Pleiades V6 2DV4 Nuvistor with 1.9MΩ or 1MΩ pull up bias resistor

Signal path, setup:


Male singing voice at 2-3in - Sennheiser MD441 U3 - Pleiades V6 2DV4, 1.2V battery - Sony TC-D5 Pro - Senheissr HD580


With pull up bias resistor from anode to grid of 1M there is some high treble increase and a corresponding increase of hiss. When connecting a 0Ω XLR male to Pleiades V6 mic input, there is not much difference in noise reduction.


When a 1.9MΩ bias resistor is used there is decrease of HF noise when short circuiting the input. The sound also seems more easy and natural. So for the time being at least 1.9ΜΩ is used.