I used the sun as a UV source for the photoresist exposure, boiled iron chloride in my mom's Pyrex containers, stained bunch of her towels permanently yellow in the process. And the circuit didn't work. It is still a sore point from my youth that I remember occasionally.
Also, Small Signal Audio Design by Douglas Self is really good, but probably not as a first EE textbook, and you have to really want to go into the weeds, as an electrical engineer would. But there is an entire chapter (chapter 12) on just electric guitars (pickup, preamps, effects, direct injection, etc.)
Microphones, amplifiers, filters speaker crossovers and so on - all explained failry nicely. The site has two main areas, projects and articles.