sinclair, i. r. (1998). audio and hi-fi handbook (3rd ed.)

Audio and Hi-Fi Handbook prelims.ian 4/8/98 11:12 AM Page i prelims.ian 4/8/98 11:12 AM Page ii Audio and Hi-Fi Handbook Third Edition Editor IAN R. SINCLAIR OXFORD BOSTON JOHANNESBURG MELBOURNE NEW DELHI SINGAPORE Newnes prelims.ian 4/8/98 11:12 AM Page iii Newnes An imprint of Butterworth-Heinemann Linacre House, Jordan Hill, Oxford OX2 8DP 225 Wildwood Avenue, Woburn, MA 01801–2041 A division of Reed Educational and Professional Publishing Ltd A member of the Reed Elsevier plc group First published as Audio Electronics Reference Book by BSP Professional Books 1989 Second edition published by Butterworth-Heinemann 1993 Paperback edition 1995 Third edition 1998 © Reed Educational and Professional Publishing 1998 All rights reserved. No part of this publication may be reproduced in any material form (including photocopying or storing in any medium by electronic means and whether or not transiently or incidentally to some other use of this publication) without the written permission of the copyright holder except in accordance with the provisions of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London, England W1P 9HE. Applications for the copyright holder’s written permission to reproduce any part of this publication should be addressed to the publishers British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library. ISBN 0 7506 3636 X Library of Congress Cataloguing in Publication Data A catalogue record for this book is available from the Library of Congress. Typeset by Jayvee, Trivandrum, India Printed and bound in Great Britain by Clays Ltd, St Ives plc prelims.ian 4/8/98 11:12 AM Page iv This book is dedicated to the memory of Fritz Langford-Smith, Mentor and Friend prelims.ian 4/8/98 11:12 AM Page v prelims.ian 4/8/98 11:12 AM Page vi Preface xi Chapter 1 Sound Waves 1 Dr W. Tempest Pure tones and complex waveforms 1 Random noise 2 Decibels 2 Sound in rooms 3 Reverberation 4 Reverberation, intelligibility and music 4 Studio and listening room acoustics 4 The ear and hearing 5 Perception of intensity and frequency 6 Pitch perception 7 Discrimination and masking 7 Binaural hearing 8 The Haas effect 8 Distortion 9 Electronic noise absorbers 12 References 12 Chapter 2 Microphones 14 John Borwick Introduction 14 Microphone characteristics 14 Microphone types 16 The microphone as a voltage generator 18 Microphones for stereo 24 Surround sound 27 References 27 Chapter 3 Studio and Control Room Acoustics 28 Peter Mapp Introduction 28 Noise control 28 Studio and control room acoustics 33 Chapter 4 Principles of Digital Audio 41 Allen Mornington-West Introduction 41 Analogue and digital 41 Elementary logic processes 43 The significance of bits and bobs 44 Transmitting digital signals 46 The analogue audio waveform 47 Arithmetic 51 Digital filtering 54 Other binary operations 58 Sampling and quantising 58 Transform and masking coders 65 Bibliography 65 Chapter 5 Compact Disc Technology 67 Ken Clements Introduction 67 The compact disc . . . some basic facts 67 The compact disc . . . what information it contains 68 Quantisation errors 69 Aliasing noise 69 Error correction 71 How are the errors corrected? 71 Interleaving 72 Control word 73 Eight to fourteen modulation 74 Compact disc construction 74 The eight to fourteen modulation process 77 Coupling bits 77 Pit lengths 77 Sync. word 78 Optical assembly 80 Servo circuits 84 The decoder 86 Digital filtering and digital to analogue conversion 87 Bibliography 92 Contents prelims.ian 4/8/98 11:12 AM Page vii Chapter 6 Digital Audio Recording 93 John Watkinson Types of media 93 Recording media compared 96 Some digital audio processes outlined 97 Hard disk recorders 104 The PCM adaptor 105 An open reel digital recorder 106 Rotary head digital recorders 107 Digital compact cassette 110 Editing digital audio tape 110 Bibliography 111 Chapter 7 Tape Recording 112 John Linsley Hood The basic system 112 The magnetic tape 112 The recording process 113 Sources of non-uniformity in frequency response 114 Record/replay equalisation 116 Head design 117 Recording track dimensions 120 HF bias 120 The tape transport mechanism 123 Transient performance 123 Tape noise 124 Electronic circuit design 125 Replay equalisation 127 The bias oscillator 129 The record amplifier 130 Recording level indication 131 Tape drive control 131 Professional tape recording equipment 131 General description 132 Multi-track machines 133 Digital recording systems 134 Recommended further reading 138 Chapter 8 Noise Reduction Systems 139 David Fisher Introduction 139 Non-complementary systems 140 Complementary systems 142 Emphasis 142 Companding systems 143 The Dolby A system 147 Telecom C4 148 dbx 148 Dolby B 149 Dolby C 150 Dolby SR 152 Dolby S 155 Bibliography 156 Chapter 9 The Vinyl Disc 157 Alvin Gold and Don Aldous Introduction 157 Background 157 Summary of major steps and processes 157 The lathe 158 Cutting the acetate 158 In pursuit of quality 160 The influence of digital processing 161 Disc cutting – problems and solutions 161 Disc pressing 162 Disc reproduction 163 Drive systems 163 Pick-up arms and cartridges 165 The cartridge/arm combination 165 Styli 167 Specifications 168 Measurement methods 169 Maintaining old recordings 169 References 170 Chapter 10 Valve Amplifiers 171 Morgan Jones Who uses valves and why? 171 Subjectivism and objectivism 172 Fixed pattern noise 172 What is a valve? 