Music – Instruments
Patent
1974-12-11
1976-10-19
Weldon, Ulysses
Music
Instruments
84 103, 84 124, 84 126, G10H 100
Patent
active
039864235
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. The control system is essentially comprised of keyboard control logic and channel selection logic, both common to all of the voice channels, and channel logic units, each unique to a different voice channel. The keyboard and channel selection logic operates to assign voice channels to key depressions by sequentially sampling (scanning) the keys during a scan cycle to determine whether or not each key is depressed. Scanning is performed by a key address counter driven by clock pulses. When a depressed key is first recognized, the count in the address counter is, subject to certain logic criteria, written into a register contained in the channel logic associated with the selected voice channel. Additionally, the DC control voltage and gate signal are supplied to the selected voice channel. The channel selection logic is structured to assure that no voice channel receiving an active gate signal is pre-empted by a new key depression. Whether or not more than one voice channel can be assigned to a single key is determined by a user controlled REASSIGN mode switch. The criteria employed by the channel selection logic to select a voice channel for assignment is determined by a user controlled RESET mode switch.
REFERENCES:
patent: 3515792 (1970-06-01), Deutsch
patent: 3610799 (1971-10-01), Watson
patent: 3828110 (1974-08-01), Colin
patent: 3844378 (1974-10-01), Tomisawa et al.
patent: 3878750 (1975-04-01), Kapps
Oberheim Electronics Inc.
Weldon Ulysses
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