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The Design of Active Crossovers, 2nd Edition

Book Description

The use of active crossovers is increasing. They are used by almost every sound reinforcement system, and by almost every recording studio monitoring set-up. There is also a big usage of active crossovers in car audio, with the emphasis on routing the bass to enormous low-frequency loudspeakers. Active crossovers are used to a small but rapidly growing extent in domestic hifi, and I argue that their widespread introduction may be the next big step in this field.

The Design of Active Crossovers has now been updated and extended for the Second Edition, taking in developments in loudspeaker technology and crossover design. Many more pre-designed filters are included so that crossover development can be faster and more certain, and the result will have a high performance. The Second Edition continues the tradition of the first in avoiding complicated algebra and complex numbers, with the mathematics reduced to the bare minimum; there is nothing more complicated to grapple with than a square root.

New features of the Second Edition include:

●   More on loudspeaker configurations and their crossover requirements:

     MTM Mid-Tweeter-Mid configurations (The d'Appolito arrangement)

     Line arrays (J arrays) for sound reinforcement

        Frequency tapering

        Band zoning

        Power tapering

     Constant-Beamwidth Transducer (CBT) loudspeaker arrays

●    More on specific sound-reinforcement issues like the loss of high frequencies due to the absorption of sound in air and how it varies.

●    Lowpass filters now have their own separate chapter.

      Much more on third, fourth, fifth, and sixth-order lowpass filters.

      Many more examples are given with component values ready-calculated

●    Highpass filters now have their own separate chapter, complementary to the chapter on lowpass filters.

      Much more on third, fourth, fifth, and sixth-order highpass filters.

      Many more examples are given with component values ready-calculated

●     A new chapter dealing with filters other than the famous Sallen & Key type. New filter types are introduced such as the third-order multiple feedback filter.

      There is new information on controlling the Q and gain of state-variable filters.

●    More on the performance of crossover filters, covering noise, distortion, and the internal overload problems of filters.

●    The chapter on bandpass and notch filters is much extended, with in-depth coverage of the Bainter filter, which can produce beautifully deep notches without precision components or adjustment.

●    Much more information on the best ways to combine standard components to get very accurate non-standard values. Not only can you get a very accurate nominal value, but also the effective tolerance of the combination can be significantly better than that of the individual components used. There is no need to keep huge numbers of resistor and capacitor values in stock.

●     More on low-noise high-performance balanced line inputs for active crossovers, including versions that give extraordinarily high common-mode rejection. (noise rejection)

●     Two new appendices giving extensive lists of crossover patents, and crossover-based articles in journals.

This book is packed full of valuable information, with virtually every page revealing nuggets of specialized knowledge never before published. Essential points of theory bearing on practical performance are lucidly and thoroughly explained, with the mathematics kept to an essential minimum. Douglas' background in design for manufacture ensures he keeps a very close eye on the cost of things.

