Symetric dual-triode mixer

Circuit #11

Two identical triodes mounted in parallel, with common-anode output, a common cathode resistor, which you may decouple by a capacitor or not.
You may refer to the book “Designing Valve Preamps for Guitar and Bass” by Merlin Blencowe, pages 109-112.

Select T1 T2 type
V supply voltage
T1 T2 anode single resistor
cathode resistor