Abstract: A programmer for a music synthesizer including a keyboard and M independent voice modules (channels) and wherein the characteristics of each module are dependent upon K independent parameters, each parameter defined by an analog voltage level. The programmer is capable of storing N distinct programs, each program including information defining K parameters for each of M modules. The programmer is comprised of a common set of K potentiometers which are coupled through an analog to digital (A/D) converter means. The output of the A/D converter means is applied selectively either to a digital memory for storage at a location defined by operator controlled switches or through a digital to analog (D/A) converter means to the voice modules. Alternatively, information applied to the D/A converter means for application to the voice modules can be derived from the digital memory.

Abstract: An electronic music synthesizer including a keyboard control system for enabling multiple independent voice channels (voices) to be controlled by the keyboard in a musically pleasing manner. The control system responds to a keyboard of M keys to control N voices where N<M; e.g. M=64 and N=10. The voice channels are preferably identical to one another, each being comprised of voltage controlled elements such as an oscillator (VCO), amplifier (VCA) and filter (VCF). Typically, the control system selects an available voice channel and in response to a key depression, supplies a DC control voltage thereto whose level is nominally linearly related to the note corresponding to the depressed key. In addition to the control voltage, the control system supplies a gate signal to the selected voice channel indicating the time duration of the key depression.

Abstract: A current controlled variable transconductance amplifier having a differential input stage and a current source output stage is employed with negative feedback, either through a buffer amplifier or directly, to provide various all-pass, low-pass or high-pass filter configurations, each with controlled bias current to the differential input stage for current control of the variable transconductance amplifier to provide dynamic control of phase shift and filter cutoff frequency.