Various embodiments of the present technology may comprise methods and apparatus for an amplifier circuit. Methods and apparatus for an amplifier circuit according to various aspects of the present invention may be utilized in a digital-to-analog converter. The amplifier circuit may comprise a first operational amplifier with a feedback circuit. The feedback circuit may comprise an inverting amplifier circuit.

An improved method of providing high burst power to audio amplifiers from limited power sources, using parallel power paths to increase system efficiency without need for a power path controller, thus utilizing a simplified circuit operation and maximizing average power available for both the amplifier and supporting circuitry.

An anti-clipping circuit for car audio systems. The circuit reduces the input voltage from a signal source to an analog-to-digital converter by using a divider or by scaling the output of the pre-amplifier to less than the saturation voltage of the ADC. A digital signal processor (DSP) with a limiter algorithm ensures that the signal never exceeds a selected threshold. Then, a multiplying block in the DSP restores the signal to the original voltage level. The anti-clipping circuit protects the speakers from high total harmonic distortion (THD) levels and from distortion during engine start-up. It can also be used for thermal power rollback.

A digital amplifier includes a digital PWM generator, a first amplifier circuit, a first low-pass filter, a second amplifier circuit, a second low-pass filter, an attenuator, an error extractor, an adder, and a voltage supply unit. The first amplifier circuit amplifies a digital PWM signal at a second voltage. The first low-pass filter extracts a low-frequency band voltage signal from the amplified digital PWM signal, and outputs the extracted voltage signal to a load. The second amplifier circuit amplifies the generated digital PWM signal at a third voltage. The error extractor extracts an error signal. The adder adds a digital error signal whose feedback gain is adjusted to a digital audio signal. The voltage supply unit generates the third voltage that has a voltage value of a predetermined ratio to a voltage value of the second voltage, and supplies the third voltage to the second amplifier circuit.

The disclosure presents a method and an amplifier system for minimizing variation in an acoustical signal caused by variation in gain of an amplifier, comprising a battery for providing a supply voltage to the amplifier, a digital signal processor for providing the acoustical signal to the amplifier, a controller unit receiving an enablement signal when the supply voltage is in an offset mode, and based on the enablement signal requesting a measured voltage during a time period, and a first analog-to-digital converter configured for measuring the supply voltage to the amplifier when receiving the request from the controller unit or the first analog-to-digital converter is configured for measuring the supply voltage to the amplifier continuously, and where variations in the measured voltage relates to variations in the supply voltage during the time period. Furthermore, the controller unit is configured to predict offset modes (i.e. changes) in the supply voltage based on the enablement signals and a fitting of the measured voltages, and wherein the controller unit is configured to generate a compensating signal based on the fitting and transmit the compensating signal to the digital signal processor, the digital signal processor is then configured to minimize variation in the acoustical signal at the output of the amplifier by compensating the variation in gain of the amplifier based on the compensating signal.

Example embodiments provide a process that includes one or more of receiving an audio signal at a feedback compressor circuit, determining how much to attenuate the audio signal when a power level of the audio signal exceeds a threshold power level, combining the audio signal with an auxiliary attenuation signal from an auxiliary attenuation source and a compressed attenuation signal from the feedback compressor circuit to create a combination signal, and generating an audio output signal of the feedback compressor circuit based on the combination signal.

Concept and ways are described of implementing a sound distortion circuit suitable for musical instruments, in particular, for electric guitars. Inputting an audio signal, low noise intrinsic to the circuit electronics is provided to the output. This type of noise, here referred to as electroacoustic noise, is produced by the interaction of the harmonic components of the audio signal with the natural ways by which sound and heat propagate in materials that make up the circuit components. The invention demonstrates that this type of noise, not foreseen by prior art, presides over the musical quality of sound even when artificially distorted, as is often required especially by guitarists. Compared to the best that is offered by comparable prior art equipment, the invention offers the musician greater freedom of tonal research and also greater ease of musical performance, thanks to the greater degree of intonation obtainable with the instrument.

The signal processing device includes: an offset adjuster; an amplitude adjuster; and a delay adjuster, wherein the offset adjuster adjusts the DC offset using a first parameter regarding the DC offset determined based on an output of the offset adjuster which is output when no signal is input to the signal processing circuit by the subtractor, the amplitude adjuster adjusts the amplitude using a second parameter regarding the amplitude determined based on (i) an output of the amplitude adjuster which is output when a first test signal is input to the signal processing circuit and (ii) the first test signal, and the delay adjuster adjusts the delay using a third parameter regarding the delay determined based on the difference signal that is an output of the subtractor when a second test signal is input to the signal processing circuit.

This application relates to methods and apparatus for amplification of audio signals with improved audio performance. An audio driving circuit has an amplifier module in a forward signal path between an input for receiving an input audio signal (S.sub.IN) and an output for outputting an audio driving signal (V.sub.OUT). A pre-distortion module is operable to apply a first transfer function to the signal in the forward signal path upstream of the amplifier module, wherein the first transfer function comprises a non-linear distortion function based on at least one distortion setting. An error block is arranged to receive a first signal (S.sub.FF) derived from the input signal and a second signal (S.sub.FB) indicative of the voltage of the audio driving signal and determine a first error signal (.sub.1) indicative of a difference between the first and second signals. The pre-distortion module is operable to control the distortion setting(s) based on the first error signal.

An improved method of providing high burst power to audio amplifiers from limited power sources, using parallel power paths to increase system efficiency without need for a power path controller, thus utilizing a simplified circuit operation and maximizing average power available for both the amplifier and supporting circuitry.