Tone control arrangement for use in sound reproducing instruments

Abstract

A tone control arrangement is disclosed which is suitable for use in various sound reproducing instruments and in which the signal-to-noise ratio of the reproduced sound can be improved by controlling the frequency response of the audible signal with a variable d.c. voltage source. Frequency response control by a single d.c. control voltage is achieved by connecting in series and in order a first mixer, passive circuit network having a signal transmission characteristic determined by the desired frequency response of the output sound signal to be reproduced, a multiplier and a second mixer. The inverting inputs of the first and second mixers both receive the output of the multiplier, while the non-inverting input of the first mixer receives the input audio signal. The non-inverting input of the second mixer receives either the output of the first mixer or the input audio signal. Finally, the second input to the multiplier is provided by a variable d.c. voltage source. Tone control is achieved through a single control member even in the case of multi-channel systems by either using a single potentiometer wiper in common as the second input to each of the multipliers in the respective channels, or by ganging together a plurality of potentiometer wipers for control by a single member.