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Sound Systems: Design and Optimization

Book Description

With this definitive guide to sound reinforcement design and optimization, Bob McCarthy shares his expert knowledge and effective methodology developed from decades of field and teaching experience. This book is written for the field professional as well as the consultant or student, in a clear and easy-to-read style and illustrated with color diagrams and screenshots throughout. McCarthy's unique guide reveals the proven techniques to ensure that your sound system design can be optimized for maximum uniformity over the space.

The book follows the audio signal path from the mix console to the audience and provides comprehensive information as to how the sound is spread over the listening area. The complex nature of the physics of speaker interaction over a listening space is revealed in terms readily understandable to audio professionals. Complex speaker arrays are broken down systematically and the means to design systems that are capable of being fully optimized for maximum spatial uniformity is shown.
The methods of alignment are shown, including measurement mic placement, and step-by-step recipes for equalization, delay setting, level setting, speaker positioning and acoustic treatment. These principles and techniques are applicable to the simplest and most complex systems alike, from the single speaker to the multi-element "line array.”

Table of Contents

  1. Cover
  2. Half Title
  3. Dedication
  4. Title Page
  5. Copyright
  6. Contents
  7. Preface
  8. Acknowledgements
  9. Section 1: Sound Systems
    1. 1. Transmission
      1. Transmission Goals
      2. Audio Transmission Defined
        1. Time and Frequency
        2. Wavelength
        3. The Waveform
      3. Transmission Quantified
        1. Decibels
        2. Power
        3. Frequency Response
        4. Polarity
        5. Latency
      4. Analog Audio Transmission
        1. Line Level Devices
        2. Line Level Interconnection
        3. Speaker Level Devices—Power Amplifiers
        4. Speaker Level Interconnection—Speaker Cables
      5. Digital Audio Transmission
        1. Digital Audio Devices
        2. Digital Audio Interconnection
      6. Acoustic Transmission
        1. Power, Pressure and Surface Area
        2. Environmental Effects: Humidity and Temperature
        3. Acoustic Transmitters: Loudspeakers
      7. Reference
    2. 2. Summation
      1. Overview
      2. Properties of Audio Summation
        1. Audio Summation Defined
        2. Summation Criteria
        3. Summation Quantity
        4. Electrical vs. Acoustical Summation
        5. Acoustical Source Direction
        6. Summation Math
        7. Summation Amplitude
        8. Summation Phase
      3. Response Ripple
        1. Summation Zones
        2. Comb Filtering: Linear vs. Log
        3. Summation Geometry
      4. Acoustical Crossovers
        1. Acoustic Crossover Defined
        2. Crossover Classes
        3. Spectral Dividers and Spectral Crossovers
        4. Spatial Dividers and Spatial Crossovers
      5. Speaker Arrays
        1. Introduction
        2. Speaker Array Types
        3. Coupled Arrays
        4. Uncoupled Arrays
      6. Speaker/Room Summation
        1. Analogous Functions
        2. Speaker/Room Summation Types
        3. Absorption Effects
        4. Environmental Effects
    3. 3. Reception
      1. Introduction
      2. Loudness
        1. Loudness and dB SPL
        2. The Equal Loudness Contours
      3. Localization
        1. Introduction
        2. Sonic Image
        3. Vertical Localization
        4. Front/Back Localization
        5. Horizontal Localization
      4. Tonal, Spatial and Echo Perception
        1. Introduction
        2. Tonal Perception
        3. Echo Perception
        4. Spatial Perception
        5. Perception Zone Detection
      5. Stereo Perception
        1. Introduction
        2. Panoramic Field
        3. Stereo Scaling
        4. Stereo Side-Effects
      6. Amplified Sound Detection
        1. Distortion
        2. Compression
        3. Frequency Response Coloration
        4. False Perspective
      7. Microphone Reception
        1. Introduction
        2. Comparing Microphones to Our Ears
        3. Measurement Microphones
      8. References
  10. Section 2: Design
    1. 4. Evaluation
      1. Introduction
      2. Natural Sound vs. Amplified Sound
        1. Contrasting Emission, Transmission and Reception Models
        2. Transmission Path Differences
      3. Relating the Worlds of Acousticians and Audio Engineers
        1. Comparing Our Goals
        2. The Middle Ground
      4. Moving Forward
      5. Reference
    2. 5. Prediction
      1. Introduction
      2. Drawings
        1. 2-D Drawing Types
        2. 3-D Drawing Types
        3. 2-D Drawings in a 3-D World
        4. Scale
      3. Acoustic Modeling Programs
        1. Introduction
        2. A Very Brief History
        3. Speaker Data Files
