Home Forums Show Off Your Build Clean Dirt – My First Combo Build

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  • #20116
    Big O

    After months of conceptualizing, laying out, testing and building with some fails along the way, I finally finished my first combo build using 4 GuitarPCB boards – GBOF, Paramix, Rototone and 3PDT switch PCB’s.  The final result is a dirt pedal that blends in clean signal.  I realized near the end of the project that I pretty much build a MKC with greater distortion ability.  The concept was developed a few years ago when reading an interview with EVH in a guitar magazine and discovered for live performances he used a blendable Y-cable setup with clean and dirty amps that could be blended any way he felt suited for the situation.

    For the “Dirt” I decided to build a modified Electra/Trotsky drive.  I breadboarded it with all of the concepts I wanted to employ and came up with my findal design.  I transferred the circuit to veroboard and could not get the thing working.  Fortunately I had a left over GBOF and build my circuit on that board and then tested it with success.  I incorporated a Rototone for variable type of diode clipping for different styles of “dirt.”  To add a clean signal to blend with the dirt, I decided to use a Paramix.

    The dirt schematic is as below:

    And the working breadboard circuit.

    The final GBOF setup:


    Final layout:

    And the end result (Guts).  The Paramix is on the left, Electra/Trotsky on the right with Rototone multi-diode clipping above.

    And the finished pedal face with graphics.  Clean Dirt.

    After very slow, painstaking assembly, it worked on the first attempt.  Similar to the MKC but with greater distortion level.  If I did this again I would blend the Paramix with a Marshall amp emulation for clean plus Brown sound.


    Beautifully executed build!  I love the graphics!


    Well done. Thanks for sharing and the image looks great.

    Big O

    Just wanted to revisited this build.

    Had an afternoon to play around with this pedal and A/B it with my MKC.  I will say it can pretty much mimic the MKC, especially with using the Ge diode pair for clipping and lower gain.  Also gets a pretty good Brown Sound with a more mid range EQ (frown curve) on my amp switched to the “British” setting and using the LED clipping diode mode on the pedal.  If I had put my EVH Phase 90 in front of the pedal, I think I would be pretty close.  AC/DC sounds can be had by using the 1N4001 clipping diode setting, although all I would have to do is put the Treble, Mid and Bass on 5 as well as the Presence at about 9 O’clock (not 9) on the amp and turn the gain up slightly to get the AC/DC vibe (probably one of the easiest band sounds to mimic).

    All in all, I am quite happy with this build.


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