From RnFR:
here’s something i churned out the other day. i have been thinking about
modeling the Supro Thunderbolt with FETs, but then thought- i just got
in these cool new Tesla GE’s, why not use those? so that’s what it is,
the preamp section of the legendary amp used by Page and supposedly
Hendrix, done up NPN germanium style. i had to eliminate a few resistors
towards the end to bring up the volume and lowered the value of an
emitter resistor to up the gain a bit. also, i made the resistor on the
input variable so you can adjust the input impedance for guitars with
different pickups.
the real gem of this circuit is the tone pot-
totally counter-clockwise you get a nice full range tone with plenty of
mids. as you go clockwise it goes to a very muffled tone, and as you go
even further, it goes to a very thin, cutting tone. there are some very
cool sweet spots, and a lot of versatility. i like it better than a
regular muff style control, but it does cut plenty of signal- hence the
two gain stages after it.
it’s a cool sounding circuit. nicely
voiced and does a good overdrive type sound. if you don’t have the
trannys, you could change out the 33K Rc’s to trimmers and adjust to
taste. the tesla trannies are extremely consistent, so no trimmers
needed. the layout below uses some large axial caps and is yet
unverified, but hopefully i’ll get it done sometime soon.
