Handbook of Recording Engineering

492 Pages·1992·10.833 MB·English

by  John Eargle (auth.)

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Copyright © 1992 by Springer Science+Business Media New York
Originally published by Van Nostrand Reinhold 1992.
Softcover reprint of the hardcover 2nd edition 1992
Library of Congress Catalog Card Number 91-11474
ISBN 978-1-4757-1131-8 ISBN 978-1-4757-1129-5 (eBook)
DOl 10.1007/978-1-4757-1129-5
All rights reserved. No part of this work covered by the copyright hereon
may be reproduced or used in any form by any means-graphic, electronic, or
mechanical, including photocopying, recording, taping, or information storage
and retrieval systems-without written permission of the publisher.
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Library of Congress Cataloging-in-Publication Data
Eargle, John.
Handbook of recording engineering/by John M. Eargle-2nd ed.
p. cm.
Includes bibliographical references and index.
1. Sound-Recording and reproducing. 1. Title.
TK7881.4.E16 1991
621. 389'3--dc20 91-11474
CIP
PREFACE
The second edition of the Handbook of Recording Engineering has been completely
rewritten and includes all recent developments in recording technology. In the last five
years, the number of degree programs and course offerings in recording arts and sciences
has increased significantly. The author has had extensive discussions with teachers in the
field, and many of their suggestions have been incorporated in the new edition in order
to make it a more effective textbook. There are more (and shorter) chapters grouped
under major topic areas. The intent is to provide the student with rapid access to specific
topics and enable the instructor to better organize the material for the length of the
course. For the professional recording engineer the book retains its organization as a true
handbook, offering ready solutions to everyday problems.
The new book is divided into ten major areas.
Section 1: Acoustical Foundations in Recording. The recording engineer must have
a thorough understanding of physical and psychological acoustics and how these come
together in the recording studio and performance spaces. Added emphasis has been
placed on stereo localization phenomena, since this is the means by which the engineer
translates acoustical relationships into an acceptable facsimile in the reproducing space.
Section 2: Microphones. Microphone choices, their directional patterns, and placement
are the prime ingredients the recording engineer uses in daily practice. This sequence of
chapters deals extensively with the electrical and physical aspects of microphones.
Section 3: Fundamentals of Stereophonic Recording. The basic systems of stereo
recording are covered here, including coincident, near-coincident, and spaced microphone
methods. The discussion emphasizes normal two-channel recording, but multichannel
surround-sound techniques are included. Techniques for image broadening and pseudo
stereo processing are presented.
iii
iv PREFACE
Section 4: Recording Systems: Architecture, Metering, and Monitoring. The
modern recording console can be an intimidating affair, and the intent in this sequence
of chapters to clarify its evolution in terms of changing musical requirements. While the
in-line console dominates multichannel recording, the older split-configuration console is
far more prevalent in general use; it is the type on which most young engineers will learn
their craft and is accordingly emphasized here.
Metering of signal levels is a subject not often covered in detail. It is the means by
which the engineer establishes effective modulation levels with respect to system noise
and distortion. Other aspects here have to do with program loudness and interchannel
correlation in stereo transmission.
Musical balances are established over monitor loudspeakers, and the large, built-in
control room systems are normally supplemented with small loudspeakers, as more music
listening is done in the automobile and by means of personal electronics. Control room
design considered in terms its acoustical and visual aspects.
Section 5: Signal Processing. This important sequence of chapters deals with the
great variety of devices that are used by the engineer to alter and enhance program
elements. These can vary from devices that affect the sound of a recording in a profound
way, to devices whose role is to shape the program subtly in terms of spectrum and
amplitude envelope for better overall transmission. Most of these techniques are covered
in chapters devoted to the aspects of frequency domain (equalizers and filters), time
domain (reverberation and signal delay), and amplitude domain (compression and noise
gating). A final chapter addresses newer technology that has grown out of advanced
digital signal processing.
