Valve Amplifiers has been recognized as the most comprehensive guide to valve amplifier design, analysis, modification and maintenance. It provides a detailed presentation of the rudiments of electronics and valve design for engineers and non-experts. The source also covers design principles and construction techniques to help end users build their own tool from scratch designs that work. The author's approach walks the reader through each step of designing and constructing, starting with an overview of the essential working principles of valve amplifiers, the simple and complex stages, the process of linking the stages, and completing the design.
The book is comprised of seven chapters all of which include a DIY guide discussion of practical aspects. The text starts with familiarization of the fundamentals of electronics, which are essential for designing and building valve amplifiers. Particular attention has been paid to providing solutions for questions that are commonly asked and faced by beginners in valve designing and construction.
Valve Amplifiers is a masterful hands-on guide for both experts and novices who work with tube audio equipment, and for electronic hobbyists, audio engineers, and audiophiles.
- The practical guide to analysis, modification, design, construction and maintenance of valve amplifiers
- The fully up-to-date approach to valve electronics
- Essential reading for audio designers and music and electronics enthusiasts alike
Inhaltsverzeichnis
1;Front Cover;1 2;Valve Amplifiers;4 3;Copyright Page;5 4;Contents;6 5;Preface;10 6;Dedication;12 7;Acknowledgements;14 8;1. Circuit Analysis;16 8.1;Mathematical Symbols;16 8.2;Electrons and Definitions;17 8.2.1;Batteries and Lamps;19 8.2.2;Ohms Law;20 8.2.3;Power;21 8.2.4;Kirchhoffs Laws;22 8.2.5;Resistors in Series and Parallel;24 8.3;Potential Dividers;29 8.3.1;Equivalent Circuits;29 8.3.2;The Thévenin Equivalent Circuit;30 8.3.3;The Norton Equivalent Circuit;33 8.3.4;Units and Multipliers;34 8.3.5;The Decibel;35 8.4;Alternating Current (AC);36 8.4.1;The Sine Wave;36 8.4.2;The Transformer;39 8.4.3;Capacitors, Inductors and Reactance;40 8.4.4;Filters;42 8.4.5;Time Constants;45 8.4.6;Resonance;46 8.4.7;RMS and Power;48 8.4.8;The Square Wave;49 8.4.9;Square Waves and Transients;50 8.4.10;Random Noise;55 8.5;Active Devices;56 8.5.1;Conventional Current Flow and Electron Flow;56 8.6;Silicon Diodes;57 8.6.1;Voltage References;58 8.7;Bipolar Junction Transistors (BJTs);60 8.7.1;The Common Emitter Amplifier;62 8.7.2;Considering DC Conditions;64 8.7.3;Input and Output Resistances;64 8.7.4;The Emitter Follower;66 8.7.5;The Darlington Pair;67 8.8;General Observations on BJTs;67 8.9;Feedback;68 8.9.1;The Feedback Equation;68 8.9.2;Practical Limitations of the Feedback Equation;69 8.9.3;Feedback Terminology and Input and Output Impedances;70 8.10;The Operational Amplifier;71 8.10.1;The Inverter and Virtual Earth Adder;72 8.10.2;The Non-Inverting Amplifier and Voltage Follower;73 8.10.3;The Integrator;75 8.10.4;The Charge Amplifier;75 8.10.5;DC Offsets;77 8.11;References;78 8.12;Recommended Further Reading;78 9;2. Basic Building Blocks;80 9.1;The Common Cathode Triode Amplifier;80 9.1.1;Limitations on Choice of the Operating Point;83 9.1.2;Conditions at the Operating Point;85 9.1.3;Dynamic, or AC, Parameters;88 9.1.4;Cathode Bias;91 9.1.5;The Effect on AC Conditions of an Unbypassed Cathode Bias Resistor;93 9.1.6;The Cathode Decoupling Capacitor;94 9.1.7;Choice of Value of Gri
