Recording Studio Design To Paul and Mum. Janet Recording Studio Design Philip Newell Focal Press An imprint of Elsevier Linacre House, Jordan Hill, Oxford OX2 8DP 200 Wheeler Road, Burlington MA 01803 First published 2003 Copyright © 2003, Philip Newell. All rights reserved The right of Philip Newell to be identified as the author of this work has been asserted in accordance with the Copyright, Designs and Patents Act 1988 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 W1T 4LP. Applications for the copyright holder’s written permission to reproduce any part of this publication should be addressed to the publisher Permissions may be sought directly from Elsevier’s Science and Technology Rights Department in Oxford, UK. Phone: (+44) (0) 1865 843830; fax: (+44) (0) 1865 853333; e-mail: [email protected]. You may also complete your request on-line via the Elsevier homepage (www.elsevier.com), by selecting ‘Customer Support’ and then ‘Obtaining Permissions’ British Library Cataloguing in Publication Data Newell, Philip Richard Recording studio design 1. Sound studios – Design 2. Acoustical engineering I. Title 621.3′823 Library of Congress Cataloging in Publication Data Newell, Philip Richard Recording studio design / Philip Newell. p. cm. Includes bibliographical references and index. ISBN 0 240 51917 5 (alk. paper) 1. Sound studios – Design and construction. I. Title. TH1725.N5 2003 621.389′3–dc21 2003048755 ISBN 0 240 51917 5 For information on all Focal Press publications visit our website at www.focalpress.com Typeset by Integra Software Services Pvt. Ltd, Pondicherry, India www.integra-india.com Printed and bound in Great Britain Contents About the author xv Acknowledgements xix Preface xxi Introduction xxiii Chapter 1 General requirements and common errors 1 1.1 The general requirements 1 1.2 Sound isolation and background noise levels 1 1.2.1 From the inside out 2 1.2.2 From the outside in 3 1.2.3 Realistic goals 3 1.2.4 Isolation versus artistry 4 1.3 Confidence in the system 4 1.4 The complete system 5 1.5 Very common mistakes 5 1.5.1 The need for space 6 1.5.2 Height 8 1.5.3 Floor loading 8 1.6 Summary 9 Chapter 2 Sound, decibels and hearing 12 2.1 Perception of sound 12 2.2 Sound itself 14 2.3 The decibel; sound power, sound pressure and sound intensity 18 2.3.1 The dBA and dBC scales 20 2.4 Human hearing 22 2.4.1 Chacun A Son Oreille 23 2.5 Summary 28 References 29 Bibliography 30 Chapter 3 Sound isolation 31 3.1 Vibrational behaviour 31 3.1.1 Relevance to isolation 33 3.2 Basic isolation concepts 33 3.2.1 Damping and the mass law 34 3.2.2 Floating structures 34 3.2.3 Floating system choices 37 3.3 Practical floors 40 3.3.1 Floors on weak sub-floors 45 vi Contents 3.4 Ceiling isolation 47 3.4.1 A trip through the ceiling 48 3.5 Summing the results 53 3.5.1 Internal reflexions 54 3.6 Wall isolation 54 3.7 Lighter weight isolation systems 56 3.8 Reciprocity and impact noises 56 3.9 The distance option 58 3.10 Discussion 60 3.11 Summary 61 Reference 62 Bibliography 62 Chapter 4 Room acoustics and means of control 63 4.1 Internal expansion 64 4.2 Modes 72 4.3 Flutter echoes and transient phenomena 82 4.4 Reverberation 82 4.4.1 Measuring reverberation time 84 4.5 Absorption 86 4.5.1 Speed of sound in gases 88 4.5.2 Other properties of fibrous materials 91 4.5.3 Absorption coefficients 91 4.5.4 Porous absorption 92 4.5.5 Resonant absorbers 93 4.5.6 Membrane absorbers 96 4.6 Q and damping 97 4.7 Diffusion 98 4.8 Diffraction 101 4.9 Refraction 103 4.10 Review 103 4.11 Summary 104 References 106 Bibliography 106 Chapter 5 Designing neutral rooms 107 5.1 Background 107 5.2 Large neutral rooms 109 5.3 Practical realisation of a neutral room 110 5.3.1 Floors 110 5.3.2 Shapes, sizes and modes 111 5.3.3 From isolation shell towards neutrality 113 5.3.4 Lower frequency control 113 5.3.5 Relative merits of neutrality and idiosyncrasy 118 5.4 What is parallel? 121 5.5 Reflexions, reverberation and diffusion 124 5.6 Floor and ceiling considerations 127 5.7 Wall treatments 130 5.8 Small and neutral 133 5.8.1 Practical constructions 135 Contents vii 5.8.2 The journey of the sound waves 137 5.8.3 The pressure zone 139 5.8.4 Wall losses 140 5.8.5 Transfer of sound between high and low densities 141 5.8.6 Combined effects of losses 143 5.8.7 A micro-problem 146 5.9 Trims 146 5.10 The degree of neutrality – an overview 147 5.11 Summary 148 References 150 Bibliography 150 Chapter 6 Rooms with characteristic acoustics 151 6.1 Definitions 151 6.2 A brief history of idiosyncrasy 151 6.2.1 From a room to a classic 152 6.2.2 Limited, or priceless? 