This book covers the operation and design of guitar-related electronics circuits. Starting with simple power supply circuits, the book then covers basic transistor amplifiers and op amps, then effects circuits including flangers, phasers, filters and so on. The last chapter covers tube amplifier design. Several practical design examples are presented, as well as complete tube amps of various power output. Details of how to add a spring reverb are also covered here. This is a pretty technical book, but still very interesting. It really helps to demystify the operation of some pretty complex circuits. The math behind all of thet circuits is presented, but you can skip it and just build the circuits to experiment with, or read the circuit descriptions to get a better feel for how effects and amps work.