A couple 12AX7 circuits for inspiration

[DC9V]

Hi,

Pazuzu's thread about what to do with a 12AX7 has reminded me of 2 schematics I have found online and have been storing in my computer in the hope that someday I would be able to make something out of them. This day hasn't come yet, and if I judge by my abysmal ignorance of electronics it isn't bound to happen anytime soon

These are just raw schematics so they didn't match Pazuzu's criteria (no layout available), therefore rather than threadjacking I figured I'd just start a new post. I'm not sure they will be of interest to anyone, but in the doubt I figured I'd post them anyway.

The first one is a schem of the Marshall VS 8240 amp that I found at DrTube.com, it looks pretty complete as far as I can tell, although I couldn't say if it's correct. It's an old 2x40W stereo transistor-powered amp of the early '90s with a 1 12AX7 preamp. So why exactly would it be interesting to a DIY effects builder? Well, first, for the preamp. It's got a nice clean sound, 2 decent and very Marshall-y distortion channels... oh, and the prettiest crunch channel I've ever heard coming from an amp, including all-tube ones! That's why I still have mine 17 years after I bought it and still use it sometimes. I guess someone with way more electronics know-how than me could possibly make a nice stompboxed crunch/dist out of it that would beat the Guv'nor hands down (the Guv is rumored to be a stompboxed version of the preamp of one of the lower power, tube-less amps in the same line).
This particular amp also includes an analog chorus that sounds pretty good. I haven't looked into it, and it might just be a clone of the CE-2 circuit for all I know, but hey, maybe not.

The second schem is for the Yerasov PD-5 Pterodriver. It's a hi-gain, 4 channel, 2 12AX7 preamp-in-a-(big) stompbox. When I first heard this thing I became obsessed with getting one, but since I had had big trouble in the past with the only distributor in Europe I thought that maybe I'd try to DIY one... until I realized it was way beyond my meager skills . I wouldn't be surprised if this was actually a clone of an existing design as Yerasov is known for that kind of thing. Once again I don't know if the schem is correct, but I suppose someone could find some inspiration in there.

I dunno if this will be useful to anyone, but you never know...