Electron tube biasing by a resistor from drain of previous stage to grid

This positive external bias that neutralizes internal negative biasing electron tube processes may serve as a simple way to make an electron tube operate at less than 4 volts anode voltage.


At the same time the electron tube is generously fed with a high enough signal. This makes the electron tube reveal its unique instatenious peak limiting analog signal conditioning or production properties.


A capacitor may be needed in parallel (similar to grid leak biasing) to lower the impedance of the resistor to the music electrical signal.


References:


On preserving transconductance - euroelectron blogspot


Connecting Pleiades K117 to Pleiades V4 - euroelectron blogspot