This circuit consists of 2x of “Fetzer Valve Revisited” with Fender Bassman’s classic Treble/Middle/Bass (TMB) tone stack of 5F6-A. Because of unavailability of JFET in EveryCircuit, I’ve tweaked the Fetzer Valve’s circuit a bit to replace JFET by MOSFET, though. Plus, I ended up to insert extra opamp to compensate the signal level loss derived from passive tone circuit; it shouldn’t be necessary in the field as long as the gain of FET common source circuit is high enough, though.
Please see also https://www.runoffgroove.com/fetzervalve.html for further details of Fetzer Valve.
