The Ultimate Tone Vol. 5
Table of Contents and List of Figures
Chapter 1: TUBE TONE
HOT TO THE TOUCH
Boiling Electrons
Home Plate
Grid Control to Major Tom
MU, Gm & rp
Mu Mu Mu
Gm
rp
MAKING A VOLTAGE AMPLIFIER
Grid-leak
“Easy” Fixed Bias
Self-bias
Plate Resistor
Transfer Curves and Distortion
Predicting Tube Voltage Gain
Cathode Feedback
CAPACITANCES IN THE GAIN STAGE
Internal Tube Capacitance
Cathode-bypass Capacitors
Plate-coupling Capacitors
CASCADING GAIN STAGES
Interstage Attenuators
Frequency-shaping Attenuators
Alternate Attenuators
Variable Attenuators
VOICING
Clean Topologies
Parallel Smoothness
“Distortion, please”
Master Volume
Distortion Voicing
PENTODES
CATHODE FOLLOWERS
CASCODE STAGES
MULTI-VOICE PREAMPS
TAILORING THE SOUND FOR SPECIFIC INSTRUMENTS
COMPONENT RATINGS
Chapter 2: GTR
WHERE THE MAGIC STARTS
Pickups
Wiring & Switches
Volume Controls
Tone Controls
Power
Acoustic Pickups
Chapter 3: SIGMA
IN SUMMATION
Chapter 4: TRIPLE-X
THREE ISN’T ALWAYS A CROWD
Input Signal Conditioning
Audio Switching
Annunciation
Independent On-off Selection
Chapter 5: TRANSFORMER SPECS
THEY DO WHAT THEY ARE CALLED
Volt-amps & Watts
Modern Transformer Ratings
“Classic” Xfmars Revisited
OUTPUT XFMARS
Drive Requirements
CLASS vs. IMPEDANCE
Supply Current Note
MATCHING PTs to OTs
Matching Procedure
HAMMOND TRANSFORMERS FOR TUBE AUDIO AMPLIFIERS
– SE Single-Ended 100-15kHz ±1dB
– SE Single-Ended 20-20kHz ±1dB at Rated Output
– PP Push-Pull 100-15kHz ±1dB
– PP Push-Pull 30-30kHz±1dB at rated output
– PP Push-Pull potted in can 30-30kHz±1dB at rated output
“CLASSIC” POWER TRANSFORMERS:
300-series UNIVERSAL PRIMARY CLASSIC TRANSFORMERS
“CLASSIC” LOW-POWER PLATE & FILAMENT TRANSFORMERS
HAMMOND PLATE TRANSFORMERS
MATCHING UP HAMMOND AUDIO OUTPUT AND POWER TRANSFORMERS
– TUT3 Projects Using Hammond transformers
MONO AMPLIFIERS
– SE Single-ended Amps
– Push-Pull Amps
STEREO AMPLIFIERS
– SE Single-ended Amps
– Stereo Push-Pull Amps
– Extended Operation for Musical Instrument Amps
Chapter 6: TOROIDAL O.T.s IN MUSICAL INSTRUMENT AMPS
PERSPECTIVE
EVOLUTION
TOROIDAL ATTRIBUTES
THE CIRCLE OF LIFE
THE 4157
A ROUND PEG IN A SQUARE HOLE
Postscript
FURTHER TESTS
TOROIDS IN REAL AMPS
PLITRON’S CURRENT LINE OPF TOROIDS FOR INSTRUMENT AMPS
Chapter 7: MAJOR
It’s Mister Blackmore on the phone…”
Major Developments
A MAJOR ANYONE CAN BUILD
Chapter 8: SOMA 84
PROFIT MOTIVE…
SPECIAL CONSIDERATIONS
POWER DETAILS
Chapter 9: STANDARD
NO COMPARISON
Evolution to a New Standard
ASSEMBLY
Chapter 10: DOPPELSONDE
“YOU WILL ENJOY”
Sound Science
Chapter 11: AX84
START SMALL
Chapter 12: KELLY
TONE PROPHET
Looking to the Past
Chapter 13: S3E
SAY “YES” TO SOLID STATE
SSSE
Mosfets to the Rescue
Chapter 14: STENTORIAN
THE LOUDEST TROJAN
Chapter 15: SUPER SCALER
“I want to take you higher…”
SUPER SCALERS TO THE RESCUE
Chapter 16: HOTBOX
HOT … Well, sometimes
Chapter 17: TUBE SCREAMER
BUT THERE’S NO TUBES
A Multi-Screamer
Chapter 18: SWEDE
FAST & FLUID
Chapter 19: SV572
BEAUTY IN A BOTTLE
How Much Power?
“Let’s get small”
Chapter 20: SYMMETRIC SOURCE
“This is a dangerous place”
Chapter 21: DUMPSTER
“I just got off the bus”
LOTS OF 6V TRANSFORMERS
Dumpster SE
Dumpster PP
Dumpster Preamp Supply
VA Ratings for the SE and PP
LINE ADJUSTER
DUMPSTER CATHODE BIAS: “I don’t think so”
MULTIPLE RECTIFIERS: That’s the ticket!
