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Valve and Transistor Audio Amplifiers Download PDF

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Valve and Transistor Audio Amplifiers
Valve and Transistor Audio Amplifiers

About Of the Book:

The book "Valve and Transistor Audio Amplifiers" by John Linsley Hood is a comprehensive guide to designing and building high-quality audio amplifiers using both valve (tube) and transistor technologies. The book covers the theory and practical aspects of audio amplifier design, including the choice of components, circuit topologies, power supplies, and construction techniques.

The book is divided into two sections: the first section covers valve amplifiers, while the second section covers transistor amplifiers. Each section includes detailed circuit diagrams and explanations, as well as examples of amplifier designs for different applications, such as guitar amplifiers and hi-fi amplifiers.

Overall, "Valve and Transistor Audio Amplifiers" is a comprehensive and authoritative guide to audio amplifier design, suitable for both beginners and experienced engineers. It provides a thorough grounding in the theory and practice of amplifier design, and is a valuable resource for anyone interested in building high-quality audio equipment.

The author, John Linsley Hood, is a well-respected audio engineer and writer with extensive experience in the design of audio equipment. In the book, he draws on his expertise to provide detailed explanations of amplifier design principles, as well as practical tips and advice for constructing high-quality amplifiers.

In the field of audio amplifiers, there has been a great interest in techniques for making small electrical voltages larger ever since mankind first attempted to transmit the human voice along lengthy telephone cables. This quest received an enormous boost with the introduction of radio broadcasts, and the resulting mass-production of domestic radio receivers intended to operate a loudspeaker output. However, the final result, in the ear of the listener, though continually improved over the passage of the years is still a relatively imperfect imitation of the real-life sounds which the engineer has attempted to copy. Although most of the shortcomings in this attempt at sonic imitation is not due to the electronic circuitry and the amplifiers which have been used, there are still some differences between them, and there is still some room for improvement. In this book, I have looked at the audio amplifier designs which have been developed over the past fifty years, in the hope that the information may be of interest to the user or would-be designer, and I have tried to explore both the residual problems in this 
field, and the ways by which these may be lessened. I believe, very strongly, that the only way by which improvements in these things can be obtained by making, analyzing, and recording for future use, the results of instrumental tests of as many relevant aspects of the amplifier's electrical performance as can be devised. One must not forget that the final result will be judged in the ear of the listener, so that, when all the purely instrumental tests have been completed, and the results judged to be satisfactory, the equipment should also be assessed for sound quality, and the opinions in this context of as many interested parties as possible should be canvassed. 
Listening trials are difficult to set up, and hard to purge of any inadvertent bias in the way equipment is chosen or the tests are carried out. Human beings are also notoriously prone to believe that their preconceived views will prove to be correct. 
The tests must therefore be carried out on a double-blind basis, when neither the listening panel nor the person selecting one or other of the items under test know what piece of hardware is being tested. 

Contents Of the Book:

Electronic amplifiers are built up from combinations of active and passive components. The active ones are those, like valves or transistors or integrated circuits, that draw electrical current from suitable voltage supply lines and then use it to generate or modify some electrical signal. The passive components are those, like capacitors, resistors, inductors, potentiometers or switches, which introduce no additional energy into the circuit, but which act upon the input or output voltages and currents of the active devices in order to control the way they operate. Of these, the active components are much more fun, so I will start with these...
 Inductors and Transformers All conductors have inductance, and the longer the conductor, the greater this will be. Although in the frequency range of interest in audio the amount of inadvertent inductance due to things like connecting leads are not likely to be significant, they may lead to occasional, unexpected, and generally unwanted, high frequency phenomena such as HF parasitic oscillation - which can spoil amplifier performance...
 The design of valve voltage amplifier stages is essentially a simple task by comparison with much solid-state linear circuit design, if only because there are not many circuit options open to the designer of valve circuits. Valves are also relatively linear in their input/output transfer characteristics, and therefore require less in the way of circuit design elaboration to improve the circuit performance and reduce any residual waveform distortion...
 In its simplest form, shown in Figure 4.1, an audio amplifier consists of an input voltage amplifier stage (A) whose gain can be varied to provide the desired output signal level, an impedance converter stage (ZC) to adjust the output impedance of the amplifier to suit the load, which could be a loudspeaker, a pair of headphones, or the cutting head in a vinyl disc manufacturing machine...
 The concept of feeding back into its input some part of the output signal from an amplifying block was invented, like so many other useful ideas in the field of electronics, by Major Edwin Armstrong, of the US Army Air Corps. His initial intention was to use positive (i.e. signal level enhancing) feedback (PFB) to make the electrical oscillators which were required as signal sources for radio broadcasts, but it was soon discovered that the feeding back of an antiphase signal - signal diminishing or negative feedback (NFB) - from the amplifier output into its input circuit also conveyed some valuable advantages. In particular, simple NFB can reduce the extent of any waveform distortion or noise introduced by the amplifier block, and can help to make the frequency response of the system more uniform...
 There was only a limited range of circuit options open to the audio amplifier designer before the widespread availability and adoption of solid-state semiconductor components, and for this reason the variety of commercially successful designs evolved for valve operated audio power amplifiers was also fairly limited. In this chapter I have mainly concerned myself with those circuits produced by UK manufacturers, or those designs offered both by the valve manufacturers' laboratories and by independent designers for home construction...
 The solid-state device technologies which are available to the amplifier designer fall, broadly, into three categories: bipolar junction transistors (BJTs), and junction diodes; junction field effect transistors (FETs); and insulated gate FETs- usually referred to as MOSFETs (metal oxide silicon FETs), because of their method of construction. These devices are available both in P type- operating from a negative supply Limesand N type- operating from a positive line. BJTs and MOSFETs are also available in small-signal and larger power versions, while FETs and MOSFETs are manufactured in both enhancement-mode and depletion-mode forms. Predictably, this allows the contemporary circuit designer very considerable scope for circuit innovation, by comparison with electronic engineers of the past, for whom there was only a very limited range of vacuum tube devices...

Information Of the Book:

Title: Valve and Transistor Audio Amplifiers
Size:  8 Mb
Pages: 262
Year: 2009
Format: PDF
Language: English
Author:  John Linsley Hood
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