1966 Johnson Intonation Trainer microtonal analog synthesizer

Published on Apr 9, 2014 Golden Gate Estate Services·2 videos

"This is the 'Intonation Trainer', a specialized keyboard or synthesizer made in Waseca, Minnesota in 1966 by the E. F. Johnson Company. Better known for their high-quality amateur ("ham") radio equipment, Johnson made the Intonation Trainer for a few years in the '60s and marketed it to orchestra and choral conductors and, to a lesser degree, to musicians, for the purpose of training the ear to recognize when a note is correctly pitched.

Each of the 12 notes in the octave can be tuned to any pitch within about 5 steps of the given note, so microtonal music is possible. You can pitch the notes for just intonation, Pythagorean, well-temperament or any other form of the 12-tone scale. It also has four different oscillator waveforms (sine, square, triangle and sawtooth), it has tremolo, and is fully polyphonic. It has a reference tone generator (440-hz) for self-tuning and a separate tuning trim for each of the adjustable tones! Furthermore, it's fully self-contained with a built-in amplifier and speaker system, and the whole thing is enclosed in a fiberglass carrying case.

Intonation Trainers are quite rare; I only know of 3 other examples in existence. They were also hugely expensive when new -- $525 in 1966, which works out to about $4,000 in 2014 dollars.

This one is in excellent condition, both cosmetically and functionally."