Single-ended triode

A single-ended triode (SET) is a vacuum tube electronic amplifier that uses a single triode to produce an output, in contrast to a push–pull amplifier which uses a pair of devices with antiphase inputs to generate an output with the wanted signals added and the distortion components subtracted. Single-ended amplifiers normally operate in Class A; push–pull amplifiers can also operate in Classes AB or B without excessive net distortion, due to cancellation.

The term single-ended triode amplifier is mainly used for output stages of audio power amplifiers. The phrase directly heated triode single-ended triode amplifier (abbreviated to DHT SET) is used when directly heated triodes are used.

There are also single-ended tetrode, beam tetrode/beam power tube/kinkless tetrode, and pentode amplifiers with the same functionality and similar circuitry; e.g. this Mullard design.