The Ultimate Tone Vol. 3

Table of Contents and List of Figures


Chapter 1: ICONS OF TONE
ICONS 101 1-1
      PRE-1 Single input simple preamp 1-1
      PRE-2 Dual-volume preamp 1-1
      PRE-3 Standard Fender preamp 1-1
      PRE-4 Standard Marshall preamp 1-1
      PRE-5 London Power Standard preamp 1-1
      PWR-1 Single-ended power amp 1-1
      PWR-2 Push-pull power amp with concertina splitter 1-2
      PWR-3 Push-pull power amp with Schmitt splitter 1-2
SINGLE-ENDED AMP: THE FIRST ICON 1-2
HOW TO BECOME AN ICON 1-3
FROM PILLARS TO ICONS 1-3
HOW THE MIGHTY HAVE FALLEN 1-4
ICONIC FOUNDATIONS 1-5
      PRE-1 1-5
      PRE-2 1-6
      PRE-3 1-6
      PRE-4 1-6
      PRE-5 1-6

Chapter 2: THE RIGHT CONNECTIONS
EQUIVALENTS THAT ARE NOT 2-1
FROM THE GROUND UP 2-1
DC SUPPLY DESIGNATIONS 2-3
SUPPLY & WIRING NOISE 2-3
      Bzzzzzzz 2-4
      Hmmmmm 2-4
      Loopy Noise 2-4
CIRCULATING CURRENTS 2-7
      AC Currents 2-7
      Rectifier Current 2-8
      DC Current 2-10
      Decoupling 2-10
      Multi-section Caps 2-11
      Distributed Power Supply 2-12
GALACTIC GROUNDS 2-14
      Star Ground 2-15
      Ground Buss 2-15
      Galactic Solution 2-16
STOCK TO SUPER-STOCK 2-16
      Bias or Biased? 2-17
      Marshall Copies Fender's Mistakes 2-20
      Traynor, Hiwatt, Laney et al. 2-22
      "For Every Screen, a Resistor of its Own" 2-24
      "Please Stand By" 2-26
BIAS METERING & ACCESS 2-28
DC & DC-STAND-OFF HEATERS 2-31
      DC Heaters 2-31
      DC-Stand-Off Heater 2-31
HOW COULD THEY BE SO WRONG? 2-32
EMERGING ICONS 2-33

Chapter 3: WIRING TECHNIQUES
GENERAL CONSIDERATIONS 3-1
      Hook-up Wire 3-1
WIRE GAUGES 3-2
      Heater Wire Gauge Selection 3-4
      Rectifier Heater Wire Selection 3-5
      AC Mains Wiring 3-5
      Speaker Output Wiring 3-6
SHIELDED WIRE 3-7
      Spiral Shields 3-8
      Braided Shields 3-9
      Foil-shielded Wire 3-9
LEAD DRESS 3-10
      Related Leads 3-11
      "Come on and Twist It" 3-11
TERMINATING SHIELDED CABLES 3-13
      Full Termination 3-13
      Floating Shields on Co-ax 3-14
WIRING ORDER 3-15
      "Free" Wire 3-16
      Criss-cross 3-17

Chapter 4: MECHANICAL LAYOUT
CONSTRUCTION METHODS 4-1
      Combo-style Construction 4-1
      Head-style Construction 4-2
IMPORTANT DETAILS 4-4
POTS & JACKS 4-8
      Pots 4-8
      Jacks 4-10
OTHER COMPONENTS 4-11
      Resistors 4-11
      Capacitors 4-11
      Magnetic Components 4-12
      Tubes 4-14
MYTHS 4-15
REVERB TANKS 4-16
HEAT 4-18
      Tubes 4-18
      Transformers 4-20
      Heat Analysis 4-21
      Heat Reduction 4-24
OVERVIEW 4-25

Chapter 5: CHAMP
SO YOU THINK IT'S SIMPLE? 5-1
      Some Things Are Simple 5-1
      Some Things Aren't Simple 5-3
      Easy Fixes 5-3
TRADITIONAL ERRORS 5-4
      In the Beginning... 5-4
      Heater Problem? 5-4
      Live Chassis 5-4
      Skimpy OTs 5-4
      Untraditional Champ 5-5
      Parallel Tubes 5-5
      Bias 5-5
MICRO GIANTS 5-13
      "More" Micro 5-13
      More Giant 5-15
      High-voltage SE Amps 5-17
FIXED-BIAS SE 5-18
      Fixed-Cathode Bias Switching 5-19
COMMON MODS 5-22
      Opening the Loop 5-24
RADICAL CHANGES 5-26
      More Can be Better 5-27
SE DREAMING 5-31
POWER SUPPLY UPDATES 5-31
      Traditional Improvements 5-31
      Modern Improvements 5-31

