Nathan Back to Basics Audio

1. Auflage 1998
ISBN: 978-0-08-049975-8
Verlag: Elsevier Science & Techn.
Format: EPUB
Kopierschutz: 6 - ePub Watermark

E-Book, Englisch, 344 Seiten

Back to Basics Audio is a thorough, yet approachable handbook on audio electronics theory and equipment. The first part of the book discusses electrical and audio principles. Those principles form a basis for understanding the operation of equipment and systems, covered in the second section. Finally, the author addresses planning and installation of a home audio system. - Notes on home theater systems, speaker placement and calibration - System planning, diagram analysis, and signal processing - Easy introduction to practical audio, acoustics, and electrical theory

Julian Nathan joined the audio service and manufacturing industry in 1954 and moved into motion picture engineering and production in 1960. He installed and operated recording theaters in Sydney, Australia, and set up similar facilities in Papua New Guinea and Hong Kong. Later he spent several years in cinema installation and service including audio visual theaters and government sound systems, then worked in the hi-fi- and professional sound equipment markets. His particular interest is home theater. He makes his home in New South Wales, Australia.

Autoren/Hrsg.

Nathan, Julian

Inhaltsverzeichnis

1;Front Cover;1
2;Back-to-Basics Audio;4
3;Copyright Page;5
4;Table of Contents;6
5;Introduction;14
6;Chapter 1. Electrical Principles;18
6.1;Audio's Three Parts;18
6.2;Electronics and Electricity;18
6.3;An Electrical Circuit;19
6.4;Electrical Principles;20
6.5;Ohm's Law;21
6.6;Using Ohm's Law;21
6.7;Voltage Drop;22
6.8;Introduction to Measurements;23
6.9;Inductance, Capacitance, and Impedance;24
6.10;Resonance;25
6.11;Line Impedance;26
6.12;Magnetism and Speaker Drivers;27
6.13;Speakers and Electric Motors;28
6.14;The Inverse Square Law and Speaker Design;29
6.15;Bi-Polarity;30
6.16;Direct and Alternating Current;30
6.17;Graphical Representation of Waveforms;31
7;Chapter 2. Meters and Electrical Measurements;34
7.1;Multimeters;34
7.2;Voltage Measurement;35
7.3;Current Measurement;36
7.4;A Word of Warning about Meter Current Ranges;38
7.5;Resistance Measurement;38
7.6;Using Analog and Digital Multimeters;39
7.7;Accuracy of a Meter;39
7.8;Meter Sensitivity;42
7.9;Additional Features Available in Multimeters;43
7.10;Oscilloscopes;43
7.11;Oscilloscope Experiments;45
8;Chapter 3. Amplifiers and Transmission Lines;46
8.1;Power Amplifier Lines and Loads;46
8.2;The Input Circuit;47
8.3;The Output Circuit;48
8.4;Avoidable Failures;49
8.5;Speaker Impedance Matching;50
8.6;Constant Voltage Lines;51
8.7;RMS Voltage and Current;53
8.8;Power;55
8.9;Amplifier Output Power Measurement;56
8.10;DC Offset Voltage;58
8.11;Catastrophic Failures;60
8.12;Dummy Loads;61
8.13;Cascading Power Amplifiers;62
8.14;Line Amplifiers;63
8.15;Voltage Amplifiers;64
8.16;Audio Lines;65
8.17;Coaxial Transmission Lines;66
8.18;Hearing-Aid Induction Loops;67
8.19;DC Coupled Amplifiers;68
9;Chapter 4. Sound Waves and Decibels;70
9.1;The Audio and Electromagnetic Spectra;70
9.2;The 630 Hz Tool;71
9.3;Frequency and Wavelength;74