Table of Contents

  1. Cover
  2. Title
  3. Copyright
  4. Dedication
  5. Contents
  6. Acknowledgments
  7. Preface
  8. Chapter 1: Crossover Basics
    1. What a Crossover Does
    2. Why a Crossover Is Necessary
    3. Beaming and Lobing
    4. Passive Crossovers
    5. Active Crossover Applications
    6. Bi-Amping and Bi-Wiring
    7. Loudspeaker Cables
    8. The Advantages and Disadvantages of Active Crossovers
      1. The Advantages of Active Crossovers
      2. Some Illusory Advantages of Active Crossovers
      3. The Disadvantages of Active Crossovers
    9. The Next Step in Hi-Fi
    10. Active Crossover Systems
    11. Matching Crossovers and Loudspeakers
    12. A Modest Proposal: Popularising Active Crossovers
    13. Multi-Way Connectors
    14. Subjectivism
  9. Chapter 2: How Loudspeakers Work
    1. Sealed-Box Loudspeakers
    2. Reflex (Ported) Loudspeakers
    3. Auxiliary Bass Radiator (ABR) Loudspeakers
    4. Transmission Line Loudspeakers
    5. Horn Loudspeakers
    6. Electrostatic Loudspeakers
    7. Ribbon Loudspeakers
    8. Electromagnetic Planar Loudspeakers
    9. Air-Motion Transformers
    10. Plasma Arc Loudspeakers
    11. The Rotary Woofer
    12. MTM Tweeter-Mid Configurations (d’Appolito)
    13. Vertical Line Arrays
      1. Line Array Amplitude Tapering
      2. Line Array Frequency Tapering
    14. CBT Line Arrays
    15. Diffraction
    16. Sound Absorption in Air
    17. Modulation Distortion
    18. Drive Unit Distortion
    19. Doppler Distortion
    20. Further Reading on Loudspeaker Design
  10. Chapter 3: Crossover Requirements
    1. General Crossover Requirements
      1. 1 Adequate Flatness of Summed Amplitude/Frequency Response On-Axis
      2. 2 Sufficiently Steep Roll-Off Slopes Between the Filter Outputs
      3. 3 Acceptable Polar Response
      4. 4 Acceptable Phase Response
      5. 5 Acceptable Group Delay Behaviour
    2. Further Requirements for Active Crossovers
      1. 1 Negligible Extra Noise
      2. 2 Negligible Impairment of System Headroom
      3. 3 Negligible Extra Distortion
      4. 4 Negligible Impairment of Frequency Response
      5. 5 Negligible Impairment of Reliability
    3. Linear Phase
    4. Minimum Phase
    5. Absolute Phase
    6. Phase Perception
    7. Target Functions
  11. Chapter 4: Crossover Types
    1. All-Pole and Non-All-Pole Crossovers
    2. Symmetric and Asymmetric Crossovers
    3. Allpass and Constant-Power Crossovers
    4. Constant-Voltage Crossovers
    5. First-Order Crossovers
    6. First-Order Solen Split Crossover
    7. First-Order Crossovers: 3-Way
    8. Second-Order Crossovers
      1. Second-Order Butterworth Crossover
      2. Second-Order Linkwitz-Riley Crossover
      3. Second-Order Bessel Crossover
      4. Second-Order 1.0 dB-Chebyshev Crossover
    9. Third-Order Crossovers
      1. Third-Order Butterworth Crossover
      2. Third-Order Linkwitz-Riley Crossover
      3. Third-Order Bessel Crossover
      4. Third-Order 1.0 dB-Chebyshev Crossover
    10. Fourth-Order Crossovers
      1. Fourth-Order Butterworth Crossover
      2. Fourth-Order Linkwitz-Riley Crossover
      3. Fourth-Order Bessel Crossover
      4. Fourth-Order 1.0 dB-Chebyshev Crossover
      5. Fourth-Order Linear-Phase Crossover
      6. Fourth-Order Gaussian Crossover
      7. Fourth-Order Legendre Crossover
    11. Higher-Order Crossovers
    12. Determining Frequency Offsets
    13. Filler-Driver Crossovers
    14. The Duelund Crossover
    15. Crossover Topology
    16. Crossover Conclusions
  12. Chapter 5: Notch Crossovers