d-Leak Resistor;96 9.1.8;Choice of Value of Output Coupling Capacitor;98 9.1.9;Miller Capacitance;98 9.1.10;Reducing Output Resistance of the Previous Stage;100 9.1.11;Guided-Grid, or Beam, Triodes;100 9.2;The Tetrode;101 9.3;The Beam Tetrode and the Pentode;102 9.3.1;The Significance of the Pentode Curves;104 9.3.2;Using the EF86 Small-Signal Pentode;106 9.4;The Cascode;109 9.5;The Charge Amplifier;117 9.6;The Cathode Follower;118 9.7;Sources and Sinks: Definitions;122 9.8;The Common Cathode Amplifier as a Constant Current Sink (CCS);124 9.8.1;Pentode Constant Current Sinks;126 9.9;The Cathode Follower with Active Load;128 9.10;The White Cathode Follower;129 9.10.1;Analysis of the Self-Contained White Cathode Follower;129 9.10.2;The White Cathode Follower as an Output Stage;132 9.11;The μ-Follower;133 9.11.1;The Importance of the AC Loadline;137 9.11.2;Upper Valve Choice in the μ-Follower;137 9.11.3;Limitations of the μ-Follower;138 9.12;The Shunt-Regulated PushPull Amplifier (SRPP);140 9.13;The β-Follower;143 9.14;The Cathode-Coupled Amplifier;145 9.15;The Differential Pair;148 9.15.1;Gain of the Differential Pair;150 9.15.2;Output Resistance of the Differential Pair;150 9.15.3;AC Balance of the Differential Pair and Signal at the Cathode Junction;151 9.15.4;Common-Mode Rejection Ratio (CMRR);151 9.15.5;Power Supply Rejection Ratio (PSRR);153 9.16;Semiconductor Constant Current Sinks;154 9.16.1;Using Transistors as Active Loads for Valves;157 9.16.2;Optimising rout by Choice of Transistor Type;160 9.16.3;Field-Effect Transistors (FETs) as Constant Current Sinks;162 9.16.4;Designing Constant Current Sinks Using the DN2540N5;164 9.17;References;168 9.18;Recommended Further Reading;169 10;3. Dynamic Range: Distortion and Noise;170 10.1;Distortion;170 10.1.1;Defining Distortion;170 10.1.2;Measuring Non-Linear Distortion;171 10.1.3;Distortion Measurement and Interpretation;172 10.1.4;Choosing the Measurement;173 10.1.5;Refining Harmonic Distortion M
easurement;174 10.1.6;Weighting of Harmonics;174 10.1.7;Summation and Rectifiers;175 10.1.8;Alternative Rectifiers;177 10.1.9;Noise and THD+N;177 10.1.10;Spectrum Analysers;178 10.2;Digital Concepts;178 10.2.1;Sampling;179 10.2.2;Scaling;179 10.2.3;Quantisation;180 10.2.4;Number Systems;180 10.2.5;Precision;180 10.3;The Fast Fourier Transform (FFT);181 10.3.1;The Periodicity Assumption;182 10.3.2;Windowing;182 10.3.3;How the Authors Distortion Measurements Were Made;183 10.4;Designing for Low Distortion;184 10.5;Signal Amplitude;184 10.5.1;Cascodes and Distortion;187 10.6;Grid Current;188 10.6.1;Distortion due to Grid Current at Contact Potential;188 10.6.2;Distortion due to Grid Current and Volume Controls;189 10.6.3;Operating with Grid Current (Class A2);190 10.7;Distortion Reduction by Parameter Restriction;192 10.8;Distortion Reduction by Cancellation;195 10.8.1;Differential Pair Distortion Cancellation;197 10.8.2;PushPull Distortion Cancellation;199 10.8.3;The Western Electric Harmonic Equaliser;199 10.8.4;Side-Effects of the Harmonic Equaliser;201 10.9;DC Bias Problems;203 10.9.1;Cathode Resistor Bias;203 10.9.2;Grid Bias (Rk=0);205 10.9.3;Rechargeable Battery Cathode Bias (rk=0);206 10.9.4;Diode Cathode Bias (rk0);206 10.9.5;Constant Current Sink Bias;210 10.10;Individual Valve Choice;211 10.10.1;Which Valves Were Explicitly Designed to be Low Distortion?;211 10.10.2;Carbonising of Envelopes;213 10.10.3;Deflecting