In this book, I made an extensive use of figures and proposed several practical examples, to design various parts of the circuits and to compute values of the needed components. I believe that this can significantly contribute to simplify some possible difficult concepts addressed.

The book first introduces some basic notions needed to design and understand vacuum tube amplifiers. Then, it considers all relevant aspects for designing an integrated vacuum tube amplifier, including its power supply unit. Finally, a real and concrete integrated push-pull vacuum tube amplifier is designed from scratch, using the various arguments discussed.

Specifically, Chapter 2: “Vacuum tube basics” introduces the needed concepts to understand vacuum tubes. This is a very basic introduction needed for the non-initiated. If you already know what vacuum tubes are and how they operate, you can skip this chapter.

Chapter 3: “Vacuum tubes as amplifiers” discusses how vacuum tubes can be used to obtain an amplifier. It introduces the notions of operating conditions, loadline, biasing techniques, and amplifier classes.

Chapter 4: “Integrated push-pull vacuum tube amplifier” is the core of this book. It goes into the details of designing an integrated push-pull vacuum tube amplifier. It discusses the single-ended and push-pull configurations, the various needed stages (power, phase-split, and input stages), and global negative feedback.

Chapter 5: “Power supply unit” discusses how to design the power supply unit for a vacuum tube amplifier. It introduces rectifier configurations and filters to reduce voltage ripple, to have a quiet amplifier. It explains how to estimate expected output DC voltage, ripple, and current delivered. It also discusses how to design power supply for the fixed bias circuit and for the filaments of the vacuum tubes.

Finally, Chapter 6: “Step by step design of a push-pull tube amplifier” uses all needed notions to design an entire integrated push-pull vacuum tube amplifier. It discusses the design of the power stage, the phase-split, and the input stage. It discusses the design of the global negative feedback loop. It also provides the design of the corresponding power supply unit.

### 1.2.1 Some difficult sections

I tried to use a simple language and to use equations and formulas just when needed. However, for completeness, I added some sections dealing with some advanced notions, which use non-trivial formulas and concepts. You can initially skip these parts, if you feel they are too complex. These difficult sections are:

- Section 3.4- “Gain of the voltage amplifier”, where you learn how to estimate the gain of an amplifier.
- Section 3.6.3- “Gain of the voltage amplifier with self-bias” where you find a discussion on how to estimate gain of an amplifier under local negative feedback introduced by self-biasing.
- Section 4.2.3- “Gain of the concertina phase splitter” where gain of the concertina phase splitter is analysed.
- Sections 4.4.1-“Gain with negative feedback”, 4.4.2-“Benefits of negative feedback”, and 4.4.3-“Stability of negative feedback”, where you find an analysis of the global feedback circuit, considering the resulting gain of the amplifier, the introduced benefits, and stability issues.