9.4;Propagation;74
9.5;Audio Measurements;75
9.6;Noise and Distortion Thresholds;77
9.7;Decibels and Power;80
9.8;Decibels Further Explained;82
9.9;Case Histories;85
10;Chapter 5. Transfer Characteristic and Networks;92
10.1;Transfer Characteristic and Distortion;92
10.2;Electro-Mechanical and Acoustic Transfer;97
10.3;Preparing for Unavoidable Transfer Errors;98
10.4;Networks;98
10.5;Attenuators;100
10.6;Variable Attenuators;101
10.7;Loss Pads;102
10.8;Filters and Equalizers;103
10.9;Resistances in Series and Parallel;109
10.10;When to Use a Fixed Equalizer;109
10.11;Cautions Regarding Equalizer Use;110
10.12;Recovery Amplifiers;111
10.13;Active Crossovers and Speaker Processors;112
11;Chapter 6. Speakers;116
11.1;Speaker Power Ratings;116
11.2;Estimating the Power to a Speaker;118
11.3;IEC Speaker Power Rating;118
11.4;Directional Properties and Stereo Image;119
11.5;Stereo Surround;120
11.6;Poor Man's Surround;121
11.7;Using Speaker Directional Properties;122
11.8;Frequency Response of Speakers;125
11.9;Response Limits of Speakers;126
11.10;Standing Waves;128
11.11;Efficient Bass Speaker Placement;128
11.12;Speaker Baffles;129
11.13;Bass Box Design;130
11.14;Intermodulation Distortion;132
11.15;Phase Response of Speakers;133
11.16;Speaker and Driver Phasing;133
11.17;Speaker Efficiency;135
11.18;Theater Speaker Evolution;136
11.19;Importance of Theater Speaker Dispersion Angle;138
11.20;Recent Developments;139
11.21;Cinema High-Frequency Roll-Off;140
11.22;Auditorium Response Limitations;142
11.23;Monitor Speakers;143
11.24;Limited Monitors;144
11.25;Auditorium and Monitor Calibration;144
11.26;Speaker Response Measurements;149
11.27;Auditorium and Monitor Levels;151
11.28;Why Do Commercials Sound Louder?;152
11.29;Headphones;153
12;Chapter 7. Tape Recorders and Monitor Selectors;154
12.1;Magnetic Recorders;155
12.2;Recorder Features and Types;158
12.3;Simplifying Complicated Concepts;159
12.4;General Purpose Monitor Selectors;161
12.5;Introduction to Studio Monitor Selectors;165
12.6;Monitor Selectors for Studio Mixers;166
12.7;Drop-Edits and Insert Recorders;168
12.8;Zero Level and Line Level;169
12.9;Recorder Line-Up Tone;170
12.10;Tape Recorder Alignment;170
13;Chapter 8. Mixers;174
13.1;Introduction to Mixers;174
13.2;The Difference between Speech and Dialog;177
13.3;Dialog Processing;178
13.4;Dialog Equalizer/Compressor Combination;180
13.5;Where Not to Use Dialog Processing;183
13.6;Background Suppression;184
13.7;Bandpass Filters;185
13.8;Dip Filters;189
13.9;Points to Consider when Mixing;189
13.10;The Effects Channels;190
13.11;Digital Sound Processing and Equipment;192
13.12;Unlocking the Noise Gate;193
14;Chapter 9. Acoustics;196
14.1;Rooms and Acoustics;196
14.2;Reverberation and the Absorption Spectrum;196
14.3;Sound Isolation and Acoustics;197
14.4;Equalizing the Absorption Frequency Response;198
14.5;Acoustic Control by Diffusers and Resonators;198
14.6;Sound Isolation Construction;203
14.7;Overcoming Building Noises;207
14.8;Planning and Supervising a Building Project;210
14.9;Silencing a Generator;211
15;Chapter 10. Audio Cabling;214
15.1;Balanced and Unbalanced Lines;214
15.2;Short Run Audio Wiring;217