APPENDIX A: HAMMOND 300-SERIES PRIMARY WIRING
List of Figures
Fig. 1-1: Directly and indirectly heated cathodes
Fig. 1-2: The light bulb of genius
Fig. 1-3: Diode
Fig. 1-4: Diode as a rectifier
Fig. 1-5: Adding a control grid to a diode to create a triode
Fig. 1-6: Plate curves for a triode
Fig. 1-7: Measuring plate resistance and transconductance from the plate curves
Fig. 1-8: Triode voltage amplifier
Fig. 1-9: Adding a grid-leak resistor
Fig. 1-10: Fixed-bias triode with a signal on the grid
Fig. 1-11: Self-bias gain stage
Fig. 1-12: Determination of bias resistor value from plate curves
Fig. 1-13: Self-bias triode with signal applied to grid
Fig. 1-14: Self-bias triode voltage amplifier
Fig. 1-15: Determination of plate resistor value from plate curves
Fig. 1-16: Using a load-line to determine signal swing
Fig. 1-17: Transfer function derived from plate curves
Fig. 1-18: First approximation of triode gain
Fig. 1-19: Second approximation of triode gain
Fig. 1-20: Self-bias gain stage analysis for bypass RK
Fig. 1-21: Self-bias gain stage analysis with unbypassed RK
Fig. 1-22: Internal triode capacitances
Fig. 1-23: Capacitative reactance
Fig. 1-24: Effect of cathode-bypass capacitor
Fig. 1-25: Coupling cap from tube plate to next grid
Fig. 1-26: Determining coupling cap frequency response influence
Fig. 1-27: Signal levels through a guitar amp
Fig. 1-28: Harmonic build-up through successive gain stages
Fig. 1-29: Grid rectification effect
Fig. 1-30: Plate clipping: saturation and cut-off
Fig. 1-31: Basic attenuator Fig 1-32: Attenuator ratio variations and loading effects on the preceding stage
Fig. 1-33: Tweaking the attenuator to eliminate grid rectification of the subsequent stage
Fig. 1-34: Final attenuator tweak to eliminate plate clipping of the subsequent stage
Fig. 1-35: Grid-stop review
Fig. 1-36: Attenuator with high-frequency emphasis
Fig. 1-37: Attenuator with high-frequency roll-off
Fig. 1-38: Varying the depth of emphasis and de-emphasis
Fig. 1-39: Potentiometer specifications
Fig. 1-40: The pot as attenuator, with variations to limit maximum or minimum attenuator gain
Fig. 1-41: Variable shunt element in the attenuator
Fig. 1-42: Variable series element in the attenuator
Fig. 1-43: Clean signal topologies
Fig. 1-44: Two-stage preamps using different 12A_7 tubes
Fig. 1-45: Alternate 2-stage clean preamps
Fig. 1-46: Multi-stage clean preamps
Fig. 1-47: Parallel triode sections
Fig. 1-48: Historic distortion generation
Fig. 1-49: Early-EQ distortion generation
Fig. 1-50: Late-EQ distortion generation
Fig. 1-51: Master volume
Fig. 1-52: Adding noise suppression to the preamp
Fig. 1-53: Noise suppression through feedback
Fig. 1-54: Feedback factors
Fig. 1-55: Optimum grounding in preamp
Fig. 1-56: Basic pentode operation
Fig. 1-57: Cathode follower review
Fig. 1-58: Cathode-driven and plate-driven EQ
Fig. 1-59: Cascode circuits
Fig. 2-1: Dynamic pickups
Fig. 2-2: Humbucking pickups
Fig. 2-3: “Active” pickups
Fig. 2-4: Pickup wiring
Fig. 2-5: 3-way / 5-way switch wiring for three pickups
Fig. 2-6: 2-way / 3-way wiring for two pickups
Fig. 2-7: Pickup loading by volume control
Fig. 2-8: Trying to get the same tone with different volume control settings
Fig. 2-9: Passive tone controls
Fig. 2-10: Active EQ
Fig. 2-11: Active bass circuitry
Fig. 2-12: Powering our active instruments
Fig. 2-13: Acoustic preamp
Fig. 3-1: Sigma block diagram & system connection
Fig. 3-2: Sigma schematic
Fig. 3-3: Sigma layout using card-mounted sockets
Fig. 3-4: Sigma layout using bracket-mounted chassis-mountable tube sockets
Fig. 4-1: Switching between three amps
Fig. 4-2: Passive three-way switchers
Fig. 4-3: Input signal conditioning
Fig. 4-4: Active three-way jfet single-ended switchers using integrator to create the voltage reference
Fig. 4-5: Active switching using BJT elements
Fig. 4-6: LED control using BJT as straight switches and as current-steering elements
Fig. 4-7: Combining BJT shunt mutes and current-steering elements
Fig. 4-8: Exclusive selection controller
Fig. 4-9: Independent selection using mechanical switches or using a controller circuit
