The Valve Caster 2.0: Tube Boost and Overdrive : 7 Steps (with Pictures) - Instructables
Tube Works 901 Real Tube 1987 - 1997 | Reverb
DISC Behringer TO100 Tube Overdrive Effects Pedal at Gear4music
Electro-Harmonix English Muff'n Tube Overdrive Pedal - Rogue Guitar Shop
A DIY valve overdrive pedal – Goldie – Dave Mac's Window on the World
Amazon.com: Sondery Overdrive Guitar Effect Pedal, Tube Overdrive of A Valve Combo Amplifier Sound - True Bypass, 2 Modes of Boost and Normal - Mini Size, Art Design Series : Musical Instruments