Sound Reinforcement Handbook

by Davis, Gary; Jones, Ralph

• ISBN13: 9780881889000
• ISBN10: 0881889008
• Edition: 2nd
• Format: Paperback
• Copyright: 1988-01-01
• Publisher: Yamaha

Summary

Sound reinforcement is the use of audio amplification systems. This book is the first and only book of its kind to cover all aspects of designing and using such systems for public address and musical performance. The book features information on both the audio theory involved and the practical applications of that theory, explaining everything from microphones to loudspeakers. This revised edition features almost 40 new pages and is even easier to follow with the addition of an index and a simplified page and chapter numbering system. New topics covered include: MIDI, Synchronization, and an Appendix on Logarithms. 416 Pages.

Table of Contents

Section 1. What is a Sound System
The audio signal	1	(3)
Sound waves	1	(1)
The electrical representation of sound	2	(1)
Phase	2	(1)
Adding sine waves	3	(1)
The basic purpose of a sound system	4	(1)
A conceptual model of a sound system	4	(1)
Input transducers	5	(1)
Output transducers	5	(1)
A practical model of a sound system	6	(3)
Section 2. Frequency Response
A definition	9	(3)
Basic specification methods	10	(1)
Octave relationships and measurements	11	(1)
Frequency response of practical audio devices	12	(3)
Electronic circuits and cables	12	(2)
Microphones	14	(1)
Loudspeakers	14	(1)
Voice and instrument ranges	15	(2)
The speaking voice	15	(1)
The singing voice and musical instruments	15	(1)
Harmonics	16	(1)
Effect of acoustical factors	17	(2)
Section 3. The Decibel, Sound Level, & Related Items
What is a decibel?	19	(3)
A mathematical definition of the dB	19	(2)
Relative versus absolute levels	21	(1)
Relating the decibel to electrical signal levels	22	(3)
dBm	22	(1)
dBu	22	(1)
dBv and dBv	23	(1)
Converting dBv to dBu (or to dBm across 600 ohms)	24	(1)
Relating dBv, dBu and dBm to specifications	24	(1)
dBw	25	(1)
Relating the decibel to acoustic levels	25	(2)
dB SPL	25	(1)
dB PWL	26	(1)
What is rms?	27	(1)
Volume, level and gain	28	(1)
Loudness	29	(4)
Equal loudness contours and phons	29	(1)
What we can deduce from equal loudness contours	30	(1)
Loudness compensation	31	(2)
Section 4. Dynamic Range
Dynamic range	33	(2)
A definition	33	(1)
The dynamic range of a typical rock concert	33	(1)
The electrical dynamic range of the sound system	33	(1)
The acoustical dynamic range of the system	34	(1)
Headroom	35	(2)
A definition	35	(1)
Why headroom is important	36	(1)
Manipulating dynamic range in a practical sound system	37	(6)
Why not build a sound system with excess dynamic range?	37	(1)
What happens when the sound system is inadequate?	37	(2)
How to fit wide program dynamics into a sound system with limited dynamic range	39	(3)
How much headroom is adequate?	42	(1)
Section 5. Sound Outdoors
The inverse square law	43	(2)
Inverse square law calculations	44	(1)
Effects of environmental factors	45	(2)
Wind	45	(1)
Temperature gradients	46	(1)
Humidity	46	(1)
Feedback control	47	(6)
Maximum gain (available gain before feedback)	47	(2)
Using directional microphones and loudspeakers	49	(4)
Section 6. Sound Indoors
Boundaries	53	(2)
The absorption coefficient	54	(1)
Standing waves	55	(2)
Standing waves in a room	56	(1)
Reverberation	57	(1)
Critical distance	58	(3)
Implications for sound reinforcement	60	(1)