Section 6: The Recording Medium. Even in this digital age, analog technology
dominates in the areas of multitrack recording and general post-production in broadcast
and motion picture applications. The coverage of analog tape recording has been
appropriately expanded, as has the coverage of code-decode noise-reduction techniques.
Digital recording is given more detailed treatment than in the earlier edition and
includes signal processing, data reduction, and interface between various recording
systems.
Section 7: Studio Production Techniques. The previous edition presented strong
chapters dealing with classical and popular recording and production techniques. These
have been updated and supplemented with a useful chapter covering speech recording.
Section 8: Post-production Techniques. Three new chapters cover editing, music
assembly, and an overview of sound for film and video. They cover the myriad techniques
that are not directly a part of the recording process, but which inevitably follow as the
recorded material finds its way into finished form for the consumer.
Section 9: Consumer Formats for Recorded Sound. These chapters cover consumer
media both in terms of basic technology and the specific shaping of recorded program to
best fit a given medium. Since the compact disc (CD) has virtually replaced the LP
PREFACE v
record, an argument could have been made for deleting the chapter devoted to disc
recording. Nonetheless, the technology of stereo disc cutting is presented in this edition,
perhaps for its last time.
The Philips Compact Cassette has long been our most important analog medium for
general music and speech program distribution, and of course the CD has emerged during
the 1980s as the world's new archival medium. The two digital tape standards, R-DAT
and the Philips Digital Compact Cassette (DCC) have not yet reached maturity but are
both important in their respective market areas.
Section 10: Commercial and Operational Aspects of Recording. The fundamentals
of studio site selection, acoustical design, operating and staffing, and equipment selection
are covered in this section.
CONTENTS
Preface / v
Section 1. Acoustical Foundations in Recording
1. Principles of Physical Acoustics / 1
2. Psychological Acoustics / 40
3. Characteristics of Performance Spaces / 59
Section 2. Microphones
4. Basic Operating Principles of Microphones / 66
5. Derivation of Microphone Directional Patterns / 73
6. Environmental Effects and Departures from Ideal Microphone
Performance / 85 .
7. Stereo and Soundfield Microphones / 94
8. Microphone Electrical Specifications and Accessories / 100
Section 3. Fundamentals of Stereophonic Recording
9. Two-Channel Stereo / 108
10. Multichannel Stereo / 130
Section 4. Recording Systems: Architecture, Metering, and Monitoring
11. Recording Consoles / 145
12. Signal Metering and Operating Levels /178
13. Monitor Loudspeakers /188
14. Control Rooms and the Monitoring Environment / 205
Section 5. Signal Processing
15. Equalizers and Filters / 215
16. Compressors, Limiters, and Noise Gates / 224
vii
viii CONTENTS
17. Reverberation and Signal Delay / 234
18. Special Techniques in Signal Processing / 247
Section 6. The Recording Medium
19. Analog Tape Recording / 270
20. Encode-Decode Noise Reduction (NR) Systems / 303
21. Digital Recording and Signal Processing / 315
Section 7. Studio Production Techniques
22. Classical Recording and Production / 335
23. Popular Recording and Production / 365
24. Recording the Spoken Voice / 393
Section 8. Post-production Techniques
25. Principles of Music and Speech Editing / 398
26. Music Preparation for Commercial Release / 409
27. Overview of Sound for Film and Video / 415
Section 9. Consumer Formats for Recorded Sound
28. The Stereo Long-Playing (LP) Record / 423
29. Recorded Tape Products for the Consumer / 441
30. The Compact Disc (CD) / 448
31. Digital Audio Tape (DAT) /454
Section 10. Commercial and Operational Aspects of Recording
32. Recording Studio Design Fundamentals / 458
33. Studio Operation and Maintenance / 469
Index /475
1
PRINCIPLES OF PHYSICAL ACOUSTICS
1.1 INTRODUCTION
This chapter will cover the basic elements of sound generation and propagation in both
indoor and outdoor environments. Sound fields and directivity of sound sources will be
discussed, as will various wavelength-dependent sound transmission phenomena. The
concept of the decibel will be introduced.
