Guitar Amplifier Electronics Soldano SLO book

Guitar Amplifier Electronics: Soldano SLO

Richard Kuehnel

When Mike Soldano designed the SLO-100 in 1987 he had no idea that it would transform the guitar amplifier industry, becoming one of the most iconic amps of all time. As we all know now, the SLO became a big hit, particularly in the heavy metal community, backing bands like Dokken, Ratt, and Dio. At Wacken Open Air it is perhaps the ultimate rig-of-death.

This book examines a circa 1996 version of the SLO-100 with an effects loop. The preamp's cascading-gain architecture requires several triodes to implement, but each is dedicated to a pivotal role in the signal chain. With only two channels and a simple switching mechanism, the SLO has a surprisingly compact architecture for creating such a rich palette of tones. The book explains how the amp works, the motivation behind its system design, and the performance of its electronics in the context of a real musical performance.

Richard Kuehnel is a member of the Circuits and Systems Society of the Institute of Electrical and Electronic Engineers.

Guitar Amplifier Electronics Soldano SLO book excerpt
Guitar Amplifier Electronics Soldano SLO book excerpt
Guitar Amplifier Electronics Soldano SLO book excerpt
Guitar Amplifier Electronics Soldano SLO book excerpt
  Guitar Amplifier Electronics Basic Theory book Fundamentals of Guitar Amplifier System Design book Guitar Amplifier Electronics Circuit Simulation book Guitar Amplifier Electronics Fender Deluxe book Guitar Amplifier Electronics Fender Bassman book Guitar Amplifier Electronics Soldano SLO book
Mastering Basic Electronics          
Preamps and Tone Stacks
Power Amps and Negative Feedback
Power Supplies
DC-Coupled Cathode Followers    
Effects Loops        
Reverb and Tremolo          
  Guitar Amplifier Electronics Basic Theory book Fundamentals of Guitar Amplifier System Design book Guitar Amplifier Electronics Circuit Simulation book Guitar Amplifier Electronics Fender Deluxe book Guitar Amplifier Electronics Fender Bassman book Guitar Amplifier Electronics Soldano SLO book
Crafting a Complete Architecture          
Testing Overdrive Dynamics          
Measuring Distortion    

Introduction

Warning: High Voltage!...1
A High-Gain Rocker...1
Acknowledgements...2

Chapter 1: System Design Concepts

An Introduction to Cascading Gain...6
Basic Architecture...9

Chapter 2: Recovery, Tone, and Power Subsystem

Power Amp...19
Grid Bias Supply...21
Plate and Screen Supplies...23
Ripple Filters...28
Plate Circuit Decoupling...29
Hum Suppression...34
Circa 1987 versus 1959 Ripple Filter Architectures...35
Full Power Performance...36
Long-Tailed-Pair Phase Inverter...39
5F6 Bassman Design...40
SLO Design...43
Global Negative Feedback...46
How Feedback Works...46
How Negative Feedback Reduces Distortion...48
Feedback Calculations for the SLO...49
Presence Control...50
Modified Bassman Tone Stack...52
How the Stack Works...52
SLO versus Tweed Bassman...57
Master Volume Controls...58
Effects Recovery and Tone Stack Driver...59
Headroom...60
Cathode Follower DC Coupling...61
Subsystem Profile...64
Subsystem Interfaces...67
Subsystem Voicing...67
Full Power Performance...68
Overdrive Dynamics...71
Feedback Effects...72
Bias Excursion...72
Power Supply Sag...73

Chapter 3: Effects Driver Module

Partially Bypassed Cathode Resistor...78
Preamp Overdrive...81
Grid-Stopper Resistor...82
Module Frequency Response...84
Effects Pedals...85
Subsystem Input Sensitivity Reference Levels...87
Module Interfaces...88

Chapter 4: Normal Channel Module

DC and AC Conditions...90
Gain and Output Impedance...91
Cascading Gain?...92
Switched Input Network...93
Module Frequency Response...96
Module Interfaces...98

Chapter 5: Overdrive Module

Third Stage...100
Second Stage and Attenuator...103
Input Network...107
Module Voicing...108
Cascading Gain...109
Module Interfaces...110

Chapter 6: Preamp Module

Module Interfaces...115

Chapter 7: Preamp Subsystem Performance

Subsystem Profile...116
Subsystem Voicing...120

Chapter 8: Preamp Overdrie Dynamics

Technology for "Sonic Depth, Clarity, and Dynamics"...123
12AX7 Grid Current...128
Grid Current's Impact on the Effects Driver Module...131
Bias Excursion...135
The Science of Sustain...137
Intermodulation Distortion...142
Upstream and Downstream Voicing...145
A Final Note on Voicing...149

Chapter 9: Optical Switching

VTL5C1 Optocoupler...150
LED DC Conditions: Footswitch Closed...152
LED DC Conditions: Footswitch Open...156
Some Final Words on the Soldano SLO...160

Appendix: Decibel-Volts (dBV)...164

Index...165


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