Active EQ

Project overview

Based on the Friedman BE-OD and the Dirty Shirley EQ section. We consider this EQ the best fit for Preamp emulator projects and high gain pedals.

Introduction

Includes an internal Presence control, followed by a Character trimpot that regulates how a set of LEDs compress the signal. Then we jump into a passive treble control, followed by an Active Bass section. Now’s when you have to choose if you want to have a volume control of the overall circuit inserted here from your main PCB board (Tube screamer, Plexi, etc) or to place just an internal trimmer as an additional control. After this volume section, it comes the active mids control.

One of the characteristic that makes this board the best solution for preamps and high output circuits it’s the Power output option, this works the best for those high output preamps to go and feed directly into a power amp, and the regular output will be tamed into a more pedal-friendly volume. If you are using this board with a pedal that’s not famous for its big output (Klon centaur for example) you should use the power output.

Controls

• Bass
• Mids
• Treble

For further analysis on Dirty Shirley´s 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.

EQ Development tool – Building Docs

Active EQ – Drilling template