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Tuesday, August 13, 2013
Reading List: Vacuum Tube Amplifier Basics
- Jurich, E. J. Vacuum Tube Amplifier Basics. 2nd. ed. Seattle: Amazon Digital Services, 2013. ASIN B00C0BMTGU.
- If you can get past the sloppy copy-editing and production values, this book is a useful introduction for those interested in designing and building their own vacuum tube audio equipment. Millennials and others who have only ever listened to compressed audio will wonder why anybody would want to use such an antiquated technology, but those of us who appreciate it have a simple answer: it sounds better. The reason for this is simple once you poke through the mysticism surrounding the topic. It is in the nature of audio that peaks in the signal are much higher than the mean value. Solid-state amplifiers tend to be linear up until some signal level, but then “clip”—truncating the signal into a square top, introducing odd harmonics which the human ear finds distasteful. Tube amplifiers, on the other hand, tend to round off transients which exceed their capacity, introducing mostly second harmonic distortion which the ear and brain deem “mellow”. “Do you actually believe that?”, the silicon purity police shriek. Well, as a matter of fact, I do, and I currently use a 40 watt per channel tube amplifier I built from a kit more than a decade ago. It's a classic ultra-linear design using EL34 output tubes, and it sounds much better than the 200 watt per channel solid-state amplifier it replaced (after the silicon went up in smoke). This book will introduce you to vacuum tube circuitry, and those accustomed to solid-state designs may be amazed at how few components are needed to get the job done. Since every component in the signal path has the potential to degrade its fidelity, the simplicity of vacuum tube designs is one of the advantages that recommend them. A variety of worked-out vacuum tube designs are presented, either to be built by the hobbyist or as starting points for original designs, and detailed specifications are presented for tubes widely used in audio gear. The production quality is what we've sadly come to expect for inexpensive Kindle-only books. I noted more than 40 typographical errors (many involving the humble apostrophe), and in the tube data at the end, information which was clearly intended to be set in columns is just run together. This book is available only in electronic form for the Kindle as cited above, under the given ASIN. No ISBN has been assigned to it.
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