Biasing Tube Amps “Hot” or “Cold”

Bias settings affect the way the output tubes on a tube guitar or bass amp function. If the biasing is set “hot,” vacuum tubes will burn out faster, but will typically sound great during the time they are functional. Conversely, a “cold” bias increases tube life but the amp dynamic range will be lower overall. Some tube amps have a fixed bias. In any case, any attempt to change the bias of an amplifier should always be left to qualified technicians, since the internal voltages in tube amps are high enough to kill!