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US 4,400,583 AGranted
Complete audio processing system
AssigneeMetme Communications
InventorGraham P. Bloy
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AssigneeMetme Communications
InventorGraham P. Bloy
Estimating the term…
A complete audio processing system of solid state design for providing improvement of audible signals through dynamic compression including an active filter for transient suppression, a gain control, and a plurality of active frequency control stages for selectively controlling internal gain of signals in different frequency bands. Outputs of the frequency control stages are mixed and provided to a compressor stage having an operational amplifier of gain fixed by a DC feedback network. A gain cell provides variable negative feedback. A rectifier circuit measures the average value of the audio input to the compressor stage and controls the gain cell as a function of the average value to provide negative feedback which increases as a function of increase in the level of said input signal. An attenuator receives the output of the operational amplifier and provides an attenuated but dynamically compressed output so that the circuit provides no substantial overall gain but achieves high compression. Optimum achievable compression is indicated by an LED indicator lamp.
A complete audio processing system for providing harmonic modification of any complex, compounded audio waveform of an audio signal, said system comprising an audio input for receiving an original audio signal from an external signal source, means for separating said audio signal into a plurality of different frequency bands, a plurality of channels, each separately gain-controllable, for receiving the respective frequency bands, gain control means in each channel for controlling the level of signals in the respective channel within each of the respective frequency bands associated with said channels thereby to control the amplitude of fundamental and harmonic audio signals within said bands, means for mixing output signals of said channels to provide a mixed audio signal, signal compressor means for dynamically compressing said mixed audio signal to provide a dynamically compressed tonally controlled audio signal, said signal compressor means providing dynamic compression of an input signal summed therein at a summing node and having a signal gain G.sub.comp expressed by the function
A complete audio processing system for providing harmonic modification of audio signals comprising an audio input for receiving an original audio signal from an external signal source, means for separating said audio signal into a plurality of different frequency bands, a plurality of gain-controllable channels for receiving the respective frequency bands, means in each channel for controlling the gain within each of the respective frequency bands associated with said channels thereby to control the amplitude of fundamental and harmonic audio signals within said bands, means for mixing output signals of said channels to provide a mixed audio signal, signal compressor means for dynamically compressing said mixed audio signal to provide a dynamically compressed tonally controlled audio signal, said signal compressor means comprising an amplifier and a feedback circuit interconnected between the output of said amplifier and the input thereof for providing nonlinearly increasing negative feedback signal to the input of said amplifier in response to increase in the level of said mixed audio signal, and an output for connection of external audio equipment to receive said dynamically compressed, tonally controlled audio output signal.
A simplified solid state complete audio processing system for providing harmonic modification of audio signals comprising an audio input for receiving a original audio signal from an external signal source, means for filtering said original audio signal to provide transient suppression filtering thereof, means for separating the transient filtered audio signal into a plurality of different frequency bands, a plurality of channels for receiving the respective frequency bands, amplifier means in each channel for amplifying frequencies of the respective band, means for selectively controlling the gain of each amplifier means for tonal control, means for mixing tonally controlled signals provided by said channels to provide a mixed audio signal, signal compressor means for dynamically compressing said mixed audio signal to provide a dynamically compressed audio signal, and attenuator means for attenuating the level of said compressed signal to provide a tonally controlled, dynamically compressed audio output signal, and an output for connection of external audio equipment to receive said dynamically compressed audio output signal, means interconnected with said signal compressor means for indicating an optimum level of compression thereof, said attenuator means providing signal attenuation of said compressed signal by a degree sufficient to cause the average level of said output audio signal to be substantially the same as that of said original audio signal.
Dependencies are inferred from the claim text.