Abstract: An electronic musical instrument having a plurality of frequency sources driving a plurality of waveshape controlling circuits rendered operative by a plurality of keyswitches comprising a keyboard to produce polyphonically, organ voices, piano and harpsichord voices, accordian voices, and other voices characterized by changing harmonic structure as the key is held down.

Abstract: A circuit is shown for changing the frequency of a basic keyed oscillator by controlling the amount of keying voltage reaching the oscillator and the circuit used for vibrato. The purpose of this circuit is the achievement of true "pipe organ celeste" effect without using an added rank or set of oscillators. Circuits are described wherein the harmonic structure of the signal resulting from this modification of a basic keyed oscillator can be made to change by means of controlling the amount of keying voltage reaching the oscillator for the purpose of achieving the desired harmonic structure of the rank when operated in the "non-celeste" mode as opposed to the "celeste" mode. A circuit is also described for amplitude modulation and harmonic structure modulation at the vibrato rate to enhance the vibrato.