172 Valve models and AC parameters 174 Practical circuit examples 176 Other circuits and sources of information 183 Chapter 11 Tuners and Radio Receivers 186 John Linsley Hood Background 186 Basic requirements for radio reception 186 The influence of the ionosphere 187 Why VHF transmissions? 188 AM or FM? 189 FM broadcast standards 190 Stereo encoding and decoding 190 The Zenith-GE ‘pilot tone’ stereophonic system 190 The BBC pulse code modulation (PCM) programme distribution system 192 Supplementary broadcast signals 195 Alternative transmission methods 195 viii Contents prelims.ian 4/8/98 11:12 AM Page viii Radio receiver design 196 Circuit design 212 New developments 213 Appendix 11.1 BBC transmitted MF and VHF signal parameters 214 Appendix 11.2 The 57 KHz sub-carrier radio data system (RDS) 214 Chapter 12 Pre-amps and Inputs 215 John Linsley Hood Requirements 215 Signal voltage and impedance levels 215 Gramophone pick-up inputs 216 Input circuitry 217 Moving coil PU head amplifier design 219 Circuit arrangements 219 Input connections 223 Input switching 223 Chapter 13 Voltage Amplifiers and Controls 226 John Linsley Hood Preamplifier stages 226 Linearity 226 Noise levels 230 Output voltage characteristics 230 Voltage amplifier design techniques 231 Constant-current sources and ‘current mirrors’ 232 Performance standards 235 Audibility of distortion components 237 General design considerations 239 Controls 240 Chapter 14 Power Output Stages 252 John Linsley Hood Valve-operated amplifier designs 252 Early transistor power amplifier designs 253 Listener fatigue and crossover distortion 253 Improved transistor output stage design 255 Power MOSFET output devices 255 Output transistor protection 258 Power output and power dissipation 259 General power amplifier design considerations 261 Slew-rate limiting and transient intermodulation distortion 262 Advanced amplifier designs 263 Alternative design approaches 269 Contemporary amplifier design practice 272 Sound quality and specifications 274 Chapter 15 Loudspeakers 276 Stan Kelly Radiation of sound 276 Characteristic impedance 277 Radiation impedance 277 Radiation from a piston 277 Directivity 277 Sound pressure produced at distance r 277 Electrical analogue 279 Diaphragm/suspension assembly 280 Diaphragm size 280 Diaphragm profile 281 Straight-sided cones 282 Material 283 Soft domes 284 Suspensions 284 Voice coil 285 Moving coil loudspeaker 285 Motional impedance 286 References 289 Chapter 16 Loudspeaker Enclosures 290 Stan Kelly Fundamentals 290 Infinite baffle 290 Reflex cabinets 292 Labyrinth enclosures 295 Professional systems 296 Networks 296 Components 298 Ribbon loudspeaker 298 Wide range ribbon systems 299 Pressure drive units 300 Electrostatic loudspeakers (ESL) 303 Chapter 17 Headphones 310 Dave Berriman A brief history 310 Pros and cons of headphone listening 310 Headphone types 311 Basic headphone types 314 Measuring headphones 316 The future 317 Chapter 18 Public Address and Sound Reinforcement 319 Peter Mapp Introduction 319 Signal distribution 319 Contents ix prelims.ian 4/8/98 11:12 AM Page ix Loudspeakers for public address and sound reinforcement 322 Cone driver units/cabinet loudspeakers 322 Loudspeaker systems and coverage 325 Speech intelligibility 328 Signal (time) delay systems 330 Equalisers and sound system equalisation 332 Compressor-limiters and other signal processing equipment 333 Amplifiers and mixers 334 Cinema systems and miscellaneous applications 335 References and bibliography 336 Chapter 19 In-Car Audio 337 Dave Berriman Modern car audio 337 FM car reception 337 Power amplifiers 338 Separate power amps 339 Multi-speaker replay 340 Ambisonics 340 Cassette players 341 Compact disc 343 Digital audio tape 344 Loudspeakers 345 Installation 352 The future for in-car audio 360 Chapter 20 Sound Synthesis 362 Mark Jenkins Electronic sound sources 362 Synthesizers, simple and complex 362 Radiophonics and sound workshops 363 Problems of working with totally artificial waveforms 366 Computers and synthesizers (MIDI and MSX) 368 Mode messages 373 Real time 376 References 377 Chapter 21 Interconnections 378 Allen Mornington-West Target and scope of the chapter 378 Basic physical background 378 Resistance and electrical effects of current 381 Capacitive effects 383 Magnetic effects 384 Characteristic impedance 387 Reactive components 388 Interconnection techniques 390 Connectors 397 Chapter 22 NICAM Stereo and Satellite Radio Systems 404 Geoff Lewis The signal structure of the NICAM-728 system 404 The NICAM-728 receiver 406 The DQPSK decoder 407 Satellite-delivered digital radio (ASTRA digital radio ADR) 407 Coded orthogonal frequency division multiplex (COFDM) 411 The JPL digital system 413 Reality of digital sound broadcasting 414 Chapter 23 Modern Audio and Hi-Fi Servicing 415 Nick Beer Mechanism trends 415 Circuit trends 417 Tuners 418 Power supplies 418 System control 419 Microprocessors 419 Amplifiers 419 Discrete output stage failures 422 Digital signal processing 423 Mini-disc 423 Test modes 424 Surface mounted and VLSI devices 424 Obsolete formats 425 Software problems 425 Good servicing practice 426 Test equipment 426 Conclusion 426 Index 427 x Contents prelims.ian 4/8/98 11:12 AM Page x [...]