Chapter 6: BASSMAN
YES, IT'S FOR BASS 6-1
BASSMAN POWER AMP EVOLUTION 6-1
      Details 6-1
PREAMP EVOLUTION 6-10
      Finding a Direction 6-12
ONE NAME, TWO CIRCUITS 6-18
CONSTRUCTION 6-19

Chapter 7: PLEXI
ACROSS THE POND 7-1
OTHER REFINEMENTS 7-2
      Power Supply Capacitance 7-2
      Layout & Signal-path Value Changes 7-3
A TALE OF TWO PLEXIS 7-4
      Gm Doubling 7-4
      Feedback Loop 7-4
      Operating-mode Transition 7-5
      Supply Voltage 7-6
THE "PERFECT" PLEXI 7-6
      The Myth of Encompassment 7-6
      Usual Considerations 7-8

Chapter 8: 800
FIVE YEARS LATER... 8-1
YET ANOTHER FIVE YEARS... 8-1
50W OR 100W? 8-3
      Preamp as the Tone Generator... 8-3
      ...and Power Amp as a Tone Changer 8-3
      Final Fix 8-4

Chapter 9: BULL DOG
IT ACTUALLY GOES TO '11' 9-1
      Max Headroom Was Here 9-2
      Power Amp with a Twist 9-3
      Funky Presence 9-4
IT'S NOT ALWAYS A GOOD IDEA 9-5
      Bias Problems 9-5
      Screen Problems 9-6
      Usual Details 9-6

Chapter 10: AC-30
CLASS-A YOU SAY? 10-1
      Defining ‘Class-A' 10-1
      Real-world Example 10-2
AC-30 is Not Really Class-A 10-3
BIAS & SCREEN FIXES 10-3
CONSTRUCTION 10-5
      Tube Rectifier 10-5
      Choke Filtering 10-5
      Voltage "Tuning" 10-6
      Simplified Preamp 10-7
      Power Amp 10-7
      Output Transformer Selection 10-8
      Fusing 10-8
OTHER OPTIONS 10-14
      A Tweed Effects Loop 10-14
      Reverb Side-chain 10-15

Chapter 11: PORTAFLEX
BASS-O-MATIC 10-1
      Preamp 10-1
      Splitter 10-2
      Output Stage 10-3
      Power Supply 10-4
      Mechanical 10-4

Chapter 12: SVT
SATISFACTION 12-1
      Electronic Irony 12-1
      Traditional Fixes 12-3
NOT SO "SUPER" 12-4
      Power Amp Overview 12-4
      Other Oddities 12-8
OUTPUT STAGE & SUPPLY 12-9
      The Hard Way... 12-9
      Toroidal Option 12-12
      Or, the Easy Way... 12-12
      A Universal Alternative 12-14
      Ideal Power Supply 12-14
CHASSIS SELECTION 12-14

Chapter 13: BASS MASTER
RELIABILITY 101 13-1
      No Fishing... Except for Tone 13-3
      Just Some Tweaks 13-3
      Tube Change With a Difference 13-5
      Same Name, More Power 13-5
      Bias Adjusts 13-7
      Screen Updates 13-7
      General Details 13-7
      Stand-by... or, Don't Stand-by 13-8
      Updated Icon 13-8

Chapter 14: CUSTOM SPECIAL
UNABASHED BOASTING 13-1
PREAMP VARIATIONS 13-1
USUAL DETAILS 13-2
      Over-the-Top 13-3

Chapter 15: GUITAR MATE
JUST THE SAME ONLY DIFFERENT 13-1
      Amendments 13-4
      Other Mods 13-5

Chapter 16: HERZOG
THAT'S "MISTER" BACHMAN TO YOU 13-1
      Construction 13-2

Chapter 17: CHAIN
LINKS IN A CHAIN 13-1
      Real-World Chains & Links 13-2
      No Chains Here 13-6
      Amp Chain from a Fender Reverb Amp 13-8