    1. Elliptical Filter Crossovers
    2. Neville Thiele MethodTM (NTM) Crossovers
  13. Chapter 6: Subtractive Crossovers
    1. Subtractive Crossovers
    2. First-Order Subtractive Crossovers
    3. Second-Order Butterworth Subtractive Crossovers
    4. Third-Order Butterworth Subtractive Crossovers
    5. Fourth-Order Butterworth Subtractive Crossovers
    6. Subtractive Crossovers With Time Delays
    7. Performing the Subtraction
  14. Chapter 7: Lowpass and Highpass Filter Characteristics
    1. Active Filters
    2. Lowpass Filters
    3. Highpass Filters
    4. Bandpass Filters
    5. Notch Filters
    6. Allpass Filters
    7. All-Stop Filters
    8. Brickwall Filters
    9. The Order of a Filter
    10. Filter Cutoff Frequencies and Characteristic Frequencies
    11. First-Order Filters
    12. Second-Order and Higher-Order Filters
    13. Filter Characteristics
      1. Amplitude Peaking and Q
      2. Butterworth Filters
      3. Linkwitz-Riley Filters
      4. Bessel Filters
      5. Chebyshev Filters
      6. 1 dB-Chebyshev Lowpass Filter
      7. 3 dB-Chebyshev Lowpass Filter
    14. Higher-Order Filters
      1. Butterworth Filters up to 8th-Order
      2. Linkwitz-Riley Filters up to 8th-Order
      3. Bessel Filters up to 8th-Order
      4. Chebyshev Filters up to 8th-Order
    15. More Complex Filters—Adding Zeros
      1. Inverse Chebyshev Filters (Chebyshev Type II)
      2. Elliptical Filters (Cauer Filters)
    16. Some Lesser-Known Filter Characteristics
      1. Transitional Filters
      2. Linear-Phase Filters
      3. Gaussian Filters
      4. Legendre-Papoulis Filters
      5. Laguerre Filters
      6. Synchronous Filters
    17. Other Filter Characteristics
  15. Chapter 8: Designing Lowpass Filters: Sallen & Key
    1. Designing Real Filters
    2. Component Sensitivity
    3. First-Order Lowpass Filters
    4. Second-Order Filters
    5. Sallen & Key 2nd-Order Lowpass Filters
    6. Sallen & Key Lowpass Filter Components
    7. Sallen & Key 2nd-Order Lowpass: Unity Gain
    8. Sallen & Key 2nd-Order Lowpass Unity Gain: Component Sensitivity
    9. Filter Frequency Scaling
    10. Sallen & Key 2nd-Order Lowpass: Equal Capacitor
    11. Sallen & Key 2nd-Order Lowpass Equal-C: Component Sensitivity
    12. Sallen & Key 2nd-Order Butterworth Lowpass: Defined Gains
    13. Sallen & Key 2nd-Order Lowpass: Non-Equal Resistors
    14. Sallen & Key 2nd-Order Lowpass: Optimisation
    15. Sallen & Key 3rd-Order Lowpass: Two Stages
    16. Sallen & Key 3rd-Order Lowpass: Single Stage
    17. Sallen & Key 3rd-Order Lowpass in a Single Stage: Non-Equal Resistors
    18. Sallen & Key 4th-Order Lowpass: Two Stages
    19. Sallen & Key 4th-Order Lowpass: Single-Stage Butterworth
    20. Sallen & Key 4th-Order Lowpass: Single-Stage Linkwitz-Riley
    21. Sallen & Key 4th-Order Lowpass: Single Stage With Non-Equal Resistors
    22. Sallen & Key 4th-Order Lowpass: Single Stage With Other Filter Characteristics
    23. Sallen & Key 5th-Order Lowpass: Three Stages
    24. Sallen & Key 5th-Order Lowpass: Two Stages
    25. Sallen & Key 5th-Order Lowpass: Single Stage
    26. Sallen & Key 6th-Order Lowpass: Three Stages
    27. Sallen & Key 6th-Order Lowpass: Single Stage
    28. Sallen & Key Lowpass: Input Impedance
    29. Linkwitz-Riley Lowpass With Sallen & Key Filters: Loading Effects
    30. Lowpass Filters With Attenuation
    31. Bandwidth Definition Filters
    32. Bandwidth Definition: Butterworth Versus Bessel
    33. Variable-Frequency Lowpass Filters: Sallen & Key
  16. Chapter 9: Designing Highpass Filters
