Abstract: To provide a chorus effect in a digital musical instrument frequency separation between tones read out of two or more memories is effected by modifying the coded digital number which controls the rate of change of voice addresses in a memory by a predetermined value to produce a modified coded digital number, and then using said coded digital number and the modified coded digital number to read voices out of two or more memories.

Abstract: In a digital musical instrument, timbre modulation is effected through the use of a digital magnitude comparator and associated digital logic. Selected note frequency signals and selected scale factors are compared in the digital magnitude comparator. Selected comparator outputs are applied to the associated digital logic in conjunction with a sample gating signal. This modulation results in a segmentation of the audio waveshape in accordance with the frequency signals selected for use in the comparator. Hence, choice of lower pitched frequency signals will result in a wider segmentation period, while choice of higher pitched frequency signals will narrow the segmentation period. Timbre modulation may be employed during note attack and/or decay.

Abstract: Spatially separated high frequency tonal effects from an electronic musical instrument having less tone generators than keys selectable. A high frequency speaker system is provided in addition to the normal audio system. The audio signals produced by the tone generator are applied to a high pass filter-amplifier circuit before application to a tweeter switch. Digital logic is provided to demultiplex the note generator capture signal for note generator assignment information. The demultiplexer information is applied to the tweeter switches to effect the activation of a tweeter switch and permit the sounding of the tweeter speaker. Thus it may be seen that the present invention permits the separate soundings of the high frequency range in a directional fashion, creating the movement of sound sources and changing spatial relationships in response to key activity.

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 digital musical instrument incorporating the effects of attack and decay by appropriately scaling the digitally synthesized waveform information at the leading and trailing portions of the waveform envelope. Such an instrument would be capable of producing two attack and decay periods with only one attack and one decay period resulting in the normal audible effect. The system is particularly adapted for use in an electronic musical instrument in which a digital multiplexed signal is generated by actuation of the keys of the instrument. The attack and decay periods generated by actuation and deactuation of the keys are processed such that each period is divided into "n" scale factors spaced in time, each such scale factor being associated with a different level of the waveform envelope. The scale factors cover the range of waveform envelope from zero to full scale. Upon receipt of a clear pulse, the digital counter begins counting, and would terminate the count upon reaching "n".