Electrons;213 10.10.4;Testing to Find Low-Distortion Valves;214 10.10.5;The Test Circuit;214 10.10.6;Audio Test Level and Frequency;215 10.10.7;Test Results;215 10.10.8;Interpretation;218 10.10.9;A Convention;220 10.10.10;Alternative Medium- Valves;220 10.10.11;Weighted-Distortion Results;221 10.10.12;Overall Conclusions;221 10.11;Coupling from One Stage to the Next;222 10.11.1;Blocking;223 10.11.2;Transformer Coupling;225 10.11.3;Low Frequency Step Networks;225 10.11.4;Level Shifting and DC Coupling;226 10.11.5;A DC Coupled Class A Electromagnetic
Headphone Amplifier;228 10.11.6;Using a Norton Level Shifter;231 10.12;Distortion and Negative Feedback;234 10.13;Carbon Resistors and Distortion;237 10.14;Noise;237 10.15;Noise from Resistances;238 10.15.1;Noise from Resistive Volume Controls;238 10.16;Noise from Amplifying Devices;239 10.16.1;Grid Current Noise and the Poisson Distribution;241 10.16.2;Electrometers and Grid Current;241 10.17;Noise in DC References;245 10.17.1;How the Authors DC Reference Noise Measurements Were Made;245 10.17.2;Gas Reference Noise Measurements;247 10.17.3;Variation of Gas Reference Noise with Operating Current;247 10.17.4;Semiconductor Reference Noise Measurements and Statistical Summation;247 10.17.5;Variation of Zener Reference Noise with Operating Current;249 10.17.6;Noise of the Composite Zener Compared to a 317;250 10.17.7;Red LED Noise;251 10.18;References;251 10.19;Recommended Further Reading;252 11;4. Component Technology;254 11.1;Resistors;254 11.1.1;Preferred Values;254 11.1.2;Heat;255 11.1.3;Metal Film Resistors;256 11.1.4;Power (Wirewound) Resistors;259 11.1.5;Ageing Wirewound Resistors;259 11.1.6;Noise and Inductance of Wirewound Resistors;260 11.1.7;Non-Inductive Thick Film Power Resistors;263 11.2;General Considerations on Choosing Resistors;263 11.2.1;Tolerance;263 11.2.2;Heat;263 11.2.3;Voltage Rating;264 11.2.4;Power Rating;264 11.3;Capacitors;264 11.3.1;The Parallel Plate Capacitor;264 11.3.2;Reducing the Gap Between the Plates and Adding Plates;265 11.3.3;The Dielectric;265 11.4;Different Types of Capacitors;266 11.4.1;Air Dielectric, Metal Plate (εr1);268 11.4.2;Plastic Film, Foil Plate Capacitors (2<εr<4);268 11.4.3;Metallised Plastic Film Capacitors;271 11.4.4;Metallised Paper Capacitors (1.8<εr<6);271 11.4.5;Silvered Mica Capacitors (Muscovite Mica, εr=7.0);272 11.4.6;Ceramic Capacitors;272 11.4.7;Electrolytic Capacitors;273 11.4.8;Aluminium Electrolytic Capacitors (εr8.5);273 11.4.9;Tantalum Electrolytic Capacitors (εr25);281
11.4.10;Variation of Capacitance with Frequency;282 11.4.11;Imaginary Capacitance;282 11.5;General Considerations in Choosing Capacitors;284 11.5.1;Voltage Rating;284 11.5.2;Capacitance Value;284 11.5.3;Heat;285 11.5.4;ESR;285 11.5.5;Leakage and d;285 11.5.6;Microphony;285 11.5.7;Bypassing;286 11.6;Magnetic Components;287 11.7;Inductors;288 11.7.1;Air-Cored Inductors;288 11.7.2;Gapped Cores for AC Only;290 11.7.3;Gapped Cores for AC and DC (Power Supply Chokes);291 11.7.4;Self-Capacitance;292 11.8;Transformers;294 11.8.1;Iron Losses;294 11.8.2;DC Magnetisation;298 11.8.3;Copper Losses;299 11.8.4;Electrostatic Screens;299 11.8.5;Magnetostriction;300 11.8.6;Output Transformers, Feedback and Loudspeakers;300 11.8.7;Transformer Models;301 11.8.8;Input Transformer Loading;304 11.9;Why Should I Use a Transformer?;306 11.10;General Considerations in Choosing Transformers;307 11.11;Uses and Abuses of Audio Transformers;308 11.11.1;Guitar