Chapter 18: LANEY
GIVE WORSHIP AT THE ALTAR OF TONE 13-1

APPENDIX A: HAMMOND 300-SERIES PRIMARY WIRING


List of Figures

Fig. 2-1: Ground symbols 2-1
Fig. 2-2: Grounds in a Typical Power Supply 2-2
Fig. 2-3: Ground Loops Between Equipment 2-6
Fig. 2-4: Circulating Currents in a Power Supply 2-7
Fig. 2-5: Transformer Lead-dress 2-8
Fig. 2-6: Making a Solid-state Diode Perform Like a Tube Rectifier 2-9
Fig. 2-7: Ground Currents Between the Audio Circuit and Supply Nodes 2-9
Fig. 2-8: Adding Decoupling 2-11
Fig. 2-9: Multi-section Caps Destroy Ground Integrity 2-12
Fig 2-10 (Part 1): Distributed Capacitance in Many Forms 2-13
Fig. 2-11: Galactic, Star and Buss Grounds 2-15
Fig. 2-12: Blackface vs. Silverface Bias Circuits 2-17
Fig. 2-13: Updating Bias Circuits and their Impact on the Audio Path 2-19
Fig. 2-14: The Canadian Connection for g3 2-23
Fig. 2-15: Screen Circuit Modifications 2-25
Fig. 2-16: Stand-by Switches in Large Amps 2-27
Fig. 2-17: Bias Pot Mounting and Meter Jack Options 2-29
Fig. 2-18: DC-stand-off Heater 2-32
Fig. 3-1: Solid-core and Stranded Hook-up Wire 3-1
Fig. 3-2: Heater Wire Current Requirements 3-4
Fig. 3-3: Selecting Speaker Jack Wire 3-7
Fig. 3-4 Shielded Wire 3-7
Fig. 3-5: Terminating Spiral-shielded Wire 3-9
Fig. 3-6: Terminating Braided-shielded Wire 3-10
Fig. 3-7: Terminating Foil-shielded Wire 3-10
Fig. 3-8: Cable-ties and Wire Harnesses 3-11
Fig. 3-9: Twisting Wires Correctly 3-12
Fig. 3-10: Heater Wire Connections on Tube Sockets 3-13
Fig. 3-11: Full Termination of Shielded Wire 3-14
Fig. 3-12: Floating-shield Termination 3-15
Fig. 4-1 (Part 1): Combo Amps 4-1
Fig. 4-2 Head-style Amps 4-2
Fig. 4-3: Rack-mounted Chassis Options 4-3
Fig. 4-4: Chassis-mounted Tube Sockets and Terminal Strips 4-5
Fig. 4-5: Turret Cards 4-5
Fig. 4-6: Eyelet Boards 4-5
Fig. 4-7: Printed Circuit Boards 4-6
Fig. 4-8: Card-mounted Tube Socket on Different Types of Card 4-7
Fig. 4-9: Easy Servicing of Card-mounted Pots 4-8
Fig. 4-10: Chassis-mounted Jacks and Pots 4-9
Fig. 4-11: Transformer Orientation 4-13
Fig. 4-12: Tube Layouts in Various Chassis Styles 4-15
Fig. 4-13 (Part 1): Reverb Tank Mounting 4-17
Fig. 4-14: Mullard KT-88 Orientation and Socket Alignment 4-19
Fig. 4-15: Tube Orientation and Socket Alignment 4-20
Fig. 4-16: Heat, Air Flow and Space 4-22
Fig. 5-1: Single-ended Output Stage 5-1
Fig. 5-2: Champ 5C1: All Octal-based Tubes 5-6
Fig. 5-3: Champ 5E1: 12AX7 Front-end and Power Amp Feedback Loop Incorporated 5-6
Fig. 5-4: Champ 5F1: Like 5E1 but Choke-filtered Plate Supply Removed 5-6
Fig. 5-5: Champ AA764: Like 5F1 but Feedback Loop Values Changed and 2-way EQ Added 5-7
Fig. 5-6: Champ AA764 Layout as Wired by Fender 5-8
Fig. 5-7: Wiring Improvements Only, Including Extra Heater Current Option to Accommodate
               Alternate Power Tube Types 5-9
Fig. 5-8: Building the Champ Marshall-style 5-10
Fig. 5-9: Rack-mounting the Marshall-style Champ 5-10
Fig. 5-10: Rack-mounted 3U Champ 5-11
Fig. 5-11: Rack-mounted 1U Champ 5-12
Fig. 5-12: Reducing Output Power through Screen and Cathode Circuit Manipulation 5-14
Fig. 5-13: Triode-pentode Switching in an SE Amp 5-15
