845

The 845 is a transmitting triode closely related to the 211 but with a higher amplification factor (mu ~8 versus ~12 for the 211), originally made by RCA and Amperex. Operating at plate voltages of 800-1250V, it delivers 15-30W in single-ended Class A with a slightly warmer, fuller tonal balance than the 211. The 845's higher mu means it requires less drive voltage, simplifying the driver stage design somewhat. It shares the 211's dramatic visual presence with its bright thoriated-tungsten filament, and the two are often compared as complementary voices in the DHT transmitting triode world.