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Self on Audio, 2nd Edition

Book Description

Whether you are a dedicated audiophile who wants to gain a more complete understanding of the design issues behind a truly great amp, or a professional electronic designer seeking to learn more about the art of amplifier design, there can be no better place to start than with the 35 classic magazine articles collected together in this book.

Douglas Self offers a tried and tested method for designing audio amplifiers in a way that improves performance at every point in the circuit where distortion can creep in – without significantly increasing cost. Through the articles in this book, he takes readers through the causes of distortion, measurement techniques, and design solutions to minimise distortion and efficiency. Most of the articles are based round the design of a specific amplifier, making this book especially valuable for anyone considering building a Self amplifier from scratch.

Self is senior designer with a high-end audio manufacturer, as well as a prolific and highly respected writer. His career in audio design is reflected in the articles in this book, originally published in the pages of Electronics World and Wireless World over a 25 year period.

* An audio amp design cookbook, comprising 35 of Douglas Self's definitive audio design articles
* Complete designs for readers to build and adapt
* An anthology of classic designs for electronics enthusiasts, Hi-Fi devotees and professional designers alike

Table of Contents

  1. Cover image
  2. Title page
  3. Table of Contents
  4. Copyright page
  5. Introduction
  6. Preamplifiers and related matters
    1. 1: Advanced preamplifier design
      1. Audio circuitry
      2. Level detection circuitry
      3. Noise gate
    2. 2: High-performance preamplifier
      1. Disc input stage
      2. Construction
    3. 3: Precision preamplifier
      1. Architecture
      2. Subsonic filter
      3. High-impedance buffer
      4. Tone-control stage
      5. Active gain-control stage
      6. Power supply
      7. Construction
    4. 4: Design of moving-coil head amplifiers
      1. Design problems
      2. A new approach
      3. The final circuit
      4. Comparing performance parameters
      5. Practice
    5. 5: Precision preamplifier ’96, Part I
      1. The evolution of preamplifiers
      2. Design philosophy
      3. The preamp gain structure
      4. Disc input
      5. Moving-coil input criteria
      6. The moving-magnet input stage
      7. In search of accurate RIAA
      8. Noise considerations
      9. Circuit details
    6. 6: Precision preamplifier ’96, Part II
      1. Line input criteria
      2. Line input buffering
      3. Controlling tone
      4. Bass and treble
      5. Turnover
      6. Active gain stage
      7. Output muting and relay control
      8. DC blocking and additional details
      9. Supplying power
      10. Choosing the right op-amps
      11. The performance
      12. The preamplifier in perspective
    7. 7: Overload matters
    8. 8: A balanced view, Part I
      1. Electronic versus transformer balancing
      2. Balancing basics
      3. Electrical noise
      4. Line outputs
    9. 9: A balanced view, Part II
      1. Balanced input technologies
      2. Input/output combinations
      3. Wiring philosophies
    10. 10: High-quality compressor/limiter
      1. Components list
    11. 11: Inside mixers
      1. Microphone inputs
      2. Equalisation
      3. Auxiliary sends: foldback and effects
      4. Panpot
      5. Summing
      6. Solid-state switching
      7. Performance factors
      8. Appendix the technique of multitrack recording
    12. 12: Electronic analogue switching, Part I: CMOS gates
      1. Electronic switching
      2. Part 1: analogue gates
      3. CMOS gates in voltage mode
      4. CMOS gates in current mode
      5. Series-shunt current mode
      6. Control voltage feedthrough in CMOS gates
    13. 13: Electronic analogue switching, Part II: discrete FETs
      1. Discrete FET switching
      2. Discrete FETs in voltage mode: the series JFET switch
      3. The shunt JFET switch
      4. Discrete FETs in current mode
      5. Soft changeover circuit
      6. Control voltage feedthrough in JFETs
  7. Power Amplifiers
    1. 14: Sound mosfet design
      1. Design fundamentals
      2. Determining performance
      3. Reducing costs
      4. Reducing distortion
    2. 15: FETs versus BJTs: the linearity competition
      1. Class A stage
    3. 16: Distortion in power amplifiers, Part I: the sources of distortion
      1. How an amplifier (really) works
      2. The seven distortions
      3. The performance
      4. Determining open-loop linearity
