Electronics for Guitarists

Preface
Who This Book Is Written For
Analog Rules!
About the Math
Building the Circuits
Vacuum Tubes
The Third Edition
Safety
Disclaimer
Acknowledgments
Contact Information
Internet Links and Descriptions Used in Text
Contents
List of Figures
Chapter 1: Power Supplies
Introduction
A Simple Power Supply Circuit
The Transformer
The Rectifier
Analysis of the Rectifier
The Frequency Domain
The Filter
Ripple Voltage
Filter Analysis: The Frequency Domain
Response Curves, Decades, and Octaves
Power Indicators
Neon Lamps
Light-Emitting Diodes
LED Current Limiting Resistor Calculation
Incandescent Lamps
A Basic Regulated Power Supply
The 78xx Voltage Regulator
Dropout Voltage
Power Dissipation
Bipolar Power Supplies
Using Batteries for Bipolar Power
A Typical Bipolar Power Supply
A Regulated Bipolar Power Supply
Two-Diode, Full-Wave Rectifier
Basic Vacuum Tube Diode Power Supplies
Vacuum Tube Diodes
Reverse Bias
Forward Bias
The 5AR4, 5U4-GB, and 5Y3-GT Diodes
Typical Vacuum Tube Diode Power Supplies
The LC, Pi Filter
RC Pi Filter
Supply Voltage Distribution
Final Comments
Summary of Equations
Chapter 2: Pickups and Volume and Tone Controls
Introduction
Single-Coil Magnetic Pickups
Humbucker Pickups
Peak and Average Output Voltages
More Magnetic Pickup Analysis
Inductance
A Pickup Winding Example
Winding Resistance
Winding Capacitance
Approximate Circuit Model for a Magnetic Pickup
Piezoelectric Pickups
Piezoelectric Pickup Analysis
Example of Calculation: Input Resistance and Corner Frequency
Guitar Volume and Tone Control Circuits
Potentiometers
Potentiometer Taper
The Transfer Function
Rheostats
Basic Guitar Tone Control Operation
Damping
Multiple Pickups
Pickup Phasing
Amplifier Tone Control Circuits
A Basic Tone Control Circuit
Improved Single-Pot Tone Control
Baxandall Tone Control
Other Tone Control Circuits
Final Comments
Summary of Equations
Chapter 3: Small-Signal and Low-Power Amplifiers
Introduction
Gain
Decibels
Other Amplifier Parameters
Distortion
Input Resistance
Output Resistance
Bandwidth
Slew Rate
Amplifier Classifications and Biasing
Bipolar Junction Transistors
The Active Region
Saturation
Cutoff
Biasing
Class A
Class B
Class AB
The Load Line
Clipping
DC and AC Load Lines
Class A Power Dissipation Characteristics
The Common Emitter Configuration
The Emitter Follower (Common Collector) Configuration
The Common Base Configuration
Field Effect Transistors
Bipolar Transistor Specifications
Basic BJT Amplifier Operation
Voltage Divider Biased CE Amplifier
DC Q-Point Analysis Equations for Fig. 3.13
Beta Independence
AC Analysis Equations for Fig. 3.13
Common Emitter Amplifier Analysis Example
DC Q-Point Analysis
AC Analysis
Experimental Results
Some Practical Testing and Measurement Tips
Amplifying a Guitar Signal
Frequency Response
Negative Feedback
Local and Global Feedback
A JFET Common Source, Class A Amplifier
JFET Parameters
JFET Amplifier Overview
JFET Centered Q-Point
BJT vs. JFET
Piezoelectric Pickup Preamplifier
Phone Jack Power Switching
Increasing Voltage Gain
A JFET-BJT Multiple-Stage Amplifier
Some Useful Modifications
A Closer Look at Transconductance
BJT, JFET, and MOSFET Transconductance Equations
A MOSFET Common Source Amplifier
Theoretical Analysis
Experimental Results
Operational Amplifiers
Basic Noninverting and Inverting Op Amp Equations
Noninverting and Inverting Amplifier Analysis
Power Bandwidth
Single-Polarity Supply Operation
Noninverting Amplifier
The Two Golden Rules of Op Amp Analysis
Inverting Amplifier
Parasitic Oscillation
Inside the Op Amp
Operational Transconductance Amplifiers
An OTA Analysis Example
The OTA as a Voltage-Controlled Amplifier
Current Difference Amplifiers
Your Turn
Miscellaneous Useful Circuits
An Audio Test Oscillator
A Closer Look at the Oscillator Output Signal
The Rail Splitter
High-Power Rail Splitter
Use with Pedal Boards and Daisy Chain Power Cords
Charge Pumps
Charge Pump vs. Rail Splitter
Class A, Collector Feedback, Germanium Transistor Amplifier
DC Analysis
AC Analysis
Experimental Results
Practical Use of the Amplifier
An Alternate JFET Input Version
Mixing Magnetic and Piezo Pickups
