Polyphonic electronic music system

Abstract

Simultaneously played notes on a keyboard are automatically provided with different voice timbres. The assignment of voices to notes is by relative frequency-scale position within the chord. If four or more notes are played, the notes are scanned along the musical scale and the three lowest notes played and the highest note are sounded in different voices with the solo voice assigned to the highest note. Assignment of voices occurs automatically when fewer than four keys are played. Time division multiplex digital logic signals representative of the played keys are applied to a memory circuit and a comparator circuit. If the information stored in the memory from the previous scan cycle is unchanged the comparator provides an enabling signal to a monostable and enable logic circuit. A priority selector circuit provides logic information to the monostable and enable logic circuit which outputs this information and information representative of the total number of keys played. This information is combined with the octave information and the note time slot information in four programmable counter circuits which divide four input frequencies from a rate scaler frequency generator to produce the four tone signals. Also, the four programmable counter circuits provide control voltages corresponding to the played notes which are applied to voltage controlled gates and filter circuits which provide the necessary voicing to produce different orchestral effects on different notes. The resulting orchestral effect can be enhanced from an ensemble standpoint by controlled detuning of the four output frequencies.