12BH7

The 12BH7 is a dual triode originally designed as a vertical deflection amplifier in television sets, with a mu of ~17 and the ability to handle high peak currents relative to its size. Its generous current capability makes it popular as a power amplifier driver and phase inverter, particularly in circuits that need to swing large voltages into capacitive loads. The tube is sometimes used as a low-power headphone amplifier output tube, delivering class A power in the 0.5-1W range. RCA and GE are the primary NOS sources; current production is available from JJ Electronic and Electro-Harmonix.