Reply To: 6U5 SUBSTITUTION

[Gerry O’Hara]

Yes, but the 6E5 is more sensitive – it needs about -22 volts to fully close the eye on the 6U5 and only -7 volts on the 6E5. A 50/50 voltage divider on the grid circuit may work to bring the 6E5 sensitivity down (maybe try a couple of 5.6Mohm resistors?). However, I think the 6U5 has remote cutoff characteristics and the 6E5 sharp cut off, giving the 6U5 greater sensitivity at lower (negative) grid voltages and less sensitivity as the (negative) grid voltage increases, ie non-linear response, whereas the 6E5 response is more linear – better-suited to instrumentation applications.