Section 7. Block Diagrams
General discussion	61	(2)
Symbolic conventions	63	(3)
Notational conventions	66	(1)
Analysis of simple block diagrams	67	(3)
Summation	70	(1)
Section 8. How to Read & Interpret Specifications
General discussion	71	(1)
Why specs are not always what they seem	71	(1)
Examples of specs that should be doubted	71	(1)
What to look for	72	(1)
Frequency response	72	(3)
Distinguishing frequency response, frequency range, and power bandwidth	72	(2)
Graphic versus printed specs	74	(1)
What is a good frequency response spec?	74	(1)
Noise	75	(6)
What is noise?	75	(1)
White noise	76	(1)
Pink noise	76	(1)
Shaping the noise	77	(1)
EIN: a measure of mic preamplifier noise	78	(1)
Specifying output noise	78	(2)
Other types of noise	80	(1)
Harmonic distortion	81	(4)
What is harmonic distortion?	81	(1)
Measuring harmonic distortion	82	(2)
Factors affecting harmonic distortion specifications	84	(1)
Intermodulation distortion	85	(2)
Measuring IM distortion	85	(1)
Sources of IM distortion	86	(1)
How much distortion is tolerable?	86	(1)
Transient intermodulation distortion	86	(1)
Input and output impedances	87	(5)
Confusion about input and output impedances	88	(2)
Output impedance	88	(1)
Input impedance	89	(1)
The implications of impedance mismatches	90	(1)
Impedance and frequency	91	(1)
Standard operating levels	92	(4)
General classification of levels	92	(1)
Expressing the wide power range of a sound system	93	(1)
How impedance relates to level specifications	94	(1)
Power vs impedance	94	(1)
Overloading an output	94	(1)
How the load affects output voltage	95	(1)
What happens when hi-fi and pro equipment mix	95	(1)
Hi-fi output to pro equipment input	95	(1)
Pro equipment output to hi-fi input	96	(1)
Crosstalk	96	(3)
What causes crosstalk?	97	(1)
Crosstalk in cables	97	(1)
Specification of crosstalk	97	(2)
Filter slope rates and turnover frequencies	99	(1)
Square wave tests	100	(3)
Oscilloscopes	101	(2)
What not to expect with square waves	103	(1)
Miscellany	103	(2)
Section 9. Why Ears Don't Always Correlate With Specs
Different points of view	105	(2)
Calibrated mics vs ears	105	(1)
Average ears vs ``golden ears''	106	(1)
Test equipment measurements vs listening tests	107	(4)
Test signals versus program material	107	(2)
Location and number of test microphones	109	(1)
Dynamic range	110	(1)
Static vs dynamic tests	111	(1)
Masking effects and equipment interaction	112	(1)
Section 10. Microphones
Methods of transduction	113	(3)
Dynamic	113	(1)
Condenser	113	(1)
Electret condenser	114	(1)
Ribbon	114	(1)
Carbon	115	(1)
Piezoelectric	116	(1)
Functional design	116	(5)
Hand-held	116	(1)
Stand-mounting	117	(1)
Lavalier	117	(1)
Contact pickup	118	(1)
Pressure response	118	(1)
Shotgun	119	(1)
Parabolic	119	(1)
Multi-element arrays	120	(1)
Noise cancelling microphones	120	(1)
Acoustical and electrical characteristics	121	(8)
Pickup patterns	121	(3)
Omnidirectional	121	(1)
Cardioid	121	(2)
Bidirectional or figure-8	123	(1)
Supercardioid	123	(1)
Frequency response	124	(1)
Proximity effect	125	(1)
Transient response	125	(1)
Output level or sensitivity	126	(1)
Overload	126	(1)
Impedance	127	(1)
Balanced and unbalanced connections	127	(2)
Application information	129	(3)
Windscreens and pop filters	129	(1)
Shock mounts	129	(1)
Phantom power	130	(1)
Effect of the number of open microphones	130	(1)
Gain and microphone placement	131	(1)
