All done and enjoying it immensely! I used some neg feedback for an always on Prescence and a 3 way “power switch”. up position is full power with asymmetrical Germanium diode clipping, middle is full power and down parallels resistance to 66k on R10 for a medium output cut, this allows me to push the preamp section a little harder.
I installed a Kustom Defender 5 output transformer for 16,8 and 4 ohm on an output switch. I used the 4 ohm tap for the presence circuit.
I also lowered the value of c7 to 300pF, still cuts ultra high noise, but it also seems to brighten up the amp a bit. I raised the value of c1 to .068 uF to let a tad more bass into the front.
As you’ve stated, it’s hard to describe the tone of this design but I’d say it’s a mix of an early 5f1 or GA5 and a Vox Night train.
Thanks again, I’m now playing this more than my AC30!