Amplifiers and Arcs;308 11.11.2;Other Modes of Destruction;309 11.11.3;Magnetic Screening Cans;309 11.11.4;Magnetic Core Deterioration;309 11.12;Thermionic Valves;310 11.12.1;History;310 11.12.2;Emission;311 11.12.3;Electron Velocity;312 11.12.4;Transit Time;313 11.13;Individual Elements of the Valve Structure;314 11.13.1;The Cathode;314 11.14;Thoriated Tungsten Filament Fragility;317 11.14.1;Direct Versus Indirectly Heated Cathodes;318 11.14.1.1;The Thermal Problem;318 11.14.1.2;The Electrostatic Problem;319 11.14.1.3;The Electromagnetic Problem;319 11.14.1.4;The Indirectly Heated Cathode Solution;319 11.14.2;Heater/Cathode Insulation;320 11.14.3;Cathode Temperature Considerations;322 11.14.4;Heaters and their Supplies;322 11.14.5;Current Hogging and Heater Power;324 11.14.6;Heater Voltage and Current;326 11.14.7;The Control Grid;329 11.14.8;Grid Current;330 11.14.9;Thermal Runaway due to Grid Current;330 11.14.10;Grid Emission;330 11.14.11;Frame-Grid Valves;331 11.14.12;Variable- Grids and Distortion;332 11.14.13;Other Grids;333 11.14.14;
The Anode;334 11.14.15;The Vacuum and Ionisation Noise;337 11.14.16;The Getter;338 11.14.17;The Mica Wafers and Envelope Temperature;339 11.14.18;Valve Sockets Losses and Noise;341 11.14.19;Valve Bases and the Loktal Base;341 11.14.20;The Glass Envelope and the Pins;343 11.14.21;PCB Materials;344 11.15;References;345 11.16;Recommended Further Reading;346 12;5. Power Supplies;348 12.1;The Major Blocks;348 12.2;Rectification and Smoothing;349 12.2.1;Choice of Rectifiers/Diodes;349 12.2.2;Rectifiers To Be Avoided (Gas);355 12.2.3;Rectifiers To Be Avoided (Selenium);357 12.2.4;Rectifiers To Be Avoided (Copper Oxide);357 12.2.5;RF Interference/Spikes;358 12.2.6;The Single Reservoir Capacitor Approach;358 12.2.7;Ripple Voltage;359 12.2.8;The Effect of Ripple Voltage on Output Voltage;360 12.2.9;Ripple Current and Conduction Angle;361 12.2.10;Transformer Core Saturation;365 12.2.11;Choosing the Reservoir Capacitor and Transformer;365 12.2.12;Back-to-Back Mains Transformers for HT Supplies;368 12.2.13;Voltage Multipliers;370 12.2.14;The Choke Input Power Supply;372 12.2.15;Minimum Load Current for a Choke Input Supply;373 12.2.16;Current Rating of the Choke;374 12.2.17;Mains Transformer Current Rating for a Choke Input Supply;376 12.2.18;Current Spikes and Snubbers;376 12.2.19;Intermediate Mode: The Region Between Choke Input and Capacitor Input;380 12.2.20;PSUD2;382 12.2.21;Broadband Response of Practical LC Filters;384 12.2.21.1;Region 1;384 12.2.21.2;Region 2;386 12.2.21.3;Region 3;386 12.2.21.4;Region 4;386 12.2.22;Estimation of Wide-Band LC Response;390 12.2.23;Sectioned RC Filters;391 12.3;Regulators;393 12.3.1;The Fundamental Series Regulator;394 12.3.2;The Two-Transistor Series Regulator;396 12.3.3;The Speed-Up Capacitor;397 12.3.4;Compensating for Regulator Output Inductance;399 12.3.5;A Variable Bias Voltage Regulator;399 12.3.6;The 317 IC Voltage Regulator;401 12.3.7;The 317 as an HT Regulator;403 12.3.8;Valve Voltage Regulators;405 12.3.9;Optimised Valve Voltage
