Schematic I drew up for my dual Maestro EP-2 preamp pedal. Basically two tube echoplex preamps in series with a switch to switch between running just one pre or both in series. :
Sortaflex: D.I.Y. Tube Bass Preamp | T. Hallenbeck
Low voltage tube guitar preamplifier circuit. Tube amplifier. in 2023 | Valve amplifier, Diy guitar amp, Amplifier
Bass Guitar Preamp Pedal DIY : Schematic & PCB Design
Alembic F-2B preamp (DIY) | Watersish.com
DIY tube preamp build part 1 - YouTube
Tube Distortion Pedal - Circuit Scheme
Overdrive - 12AX7 Tube Pedal – Hagerman Amplification
DIY 12AU7 Tube Preamplifier Project | Valve amplifier, Vacuum tube, Electronic schematics
FET Preamp with LND150 Operates on Tube B+, part 1
Switchable vacuum tubes on a guitar pedal... - General Electronics - Arduino Forum
12AX7 Tube (valve) Preamplifier Kit
tube overdrive pedal under Repository-circuits -53558- : Next.gr
Tubehead Pre-amp Circuit Diagram | Electronic Schematic Diagram
A DIY valve overdrive pedal – Goldie – Dave Mac's Window on the World
Blackbird Vacuum Tube Preamp for guitar - Effectrode
preamp - 12AX7 Valve Overdrive/Distortion Effect Pedal - Electrical Engineering Stack Exchange
12AU7 / 12AX7 Tube Preamplifier Schematic
preamp - 12AX7 Valve Overdrive/Distortion Effect Pedal - Electrical Engineering Stack Exchange
Building the Tube Overdrive | SYINSI
12AU7 / 12AX7 Tube Preamplifier Power Supply Schematic
STUFF - LOOK MUM NO COMPUTER
A DIY valve overdrive pedal – Goldie – Dave Mac's Window on the World
High voltage tube guitar preamplifier with 12AX7 - H&G Amplifiers
Soldano Preamp | DIY Fever
Bassline - Bass Guitar Tube Preamplifier - H&G Amplifiers
