Gave myself a rare Saturday off today to finish my Christmas project. Wanted to make something that would do the JCM800 thing, but at a bit lower volume.
Knocked up a little lunchbox sized head over the Christmas break, finally had chance to finish the circuit and assemble today.
Marshall JCM800 preamp with a host of tweaks - Full TMB tone control, gain trim (like an overdrive fine-adjustment dial), PPIMV, presence and resonance controls plus external bias points. Switches for bright (3-position), boost (lifts tonestack for a lot more drive) and fat.
Uses 3x 12AX7 preamp valves and a pair of JJ 6v6, fixed bias for 20w output.
Packs a massive punch for a small chassis.
I've also tried a new technique - etching a PCB for the build. I know it may annoy some purists, but it makes for a neater build and seems to work perfectly.
Anyway, on with the pics.