Noise in Valves (US: Tubes)

Abstract

Concerning electronic noise, we cannot compare the world of valves with the one of the solid-state world. Whereas the latter offers a rather narrow bandwidth of noise voltage tolerance, respectively, valves come along with a very broad tolerance noise voltage bandwidth. Sometimes the noise voltage difference between a selected low-noise type and a non-selected, “normal” one can reach up to 20 dB in the audio band. That is why the calculation of the audio band noise of a valve gain stage requires exact operating data of the chosen valve.