Hammond S-2 Electronic Chord Organ

Hammond Organ Company introduced the chord organ in 1950 with the S series. Its "easy to play" style initiated a new market segment leading to today's home keyboard market. The chord organ was invented primarily by John M. Hanert, who was Hammond's primary musical engineer at the time. He had previously developed the Novachord and Solovox, two instruments which used vacuum-tube circuitry rather than tone or phonic wheels to generate the tones as in a Hammond Organ. Chord organ is a kind of home organ that has a single short keyboard and a set of chord buttons, enabling the musician to play a melody with one hand and accompanying chords with the other, like the accordion with a set of chord buttons. There were five different versions of the basic Chord Organ, which was called the S-series. The original model "S" used octal tubes and one 12" speaker while the S-1 used miniature tubes and one 12" speaker. (source: Wikipedia)

The S-series chord organ can be played via following interfaces: 37-note keyboard for solo or chords, 96-chord buttons (12-semitones × 8-chords variation) for chords, 2 wire touch-plates for strumming effect, 2 bass pedals for root & 5th, 1 expression pedal (or knee lever) for total volume control, 3 volume knobs for volume of each part (solo, chord, bass).