Rudolf Moers' 834 pages on tube amplifiers

Elektor has published a massive 800 page book on tube amplifiers for all tube lovers and the growing circle of retro-audio-aficionados.

It's been written by Rudolf Moers and meant as a reference book that "covers just about everything you need to know about the fundamentals of electron tubes and the way these wonderful devices were designed to function at their best in their best known application: the (now vintage) tube audio amplifier."

The contents is devided into ten chapters. After the introduction, the principles of electron emission are explained in chapter 2. Chapters 3, 4, 5 and 6 consider the diode, triode, tetrode and pentode respectively, each with a different framework. Both ends of audio frequency band are dealt with in chapter 7. Distortion and noise is the topic of the chapter 8, and chapter 9 discusses negative feedback. 

Here's what the publisher says about the chosen approach: "The aim of the book is to give the reader useful knowledge about electron tube technology in the application of audio amplifiers, including their power supplies, for the design and DIY construction of these electron tube amplifiers. This is much more than just building an electron tube amplifier from a schematic made from the design from someone else: not only academic theory for scientific evidence, but also a theoretical explanation of how the practice works. No modern simulations, but because you first understand the circuit calculations, then you can work with your hands to build the circuit and last, but not least, if you have a multimeter, a signal generator and an oscilloscope, you can measure the circuit parameters yourself to see that theory and practice are very close."

The book is a massive undertaking with plenty of theoretical and less theoretical information on numerous subjects related to understanding and designing tube amplifiers. It's was clear from the beginning that the book is so rich and tense that I cannot but give a few general comments on it.    

The book is intended, as explained in the preface, to be a text book for self-builders having reasonable skills in analogue electronics. This poses the basic difficulty: what is "reasonable"? Moers' book is definitely not a book for newbies in the field of building tube amplifiers- Rather, it seems to me that it is directed for students or fresh graduates in electrical engineering. For professionals, BSc’s or MSc’s the text and formulaes are reasonably easy to follow but much less so outside that circle.

Secondly, and despite the publisher's claim that "much of the theory is checked against practice, and design methods give the reader help to start with the design and construction of electron tubes amplifiers", I'd say the book cannot be considered as a handbook. My recommendation to the readers of this book is to proceed logically and accurately from the beginning to the end. But by doing so, the reader may face internal resistance to go through all the mathematical formulaes along the way. I noticed this with myself but soon found out that there's no point in jumping over the uninteresting parts or chapters: the key is lost. So I recommend that Moers' book is treated and studied as a text book and proceeded step by step. Actually it might not be a bad idea to build a lecture course around this book, e.g. in some technical school. For a teacher the book would offer much assistance in this respect.

For a constructer with some skills and experience (as is my case) I noticed a further difficulty: it is not easy to find the minimum sufficient essentials quickly fom the text or chapters. The old world of tube design is full of valuable and practical thumb rules with which you can proceed quickly to the practical testing phase. I could not find such elements in this book, and I guess on purpose so. In this respect, for example the old Radio Designers Handbook, a classic in its area, is far easier to use and to search for essentials and quick keys. 

All in all Moers' carefully written book is a valuable and accurate attempt to open up the fascinating world of tube circuits, and I must give a big handshake to Mr. Moers and his colleques for a huge work they've done to make the book to come alive.

Mr. Mauri Pännäri has MSc in electrical engineering. He has a working history of 39 years in telephony at the research and development department of Teliasonera Finland. He has designed and constructed several top end tube amplifiers, and published related articles in the Finnish and international Hi-fi Magazines. 

Fundamental Amplifier Techniques with Electron Tubes (ISBN: 978-0-905705-93-4) is available from the Webshop at Elektor.com. Hard Cover, 834 pages. Price £ 65.00.