Regulators;408 12.3.10;Using a Pentodes g2 as an Input for Hum Cancellation;409 12.3.11;Increasing Output Current Cheaply;409 12.3.12;Regulator Sound;412 12.3.13;Power Supply Output Resistance and Stereo Crosstalk;412 12.3.14;Power Supply Output Resistance and Amplifier Stability;413 12.3.15;The Statistical Regulator;414 12.3.16;Bypassing the Composite Zener;417 12.3.17;Optimising the Statistical Regulator;419 12.3.18;References for Elevated Heater Supplies the THINGY;420 12.4;Common-Mode Interference;423 12.4.1;Heaters and History;423 12.4.2;How Common-Mode Heater Interference Enters the Audio Signal;424 12.4.3;Mains Transformers and Inter-Winding Capacitance;424 12.4.4;Reducing Transformer Inter-Winding Capacitance;425 12.4.5;Post-Transformer Filtering;426 12.5;Practical Issues;427 12.5.1;Transformer Regulation;427 12.5.2;HT Capacitors and Voltage Ratings;428 12.5.3;Can Potentials and Undischarged HT Capacitors;429 12.5.4;The Switch-On Surge;430 12.5.5;Mains Fusing;430 12.5.6;Mains Switching;431 12.6;A Practical Design;432 12.6.1;HT Regulation;433 12.6.2;HT Rectification and Smoothing (a PSUD2 Exercise);435 12.6.3;Heater Rectification and Smoothing (a Manual Exercise);438 12.6.4;Heater Regulation;439 12.6.5;Mains Filtering;440 12.7;Adapting the Power Supply to the EC8010 RIAA Stage;441 12.7.1;HT Regulation;443 12.7.2;Reference Voltages;444 12.7.3;HT Rectification and Smoothing (a PSUD2 Exercise);444 12.7.4;Heater Regulation;446 12.7.5;Heater Rectification and Smoothing (a Manual Exercise);447 12.8;References;448 12.9;Recommended Further Reading;449 13;6. The Power Amplifier;450 13.1;The Output Stage;450 13.1.1;The Single-Ended Class A Output Stage;451 13.1.2;The Significance of High Output Resistance;453 13.1.3;Transformer Imperfections;454 13.2;Classes of Amplifiers;456 13.2.1;Class A;456 13.2.2;Class B;456 13.2.3;Class C;456 13.2.4;Class *1;458 13.2.5;Class *2;458 13.3;The PushPull Output Stage and the Output Transformer;458 13.3.1;Modifying the Connection of t
he Output Transformer;461 13.4;Output Transformer-Less (OTL) Amplifiers;465 13.5;The Entire Amplifier;465 13.6;The Driver Stage;467 13.7;The Phase Splitter;469 13.7.1;The Differential Pair and Its Derivatives;470 13.8;The Input Stage;479 13.9;Stability;480 13.9.1;Slugging the Dominant Pole;480 13.9.2;Low Frequency Instability, or Motorboating;482 13.9.3;Parasitic Oscillation and Control Grid-Stoppers;483 13.9.4;Parasitic Oscillation of Ultra-Linear Output Stages, and g2 Stoppers;484 13.9.5;Parasitic Oscillation and Anode Stoppers;484 13.9.6;High Frequency Stability and the 0V Chassis Bond;484 13.9.7;Stability Margin;484 13.10;Classic Power Amplifiers;485 13.10.1;The Williamson;485 13.10.2;The Mullard 5-20;487 13.10.3;The Quad II;492 13.11;New Designs;495 13.12;Single-Ended Madness;495 13.13;The Scrapbox Challenge Single-Ended Amplifier;495 13.13.1;Choice of Output Valve;496 13.13.2;Choice of Output Class;497 13.13.3;Choosing the DC Operating Point by Considering Output Power and Distortion;497 13.13.4;Specifying the Output Transformer;498 13.13.5;Biassing the Valve;498 13.13.6;The Cathode Bypass Capacitor;499 13.13.7;Finding the Required HT Voltage;500 13.13.8;HT Smoothing;500 13.13.9;HT Rectification;500 13.13.10;The HT Transformer;501 13.13.11;HT Choke Suitability;502 13.13.12;The HT Regulator Option;503 13.13.13;Estimating Amplifier Output Resistance;505 13.13.14;What are the Driver Stage Requirements?;506 13.13.15;Driver Stage Topology;506 13.13.16;Choice of Valve for the Driver Stage;507 13.13.17;Determining the Driver Stage Operating Point;507 13.13.18;Setting Driver Stage Bias;508 13.13.19;Is the Output Resistance and Gain of the Proposed Driver Stage Adequate?;508 13.13.20;But What About Global Feedback?;509 13.13.21;Summing Up;509 13.13.22;Teething Problems;509 13.13.23;Listening Tests;512 13.13.24;Designers Observations;512 13.13.25;Conclusions;513 13.14;Obtaining more than Single Digit Output Power;515 13.14.1;Sex, Lies and Output Power;515 13.14.2;Loudsp