Fig. 4-10: Selecting between exclusive and independent controllers
Fig. 4-11: Power supply options for the Triple-X Chap. 5 Assorted transformer outlines and lead connections
Fig. 6-1: 20W toroid OT compared to 20W EI
Fig. 6-2: Vertical bracket for retrofitting
Fig. 6-3: ‘Bent’ bracket for power transformer
Fig. 7-1: Ultra-linear and standard tetrode power tube connections
Fig. 7-2: Screen voltage vs. plate current
Fig. 7-3: Major audio path
Fig. 7-4: MV options in the Major
Fig. 7-5: Stock power supply
Fig. 7-6: Power supply options
Fig. 7-7: Modified audio path
Fig. 7-8: Major layout for Marshall-style chassis but with controls oriented in North American fashion
Fig. 8-1: Soma 84 audio path
Fig. 8-2: Soma 84 power supply
Fig. 8-3: Soma 84 wiring layout
Fig. 9-1: Modified uses of Fender and Marshall front panels
Fig. 9-2: Standard preamp schematic
Fig. 9-3: FX and reverb loops schematic
Fig. 9-4: Power amp & line-out schematic
Fig. 9-5: Power supply schematic
Fig. 9-6: Internal card and tube layout
Fig. 9-7: Chassis drill detail
Fig. 9-8: Front panel drill detail
Fig. 9-9: Rear panel drill detail
Fig. 9-10: Infrastructure wiring
Fig. 9-11: Power supply card layout
Fig. 9-12: PA + main filter card
Fig. 9-13: PS + Sag card
Fig. 9-14: Second layer of output stage wiring
Fig. 9-15: Preamp-FX-reverb card & switching control card
Fig. 9-16: Line-out wiring
Fig. 10-1: Power vs. tone vs. tube types
Fig. 10-2: Tube switching methods
Fig. 10-3: Doppelsonde schematic
Fig. 10-4: Doppelsonde layout
Fig. 11-1: Firefly-like output stage with parallel tube option
Fig. 12-1 Concertina splitter variations
Fig. 12-2: Jim Kelly amp schematic
Fig. 12-3: Modified layout for Kelly amp in Marshall-style chassis with corrected control layout
Fig. 12-4: Modified layout for Kelly amp in Marshall-style chassis with corrected control layout
Fig. 13-1: Randall jfet preamp
Fig. 13-2: Roland Cube-series preamp
Fig. 13-3: Jfet mu-amp and other options
Fig. 13-4: Single-ended solid-state power amp options
Fig. 13-5: S3E solid-state single-ended power amp
Fig. 13-6: S3E card layout for manual voltage centering version – parts side
Fig. 13-7: S3E manual voltage centering version card – wire side
Fig. 13-8: S3E card layout for automatic voltage centering version – parts side
Fig. 13-9: S3E automatic voltage centering version card – wire side
Fig. 13-10: S3E amp layout and mosfet mounting
Fig. 14-1: Rack-mounting the Stentorian
Fig. 14-2: Stentorian schematic
Fig. 14-3: Stentorian layout
Fig. 15-1: Ideal current and voltage sources
Fig. 15-2: Domain integrity
Fig. 15-3: Drive power vs. output power
Fig. 15-4: Musicman output stage
Fig. 15-5: Super Scaler schematic
Fig. 15-6: Super Scaler layout
Fig. 16-1: Power supply variations
Fig. 16-2: Improved Hotbox schematic
Fig. 16-3: Layout of improved circuit
Fig. 17-1: Bounding circuits and symmetry
Fig. 17-2: Boost and distortion pedals from MXR
Fig. 17-3: Tube Screamer
Fig. 17-4: Multispectral distortion approach
Fig. 17-5: CMOS distortion approach
Fig. 17-6: Multi0Screamer schematic
Fig. 17-7: Audio card layout – parts side
Fig. 17-8: Audio card layout – solder side
Fig. 17-9: Switching card layout – parts side
Fig. 17-10: Switching card layout – solder side
Fig. 17-11: Box wiring
Fig. 18-1: Swede schematic
Fig. 18-2: Swede layout in Marshall-style chassis with corrected control layout
Fig. 19-1: SV572 and 572B tubes
Fig. 19-2: Hum reduction in DHT circuits
Fig. 19-3: 300W SV572 “Beast” amp schematic
Fig. 19-4: Simplified SV572 amp schematic
Fig. 19-5: SV572 amp layout
Fig. 20-1: Single-phase, 2-phase power and and symmetric power
Fig. 20-2: Symmetric Source schematic
Fig. 20-3: Symmetric Source layout
Fig. 21-1: Dumpster SE power supply and output stage transformer wiring
Fig. 21-2: Dumpster PP output transformer connections
Fig. 21-3: Dumpster preamp power supply
Fig. 21-4: Dumpster line adjusters
Fig. 21-5: Dumpster zener creations
Fig. 21-6: Dumpster “cathode bias” that isn’t, using composite zener
Fig. 21-7: Dumpster triple-rectifier
Fig. 21-8: Dumpster variable and settable sag
List of Tables
Table 13-1: Mosfet Specifications
