How did the Hammond organ generate its sound?

The Hammond organ generates sound through a process known as additive synthesis, which distinguishes it from many other electronic instruments that rely on subtractive synthesis or simple oscillators.12

The instrument’s sound production is driven by a synchronous motor that rotates a complex set of 91 small electromagnetic tonewheel generators. As these wheels rotate, they produce individual sine waves at specific frequencies. When a player presses a key, the organ combines these individually generated sine waves in varying proportions to create a complex waveform.312

Performers control the harmonic content—or the component tones—of the sound using a series of drawbars located above the keyboard. By adjusting these drawbars, the player can mix different harmonics to produce a wide variety of timbres, allowing the instrument to imitate the sounds of other instruments like the flute, violin, or oboe. A unique characteristic of this design is that the richness of the harmonic content does not diminish as the player moves higher up the keyboard.312