    1. First-Order Highpass Filters
    2. Sallen & Key 2nd-Order Filters
    3. Sallen & Key 2nd-Order Highpass Filters
    4. Sallen & Key Highpass Filter Components
    5. Sallen & Key 2nd-Order Highpass: Unity Gain
    6. Sallen & Key 2nd-Order Highpass: Equal Resistors
    7. Sallen & Key 2nd-Order Butterworth Highpass: Defined Gains
    8. Sallen & Key 2nd-Order Highpass: Non-Equal Capacitors
    9. Sallen & Key 3rd-Order Highpass: Two Stages
    10. Sallen & Key 3rd-Order Highpass in a Single Stage
    11. Sallen & Key 4th-Order Highpass: Two Stages
    12. Sallen & Key 4th-Order Highpass: Butterworth in a Single Stage
    13. Sallen & Key 4th-Order Highpass: Linkwitz-Riley in a Single Stage
    14. Sallen & Key 4th-Order Highpass: Single-Stage With Other Filter Characteristics
    15. Sallen & Key 5th-Order Highpass: Three Stages
    16. Sallen & Key 5th-Order Butterworth Filter: Two Stages
    17. Sallen & Key 5th-Order Highpass: Single Stage
    18. Sallen & Key 6th-Order Highpass: Three Stages
    19. Sallen & Key 6th-Order Highpass: Single Stage
    20. Sallen & Key Highpass: Input Impedance
    21. Bandwidth Definition Filters
    22. Bandwidth Definition: Subsonic Filters
    23. Bandwidth Definition: Combined Ultrasonic and Subsonic Filters
    24. Variable-Frequency Highpass Filters: Sallen & Key
  17. Chapter 10: Other Lowpass and Highpass Filters
    1. Designing Filters
    2. Multiple-Feedback Filters
    3. Multiple-Feedback 2nd-Order Lowpass Filters
    4. Multiple-Feedback 2nd-Order Highpass Filters
    5. Multiple-Feedback 3rd-Order Filters
      1. Multiple-Feedback 3rd-Order Lowpass Filters
      2. Multiple-Feedback 3rd-Order Highpass Filters
    6. Biquad Filters
    7. Akerberg-Mossberg Lowpass Filter
    8. Akerberg-Mossberg Highpass Filters
    9. Tow-Thomas Biquad Lowpass and Bandpass Filter
    10. Tow-Thomas Biquad Notch and Allpass Responses
    11. Tow-Thomas Biquad Highpass Filter
    12. State-Variable Filters
    13. Variable-Frequency Filters: State-Variable 2nd Order
    14. Variable-Frequency Filters: State-Variable 4th-Order
    15. Variable-Frequency Filters: Other Orders of State-Variable
    16. Other Filters
  18. Chapter 11: Lowpass and Highpass Filter Performance
    1. Aspects of Filter Performance: Noise and Distortion
    2. Distortion in Active Filters
    3. Distortion in Sallen & Key Filters: The Distortion Aggravation Factor
    4. Distortion in Sallen & Key Filters: Looking for DAF
    5. Distortion in Sallen & Key Filters: 2nd-Order Lowpass
    6. Distortion in Sallen & Key Filters: 2nd-Order Highpass
    7. Mixed Capacitors in Low-Distortion 2nd-Order Sallen & Key Filters
    8. Distortion in Sallen & Key Filters: 3rd-Order Lowpass Single Stage
    9. Distortion in Sallen & Key Filters: 3rd-Order Highpass Single Stage
    10. Distortion in Sallen & Key Filters: 4th-Order Lowpass Single Stage
    11. Distortion in Sallen & Key Filters: 4th-Order Highpass Single Stage
    12. Distortion in Sallen & Key Filters: Simulations
    13. Distortion in Sallen & Key Filters: Capacitor Conclusions
    14. Distortion in Multiple-Feedback Filters: The Distortion Aggravation Factor
    15. Distortion in Multiple-Feedback Filters: 2nd-Order Lowpass
    16. Distortion in Multiple-Feedback Filters: 2nd-Order Highpass
    17. Distortion in Tow-Thomas Filters: 2nd-Order Lowpass
    18. Distortion in Tow-Thomas Filters: 2nd-Order Highpass
    19. Noise in Active Filters
    20. Noise and Bandwidth
    21. Noise in Sallen & Key Filters: 2nd-Order Lowpass
    22. Noise in Sallen & Key Filters: 2nd-Order Highpass