eaker Efficiency and Power Compression;516 13.14.3;Active Crossovers and Zobel Networks;516 13.14.4;Parallel Output Valves and Transformer Design;518 13.15;Driving Higher Power Output Stages;519 13.16;The Crystal Palace Amplifier;520 13.16.1;13E1 Conditions;522 13.16.2;Driver Requirements;525 13.16.3;Finding a Topology that Satisfies the Driver Requirements;525 13.16.3.1;(1) Minimal Measured Distortion;525 13.16.3.2;(2) Distortion to be Composed of Low Order Harmonics;525 13.16.3.3;(3) Pushpull Output with Good Balance;525 13.16.3.4;(4) Large Undistorted Voltage Swing;526 13.16.3.5;(5) Sufficient Gain to Enable Global Negative Feedback if Required;526 13.16.3.6;(6) Low DC Output Resistance to Avoid Problems with DC Grid Current;526 13.16.3.7;(7) Low AC Output Resistance to Drive Load Capacitance;526 13.16.3.8;(8) Tolerance of Output Stage Conduction Angle Changes from 360 to 0;526 13.16.3.9;(9) Instantaneous Recovery Even After Gross Overload;527 13.16.4;Circuit Topology: Power Supplies and Their Effect on Constant Current Sinks;527 13.16.5;Va(max) and the Positive HT Supply;528 13.16.6;Symmetry and the Negative HT Supply;529 13.16.7;The Second Differential Pair and Output Stage Current;529 13.16.8;Why Not Have Tighter Stabilisation?;530 13.16.9;The First Differential Pair, Its HT Supply, and Linearity;532 13.16.10;Valve Matching;532 13.16.11;The Essential Twiddly Bits;533 13.16.12;The Cascode Constant Current Sink and Stabilisation Against Mains Variation;533 13.16.13;The 334Z Constant Current Sink and Thermal Stability;536 13.16.14;High Frequency Stability;537 13.16.15;HT Regulators;537 13.16.16;Stereo versus Mass;539 13.16.17;Power Supply Design;539 13.16.18;Designers Observations;540 13.16.19;Exceeding Vg2;540 13.16.20;GM70;542 13.16.21;Measuring Ik;542 13.16.22;Global Negative Feedback;542 13.16.23;Conclusions;546 13.17;The Bulwer-Lytton Scalable Parallel PushPull Amplifier;546 13.17.1;Background;546 13.17.2;Designing the Followers to Drive the Output Valves;54
8 13.17.3;Comparing Cathode and FET Source Followers;548 13.17.4;Output Stage Bias, Balance and Coupling;551 13.17.5;Providing Gain;554 13.17.6;Gain Stage CCS and Gain Balance;554 13.17.7;Balanced Inputs on Power Amplifiers;555 13.17.8;The Volume Control and Baffle Step Compensation;556 13.17.9;Audio Circuit Comments;557 13.17.10;Power Supplies;558 13.17.11;Global Negative Feedback;560 13.18;References;560 13.19;Further reading;561 14;7. The Pre-Amplifier;562 14.1;Input Selection;563 14.1.1;Disparate Levels between Sources;563 14.1.2;Adjacent Contact Capacitance (Crosstalk Between Sources);564 14.1.3;Contact and Leakage Resistance (Noise);565 14.1.4;Solutions and Problems Peculiar to Electromechanical Switches (Relays);565 14.2;Volume Control;566 14.2.1;Limitations on the Controls Value (Disturbing Frequency Response);567 14.2.2;Logarithmic Law (Perceived Volume Not Changing Smoothly with Rotation);568 14.2.3;Switched Attenuators (Disturbing Channel Matching);569 14.2.4;Switched Attenuator Design;570 14.2.5;Spreadsheets and Volume Controls;573 14.2.6;Volume Controls for Digital Active Crossovers;574 14.2.7;Volume Control Values and Their Effect on Noise;577 14.2.8;Grid-Leak Resistors and Volume Controls;578 14.2.9;Balanced Volume Controls;580 14.2.10;Light-Sensitive Resistors as Volume Controls;580 14.2.11;Transformer