Standby switch

A switch on a valve amplifier that cuts the high-voltage supply to the valves while leaving their heaters running.

It exists because the heaters need time to bring the cathodes to temperature before the high voltage is applied, and because a warm amplifier that is not being played can be idled without repeated full power cycles. Some designs use it to mute the amplifier without switching it off, and some players use the standby as a mute between sets. Its usefulness is debated, and it does not protect an amplifier from a missing load.

Example: leaving an amplifier on standby between sets keeps the valves warm so the tone is stable the moment playing resumes.

Standby switch

See also