Amps for dummies who failed high school physics

[HarlowTheFish]

Hey amp wizards, I have a couple of questions:
I was on a late night mid-80s Maiden kick recently and managed to dig up the manual (with schematic) for the old Gallien-Krueger 250RL they were using at the time, and I'm interested in DIYing a slightly-modded one for myself. There's a catch though . . .

I'm a fucking moron and this is how I felt when I saw it:


I'm not asking for a complete breakdown on this circuit and amp building and stuff, but if y'all could point me to some resources to start with it would be much appreciated. I don't wanna just clone the thing, which would probably not be too bad, I wanna mod it up to get a bit more practical use out of it for my sound and style of playing, so I'm more specifically looking for stuff that will give me a good idea of how the logic of reading schematics, modding existing circuits, and eventually designing and building my own (mostly) from scratch.

Thanks in advance y'all

[MattK]

I strongly recommend you don't learn on an expensive, mains powered amp. You won't have any idea how to troubleshoot mistakes, which will either (a) fuck your amp, or (b) kill you with miswired mains power - or (c) both, but (b) tends to override (a). The odds of getting it right without experience are low.
Try building a pedal or two, or modding a pedal if you are not worried about wrecking it, and get a feel for the skills and the processes. If you can't solder a resistor without burning it or lifting a trace off the board, that's good to know when you are only risking the $30 you spent on a kit, rather than your life.
You could build a clean boost pedal which would have circuit elements in common with the preamps in a bass head - then you can mess with it and see what happens.

[sookwinder]

Looking back at my development as an amp builder/designer, I would think the best way to start down that process is to build a very simple amp from a kit. Maybe a tweed champ. The kits are very cheap (relatively speaking) and trouble shooting is easy because of their simplicity.
Plus you have plenty of members here who can assist with advice.

[wproffitt]

I haven’t seen the schematic, but I did find pictures of the 250RL. Based on the way the control layout looks alone, I’d say this would be a complicated place to start. I’m guessing these solid state amps also were designed from the ground up with PCB construction in mind. Most people don’t build tribute versions of these in their garages for a reason: there probably aren’t ready to hand circuit boards for these sitting around for you to buy.

Perhaps someone will come along who knows more about these than I do, but my suspicion is that David’s advice about a kit is really good one if you’ve been bitten by the amp building bug and want a fun place to start. I hadn’t had a physics class for 20 years when I built my amp a few years back. I read up on the basics of tube amps. The Guitar Amp Handbook by Dave Hunter is good for those of us with less science in our background. If you really want to dive in, there’s this website, which has a lot of really amazing knowledge: http://www.valvewizard.co.uk/
I hope you land on a fun project!

[sholkham]

I found this video and its subsequent part to be a really good intro to how a valve amp works. I don't know if I would build one, but I'm able to kind of work out whats happening in a schematic now.

https://www.youtube.com/watch?v=x5SSKX74DKg