153 6.3 Drawbacks of the containment shells 156 6.4 Design considerations 157 6.4.1 Room character differences 158 6.5 Driving and collecting the rooms 159 6.6 Evolution of stone rooms 162 6.6.1 Construction options 164 6.7 Live versus electronic reverberation 166 6.8 The 20% rule 168 6.9 Reverberant rooms and bright rooms – reflexion and diffusion 168 6.9.1 Bright rooms 172 6.10 Low frequency considerations in live rooms 175 6.11 General comments on live rooms 178 6.12 Orchestral rooms 178 6.12.1 Choice of venues, and musicians’ needs 179 6.13 RT considerations 181 6.14 Fixed studio environments 182 6.15 Psychoacoustic considerations and spacial awareness 185 6.16 Dead rooms 189 6.17 Summary 190 References 191 Bibliography 191 Chapter 7 Variable acoustics 192 7.1 The geometry of change 192 7.2 Small room considerations 200 7.3 Summary 202 Chapter 8 Room combinations and operational considerations 204 8.1 Options and influences 204 8.1.1 Demands from control rooms 207 8.2 Layout of rooms 208 8.2.1 Priorities and practice 209 viii Contents 8.3 Isolation considerations: doors and windows 211 8.3.1 Sliding doors 211 8.3.2 Window systems 213 8.3.3 Multiple glazing considerations 215 8.3.4 High degrees of isolation 216 8.4 The Geddes approach 217 8.5 Recording techniques for limited acoustics 220 8.5.1 Moving musicians and changing microphones 221 8.6 A compact studio 222 8.7 Review 224 8.8 Summary 224 References 226 Chapter 9 The studio environment 227 9.1 Some human needs 227 9.1.1 Daylight 227 9.1.2 Artificial light 227 9.1.3 Ease and comfort 229 9.2 Ventilation and air-conditioning 229 9.2.1 Ventilation 230 9.2.2 Air-conditioning systems and general mechanical noises 232 9.3 Headphone foldback 234 9.3.1 Loudspeaker foldback 237 9.4 Colours, and general decoration 237 9.5 AC mains supplies 239 9.5.1 Phase 240 9.5.2 Power cabling 241 9.5.3 Balanced power 242 9.5.4 Mains feeds 242 9.5.5 Earthing 243 9.6 Summary 243 References 244 Chapter 10 Limitations to design predictions 245 10.1 Room responses 245 10.1.1 The envelope of the impulse response, and reverberation time 249 10.1.2 Schroeder plots 251 10.1.3 Energy/time curves 252 10.1.4 Waterfall plots 253 10.1.5 Directional effects 253 10.2 Scale models 254 10.3 Computer models 255 10.4 Sound pulse modelling 257 10.5 Light ray modelling 257 10.6 Ripple tank modelling 258 10.7 Review 258 10.8 Summary 259 References 259 Contents ix Chapter 11 Loudspeakers in rooms 260 11.1 From the studio to the control room 260 11.2 Room influences 260 11.2.1 Radiation patterns 261 11.2.2 Loading by boundaries 266 11.2.3 Dipole considerations 271 11.2.4 Diffraction sources 276 11.3 Room reverberation and the critical distance 278 11.4 Sound power radiation 280 11.5 Corrective measures 283 11.5.1 Minimum and non-minimum phase 285 11.5.2 Digital correction techniques 288 11.5.3 Related problems in loudspeaker 289 11.5.4 Summary of correct applications of equalisation 289 11.6 Phase and time 291 11.7 The black art 293 11.8 Summary 293 Bibliography 294 Chapter 12 Flattening the room response 295 12.1 Electronic correction concerns 296 12.2 The standard room 300 12.3 The anechoic chamber 303 12.4 The hybrid room 303 12.5 A BBC solution 305 12.6 On listening rooms in general 307 12.7 Close-field monitoring 309 12.8 Summary 311 References 313 Chapter 13 Control rooms 314 13.1 The advent of specialised control rooms 315 13.1.1 Geometrically controlled rooms 315 13.1.2 Directional dual acoustics 317 13.1.3 The LEDE 318 13.1.4 The Non-Environment 320 13.1.5 Toyoshima rooms 320 13.2 Built-in monitors 324 13.3 Directional acoustics 326 13.4 Scaling problems 326 13.5 The pressure zone 327 13.6 One system 330 13.7 Aspects of small control room designs 331 13.7.1 Conflicting requirements 335 13.7.2 Active absorbers 336 13.8 A short overview 336 13.9 Summary 337 References 337 Bibliography 338 x Contents Chapter 14 The behaviour of multiple loudspeakers in rooms 339 14.1 Mono sources 339 14.2 Stereo sources 341 14.3 Steady-state performance 344 14.4 Transient considerations 345 14.5 The pan-pot dilemma 349 14.6 Limitations, exceptions and multi-channel considerations 350 14.7 Surround in practice 351 14.8 A general view 359 14.9 Summary 359 References 360 Bibliography 360 Chapter 15 Studio monitoring: the principal objectives 361 15.1 The forces at work 361 15.2 Where is the reference? 363 15.3 Different needs 366 15.4 What is right? 367 15.5 Close field monitoring 370 15.6 Why the NS10M? 371 15.7 General needs 372 15.8 Summary 373 References 373