Abstract: A digitally-controlled variable-gain amplifier is disclosed, which comprises a polarization means to transform the input signal into differential signals of positive and negative polarity; first and second gain blocks, each composed of dual-multiplying digital-to-analog converters, which multiply the polarized signals to produce positive and negative amplified signals; and a differential amplification means which receives the amplified signals, and subtracts them from each other. The resulting output signal is proportional to the input signal and yields a 3 dB improvement in signal-to-noise ratio over a single multiplying digital-to-analog converter stage. A plurality of amplification chains, each comprising a first and second gain block, may be used to amplify the differential signals for summing by the differential amplification means to provide a greater signal-to-noise ratio improvement.

Abstract: A functional control block (FCB) device for use in conjunction with a signal regulating apparatus which has a signal regulator for producing an output signal and delivers an actual signal on a load through an external conductor, and which further has an inner servo loop and an outer servo loop. The FCB device includes a first input connected to the signal regulator, and a second input connected to the outer servo loop. The FCB device has an internal functional signal processing circuity for processing an output signal from the signal regulator, and the signal from the outer servo loop, and producing a functional sense signal and a functional reference signal. The FCB device further has a first output connected to a sense input of the inner servo loop for delivering the functional sense signal, and a second output connected to a reference input of the inner servo loop for delivering the functional reference signal.

Abstract: The present invention is a concentric servo method and apparatus using two servo loops to control and stabilize the output of an electronic voltage regulator. An inner and outer servo loop are employed. The inner servo loop resembles the control loop of a conventional voltage regulator while the outer servo loop controls the sense threshold of the inner servo loop. The outer servo loop senses the voltage delivered to an external load resistance and controls the sense threshold of the inner servo loop to compensate for the voltage loss which may occur between the regulator output and the actual load resistance. The inner loop retains its high speed to regulate out any input voltage irregularities such as ripple and noise. The present invention gives better stability than conventional remote sensing voltage regulator circuits.

Abstract: An audio compressor using interactive layered time constants to create an easy to use compressor which self adapts to the program characteristics and provides a desirable and pleasing effect over a wide range of audio program material. The audio compressor includes an adaptable filter connected between an output signal path and a control feedback signal path of a voltage control amplifier. The adaptable filter comprises a first resistor-capacitor circuit connected to the output signal path and producing a charging/discharging voltage which is more dependent on a transient peak value of the audio signals and a second resistor-capacitor circuit working under the charging/discharging voltage of the first resistor/capacitor circuit for producing a charging/discharging voltage which is more dependent on an average value of the audio signals.

Abstract: A peak accelerated compressor comprising a voltage controlled amplifier, a level detector and a peak accelerated filter circuit. The voltage controlled amplifier circuit is utilized for processing an input audio signal and producing an output audio signal. The level detector circuit is utilized for processing a sample audio signal which contains transient peaks and average waveforms. The peak accelerated filter circuit is coupled between the level detector circuit and the voltage controlled amplifier circuit for producing a control output signal to change the gain of the voltage controlled amplifier circuit in response to the transient peaks in the sample audio signal. The peak accelerated compressor effectively enhances the compression for transient peaks without adversely affecting the normal compression of average waveforms.

Abstract: A reflected plate amplifier (RPA) for use with electronic audio equipment. The RPA comprises an input circuit for receiving an input signal, a vacuum tube, a plate current reflector, and an output circuit for delivering an output signal. The vacuum tube has a control grid coupled to the input circuit for receiving the input signal, and a plate for delivering a plate current responsive to the input signal. The plate current reflector is a transistor having an input terminal coupled to the plate of the vacuum tube for receiving the plate current, and an output terminal for delivering a reflected current which is responsive to the plate current of the vacuum tube and therefore responsive to the input signal, while the plate current reflector holds the plate voltage of the vacuum tube substantially constant for a wide range of the plate current of the vacuum tube.

Abstract: A transient discriminate harmonics generator which receives an audio input signal and produces an output signal containing harmonics of the input signal. The output signal is amplitude shaped as a function of the input signal's time and amplitude envelope.

Abstract: A frequency discriminate leveler ("FDL") which controls its attack rate depending on the audio frequency to more perfectly preserve the natural sound of the audio program while very effectively controlling the long term average program level. The FDL has a function to attack more slowly for low frequency signals than for high frequency signals. The FDL includes a gain controller, an FDL control generator and a leveling detector. The gain controller coupled to an input signal and an output signal. The input signal is the unleveled audio program which can vary widely in average level. The output signal is the leveled signal which contains a more constant average level. The FDL control generator generates a suitable control output to cause the gain controller to increase or decrease gain. The FDL control generator is coupled to the leveling detector for the purpose of receiving the output of the leveling detector, and generating a control output to control the gain of the gain controller.

Abstract: An apparatus and a method using logical functions to improve the performance of a noise gate. When the input or triggering signal exceeds the gate threshold, a first bistable logic element is set. Simultaneously, a second monostable logic element is triggered for a set time-out. A third logic element determines if the second monostable logic element is reset after the time-out and the triggering signal is below the gate threshold, at which time the first bistable logic element is forced to the reset condition. Under no other condition can the first bistable logic element be reset. The logic output of the first bistable logic element controls the noise gate, causing it to open when set and close when reset. The advantage of this method over prior art is a more decisive gate operation whereby a short transient triggering signal can fully and definitely trigger the gate open.