Mad Stone

Project overview

Razor-sharp dynamic high gain drive is designed for modern extreme players seeking a high gain drive with string to string definition without sounding muddy or mushy.

Versatile enough to deliver overdrive-like textures and responsive to capture the player’s touch and dynamics like most of this Finish scientist’s designs!

Introduction

Mad professor’s Stone Grey distortion ™ is their take on putting modern metal tones and heavy distortion in a pedal without simply cloning an existing circuit. A very powerful one-knob tone control, outstanding sting to string definition, tight low end, and a gain control that’s not losing crucial definition when dimmed out will stand right in front of you in any fight you and your axe may could have. As a mod, and to make this beast even better, we added a toggle where you can switch between different FETs and MOSFET.
I highly recommend using sockets and experiment with different types, 2n7000, for instance. But take your time with that; you probably would dial it differently. Just cranked all the way, the differences can be very subtle.

*You could try replacing 2N3819 with a J201 or 2n547; just bear in mind the different pins out of those (Gate and source are reversed, Drain stills the same). They are acting as clipping diodes of the feedback loop at the opamp.

Because of its low amount of components and its wide range of distortion, I can recommend this as a beginner project.

Controls

• Gain
• Tone
• Volume

For further analysis on this circuit take a look at this thread on Free Stomp Boxes Forum.

For any technical questions regarding this build don’t forget to check out our Facebook Group and our forum at Free Stomp Boxes.

Mad Stone – Building Docs

Mad stone – Drilling Template