The effect of continuously varying the pull up bias resistor on the 2DV4 operating at Vb=1.2V

Referring to today's and yesterday's post on the first tests of Nuvistor 2DV4 operating with 1.2V for both heater and plate (anode).


An AA 1.2V rechargeable battery is used for both circuits. (Always use a suitable fuse in series with a battery for safety).


In curiosity on what would happen if the tiny, 1μA but world class sounding anode current is increased various plate to anode resistors were tried.


A potentiometer from 5.7MΩ to 1MΩ was tried too. Created by a 1ΜΩ resitor in series with a viable 4Μ7.


As bias resitor was decreased towards 1MΩ, high frequency detail was increasing. The best sound was possibly at 1MΩ from anode to control grid.


Then a 680KΩ fixed resistor was tried with not too good sound results and more noise.