An electronic music instrument produced by the Hammond Organ Company prior to World War II. It is generally recognized as the world's first subtractive synthesis machine to be commercially produced. The basic concept was developed by Laurens Hammond in the mid-1930s, as an outgrowth of his company's R&D on its organs.
The Novachord, unlike the Hammond organs, is all electronic except for its vibrato mechanism. It has 72 keys and is fully polyphonic, having two vacuum tubes and ancillary circuitry per note. It uses a sort of top octave division, with 12 oscillator circuits producing the 12 notes for the highest octave in the keyboard's span. A novel type of oscillator sync circuit is used to derive the lower octave notes from these 12 (binary counter circuits being unknown at the time), with all octaves producing an approximate sawtooth wave output. Each note has its own sort-of VCA, with an attack-sustain-release type envelope, which can be modified via sustain pedals.
From there, all notes feed through a bank of lowpass, bandpass, and high pass filters and resonators, in a paraphonic setup. The output mix goes through a vibrating-reed vibrato circuit (the only part of the instrument, other than the keyboard, that is mechanical), and then to a built-in amplifier and speaker. The instrument contained a total of 163 vacuum tubes, operating at reduced plate and heater voltages to improve tube life. Still, it consumed about 300 watts of electricity, most of which wound up as dissipated heat.
The Novachord went into production in late 1938, and was produced through July 1942 when WWII forced a halt to production. For unknown reasons, the Hammond company never resumed production of the Novachord after WWII ended. Information on serial numbers and dating, from Mike Fulk at HammondWiki, indicates that 1037 were produced, very few of which survive today. Speculation on why this is includes the difficulty of repair owing to the complexity of the circuitry, the difficulty of moving a Novachord (in its wooden case, the instrument weighs over 500 lbs.), stripping and salvage during WWII, and the instrument perhaps being just a bit too ahead of its time.