Volume Controls;582 14.3;Balance Control;583 14.3.1;Law Faking;583 14.4;Cable Driver;587 14.4.1;Determination of Required Quiescent Current;587 14.4.2;Choice of Follower Valve;589 14.4.3;Practical Considerations;590 14.4.4;Adding Gain;592 14.4.5;Polarity Inversion;593 14.5;Tone Control;594 14.6;Obtaining a Clean Signal from Analogue Disc;600 14.6.1;Comparison of Analogue Levels between Vinyl and Digital Sources;600 14.6.2;RIAA and Replay Rumble;601 14.6.3;The Mechanical Problem;602 14.6.4;Arm Wiring and Moving Coil Cartridge DC Resistance;603 14.6.5;Hum Loops and Unbalanced Interfaces;604 14.6.6;Balanced Working and Pick-Up Arm Wiring;604 14.7;RIAA Sta
ge Design;606 14.7.1;Determination of Requirements;607 14.7.2;Implementing RIAA Equalisation;609 14.7.3;All in One Go Equalisation;611 14.7.4;Split RIAA Equalisation;612 14.7.5;The Final Choice;614 14.8;A Simplified Example RIAA Stage;614 14.8.1;Noise and Input Capacitance of the Input Stage;614 14.8.2;Valve Noise;620 14.8.3;1/f Noise;621 14.8.4;Connecting Devices in Parallel to Reduce noise;621 14.8.5;Valve Noise Summary;622 14.8.6;Noise Advantage due to RIAA Equalisation;622 14.8.7;Stray Capacitances;623 14.8.8;Calculation of Component Values for 75μs;623 14.8.9;180μs, 318μs Equalisation and the Problem of Interaction;625 14.9;3180μs and 318μs Equalisation;626 14.9.1;Awkward Values and Tolerances;627 14.10;The EC8010 RIAA Stage;629 14.10.1;The Input Stage;629 14.10.2;Optimising the Input Transformer;632 14.10.3;The Second Stage;633 14.10.4;The Output Stage;634 14.10.5;Refining Valve Choice by Heaters;634 14.10.6;Choosing the Implementation of RIAA Equalisation;635 14.10.7;Grid Current Distortion and RIAA Equaliser Series Resistances;635 14.10.8;3180μs, 318μs Pairing Errors due to Miller Capacitance;636 14.10.9;The 75μs Problem;636 14.10.10;The Computer Aided Design (CAD) Solution;637 14.10.11;3180μs, 318μs Pairing Manipulation;637 14.10.12;75μs/3.18μs Manipulation;638 14.10.13;Practical RIAA Considerations;639 14.10.14;RIAA Direct Measurement Problems;639 14.10.15;Production Tolerances and Component Selection;642 14.10.16;RIAA Equalisation Errors due to Valve Tolerances;643 14.11;The Balanced Hybrid RIAA Stage;643 14.11.1;No Step-Up Transformers;644 14.11.2;Semiconductors to the Rescue;644 14.11.3;Miller Capacitance;645 14.11.4;DC Stabilisation and Consequent Gain Reduction;646 14.11.5;JFET Noise;646 14.11.6;BJT Noise;647 14.11.7;Choosing between the BJT and JFET: Equalisation, Distortion and HT Power;648 14.11.8;Reconciling the Balanced Decision with Practicalities;649 14.11.9;Implications of the Block D
iagram;649 14.11.10;The Unity-Gain Cable Drivers;650 14.11.11;Deciding the HT Voltage;651 14.11.12;Input Stage BJT Miller Capacitance;652 14.11.13;VCE and BJT Linearity;653 14.11.14;Input Resistance and Bias Current;654 14.11.15;Input Stage Noise;655 14.11.16;RIAA Calculations;656 14.11.17;The Source Followers;657 14.11.18;The Constant Current Sinks;658 14.11.19;The HT Supply;658 14.11.20;Total Gain and Channel Balance;660 14.11.21;Summary;660 14.12;References;661 14.13;Recommended Further Reading;661 15;Appendix;662 15.1;Valve Data;662 15.2;Standard Component Values;666 15.3;Resistor Colour Code;666 15.4;Plastic Capacitor Coding;668 15.5;Cable;668 15.6;Square Wave Sag and Low Frequency f3 dB;669 15.7;Playing 78s;671 15.8;Equalisation;672 15.9;CD;674 15.10;Sourcing Components: Bargains and Dealing Directly;675 15.11;References;677 16;Index;678