Fig. 5-14: "High-power" SE Output Stage Using Parallel Tubes 5-16
Fig. 5-15: "High-power" SE Output Stage Using Parallel Tubes with Mixing Pots 5-16
Fig. 5-16: Adjustable Cathode-bias in an SE Amp 5-18
Fig. 5-17: Fixed-bias in an SE Amp 5-19
Fig. 5-18: "High-power" SE Output Stage Using Parallel Tubes and Fixed Bias 5-20
Fig. 5-19: Switchable Fixed-to-Cathode Bias for a Single Tube 5-21
Fig. 5-20 (Part 1): Fixed-to-Cathode Bias Switching in a Parallel SE Stage 5-22
Fig. 5-21: Open-loop Power Stage 5-24
Fig. 5-22: Ultra-linear Connections in the SE Output Stage 5-25
Fig. 5-23: Mild-overdrive Preamp with Master Volume 5-26
Fig. 5-24: Adding a Preamp Tube Affords Great Versatility 5-28
Fig. 5-25: Marshall-800 Preamp SE Amp 5-29
Fig. 5-26: Channel-switching Preamp for Individual Clean and Lead Sounds 5-29
Fig. 5-27: Channel-switching Preamp for Individual Clean and Lead Sounds with
                  Reverb and Effects Loop Added 5-30
Fig. 5-28: Traditional Methods for Cleaning Up Power Supplies 5-31
Fig. 5-29: Mosfet Supply Noise-quietener 5-32
Fig 6-1: Old-Bassman Power Amp Using Octal Tubes 6-2
Fig. 6-2: 5E6-A Bassman Power Amp 6-3
Fig. 6-3: 5F6 Bassman Power Amp Variations 6-3
Fig 6-4: 6G6 Bassman Power Amp Variations 6-4
Fig. 6-5: Bassman Ten Power Amp Variations 6-5
Fig. 6-6: AA864 Bassman Power Amp 6-6
Fig. 6-7: Bassman Inverting Power Amp Variations 6-6
Fig. 6-8: 100W Bassman Power Amp 6-9
Fig. 6-9: 135W UL Bassman Power Amp 6-9
Fig. 6-10: 200W Super Bassman Power Amp 6-10
Fig. 6-11: Early Bassman Preamps 6-11
Fig. 6-12: 5E6-A Preamp with Active Mixing 6-11
Fig. 6-13: 5F6 Preamp Variations 6-13
Fig. 6-14: 6G6 Preamp Variations 6-14
Fig. 6-15: Bassman-Ten Preamp 6-15
Fig. 6-16: AA270 & AC568 Preamps 6-15
Fig. 6-17: AB165 & AA864 Preamps 6-16
Fig. 6-18: Super Bassman CFA7002 Preamp 6-17
Fig. 6-19: 200W Bass Amp Preamp 6-18
Fig. 6-20: Improved 5F6 with Noise Reduction Added 6-22
Fig. 6-21 Improved 5F6 Wired in Marshall-style Chassis but with Controls in Correct Order 6-24
Fig. 6-22: Late-Bassman with Noise Reduction Improvements 6-26
Fig. 6-23: Improved Late-Bassman Wiring for Marshall-style Chassis but with Controls in
                 Correct Order 6-28
Fig. 7-1: Some Marshall Power Supply Filter Variations Over Time 7-3
Fig. 7-2: Plexi Preamp Variations 7-9
Fig. 7-3: Marshall-style Chassis with Traditional
Fig. 7-4: Marshall-style Chassis with North American "Backwards" Control Orientation
               Control Orientation 7-10
Fig. 7-5: Rack-mounting the Marshall-style Chassis 7-10
Fig. 7-6: "5100" Plexi with Noise Reduction and Sonic Capabilities of Both the 50W
                and 100W Models 7-12
Fig. 7-7: "5100" Plexi Layout 7-14
Fig. 8-1: 800 vs. Plexi Input Stages 8-2
Fig. 8-2: Improved Master Volume 8-4
Fig. 8-3: 800-preamp with Alternate Wirings for the Master Volume 8-5
Fig. 8-4: Marshall-style Chassis with Traditional "Backwards" Control Orientation 8-6
Fig. 8-5: Marshall-Style Chassis with North American Control Orientation 8-6
Fig. 8-6: Rack-mounting the Marshall-style Chassis 8-7
Fig. 8-7: Improved 800 Schematic with Noise Reduction and "Constant-tone-MV" 8-8
Fig. 8-8: Improved 800 Layout 8-10
Fig. 9-1: Earlier Hiwatt Preamp 9-1