1.2 CONCEPT OF VIBRATION
1.2.1 Periodic Motion
A sine wave represents the simplest kind of vibration; it is the natural motion of a weight
as it bobs up and down on a spring, or of a pendulum swinging at moderate displacement.
Its characteristic motion is shown in Figure l-l(a) as an undulating movement about a
reference line. The motion can also be described as the projection of a point on a circle
as that point moves about the circle with uniform angular velocity. One cycle of the wave
constitutes rotation through the complete 360 degrees of the circle, and the time required
for one cycle of the wave is called its period (n. A related term is frequency, which is
the number of periods in a time interval of one second. For example, if a sine wave has
a period of one-fourth second (T = .25 sec), then its frequency is liT, or 4 cycles per
second. The term hertz (Hz) is universally used to indicate cycles per second.
EXAMPLE: Determine the frequency of a sine wave with a period of 111000 of a
second.
1
Frequency = lIT = .001 = 1000 Hz (or 1 kHz) (1-1)
The term kHz, or kilohertz, is equivalent to one thousand hertz.
1
2 HANDBOOK OF RECORDING ENGINEERING
I- Period -I
90·
I' \; ,j • time
270·
(a)
(b)
Figure 1-1. (a) Generation of a sine wave, showing amplitude and period. (b) Phase relationship between two
sine waves of the same frequency.
Another characteristic of a sine wave is its amplitude (A), which is its maximum
displacement from the reference line. Depending on the physical domain we are discussing,
this displacement can be in space, as in the case of a pendulum, or in electrical voltage
or current, if it is an electrical sine wave. The amplitude of a sound wave is customarily
measured in pressure fluctuations above and below normal atmospheric pressure.
The concept of phase is important in describing sine waves. It refers to the relative
displacement in time between sine waves of the same frequency, and this is shown in
Figure 1-1(b). Here, the dashed sine wave is displaced from the solid one by some
distance <1>, which is usually expressed in degrees, with one period of the wave representing
360 degrees. If two sine waves of the same frequency are displaced in phase by 1800,
they are said to be in opposite polarity or, more informally, as being out of phase.
Obviously, a simple transposition of wiring in a two-conductor signal path can result in
this condition.
As common as sine waves are in electrical and mechanical engineering, they are rare
in the world of sound, for the reason that nearly all vibrating elements used in the
generation of sound have a tendency to execute complex motion. If the motion is a
sustained one, as in the case of a bowed string, then the complex waveform can usually
be represented as an ensemble of sine waves, beginning with a fundamental wave and
progressing upward through a set of sine waves whose periods are related as 1, i, 1, t,
;, and so on. This is shown in Figure 1-2, where four harmonically related waves are
PRINCIPLES OF PHYSICAL ACOUSTICS 3
First Harmonic
t
fo
Second Harmonic
t
2fo
Third Harmonic
t
3fo
Fourth Harmonic
t
4fo
frequency_
(a) (b)
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Itt t
fo 2fo 3fo 4fo
frequency_
(c) (d)
Figure 1-2. (a) Illustration of harmonically related sine waves. (b) Frequency spectra for sine waves shown in
(a). (c) Generation of a complex wave by adding the sine wave components of (a). (d) Frequency spectrum
for the complex wave shown in (c).
added together to produce a complex wave (Figure 1-2c). The components of a complex
wave are referred to as harmonics. In Figure 1-2(b) and 1-2(d), we have shown the
frequency spectrum for each component as well as for the complex wave itself. By
specifying the number of harmonics and their relative amplitudes and phase relationships,
we can generate any repetitive wave form.
1.2.2 Aperiodic Motion: Noise
Although we can describe any unwanted sound as noise, the term is usually reserved for
waveforms of the kind shown in Figure 1-3(a). The wave has no discernible period, and
is thus called aperiodic. Just as a complex repetitive wave form can be shown to consist
of harmonically related sine waves, noise can be shown to consist of a continuous band
of an unbounded number of sine waves. If the array of frequencies present is as shown
in Figure 1-3(b), the noise is referred to as white noise (similar to the interstation noise