    23. Noise in Sallen & Key Filters: 3rd-Order Lowpass Single Stage
    24. Noise in Sallen & Key Filters: 3rd-Order Highpass Single Stage
    25. Noise in Sallen & Key Filters: 4th-Order Lowpass Single Stage
    26. Noise in Sallen & Key Filters: 4th-Order Highpass Single Stage
    27. Noise in Multiple-Feedback Filters: 2nd-Order Lowpass
    28. Noise in Multiple-Feedback Filters: 2nd-Order Highpass
    29. Noise in Tow-Thomas Filters
  19. Chapter 12: Bandpass and Notch Filters
    1. Multiple-Feedback Bandpass Filters
    2. High-Q Bandpass Filters
    3. Notch Filters
    4. The Twin-T Notch Filter
    5. The 1-Bandpass Notch Filter
    6. The Bainter Notch Filter
      1. Bainter Notch Filter Design
      2. Bainter Notch Filter Example
      3. An Elliptical Filter Using a Bainter Highpass Notch
    7. The Bridged-Differentiator Notch Filter
    8. Boctor Notch Filters
    9. Other Notch Filters
    10. Simulating Notch Filters
  20. Chapter 13: Time-Delay Filters
    1. The Requirement for Delay Compensation
    2. Calculating the Required Delays
    3. Signal Summation
    4. Physical Methods of Delay Compensation
    5. Delay Filter Technology
    6. Sample Crossover and Delay Filter Specification
    7. Allpass Filters in General
    8. First-Order Allpass Filters
    9. Distortion and Noise in 1st-Order Allpass Filters
    10. Cascaded 1st-Order Allpass Filters
    11. Second-Order Allpass Filters
    12. Distortion and Noise in 2nd-Order Allpass Filters
    13. Third-Order Allpass Filters
    14. Distortion and Noise in 3rd-Order Allpass Filters
    15. Higher-Order Allpass Filters
    16. Delay Lines for Subtractive Crossovers
    17. Variable Allpass Time Delays
    18. Lowpass Filters for Time Delays
  21. Chapter 14: Equalisation
    1. The Need for Equalisation
    2. What Equalisation Can and Can’t Do
    3. Loudspeaker Equalisation
    4. 1 Drive Unit Equalisation
    5. 2 6 dB/octave Dipole Equalisation
    6. 3 Bass Response Extension
    7. 4 Diffraction Compensation Equalisation
    8. 5 Room Interaction Correction
    9. Equalisation Circuits
    10. HF-Boost and LF-Cut Equaliser
    11. HF-Cut and LF-Boost Equaliser
    12. Combined HF-Boost and HF-Cut Equaliser
    13. Adjustable Peak/Dip Equalisers: Fixed Frequency and Low Q
    14. Adjustable Peak/Dip Equalisers: Variable Centre Frequency and Low Q
    15. Adjustable Peak/Dip Equalisers With High Q
    16. Parametric Equalisers
    17. The Bridged-T Equaliser
    18. The Biquad Equaliser
    19. Capacitance Multiplication for the Biquad Equaliser
    20. Equalisers With Non-Standard Slopes
      1. Equalisers With −3 dB/Octave Slopes
      2. Equalisers With −3 dB/Octave Slopes Over Limited Range
      3. Equalisers With −4.5 dB/Octave Slopes
      4. Equalisers With Other Slopes
    21. Equalisation by Filter Frequency Offset
    22. Equalisation by Adjusting All Filter Parameters
  22. Chapter 15: Passive Components for Active Crossovers
    1. Component Values
    2. Resistors
      1. Through-Hole Resistors
      2. Surface-Mount Resistors
    3. Resistors: Values and Tolerances
    4. Improving Accuracy With Multiple Components: Gaussian Distribution
    5. Resistor Value Distributions
    6. Improving Accuracy With Multiple Components: Uniform Distribution
    7. Obtaining Arbitrary Resistance Values
    8. Other Resistor Combinations
    9. Resistor Noise: Johnson and Excess Noise
    10. Resistor Non-Linearity
    11. Capacitors: Values and Tolerances
    12. Obtaining Arbitrary Capacitance Values
    13. Capacitor Shortcomings