Final Comments
Summary of Equations
Chapter 4: Solid-State Power Amplifiers
Introduction
The Basic Push-Pull Stage
Class AB: Eliminating Crossover Distortion
Output Power Determination
Bipolar Power Supply Operation
Power Transistors
Composite Transistors
Darlington Transistors
Sziklai Transistors
A Complete Power Amplifier
Output Stage Analysis
Transistor Thermal Analysis
Parallel-Connected Power Transistors
Thermal Runaway
Push-Pull Stage with Parallel Transistors
Adding a Tone Control
Amplifier Stability Issues
Ground Reference
Star Grounding
Motorboating
Decoupling Capacitors
The Zobel Network
MOSFET Output Stages
The VBE Multiplier
The Rail Splitter Revisited
Enclosing Base-Emitter Junction in the Feedback Loop
Converting the Rail Splitter to an Amplifier
Slew Rate-Induced Crossover Distortion
Final Comments
Summary of Equations
Chapter 5: Effects Circuits
Introduction
Signals and Spectra
Time, Period, Frequency, and Pitch
Sinusoids in the Time Domain
Waveform Shape, Symmetry, and Harmonic Relationships
Transfer Function Symmetry and Harmonic Distortion
An Odd Symmetry Example
An Even Symmetry Example
An Example of Neither Even Nor Odd Symmetry
Intermodulation Distortion
Influence of Amplifier Design on Distortion
Effects of Negative Feedback
Single-Ended vs. Push-Pull
Effects of Device Transfer Characteristics on Distortion
BJTs
FETs
Triodes
Effect Bypassing
Overdrive Circuits
Single-Stage Transistor Overdrives
Simple BJT Overdrive
Sziklai Overdrive Circuit
Darlington Overdrive Circuit
Multiple-Stage Overdrive Circuits
JFET/BJT Overdrive
MOSFET/PNP Germanium Overdrive
An Op Amp Overdrive Circuit
Distortion Circuits
Fuzz vs. Distortion
Diode Clippers
Asymmetrical Clipper with Power Indicator
Adjustable Op Amp Distortion Circuit
Logarithmic Amplifiers
Log Amp Output Equation Derivation
Log Amp Distortion Circuit
Phase Shifters
The All-Pass Filter
Optocouplers
An Experimental Phase Shifter Circuit
Flangers
Flanging vs. Phase-Shifting
Bucket-Brigade Devices
Clock and LFO Generation
A BBD-Based Flanger
Sampling Frequency and Aliasing
Anti-aliasing and Reconstruction Filters
Oversampling
Chorus Effect
Envelope Followers
Signal Envelope
Precision Rectifier Circuits
Precision Half-Wave Rectifiers
Precision Full-Wave Rectifier
An Experimental Envelope Follower
String Frequency-to-Pulse Converter
Compression, Sustain, and Dynamic Range
Voltage-Controlled Amplifiers
Experimental OTA-Based Compressor
Experimental LDR-Based Compression/Sustain
Tremolo
Reverberation
Delay Time
Decay Time
Reverb Springs
A Digital Reverb
Modulation and Pitch Shifting
Amplitude Modulation
Balanced (Ring) Modulation
An Experimental Ring Modulator
Frequency Doubling
A Deeper Dive
Analog Multipliers
Vocoders
Wah-Wah Circuits
IGMF Bandpass Filter
An IGMF Design Example
Varying fo of the IGMF
Experimental IGMF Wah-Wah Circuits
Eliminating Switching Pop
A Gyrator-Based Wah-Wah Circuit
Envelope-Controlled Filter (Auto-Wah)
Noise Gates
A Little Deeper Look at the LM358
Sampling, Quantization, DACs, and ADCs
The R-2R Ladder
DAC Operation
Effect on an Audio Signal
Final Comments
Summary of Equations
Chapter 6: Low-Power Vacuum Tube Amplifiers
Introduction
Commonly Used Vacuum Tubes
Parts Sources and Availability
Vacuum Tube Parameters and Data Sheets
Absolute Maximum Ratings
Other Data Sheet Parameters
Tube Pin Numbering
General Amplifier Design Principles
Cathode Feedback Biasing
Fixed Biasing
Class A, Resistance-Coupled, Common Cathode Amps
12AU7 Low-Power Amp Design Example
Alternative Determination of Cathode Resistance RK
DC and AC Load Lines
Amplifier AC Performance
Output Voltage Compliance
Experimental Test Results
Q-Point Location and Distortion
6AN8 Triode, Low-Power Amp Design Example
Amplifier AC Performance
The AC Load Line
Output Voltage Compliance
12AX7 Low-Power Amp Design Example
Amplifier AC Performance
The AC Load Line
Output Voltage Compliance
Experimental Results
12AT7 Low-Power Amp Design Example
Amplifier AC Performance
Output Voltage Compliance
Pentodes
Screen Grid (G2)
Suppressor Grid (G3)
6AN8 Pentode, Low-Power Amp Design Example
Amplifier AC Performance
Output Voltage Compliance
