Circuit #12
This is a mixer with identical or dissimilar cathode circuits. With identical cathode resistors, plus a potentiometer and 2 electrolytic capacitors, it can be used as a blender. The potentiometer and both capacitors have no role in DC bias.
See “Designing Valve Preamps for Guitar and Bass” of Merlin Blencowe, pages 111-112.
PARAMETERS
Select T1 T2 type
V supply voltage
T1 T2 anode single resistor
T1 cathode resistor
T2 cathode resistor
SCHEMATICS