US 4,055,818 A · Tone control circuit

Abstract

Circuits for a high fidelity sound reproducing system which are suitable for providing treble, bass tone boost and cut functions. The audio input signal is utilized for producing a signal having the magnitude thereof frequency dependent. This frequency dependent signal is divided by a splitter circuit into feedback and feed forward signals and combined with the audio signal to either decrease or increase the magnitude of the audio signal appearing at an output thereof as a function of frequency. The ratio of feedback to feed forward signals produced by the splitter circuit is controlled by a direct current (DC) control voltage applied thereto. Because the control of the frequency dependent signals to vary the function of the circuit is accomplished elsewhere than in signal path of the audio signal the circuit is suitable for providing tone control remotely.

Claims18

Dependent claims

In an electronic circuit for receiving, and processing an audio signal, a control circuit for varying the frequency response of the electronic circuit, comprising:

means responsive to the audio signal for producing a signal of which the magnitude thereof is dependent on the frequency of the audio signal;
circuit means, coupled to said means for producing a frequency dependent signal, which is adapted to receive an externally supplied control signal, for electronically dividing said frequency dependent signal into a feedback and a feed forward signal, the ratio of said feedback signal to said feed forward signal being varied in accordance with the magnitude of said control signal;
means for combining said feedback signal with said audio signal to vary the frequency response of the electronic circuit in a first prescribed manner;
and
means for combining said feed forward signal with the audio signal to vary the frequency response of the electronic circuit in a second prescribed manner.

2 more elements

A tone control circuit suitable to be provided in a high fidelity sound reproduction system or the like for controlling treble and bass tones, comprising:

frequency sensitive circuit means responsive to an applied audio signal for developing at an output thereof a signal having a magnitude which varies with frequency;
means adapted to receive a direct current control signal and said signal from said frequency sensitive circuit means for producing first and second differential signals at respective output terminals thereof including a pair of differentially connected transistors, the base electrodes of said transistors being adapted to receive said direct current control signal thereacross, the connected emitter electrodes of said transistors being adapted to receive the frequency dependent signal from said frequency sensitive circuit means, the collector electrode of the first one of said transistors being directly connected to the output of the tone control circuit and the collector electrode of the second one of said transistors being coupled both to the output of the tone control circuit and to the input thereof, the ratio of the magnitudes of said first and second differential signals being controlled by said direct current control signal;
and
said first and second differential signals being selectively combined with the audio signal to vary the frequency response at the output of the tone control circuit to adjust the tone of the audio signal accordingly.

1 more element

A tone control circuit suitable to be fabricated in monolithic integrated circuit form for providing tone control in a sound reproduction system including an input terminal adapted to receive an audio signal, an output terminal, and an additional terminal adapted to be connected to a reactive component, comprising:

first circuit means, coupled to the additional terminal, which in conjunction with the reactive component is responsive to the audio signal for producing a signal the magnitude of which is dependent on the frequency of the audio signal;
second circuit means adapted to receive a direct current control signal and being coupled to said first circuit means for electronically producing first and second differential frequency dependent signals at respective outputs thereof, the ratio of the magnitude of said first and second differential signals being controlled by said direct current control signal said outputs being coupled respectively to the input and output terminals of the tone control circuit such that said first and second differential signals are combined with the audio signal to vary the frequency response of the tone control circuit in a prescribed manner.

Dependencies are inferred from the claim text.

Tone control circuit

Life of this patent

Tone control circuit

Life of this patent

Abstract

Claims18