Reporting question for Building Vacuum Tube Guitar & Bass Amplifiers, Volume 1

Product:
Building Vacuum Tube Guitar & Bass Amplifiers, Volume 1

Question:
Is this book just a step by step walkthrough how to assemble these amps or does it cover theory on how the different parts function?

Answer:
It has elements of both a step by step walkthrough as well as electronic theory to explain what is happening inside the circuit/amp.