Modern High-end Valve Amplifiers

Book excerpt: Explains the whys and wherefores of toroidal output transformers at various technical levels, starting with elementary concepts and culminating in complete mathematical descriptions. In all of this, the interactions of the output valves, transformer and loudspeaker form the central theme. Next come the practical aspects. The schematic diagram of a valve amplifier often appears to be very simple at first glance, but anyone who has built a modern valve amplifier knows that a lot of critical details are hidden behind the apparent simplicity. These are discussed extensively, in connection with designs for amplifiers without output powers ranging from 10 to 100 watts. Finally, the author gives some attention to a number of special valve amplifiers, and to the theory and practice of negative feedback.