Valve amplifiers

Bias circuit

Impedance converter and condenser microphone

Architecture of a wideband distributed amplification device

Rectifier circuit for monitoring dc offset of a single-supply audio power amplifier

Power amplifier and input signal adjusting method

Impedance converter circuit for condenser microphone

Rectifier circuit for monitoring DC offset of a single-supply audio power amplifier

Guitar amplifier circuitry

Electronic device and control method thereof

Method and apparatus for outputting audio signal

Sound output device using vacuum tube, audio apparatus and method for sound output thereof

Method of outputting audio signal and audio signal output apparatus using the method

Controlling the Performance of a Thermionic tube

Audio frequency amplifier

Controlling the performance of a thermionic tube

Output circuit of vacuum-tube amplifier

Vacuum tube replacement device, circuit and system

Expanded performance and functions for vacuum tube replacement devices

Electronic system of a hybrid amplifier

Lightweight amplifier