Cathode Followers and Phase Splitters
Cathodyne Phase Splitter Design
Cathode Resistor Determination
AC Characteristics
A Cathodyne Variation
Differential Pair Phase Splitter
A Practical Differential Phase Splitter
Transformer-Coupled Phase Splitter
Determination of Tube Parameters: gm, rP, and μ
Basic Definitions of gm, rP, and μ
Determination of Triode-Mode Transconductance
Determination of Triode-Mode Mu
Determination of Triode Dynamic Plate Resistance
Final Comments
Summary of Equations
Chapter 7: Vacuum Tube Power Amplifiers
Introduction
Maximum Power Transfer
Basic Transformer Operation
Reflected Load Resistance
Magnetic Saturation
Transformer Coupling
Advantages and Disadvantages
A Sampling of Audio Output Transformers
Class A, Single-Ended Amplifiers
6L6GC Triode-Mode, SE Amplifier Design Example
Choosing an Output Tube
Choosing Power Supply Voltage
Choosing Quiescent Plate Current IPQ
Output Transformer Selection
The DC Load Line
Two Useful Approximations
The AC Load Line
Q-Point Voltage Limits
AC Characteristics of the Amplifier
Grid Resistors and the Gamma Network
Substituting an EL34
Q-Point Analysis
6L6GC Pentode-Mode, SE Amplifier Design Example
Choosing Power Supply Voltage
Choosing Quiescent Plate Current IPQ
Output Transformer Selection
The AC Load Line
Q-Point Voltage Limits
AC Characteristics of the Amplifier
Grid Resistor and Gamma Network
The Screen Grid Resistor, R3
EL84 Pentode-Mode, SE Amplifier Design Example
Choosing Power Supply Voltage
Q-Point Selection
Output Transformer and R′L Selection
Determine Cathode Resistance R4
The AC Load Line
Q-Point Voltage Limits
AC Characteristics of the Amplifier
Grid Resistor and Gamma Network
The Screen Grid Resistor
EL34 Pentode-Mode, SE Amplifier Design Example
Plot Q-Point
Determine Cathode Resistance RK
Select Output Transformer
Plot AC Load Line
Q-Point Voltage Compliance
AC Characteristics of the Amplifier
Grid Resistors and Gamma Network
Selectable Triode/Pentode Operation
Switching RK and Suppressor Grid G2
Switching Only G2
Parallel-Connected Tubes
Complete SE Amplifier Examples
6AQ5 Low-Power, SE Practice Amp
Amplifier Analysis
The Power Supply
Efficiency
The Finished Amplifier
6L6/EL34 Dual-Mode, SE Amplifier
The Power Supply
Eliminating the Choke
Amplifier Performance
Adding A Spring Reverb
The Reverb Tank
Reverb Design Considerations
EL84, 4 Watt, SE Amplifier
Adding a Reverb
The Power Supply
Class A, Single-Ended Amp Distortion
Push-Pull Amplifiers
Basic DC Operation
Basic AC Operation
AC Analysis of the Push-Pull Output Transformer
Push-Pull Class A Distortion
EL34 Triode-Mode, Push-Pull Design Example
Q-Point Location and Determination of RK
Output Transformer Selection
The AC Load Line
AC Characteristics of the Amplifier
The Cathode Bypass Capacitor
A Complete EL34 Triode-Mode Amplifier
6L6GC Pentode-Mode, Push-Pull Design Example
Q-Point Location and Determination of RK
Output Transformer Selection
The AC Load Line
AC Characteristics of the Amplifier
A Complete 6L6GC Amplifier
Standby Operation
6V6 Amplifier with Effects Loop
The Effects Loop
Low-Power Sections
The Output Stage
The Power Supply
Ultralinear Amplifiers
Construction Techniques and Tips
Chassis Materials
Wiring Tips
Testing Tips
Build and Test the Amp in Stages
Never Operate the Amp Without a Load
Final Comments
Summary of Equations
Appendices
Appendix A: Some Basic Circuit Theory
Voltage and Current Polarities and Conventions
Linear Circuits
Series Circuits
Ohm´s Law
Kirchhoff´s Voltage Law
Parallel Circuits
Nodes
Branches
Kirchhoff´s Current Law
The Superposition Principle
Capacitors, Inductors, and Complex Numbers
Transient Behavior
Steady-State Behavior
Summary of Useful Formulas
Ohm´s Law
n Series Resistances
n Parallel Resistances
Frequency and Period
Charging and Discharging Capacitor
Inductive and Capacitive Reactance
Bipolar Transistor Relationships
Triode Relationships
JFET Relationships
Appendix B: Selected Tube Characteristic Curves
Appendix C: Basic Vacuum Tube Operating Principles
Diodes
Reverse Bias
Forward Bias
Triodes
Amplification Factor
Transconductance
Dynamic Plate Resistance
Tetrodes
Pentodes
Index