector, and woman in a bathing suit laying across the teacher’s desk. It was quite an eye opener! But Herman was a more refined, traditional, and ” serious” musician.
    I admired him
    … Rick Rogers

  2. In 1977 when I was at Aaron Copland School of Music professor Joel Mandelbaum requisitioned a Skeletron for the schcool. He wanted to compose with it and eventually teach a course on it but I don’t think it ever got off the ground. I think the fact that it was a simple Square wave
    output and had no real musical tone was its downfall.

  3. Herman Pedtke was my Father. I have many of his original files and equipment for the Scalatron in my possession. Also he was interviewed on a Chicago radio station in the early 1970’s, the exact year escapes me. I have the recording. He was instrumental in getting this technology off the ground, having had these ideas in his head for years and years. I have not kept up with where it all progressed, but one day hope to go through all I have in my possession and decide where it best resides, from a historical standpoint. It was a great passion of his, no doubt.

  4. A few clarifications are in order.

    The illustration labeled “Secor Keyboard Diagram” is NOT the generalized keyboard layout (originally invented by Robert Bosanquet) that I proposed for the Scalatron. It is my design for a “decimal keyboard” (having 10 lateral keys per octave) which allows mapping the 31, 41, and 72 divisions of the octave, as well as Harry Partch’s just intonation and (what would later be named) the Miracle temperament. This diagram has nothing to do with the Scalatron and does not belong in this article.

    Most articles about the Scalatron (and this one is a lot better than most) contain other inaccuracies, and I feel that it’s time to give credit to those who had a major part in the development of this unusual instrument. The concept of an electronic musical instrument with digitally programmable pitch originated with Herman Pedtke, and it was inspired by the appearance of electronic music instruments with programmable rhythm (a/k/a drum machines). I understand that Pedtke was a neighbor of Motorola employee Richard Harasek and that the two were frequently in contact, since both were musicians. Harasek was intrigued with the idea and succeeded in getting Motorola to support a new subsidiary under its New Ventures program. The Scalatron was developed by the Motorola Scalatron company with Harasek as president and Don Ryon as electrical engineer. The product was basically a two-manual electronic organ with independently retunable keyboards. My proposal for a generalized keyboard came several years later, and Erv Wilson provided valuable input regarding the most optimal shape for the keys.

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