... frequency response Olsen and May’s work appears to have been confined to the laboratory, but more recent research has now begun to produce worthwhile applications A noise reduction system for air-crew helmets has been pro- Langford-Smith, F., Radio Designer’s Handbook, (Chapter 14 Fidelity and Distortion) Illiffe (1954) Parkin, P.H and Humphries, H .R., Acoustics, Noise and Buildings Faber and Faber, London... instead of the traditional microphone cable and are being employed more and more for stage and televisions shows, and other applications where complete freedom of movement is demanded The radio microphone itself is usually very small and attached to or concealed in the clothing Larger handheld versions are also available having the transmitter built into the handgrip to which a short aerial is attached... calculator and connected to the microphone by about a metre of cable which may also act as the aerial The microphone audio signal is frequency modulated on to the radio carrier Frequency band allocations and licensing regulations vary from country to country, with both the VHF and UHF bands used and elaborate design measures taken to overcome the practical problems of maintaining consistent signal levels and. .. antiphase forces and the output falls to zero thus producing the cardioid pattern Figure 2.9 Dual-diaphragm cardioid condenser microphone, showing (a) the holes and cavities in the central fixed plate, and how the pressure and PG forces combine for sounds arriving at (b) 0°; (c) 90°; and (d) 180° In later versions both diaphragms are electrically connected and, with suitable switching of polarity and relative... hole in the casing equalises the long-term external and internal pressures, whilst audio frequency swings above and below normal atmospheric pressure due to the incident sound waves will cause the diaphragm to move outwards and inwards The force on the diaphragm is equal to the product of sound pressure (per unit area) and the area of the diaphragm, and is essentially independent of frequency Other criteria... noise from electrical wiring and radio frequency interference This is specially important in the vicinity of TV monitors, cameras, lighting regulators or transmitters For outdoor work, or close vocals, the microphone should be proof against wind noise Handheld microphones and microphones mounted on television booms also need to be rugged and able to withstand mechanical shocks and vibrations Microphone... including those shown earlier in Figs 2.2 and 2.3 ation (which tends to move both diaphragms inwards and outwards on alternate half-cycles) and PG operation (in which only the front diaphragm moves whilst the rear diaphragm remains stationary due to equal and opposite pressure and PG forces) At 90° the PG forces on both diaphragms fall to zero, reducing the output to half, and at 180° the front diaphragm experiences... a bigger stimulus, and therefore the first stimulus becomes inaudible Binaural Hearing The ability of humans (and animals) to localise sources of sound is of considerable importance Man’s hearing evolved long before speech and music, and would be of value both in locating prey and avoiding predators The term ‘localisation’ refers to judgements of the direction of a sound source, and, in some cases its... ribbon acts both as diaphragm and conductor and is typically made of aluminium foil about 0.1 mm thick and 2–4 mm wide It is mildly corrugated to prevent curling and allow accurate tensioning to set the resonance to the required low frequency of around 2–4 Hz DC resistance of the ribbon is very low and so a built-in step-up transformer is essential to provide an output at a standard matching impedance... with sum and difference frequencies These sum and difference frequencies include f1 f2 and f1 —f2 (where f1 and f2 are the two fundamentals), second order terms 2 f1 + f2, 2f1 —f2, f1 + 2f2, f1 —2f2 and higher order beats Thus the intermodulation products may include a large number of tones None of these is harmonically related to the original components in the signal, except by accident, and therefore . Audio and Hi-Fi Handbook prelims.ian 4/8/98 11:12 AM Page i prelims.ian 4/8/98 11:12 AM Page ii Audio and Hi-Fi Handbook Third Edition Editor IAN R. SINCLAIR OXFORD BOSTON JOHANNESBURG MELBOURNE. 93 Recording media compared 96 Some digital audio processes outlined 97 Hard disk recorders 104 The PCM adaptor 105 An open reel digital recorder 106 Rotary head digital recorders 107 Digital. powers of discrimination, the ability to extract wanted information from unwanted background noise and signals. However, there are limits to these discriminatory powers, particularly with respect to