A power amplifier includes a class-D amplifier and an input signal supplier. The class-D amplifier includes an input portion and a switching device. The switching device is switched according to an input signal that is input to the input portion so that a current is supplied to a load from a power source via the switching device. The input signal supplier supplies the input signal to the input portion of the class-D amplifier, calculates a virtual output voltage to be output from a virtual power source having a prescribed internal impedance characteristic when a current to flow through the load is output from the virtual power source, and adjust an amplitude of the input signal according to the virtual output voltage.

A power amplifier includes a class-D amplifier and an input signal supplier. The class-D amplifier includes an input portion and a switching device. The switching device is switched according to an input signal that is input to the input portion so that a current is supplied to a load from a power source via the switching device. The input signal supplier supplies the input signal to the input portion of the class-D amplifier, calculates a virtual output voltage to be output from a virtual power source having a prescribed internal impedance characteristic when a current to flow through the load is output from the virtual power source, and adjust an amplitude of the input signal according to the virtual output voltage.

An audio power amplifier arrangement includes an audio power amplification integrated circuit having two loudspeaker outputs. A rectifier circuit includes a first diode having a cathode connected to one of the two loudspeaker outputs and an anode connected to a rectifier output node. A second diode has an anode connected to the one loudspeaker output. A first resistor has a first end connected to a cathode of the second diode and a second end connected to the rectifier output node. A capacitor has a first end connected to the rectifier output node and a second end connected to electrical ground. A second resistor has a first end connected to the rectifier output node and a second end connected to electrical ground.

An audio power amplifier arrangement includes an audio power amplification integrated circuit having two loudspeaker outputs. A rectifier circuit includes a first diode having a cathode connected to one of the two loudspeaker outputs and an anode connected to a rectifier output node. A second diode has an anode connected to the one loudspeaker output. A first resistor has a first end connected to a cathode of the second diode and a second end connected to the rectifier output node. A capacitor has a first end connected to the rectifier output node and a second end connected to electrical ground. A second resistor has a first end connected to the rectifier output node and a second end connected to electrical ground.

A distributed amplification device with p inputs, p outputs, p amplification paths comprises a redundant reservoir of n amplifiers including n-p back-up amplifiers, an input redundancy ring and an output redundancy ring formed by rotary switches, the input and output redundancy rings sharing the same technology. The internal amplification pathways associated with the n-p back-up amplifiers frame in an interlaced manner the internal amplification pathways associated with the p nominal amplifiers and the amplification paths of the routing configurations each pass through at least five rotary switches. The input and output redundancy rings are topologically and geometrically configured and the family of the routing configurations is chosen such that the electrical lengths of all the paths of one and the same routing configuration of the family are equal.

A distributed amplification device with p inputs, p outputs, p amplification paths comprises a redundant reservoir of n amplifiers including n-p back-up amplifiers, an input redundancy ring and an output redundancy ring formed by rotary switches, the input and output redundancy rings sharing the same technology. The internal amplification pathways associated with the n-p back-up amplifiers frame in an interlaced manner the internal amplification pathways associated with the p nominal amplifiers and the amplification paths of the routing configurations each pass through at least five rotary switches. The input and output redundancy rings are topologically and geometrically configured and the family of the routing configurations is chosen such that the electrical lengths of all the paths of one and the same routing configuration of the family are equal.

Amplifier circuitry that is operative to provide selective control of the amplitude of a musical signal as the signal transitions from the pre-amplifier to power amplifier components of an electric guitar amplifier. According to a preferred embodiment, at least one low variable power amplifier is integrated into the signal path from the pre-amplifier to the power amplifier components of the guitar amplifier. The low power amplifier allows for selective control of the amplitude of the musical signal such that the signal ranges from zero volts to more than 100 DB. Such low power amplifiers may be selectively deployed in guitar amplifiers utilizing either Class A or Class A/B circuitry and enables a musician to have full control of the power amplifier from 0% gain to 100% gain at any tone selection and any power amp wattage, as may be desired.

Amplifier circuitry that is operative to provide selective control of the amplitude of a musical signal as the signal transitions from the pre-amplifier to power amplifier components of an electric guitar amplifier. According to a preferred embodiment, at least one low variable power amplifier is integrated into the signal path from the pre-amplifier to the power amplifier components of the guitar amplifier. The low power amplifier allows for selective control of the amplitude of the musical signal such that the signal ranges from zero volts to more than 100 DB. Such low power amplifiers may be selectively deployed in guitar amplifiers utilizing either Class A or Class A/B circuitry and enables a musician to have full control of the power amplifier from 0% gain to 100% gain at any tone selection and any power amp wattage, as may be desired.

To provide an impedance converter circuit for a condenser microphone which can secure a wide dynamic range using a voltage amplifier circuit. The impedance converter circuit is provided with: a first electron tube of a cathode grounded type in which an output signal of a condenser microphone unit is input into a grid and output from a plate; a second electron tube in which an output signal from the plate of the first electron tube is input into a grid and output from at least a cathode; and a feedback element configured to transmit a feedback signal from the cathode of the second electron tube to the grid of the first electron tube.

To provide an impedance converter circuit for a condenser microphone which can secure a wide dynamic range using a voltage amplifier circuit. The impedance converter circuit is provided with: a first electron tube of a cathode grounded type in which an output signal of a condenser microphone unit is input into a grid and output from a plate; a second electron tube in which an output signal from the plate of the first electron tube is input into a grid and output from at least a cathode; and a feedback element configured to transmit a feedback signal from the cathode of the second electron tube to the grid of the first electron tube.