15.3;Long Balanced and Unbalanced Lines;217
15.4;Reducing Noise Interference at Source;221
15.5;Safety;222
15.6;Connections to Various Types of Equipment;223
15.7;Cable Segregation and Rack Termination;225
15.8;There-and-Back Cable Termination;225
15.9;Pre-Measured Cable Runs and Junction Boxes;227
15.10;Prefabricated Cable Looms;227
15.11;Keeping RF Out of Systems and Cables;228
16;Chapter 11. Transformers and Power Supplies;232
16.1;Transformers;232
16.2;Auto-Transformers;237
16.3;Making Auto-Transformers to Order;238
16.4;Transformer Frequency Response;238
16.5;The Electricity Supply Mains;239
16.6;Rectifiers and Power Supplies;240
16.7;Regulators;243
16.8;Voltage and Current Regulation;244
16.9;Zener Diodes;245
16.10;Regulator Noise;245
16.11;Switch-Mode Power Supplies;246
16.12;Three Dollar Tester;246
16.13;Power Supply Faults;247
16.14;Batteries and Chargers;248
16.15;Lead-Acid Batteries;249
16.16;Precautions with Acid Batteries;250
16.17;Nickel-Cadmium Batteries;251
16.18;Choice of Battery;252
17;Chapter 12. Control Systems;254
17.1;Basic Control Groups;254
17.2;Relays;255
17.3;Relay Timer Circuits;258
17.4;Motor Reversing;259
17.5;Solid State Control Devises;260
17.6;Relays Versus Electronic Control;262
18;Chapter 13. Solder and Assembly Methods;264
18.1;Soldering;264
18.2;Tools;264
18.3;Soldering Techniques;265
18.4;Using Additional Flux;269
18.5;Troubleshooting, Inspection, and Re-Soldering;270
18.6;When Not to Re-Solder;271
18.7;Choosing and Fitting Connectors;271
18.8;Solderless and Crimp Connectors;274
18.9;Wire Wrap;275
19;Chapter 14. Installation Planning;276
19.1;Diagrams;276
19.2;How Far to Go with Drawing Detail;281
19.3;Drawing a System Block Diagram;281
19.4;Patchbay Layout and Wiring;285
19.5;Racks and Panels;287
19.6;Examples of Standard and Special Racks;293
19.7;Communicating Ideas;293
19.8;Front Opening Racks;299
19.9;Panel Design;299
19.10;Control Grouping;301
19.11;Laying Out a Panel;304
19.12;Lettering, Styling, and Engraving;304
19.13;Scales for Potentiometers and Switches;305
19.14;Before Starting Work on a Panel;306
19.15;Materials and Panel Thickness;307
19.16;Panels for Membrane Switches;308
19.17;Brackets and Shelf Units for Mobile Equipment;309
19.18;Drilling Precision Holes in Metal and Plastic;311
20;Chapter 15: Home Theater Sound;314
20.1;Real Theater Sound at Home;316
20.2;Surround Speaker Position;317
20.3;Equalizing the Center Channel;318
20.4;Case History;319
20.5;Adding a Sub-Bass;321
20.6;Bass Distortion and Power Loss;323
20.7;Maintaining Program Dynamic Range;324
21;Appendix A: Working with Formulae – Practical Examples of Common Calculations;326
21.1;Calculating Voltage Drop Resistance;326
21.2;Calculating Amplifier Output Power;327
21.3;Calculating LED Resistor Values;327
21.4;Calculating AC Transformer Secondary Voltage for a Given DC Rectifier Output;328
22;Appendix B: Diagram Symbols;330
23;Appendix C: A Mechanical Design Exercise;338
23.1;Making a High Gain Video Projection Screen;338
23.2;Consequential Design Steps;341
24;Appendix D: Estimating Power to Speakers;344
24.1;How Much Power is Going to the Speakers?;345
24.2;Field Assessment of Power to a Speaker;345
25;Glossary – lndex;348

