Digital Control in Tube Power Amplifiers

Vacuum tubes are an old technology with a very important use in the audio electronics industry. They have a comparatively short life cycle and must be replaced often. This is a burden for the consumer since they must then calibrate (bias) the new set of tubes. This exposes the consumer to potentially lethal voltages. If the bias is not set correctly the tubes could be destroyed or the amplifier could operate inefficiently. The work presented in this thesis describes a digital control system that maintains optimum biasing for any tube used in the power amplifier. This system automatically determines the ideal bias voltage every time the amplifier is turned on. Unlike other designs, this system is completely non-intrusive and does not affect audio quality. The system requires no consumer maintenance and has nearly eliminated the burden of replacing the tubes in an audio power amplifier