    14. Non-Electrolytic Capacitor Non-Linearity
    15. Electrolytic Capacitor Non-Linearity
  23. Chapter 16: Opamps for Active Crossovers
    1. Active Devices for Active Crossovers
    2. Opamp Types
    3. Opamp Properties: Noise
    4. Opamp Properties: Slew Rate
    5. Opamp Properties: Common-Mode Range
    6. Opamp Properties: Input Offset Voltage
    7. Opamp Properties: Bias Current
    8. Opamp Properties: Cost
    9. Opamp Properties: Internal Distortion
    10. Opamp Properties: Slew Rate Limiting Distortion
    11. Opamp Properties: Distortion Due to Loading
    12. Opamp Properties: Common-Mode Distortion
    13. Opamps Surveyed
    14. The TL072 Opamp
    15. The NE5532 and 5534 Opamps
      1. The 5532 With Shunt Feedback
      2. 5532 Output Loading in Shunt-Feedback Mode
      3. The 5532 With Series Feedback
      4. Common-Mode Distortion in the 5532
      5. Reducing 5532 Distortion by Output Stage Biasing
      6. Which 5532?
      7. The 5534 Opamp
    16. The LM4562 Opamp
      1. Common-Mode Distortion in the LM4562
    17. The LME49990 Opamp
      1. Common-Mode Distortion in the LME49990
    18. The AD797 Opamp
      1. Common-Mode Distortion in the AD797
    19. The OP27 Opamp
    20. Opamp Selection
  24. Chapter 17: Active Crossover System Design
    1. Crossover Features
      1. Input Level Controls
      2. Subsonic Filters
      3. Ultrasonic Filters
      4. Output Level Trims
      5. Output Mute Switches, Output Phase-Reverse Switches
      6. Control Protection
    2. Features Usually Absent
      1. Metering
      2. Relay Output Muting
    3. Switchable Crossover Modes
    4. Noise, Headroom, and Internal Levels
    5. Circuit Noise and Low-Impedance Design
    6. Using Raised Internal Levels
    7. Placing the Output Attenuator
    8. The Amplitude/Frequency Distribution of Musical Signals and Internal Levels
    9. Gain Structures
    10. Noise Gain
    11. Active Gain Controls
    12. Filter Order in the Signal Path
    13. Output Level Controls
    14. Mute Switches
    15. Phase-Invert Switches
    16. Distributed Peak Detection
    17. Power Amplifier Considerations
  25. Chapter 18: Subwoofer Crossovers
    1. Subwoofer Applications
    2. Subwoofer Technologies
      1. Sealed-Box (Infinite Baffle) Subwoofers
      2. Reflex (Ported) Subwoofers
      3. Auxiliary Bass Radiator (ABR) Subwoofers
      4. Transmission Line Subwoofers
      5. Bandpass Subwoofers
      6. Isobaric Subwoofers
      7. Dipole Subwoofers
      8. Horn-Loaded Subwoofers
    3. Subwoofer Drive Units
    4. Hi-Fi Subwoofers
    5. Home Entertainment Subwoofers
      1. Low-Level Inputs (Unbalanced)
      2. Low-Level Inputs (Balanced)
      3. High-Level Inputs
      4. High-Level Outputs
      5. Mono Summing
      6. LFE Input
      7. Level Control
      8. Crossover In/Out Switch
      9. Crossover Frequency Control (Lowpass Filter)
      10. Highpass Subsonic Filter
      11. Phase Switch (Normal/Inverted)
      12. Variable Phase Control
      13. Signal Activation Out of Standby
    6. Home Entertainment Crossovers
      1. Fixed Frequency
      2. Variable Frequency
      3. Multiple Variable
    7. Power Amplifiers for Home Entertainment Subwoofers
    8. Subwoofer Integration
    9. Sound-Reinforcement Subwoofers
      1. Line or Area Arrays
      2. Cardioid Subwoofer Arrays
    10. Aux-Fed Subwoofers
    11. Automotive Audio Subwoofers
  26. Chapter 19: Motional Feedback Loudspeakers
    1. Motional Feedback Loudspeakers
    2. History
    3. Feedback of Position
    4. Feedback of Velocity