Leseproben

Chapter 1 Electrical Principles
AUDIO’S THREE PARTS
Audio is Acoustic, Mechanical, and Electric. Sound, or wave-motion in air, is sensed, processed, and reproduced by electro-mechanical and electronic devices. It wasn’t always electric, but that’s the medium we use to do almost everything, and do it better. Sound is transient, it’s gone as soon as it happens, but it can be examined and its equipment tested, largely with continuous tones, or in the steady state. More details of the nature of sound are given in Chapter 4, but as a necessary background to the technology of audio, the briefest account of electricity and its associated parts occupies most of this chapter. ELECTRONICS AND ELECTRICITY
All matter is made up of identical Neutrons, Protons, and Electrons. In various combinations they form atoms; the basic clusters that form the elements. In turn, one or more atoms make up a molecule, the smallest functional form of an element or compound. The atomic weight of a stable element is determined by the number of negative charge electrons circling the nucleus of its atom, which in turn is made of an equivalent number of positive charge protons, plus various numbers of neutrons. Electrical conductors have loosely bonded electrons in their atoms. Electrons are able to flow from atom to atom in conductors, and since they have a negative charge, convention says that positive current flows in the opposite direction to electron flow. Electrons flow from negative to positive in conductive media because unlike charges attract, so current flows from positive to negative. Poor conductors have closely bonded electrons, making flow difficult. They have high resistance. All the use we make of electronics is based on working with the outer electron shell of atoms. We can make electrons pass from atom to atom. By heating conductors we can make them incandescent; photon emission is an indication of super-excited electrons. In fluorescent, carbon and xenon arc, and neon lamps, we see a demonstration of plasma; conducting, ionized gas; the fourth state of matter. Maser and laser technology, including semi-laser devices like LEDs (light emitting diodes), proves the connection between excitation of electrons by one form of energy, and production of microwaves or coherent light (single frequency or narrow band photon emission) by the electrons thus stimulated. Nucleonics, on the other hand, is concerned with mobilizing the neutrons and protons that form atomic nuclei, in order to release energy. Nuclear engineering is beyond the reach of most people because it’s expensive and difficult to handle. Electronics, understood and thoroughly exploited, is easy to get into, and safe as a box of matches. AN ELECTRICAL CIRCUIT
1. When the switch in the circuit of Fig. 1.1 is open, voltage is present across the battery and therefore across the switch. But no current flows. Fig. 1.1 An electric circuit. 2. When the switch is closed, current flows through the (lamp) load, limited by the combined resistance of the load, the source, the conductors, and the switch. 3. Work (Watts) done in the load equals electrical pressure (Volts) times current (Amps). A small proportion is wasted in heating the other resistive components, including the battery. 4. The current (flow) at any point in the circuit is the same at any other point (in a simple circuit that does not branch). 5. Electricity requires a complete circuit for current to flow. ELECTRICAL PRINCIPLES
Volts, Amps (amperes) and Ohms are inter-related quantities, and refer to the physical properties of Electricity. Without an easily acquired understanding of these three basics, very little progress can be made in any application. A working knowledge is given in the following few pages, containing nothing more complex than simple equations. Voltage is Electrical Pressure. Just as water in a tank exerts physical pressure on the pipe it supplies, so a voltage source exerts electrical pressure, or a potential difference, at the parts of a circuit to which it is connected. Voltage is also referred to as Electromotive Force, or EMF. VOLT : The unit of ELECTRICAL PRESSURE Symbol : V Amperes denote Electric Current Flow. When pressure is released, water in a pipe flows. The flow rate could be expressed in liters per minute. A fundamental observation is that the flow rate is the same at any point in the pipe, assuming it does not branch. Three liters per minute at one end guarantees three liters per minute at the other. Electric current flow is the same. AMP : The unit of ELECTRIC CURRENT FLOW Symbol : I Ohms are units of Electrical Resistance (to current flow). Again consider the water pipe. If it is rough inside, or narrow, it could be said to have high resistance. Even if it is perfectly smooth, it will have some resistance. Resistance is also a feature of Electrical Conductors. The degree of resistance depends on the material and cross section area of the conductor, at normal temperatures. OHM : The unit of ELECTRICAL RESISTANCE Symbol : R OHM’S LAW
Current flow is the operative factor in an electric circuit. Voltage makes it happen. Resistance retards it. This all works by good fortune, since without resistance, the simple act of switching on a light would initiate enormous currents, and other means would have to be found to limit the flow. Resistance is like friction, without which we would all need spiked shoes to stand erect. Volts and amps are related by the equation: AMPS EQUALS VOLTS DIVIDED BY OHMS
This is the basis of Ohm’s Law. Current flow is directly related to Voltage, but inversely to Resistance. More Volts, more Amps, but more Ohms, less Amps. USING OHM’S LAW
The equation can be converted to determine any one quantity, given the other two, by the rules of simple equations: A figure can cross the equals sign provided it also crosses the divide line. Therefore: OHMS EQUALS VOLTS DIVIDED BY AMPS
By the same equation, V = I R VOLTS EQUALS AMPS x OHMS
This classic formula is valid under all conditions. It applies to materials that change resistance when they get hot, and equally to AC circuits where R represents impedance, a combination of resistance with inductive and capacitive reactance (see page 7). Draw a button inscribed with the following: Place a finger on the quantity you need to know. Calculate the other two. VOLTAGE DROP
Referring to the next chapter, on pages 19 and 20, it will be seen that voltage drop is the quantity being measured in the majority of cases when a series resistor is the focus of attention. Calculation of a series resistor, for the purpose of reducing the voltage across the following circuit, requires an appreciation of voltage drop, rather than the voltage that results from the resistor’s presence, or the supply voltage. Practical examples of voltage drop calculation appear in Appendix A at the end of the book. POWER
Volts and Amps by themselves are not Power, the part that does the work, but in combination, they will be Power. A WATT IS A JOULE PER SECOND
We won’t be much concerned with Joules, except to say that the Joule is one of the basic units denoting an amount of energy. Example: a 450 joule photographic flash; 450 joules of energy expended in a millisecond. An amount of energy converted 95 percent into light; 5 percent into heat. Energy, like matter, can neither be created nor lost. If it doesn’t light up or get hot, it must rotate, make noises, or do something. 1 JOULE PER SECOND = 1 WATT 746 WATTS = 1 HORSEPOWER WATT: The unit that represents RA TE OF ENERGY CONSUMPTION (OR CONVERSION) Symbol: W A 60 watt lamp consumes 60 watts; 60 Joules per second; 3,600 Joules...