Stereo recording	131	(1)
Wireless intercom systems	132	(7)
What is a wireless intercom?	132	(1)
Who uses wireless intercoms?	132	(1)
What is the background of wireless intercoms?	133	(1)
Types of wireless intercoms	133	(2)
Frequencies used	135	(1)
Improved range and noise reduction	136	(1)
Evaluating and selecting a system	136	(1)
Conclusions	137	(1)
Glossary of wireless intercom terms	138	(1)
Wireless microphone systems	139	(10)
What is a wireless mic?	139	(1)
Who uses wireless mics?	139	(1)
What is the background of wireless mics?	139	(1)
Radio frequencies used	140	(1)
Technical problems	141	(1)
Solutions	142	(3)
Compatibility of wireless mic systems	145	(1)
Antenna cables	146	(1)
Evaluating wireless microphone systems	146	(1)
Conclusions	147	(1)
Glossary of wireless microphone terms	148	(1)
Section 11. Preamplifiers, Small Mixers, & Mixing Consoles
General discussion	149	(3)
Preamplifiers	152	(2)
What are they, and what do they do?	152	(1)
Impedance converters	153	(1)
Phono preamps	153	(1)
Mixers	154	(1)
Consoles	155	(7)
What is a console?	155	(1)
How mixes differ: pre & post fader considerations	155	(2)
Panning, summing and master faders	157	(5)
Understanding console specifications	162	(5)
How many inputs, mixes and outputs?	162	(1)
Signal-to-noise ratio	162	(2)
Maximum voltage gain	164	(1)
Headroom	165	(1)
Indicators	166	(1)
Transformer isolated versus electronically balanced inputs & outputs	167	(5)
Transformers versus differetial amps: price concerns	168	(1)
Discrete versus IC differential amps	168	(1)
The case for the transformer	169	(1)
Transformers and AC safety	170	(1)
More on transformers	170	(2)
Gain staging and gain structure	172	(3)
Why does gain have to be manipulated? a review of sound levels fed to the console	172	(1)
Gain control at the microphone input	173	(1)
Input attenuation or padding	173	(1)
Eliminating other causes of signal-level (& gain) related distortion	174	(1)
Summing amp overdrive	174	(1)
Power amp overdrive	174	(1)
Interface with sub-mixers	175	(3)
Stage monitor mixing consoles	178	(4)
What is a stage monitor system?	178	(1)
Why a monitor console is preferable to a mix from the main house console	179	(1)
The importance of a high quality monitor mix	180	(1)
Other benefits of a separate monitor console	180	(1)
Polarity (phase) reversal as a tool to fight feedback	181	(1)
Eliminating SCR dimmer noise	182	(1)
Microphone splitting	182	(4)
The splitter transformer	183	(1)
Additional isolation for high-noise environments	184	(1)
Splitting a mic without a transformer	185	(1)
Reducing feedback in the stage monitor system	186	(3)
Directional microphones	186	(1)
Polarity reversal (or ``phase'' reversal)	186	(1)
Ringing out a monitor system	187	(2)
Aiming monitor loudspeakers	189	(1)
Equipment placement	189	(4)
Additional monitor console placement factors	189	(1)
Main house mixing console placement	190	(3)
Section 12. Power Amplifiers
General discussion	193	(1)
Ohm's law & related equations	193	(4)
Voltage, resistance and current	193	(1)
Electrical power	194	(1)
Ohm's law chart	195	(1)
Electrical power and amplifier gain	196	(1)
Power ratings of amplifiers	197	(5)
FTC preconditioning	198	(1)
Power bandwidth	198	(1)
Slew rate and output power	199	(1)
Bridged operation	200	(1)
The effect of clipping	201	(1)
The relationship between amplifier power and SPL	202	(2)
Matching power amplifiers to loudspeakers	204	(5)