      5. Direct open-loop gain measurement
      6. Model amplifiers
    4. 17: Distortion in power amplifiers, Part II: the input stage
      1. Vive la differential
      2. Input stage in isolation
      3. Input stage balance
      4. The joy of current mirrors
      5. Improving linearity
      6. Other considerations
    5. 18: Distortion in power amplifiers, Part III: the voltage-amplifier stage
      1. Examining the mechanism
      2. Stage distortion
      3. Voltage stage enhancements
      4. Benefits of voltage drive
      5. Balanced voltage amplifier stage
      6. Open loop bandwidth
    6. 19: Distortion in power amplifiers, Part IV: the power amplifier stages
      1. The class war
      2. Distortions of the output
      3. The emitter follower output
      4. Complementary feedback output
      5. Quasicomplementary outputs
      6. Triples
      7. Power FET outputs
    7. 20: Distortion in power amplifiers, Part V: output stages
      1. Large-signal distortion
      2. Improving large signal linearity
      3. Crossover distortion
      4. Switching distortion
      5. Selecting an output stage
      6. Closing the loop
      7. Conclusions
    8. 21: Distortion in power amplifiers, Part VI: the remaining distortions
      1. Distortion 3: quiescent current control
      2. Emitter follower outputs
      3. The CFP output
      4. Distortion 4: nonlinear loading of the voltage amplifier stage by the nonlinear impedance of the output stage
      5. Distortion 5: supply ground loops
      6. Power supply rejection
      7. Distortion 6: induced output current coupling
      8. Distortion 7: nonlinearity from incorrect NFB connection point
    9. 22: Distortion in power amplifiers, Part VII: frequency compensation and real designs
      1. Making a pole dominant
      2. Including the output stage
      3. Nested feedback loops
      4. Two pole compensation
      5. Design example: a 50 W class B amplifier
      6. Quiescent current stability
      7. Output stage
    10. 23: Distortion in power amplifiers, Part VIII: Class A amplifiers
      1. The art of compromise
      2. The class A output stage
      3. Quiescent control systems
      4. A new class A design
      5. Performance
      6. And finally
    11. 24: Power amplifier input currents and their troubles
      1. Conclusions
    12. 25: Diagnosing distortions
      1. Making distortion measurements
      2. Two technical challenges
      3. Crossover distortion
      4. Classes B and AB
      5. Large-signal non-linearity
      6. Other distortions
      7. Diagnosis
    13. 26: Trimodal audio power, Part I
      1. The power and the glory
      2. Health and efficiency
      3. Improving noise performance
    14. 27: Trimodal audio power, Part II
      1. Test mode
      2. Thermal design
      3. The complete circuit
      4. Performance
    15. 28: Load-invariant audio power
      1. Output loading and distortion
      2. The load-invariant concept
      3. Large signal nonlinearity
      4. Doubled output devices
      5. Better output devices
      6. Feeding forward
      7. The trouble with triples
      8. Loads below 4 Ω
      9. Improved 8 Ω performance
      10. Implementing the load-invariant concept
      11. A point of departure
      12. In summary
    16. 29: Common-emitter power amplifiers: a different perception?
      1. Topology to the test
      2. Adding Spice to the investigation
      3. Squaring the circle
    17. 30: Few compliments for non-complements
      1. An alternative architecture
      2. Fewer stages, more complexity?
      3. Devices and desires
      4. Output considerations
    18. 31: Loudspeaker undercurrents
      1. Speaker model
      2. Simulating the effects
      3. And with multiple speakers?
    19. 32: Class distinction
      1. Class structure
      2. Combinations of classes
      3. Parallel or series connection
      4. Series connection category
      5. In summary
    20. 33: Muting relays
      1. Protection circuit operation
      2. Relay-on timing
      3. Off timing criteria
      4. AC loss detection
      5. Preamp enhancement
      6. Other relay functions
      7. Power amplifier relay control
      8. Efficiency circuit
    21. 34: Cool audio power
      1. The mathematical approach
      2. Simulating dissipation
      3. Power-partition diagrams
      4. Effects of increased bias
      5. Class-B and reactive loads
    22. 35: Audio power analysis
      1. The probability density function
      2. The cumulative distribution function
      3. Some probability density functions
      4. Measuring probability density functions
      5. Probability density functions via DSP
      6. Deriving actual power
      7. Reactive loads
      8. In summary
  8. Index