        4. Acoustic Transmission Properties
        5. Material Absorption Properties
        6. Characterizing Summations
        7. Applications
      4. Conclusions
    3. 6. Variation
      1. Introduction
      2. The Minimum Variance Principles
        1. Variation Defined
        2. Causes and Standard Progressions of Variance
        3. Minimum Variance vs. Maximum SPL
      3. The Speaker/Room Link: Aspect Ratio
        1. Protractors and Pizza
        2. Maximum Acceptable Variance
        3. Asymmetric Coverage Considerations
        4. The Coverage Bow Method
        5. The Forward Aspect Ratio
      4. The Proximity Ratio
      5. Minimum Level Variance
        1. Single Speakers
        2. Coupled Speaker Arrays
        3. Uncoupled Speaker Arrays
      6. Minimum Spectral Variance
        1. Relating Aspect Ratio, Beamwidth and Speaker Order
        2. Speaker Array Methods
      7. Minimum Ripple Variance
      8. Subwoofer Arrays
        1. End Fire
        2. Two-Element In-Line Technique
        3. Inverted Stack
        4. Coupled and Uncoupled Line Source
        5. Coupled and Uncoupled Point Source
      9. Conclusion
        1. Speaker Order and Beamwidth
        2. Maximum Power vs. Minimum Variance
        3. Minimum Variance Coverage Shapes
    4. 7. Specification
      1. Introduction
      2. The Principles of Specification
        1. Specification Defined
        2. Goals and Challenges
        3. Specific Questions
        4. Specific Answers
        5. Compromise
      3. Channel/System Types
        1. Mono
        2. Stereo
        3. Surround
        4. Source Effects
      4. System Subdivision
      5. Subsystem Types
        1. Main Systems
        2. Sidefill
        3. Infill
        4. Downfill
        5. Frontfill
        6. Delays
      6. The Scalable Design
        1. Scaling for Power
        2. Overlapping for Power
        3. Scaling the Shape
      7. Array Design Procedures
        1. Main System Design
        2. Symmetric Coupled Point Source
        3. Asymmetric Coupled Point Source
        4. Asymmetric-Composite Coupled Point Source
        5. Symmetric Uncoupled Line Source
        6. Asymmetric Uncoupled Line Source
        7. Symmetric Uncoupled Point Source
        8. Asymmetric Uncoupled Point Source
        9. Symmetric Uncoupled Point Destination
        10. Asymmetric Uncoupled Point Destination
      8. The Diagonal Plane
      9. Balcony Battles
      10. Multichannel Sound
  11. Section 3: Optimization
    1. 8. Examination
      1. Examination Defined
      2. Physical Measurement Tools
        1. Inclinometer
        2. Protractor
        3. Origami Angle Finder
        4. Laser Pointer
        5. Thermometer
        6. Hygrometer
      3. Simple Audio Measurement Tools
        1. Volt/ohm meter (VOM)
        2. Polarity Tester
        3. Listen Box
        4. Impedance Tester
        5. Oscilloscope
        6. Sound Level Meter
        7. Real-Time Analyzer (RTA)
      4. Complex Audio Measurement Tools
        1. The Fourier Transform
        2. Analyzer Basics
        3. Signal Averaging
        4. Single-Channel Spectrum Applications
        5. Transfer Function Measurement
      5. Other Complex Signal Analyzers
      6. Analysis Systems
      7. Reference
    2. 9. Verification
      1. Introduction
      2. Test Structure
        1. Testing Stages
        2. Access Points
        3. Test Setup
      3. Procedures
        1. Noise Over Frequency
        2. Total Harmonic Distortion + Noise (THD + n)
        3. Maximum Input/Output Capability Over Frequency
        4. Latency
        5. Polarity
        6. Frequency Response
        7. Phase Response over Frequency
        8. Compression
      4. Microphone Verification
        1. Microphone Match
        2. Microphone Response
      5. Post-Calibration Verification
      6. Additional Considerations
    3. 10. Calibration
      1. Calibration Defined
        1. Goals
        2. Challenges
        3. Strategies
        4. Techniques
      2. Approaches to Calibration
        1. Anarchy
        2. Monarchy
        3. Capitalism
        4. Democracy
        5. TANSTAAFL and Triage
      3. Access to Information
        1. Calibration Subdivision
        2. Physical Access
        3. Electronic Access
        4. Acoustic Access
        5. Microphone Position Strategies
      4. Procedures
        1. Acoustic Evaluation
        2. Level Setting
        3. Speaker Position Adjustment
        4. Equalization
        5. Delay Setting
      5. Order of Operations
      6. Practical Applications
      7. Finishing the Process
        1. Listening
      8. Ongoing Optimization
        1. Using Program Material as the Source
        2. Audience Presence
        3. Temperature and Humidity
        4. Stage Leakage
        5. Stage Microphone Summation
        6. Feedback
        7. Multichannel Program Material
        8. Show Mic Positions
        9. Subwoofers as a Program Channel
        10. Final Word
  12. Afterword
  13. Glossary
  14. Bibliography
  15. Index