Abstract: A touch sensitive system for an electronic musical instrument providing a multiple key switch contact system for effecting control over two or more tone generating systems. The first tone generating system operating rapidly in response to the actuation of the key switch to produce a desired voice. The second or subsequent tone generating systems operate sequentially in a delayed manner on the actuation of the key switch effecting a predetermined delay in the production of the desired voice. The audio output of each of the tone generating systems is summed forming a resultant waveform for audio amplification. The key switch actuation, depression and release, causes the tone generating systems to respond immediately to the depression or release of the key switch which effects a change in the envelope characteristics of the resultant waveform.

Abstract: In an electronic musical instrument a demultiplexing audio waveshape generator, which accepts multiplexed frequency signals and generates a complex audio waveshape. This is accomplished by having a multiplexed frequency source with one or more outputs with each output being individually connected to a weighted resistor. The outputs of the resistors are connected in common to create a current source for presentation to an analog switch. The analog switch selects the multiplexed channels to be combined to produce the audio output signal, and through the use of gating signals can be made to create pulsed waveshapes. In the preferred embodiment of the present invention the signal from the analog switch is presented to a capacitance-resistance combination. The switched current presented to the capacitor causes an incremental charging and discharging of the capacitor which corresponds to the desired contribution of that particular channel to the audio output signal.

Abstract: A method and apparatus for interpolating between the harmonic structures of a waveform stored in memory during the transient periods of said waveform. In an electronic musical instrument having a greater number of selectively actuable switches than generators to cause the production of sound corresponding to the respective notes of the musical scale the present invention interpolates between the harmonic structures of a waveform stored in memory during the transient period of that waveform. This is accomplished through the use of memory units having a number of locations or zones within each memory where the number of zones is equivalent to the number of discrete harmonic structures. The first of the memory units contains a discrete fixed harmonic structure in each of its zones, and a second of the memory units contains a difference value in each of its zones where the difference value is equal to the difference between the discrete fixed harmonic structure in adjacent zones of the first memory.

Abstract: A method and apparatus for interpolating between the harmonic structures of a waveform stored in memory during portions or the entire transient periods of said waveform. In an electronic musical instrument having a greater number of selectively actuable switches than note generators to cause the production of sounds corresponding to the respective notes of a musical scale, the present invention interpolates between the harmonic structures of a waveform stored in memory during portions or the entire transient periods of said waveform. This is accomplished through the use of memory units having a number of locations or zones within each memory where the number of zones is equivalent to the number of discrete harmonic structures.