Interpreting loudspeaker power ratings	204	(1)
Impedance calculations	205	(3)
Constant-voltage distribution systems	208	(1)
Section 13. Loudspeakers
Introduction	209	(1)
Common methods of acoustic transduction	210	(2)
Electromagnetic transduction	210	(1)
Piezoelectric transduction	211	(1)
Low frequency drivers	212	(2)
Directional characteristics of cone drivers	213	(1)
Low frequency enclosures	214	(4)
Vented enclosures	215	(1)
Low frequency horns	216	(2)
High frequency drivers	218	(1)
High frequency horns	219	(3)
Crossovers	222	(6)
General model	222	(1)
Passive, high level crossovers	223	(2)
Active, low level crossovers	225	(3)
Headroom	225	(2)
Efficiency	227	(1)
Damping	227	(1)
Distortion	227	(1)
Biamp or triamp versus conventional system	227	(1)
Full-range loudspeakers	228	(2)
Effect of boundary conditions	229	(1)
Loudspeaker specifications	230	(6)
Frequency response	230	(1)
Power handling	231	(1)
Sensitivity	232	(1)
Impedance	233	(1)
Directional characteristics	234	(2)
Sources of distortion	236	(2)
Over-excursion	236	(1)
Intermodulation distortion	236	(1)
Mechanical defects	237	(1)
Typical failure modes	238	(6)
Manufacturing defects	238	(1)
Improper operation	239	(2)
Failures due to other components in the signal chain	241	(3)
Section 14. Signal Processing Equipment
Equalizers	244	(15)
General discussion	244	(1)
Common tone controls	244	(2)
Multi-band conventional equalizers	246	(2)
Sweep-type equalizers	248	(1)
Parametric equalizers	248	(3)
Graphic equalizers	251	(3)
Paragraphic equalizers	254	(1)
Tuning a sound system with graphic (or paragraphic) equalization	254	(2)
High pass and low pass filters	256	(3)
Reverberation and delay	259	(11)
Reverb chambers	261	(1)
Duct-type reverbs	262	(1)
Spring-type reverbs	262	(2)
Plate-type reverbs	264	(1)
Digital reverberation	264	(2)
Tape delay	266	(1)
Digital delay	267	(2)
Analog delay	269	(1)
Compressors & limiters	270	(4)
General discussion	270	(1)
How compressor/limiters work	271	(1)
Setup adjustments	272	(2)
Noise gates & expanders	274	(3)
General	274	(1)
Noise gate applications	275	(1)
Expander applications	276	(1)
Flangers and phasers	277	(2)
Flanging	277	(1)
Phasing	278	(1)
What to look for	278	(1)
Exciters	279	(2)
Section 15. Cabling
The importance of good cables	281	(1)
Types of cables, their construction and use	282	(9)
Electrostatic and electromagnetic shielding	282	(1)
Cable self-capacitance	283	(1)
Single and dual conductor shielded cables	284	(3)
Strain relief	287	(1)
Unshielded cables and speaker cables	288	(1)
Multicore audio cables (``snakes'')	289	(2)
Connectors	291	(12)
General	291	(1)
Phone plugs	291	(6)
Phono (pin) conncectors	297	(2)
XLR connectors	299	(4)
Section 16. Sound System Test Equipment
The volt-ohm meter	303	(2)
The sine wave oscillator	305	(2)
The oscilloscope	307	(2)
The phase tester	309	(1)
The sound pressure level meter	310	(1)
The real-time analyzer	311	(1)
The loudness monitor	312	(1)
Summary	312	(1)
Section 17. The Electronics
Basic sound system types	313	(2)
Sound reproduction systems	313	(1)
Sound reinforcement systems	314	(1)
Developing a logical system architecture	315	(10)
Functional grouping	316	(1)
System examples	317	(8)
Basic connections	325	(2)
Signal levels and impedance	325	(1)
Unbalanced and balanced connections	326	(1)
Grounding	327	(6)
Why is proper grounding important?	328	(1)
Ground loops	329	(1)
Basic grounding techniques	330	(3)
