Vintage Rare 1966 Johnson Intonation Trainer Synthesizer Tunable Keyboard

Note: Auction links are affiliate links for which the site may be compensated.
Published on Aug 1, 2018 Sharief Hoffman

via this auction

You can find another video of one previously posted here.

"Very Rare to find Johnson Intonation Trainer
Made by the E.F. Johnson Co in 1966
Waseca, Minnesota U.S.A.

* Cool four-voice tunable electronic keyboard (scale selector switch offers choice of standard/tempered tuning or tunable modes)
* Originally used to test the relationship of pitch-matching and pitch-discrimination abilities

Highlights
* Three octave keyboard
* Scale Selector - choose between reference (tempered tuning) or tunable
* Tunable Scale Controls - correspond to notes on keyboard and adjust pitch in tunable mode
* Voicing - choose from four voices - - basic sine wave to reedy / edgy

* Speaker in case (can also connect to external amp, mixer, etc)"