Perhaps by the Pleiades principle of using an anode to grid high Megohm electron accelerator resistor extended to tubes already made for 6V.
For example EF98, EF97 but perhaps more importantly the multigrid ECH83?
A very high turn ratio Pleiades input transformer driving the grid of such an electron tube operating at 1.2V for both heaters and anode?
Would this create the gentle electron tube peak limiting behaviour using just one stage of amplification by connecting just a mic?
Perhaps the electron accelerator term is wrong. What can be observed by measurment is that the tube self biases internaly negatively. The missing electrons from cathode to the cathode cloud leave protons at the cathode on their own.
So the cathode is positive with respect to grid. In other words the grid has become negatively biased (with respect to cathode).
The external high Megohm resistor still keeps the grid negative but much less, therefore making possible the electron tube operation at anode voltages as low as 3V.
Is 1V possible?
So far 1.2V is used on the Pleiades V1 with the CV2269 electrometer tube. There was some hiss with this circuit. Could this circuit be improved by substituting an output transformer instead of the anode resistor. And perhaps changing the 50 Megohm resistor to a few Megohm from anode to grid? This circuit is interesting as the 1.2V AAA is connected to the direct filament heater. The same voltage is used for the plate or anode circuit. For a full description of the Pleiades V1 please see the next euroelectron post.
A song recorded with the V1, a possibly defective MD421 and the singer deliberately near an acoustic cavity, is Tezcatlipoca, the V1 driving Tascam porta 01.
https://m.youtube.com/watch?v=2RD02ATDPAk
References:
Operating features of the Audion - Edwin Armstrong
On preserving transconuctance of electron tubes at anode potential as low as 3 volts - euroelectron blogspot
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