Using audio signal transformers	333	(4)
Properties and functions of signal transformers	333	(2)
Some practical applications	335	(2)
The main power source	337	(5)
Verify the correct mains voltage	337	(1)
Ensure there is a good earth ground	338	(1)
How to obtain a safety ground when using a two-wire outlet	339	(1)
Imporperly wired AC outlets: lifted grounds	339	(1)
Improperly wired AC outlets: lifted neutral	340	(1)
AC safety tips	341	(1)
Turn-on sequencing	341	(1)
Power source integrity	341	(1)
Configuring equipment racks	342	(1)
Troubleshooting	343	(4)
Absence of signal	343	(1)
Undesired signals	343	(4)
Section 18. the loudspeakers
Analyzing the application	347	(1)
The program material	347	(1)
The environment	348	(1)
Directional control	348	(3)
Widening dispersion	349	(1)
Narrowing dispersion	350	(1)
SPL estimations	351	(1)
Placement considerations	351	(4)
Directionality and coverage	351	(2)
Feedback control review	353	(1)
Outdoor sound systems	353	(1)
Controlling feedback indoors	354	(1)
Loudspeaker placement indoors	354	(1)
Connections	355	(3)
Wire size	355	(1)
Connectors	355	(2)
Polarity of connections	357	(1)
General guidelines	358	(1)
Setting electronic crossovers	358	(6)
Choice of crossover frequency and slope	358	(2)
Setting up the loudspeaker system	360	(1)
Testing and optimizing the system	361	(2)
High frequency driver protection networks	363	(1)
Use of fill systems	364	(4)
Balancing fill systems	368	(1)
Testing and Equalization	368	(3)
Single loudspeakers	368	(1)
Multiple loudspeaker systems	369	(1)
Room equalization	370	(1)
Section 19. MIDI
Interface specifications	371	(4)
Hardware configuration	372	(1)
Data structure	373	(1)
Channel messages	374	(1)
System messages	374	(1)
Control of musical instruments	375	(7)
MIDI modes	377	(1)
Controllers	378	(1)
Patch editor/librarian functions	379	(1)
MIDI implementation charts	380	(2)
MIDI sequencing	382	(5)
Basic theory	382	(1)
Channels & tracks	383	(2)
Hardware vs computer-based sequencers	385	(1)
Typical sequencer features	385	(2)
Song editing	386	(1)
Step editing	386	(1)
Common editing features	386	(1)
MIDI data processors	387	(2)
Thru boxes	387	(1)
MIDI mergers	387	(1)
MIDI patchers	388	(1)
Mapping devices	388	(1)
SysEx data storage	388	(1)
Automation through MIDI	389	(2)
Instrument patch changes	389	(1)
Signal processors	390	(1)
Console functions	390	(1)
Sync to media	391	(1)
Troubleshooting	391	(4)
Lack of response	391	(1)
Stuck notes	392	(1)
MIDI feedback	392	(1)
MIDI time delays	393	(2)
Section 20. Synchronization
General discussion	395	(3)
Basic theory	395	(1)
Pulse methods	396	(1)
Timepiece methods	397	(1)
AMPTW/EBU time code	398	(8)
Signal structure	398	(2)
Frame rates and line references	400	(1)
Longitudinal, vertical interval and visible time code	401	(1)
Machine control	402	(2)
Slave code error	402	(1)
Slave code offset	402	(1)
Flying offsets	403	(1)
Slew	403	(1)
Advanced transport controls	403	(1)
Event triggers	403	(1)
Time code and audio tape	404	(1)
Printing SMPTE time code	404	(1)
Copying SMPTE time code	405	(1)
SMPTE-to-MIDI conversion	405	(1)
Edit decision lists	406	(6)
Appendix A. Logarithms
A.1 Raising Numbers to a Power: The Key to Logs	409	(1)
A.2 Simple Logs (and Antilogs) to the Base 10	409	(1)
A.3 Less Obvious Logs to The Base 10	410	(1)
A.4 Mathematical Properties of Logs	411	(1)
A.5 One More Look At Logs and Decibels	412	(1)
Index