Fig. 9-2: Hiwatt Power Amp and Power Supply 9-2
Fig. 9-3: Tweed Mixer Interactions 9-3
Fig. 9-4: Presence Control Operation 9-4
Fig. 9-5: Improved Bias and Screen Circuits 9-5
Fig. 9-6: General Layout of the Hiwatt Chassis 9-6
Fig. 9-7: Bull Dog Schematic with Power Supply and Screen Updates 9-8
Fig. 9-8: Improved Bull Dog Layout 9-10
Fig. 10-1: Push-pull Class-A Operation 10-2
Fig. 10-2: AC-30 Output Stage with Improvements 10-4
Fig. 10-3: AC-30 Power Supply Variations 10-5
Fig. 10-4: Choke-filtered Plate Supply 10-6
Fig. 10-5: Voltage Tuning in the Supply 10-6
Fig. 10-6: Single-channel AC-30 Schematic with Options Indicated 10-10
Fig. 10-7: Improved AC-30 Layout for Single-Channel AC-30 10-12
Fig. 10-8: Effects Loop Options using the Schmitt Splitter as a Tweed-mixer Variant 10-14
Fig. 10-9: Adding Reverb to our AC-30 10-15
Fig. 10-10: AC-15 Variation 10-17
Fig. 11-1: Portaflex Preamp Variations 10-2
Fig. 11-2: Splitter Variations 10-3
Fig. 11-3: Portaflex Schematic 10-6
Fig. 11-4: Improved Portaflex Schematic Using 6SL7s 10-7
Fig. 11-5: 6SL7 Portaflex Layout 10-8
Fig. 11-6: Adapting the Portaflex to Use 12AT7s 10-10
Fig. 12-1: SVT Preamp Schematic 12-2
Fig. 12-2: SVT Power Amp Front-end 12-4
Fig. 12-3: Early Power Output Stage Using 6146s 12-5
Fig. 12-4: Later Power Output Stage Using 6550s 12-6
Fig. 12-5: Simplified SVT Schematic 12-7
Fig. 12-6: Power Supply Using a Mix of Hammond Transformers 12-8
Fig. 12-7: Power Supply Options 12-10
Fig. 12-8: "Easy" Power Supply for SVT 12-13
Fig. 12-9: Ideal Power Supply for SVT 12-15
Fig. 12-10: Chassis Layout and Doubling Elements for Extra Strength 12-18
Fig. 12-11: Layout for Simplified SVT Signal Path 12-20
Fig. 13-1: 40W YBA-1 Schematic 13-2
Fig. 13-2: 80W YBA-1A Schematic 13-4
Fig. 13-3: 40W & 80W Power Supplies 13-6
Fig. 13-4: Improved 80W YBA-1A 13-10
Fig. 13-5: Improved 80W YBA-1A Layout 13-12
Fig. 14-1: Early Preamp 13-2
Fig. 14-2: Later Preamp 13-3
Fig. 14-3: Custom Special Output Section and Power Supplies 13-4
Fig. 14-4: Super Custom Special Output Section and Power Supplies 13-5
Fig. 14-5: Custom Special Schematic with Amendments 13-6
Fig. 14-6: Modified Custom Special Layout 13-8
Fig. 15-1: Guitar Mate & Studio Mate Early Version 13-2
Fig. 15-2: Guitar Mate & Studio Mate Later Version 13-3
Fig. 15-3: Using Tremolo Tube as Extra "Early"and "Late" Gain with Master Volume 13-4
Fig. 15-4: Incorporating Switchable Cathode- or Fixed-bias while Retaining Tremolo 13-5
Fig. 15-5: Adding a Tube Rectifier 13-6
Fig. 15-6: Updated Guitar Mate Schematic 13-8
Fig. 15-7: Guitar Mate Layout 13-10
Fig. 16-1: Herzog Schematic with Some Options 13-3
Fig. 16-2: Herzog Layout 13-4
Fig. 16-3: Layout Adaptation Using the 229-series Transformers 13-5
Fig. 17-1: Chain Principle 13-1
Fig. 17-2: Amp-chain Possibilities 13-3
Fig. 17-3: Classic Chain Using Line-operated Amps, and Two Ways to Make the
                  System Safe 13-5
Fig. 17-4: Chain Using Modern Amps 13-7
Fig. 17-5: Current-boosting Arrangements that are not Amp Chains 13-9
Fig. 17-6: Modifying a Fender Reverb Amp to be an Amp Chain 13-10
Fig. 18-1: Laney Schematic with Minor Improvements 13-3
Fig. 18-2: Laney Layout 13-4