Geez, can't believe it's been almost a whole year since I posted here. I haven't had much disposable income to spend on projects, but I do have a bunch of stuff I've done but not uploaded here.
These are the mods I've done to my Windsor as best I can recall, going from memory and a couple scratch pages. It's not complete yet, but I thought I'd share these.
The idea was to have a Matamp-style amp with the ability to footswitch into something not unlike a JCM800... or at least that level of gain. The whole 'boost' circuit needs more voicing and tweaking, but it works as is. There's too much different between the two amps, of course, so I stayed mostly towards the Matamp side. The 'boost' takes in and out a third gain stage DC coupled to a cathode follower (e.g. the second preamp tube.) I really like the way that cathode follower crunches, but I didn't want to lose the headroom in non-boost mode. It would be easier probably to make a Windsor go between JCM800 high and low gain (sort of) by simply using the relays to take the second gain stage in and out.
Where was I... Yeah, I just marked up the original Peavey schematic because it would take way too long to start from scratch. There are probably errors or inaccuracies in here too, so maybe don't blindly copy it. I used a bunch of shielded wire and also hacked up the amp's PCBs pretty extensively to do this. Probably a better idea to just use the second preamp tube for an effects loop, or just do a JCM800 clone instead.
Anyway, 3 pages of PDF:
PP Amps - Windsor Mods