    5. Feedback of Acceleration
    6. Other MFB Speakers
    7. Published Projects
    8. Conclusions
  27. Chapter 20: Line Inputs
    1. External Signal Levels
    2. Internal Signal Levels
    3. Input Amplifier Functions
    4. Unbalanced Inputs
    5. Balanced Interconnections
    6. The Advantages of Balanced Interconnections
    7. The Disadvantages of Balanced Interconnections
    8. Balanced Cables and Interference
    9. Balanced Connectors
    10. Balanced Signal Levels
    11. Electronic vs Transformer Balanced Inputs
    12. Common-Mode Rejection Ratio (CMRR)
    13. The Basic Electronic Balanced Input
    14. Common-Mode Rejection Ratio: Opamp Gain
    15. Common-Mode Rejection Ratio: Opamp Frequency Response
    16. Common-Mode Rejection Ratio: Opamp CMRR
    17. Common-Mode Rejection Ratio: Amplifier Component Mismatches
    18. A Practical Balanced Input
    19. Variations on the Balanced Input Stage
    20. Combined Unbalanced and Balanced Inputs
    21. The Superbal Input
    22. Switched-Gain Balanced Inputs
    23. Variable-Gain Balanced Inputs
    24. The Self Variable-Gain Balanced Input
    25. High Input Impedance Balanced Inputs
    26. The Instrumentation Amplifier
    27. Instrumentation Amplifier Applications
    28. The Instrumentation Amplifier With 4x Gain
    29. The Instrumentation Amplifier at Unity Gain
    30. Transformer Balanced Inputs
    31. Input Overvoltage Protection
    32. Noise and Balanced Inputs
    33. Low-Noise Balanced Inputs
    34. Low-Noise Balanced Inputs in Real Life
    35. Ultra-Low-Noise Balanced Inputs
  28. Chapter 21: Line Outputs
    1. Unbalanced Outputs
    2. Zero-Impedance Outputs
    3. Ground-Cancelling Outputs
    4. Balanced Outputs
    5. Transformer Balanced Outputs
    6. Output Transformer Frequency Response
    7. Transformer Distortion
    8. Reducing Transformer Distortion
  29. Chapter 22: Power Supply Design
    1. Opamp Supply Rail Voltages
    2. Designing a ±15 V Supply
    3. Designing a ±17 V Supply
    4. Using Variable-Voltage Regulators
    5. Improving Ripple Performance
    6. Dual Supplies From a Single Winding
    7. Mutual Shutdown Circuitry
    8. Power Supplies for Discrete Circuitry
  30. Chapter 23: An Active Crossover Design
    1. Design Principles
    2. Example Crossover Specification
    3. The Gain Structure
    4. Resistor Selection
    5. Capacitor Selection
    6. The Balanced Line Input Stage
    7. The Bandwidth Definition Filter
    8. The HF Path: 3 kHz Linkwitz-Riley Highpass Filter
    9. The HF Path: Time-Delay Compensation
    10. The MID Path: Topology
    11. The MID Path: 400 Hz Linkwitz-Riley Highpass Filter
    12. The MID Path: 3 kHz Linkwitz-Riley Lowpass Filter
    13. The MID Path: Time-Delay Compensation
    14. The LF Path: 400 Hz Linkwitz-Riley Lowpass Filter
    15. The LF Path: No Time-Delay Compensation
    16. Output Attenuators and Level Trim Controls
    17. Balanced Outputs
    18. Crossover Programming
    19. Noise Analysis: Input Circuitry
    20. Noise Analysis: HF Path
    21. Noise Analysis: MID Path
    22. Noise Analysis: LF Path
    23. Improving the Noise Performance: The MID Path
    24. Improving the Noise Performance: The Input Circuitry
    25. The Noise Performance: Comparisons With Power Amplifier Noise
    26. Conclusion
  31. Appendix 1 Crossover Design References
  32. Appendix 2 US Crossover Patents
  33. Appendix 3 Crossover and Loudspeaker Articles in Wireless World/Electronics World
  34. Appendix 4 Loudspeaker Design References
  35. Appendix 5 Component Series E3 to E96
  36. Index