Electronic Production of Choral Tone

Abstract

An important quality of traditional musical sound is the rich ensemble effect which results in part from the combination of multiple sources that have the same nominal pitch but slightly different frequencies. Organ builders provide celeste ranks of pipes which are intentionally detuned from their neighbors. Electronic organs generally have fewer sources than pipe organs at a given pitch and their oscillators are inherently much more stable in frequency. It is not necessary to provide an extra set of detuned electrical generators for it is possible to translate signal frequencies electronically. This is accomplished by a group of single-side band, suppressed carrier modulators, and associated band-pass filters. The combined modulator outputs are preferably acoustically radiated by a loudspeaker channel which is spatially separated from the unmodulated loudspeaker channel in order that a subjective dimensional impression be achieved. Equipment of this type can be added to any electronic music system to provide a new set of sources of similar timbre yet transposed in frequency either up or down from the corresponding input frequencies. From an economic standpoint, the musician is thereby provided with many more sources for only a modest increment in cost.