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Striking the Final Chord: Crafting Your Own Marshall Blues Breaker Pedal—The Grand Finale

Updated: Oct 2, 2023




The conclusion of our 3-part series on how to design your own pedal PCB! As a reminder, this project is 100% free and open source for educational purposes. My goal is to give you the tools to design your own PCB and how to order them from JLCPCB. For more on that, see parts 1 and 2 here.


For those who want to skip straight towards buying the PCB from me like usual. I also am making that available in my shop!


Let's great straight toward the build documentation!


Building a Project Blue Book

My PCB has a few goals:

  • Top mount jacks

  • Design for 1:1 component selection of the original 90's Marsh Blues Breaker

  • Component footprint to allow "modern" or "boutique" component selection such as silver mica capacitors, WIMA box film capacitors, and an extra 100uF cap for the incoming 9v power.

  • Footswitch wiring options for 1:1 original (non-true bypass) as well as true bypass wiring.

The whole project can easily be ordered from Tayda but more specific component selection can be found in the Mouser BOM but you will need to source pots and other things in addition to the Mouser BOM.


**Note that B22K pots are kinda hard to find. I did find a UK supplier via eBay that is selling them. Alternatively, you can use W20K, B25k, or B20k pots and see if they measure close. Remember, pots are typically 20% tolerance so 25k is within the tolerance from 22k.



The Tone Geek Touch

For a more boutique component selection. I recommend going with

  • 500v silver mica capacitors for the 10pf and 47pf capacitors.

  • WIMA Box film capacitors for 10nF, 220nF, and the 100nF caps

  • Toggle switches to change the pedal from Mk1v1 or Mk1v2 component selection.

  • 100uf 25v+ solid organic polymer filter caps.



Below is the drill template for the pedal if you drill yourself in a 125B enclosure. If you're using Tayda electronics to do the drilling for you, the BOM includes the drill template shared link.

The Tone Geek PBB Drill Template
.pdf
Download PDF • 673KB

As for wiring, you have two options. You can go with a more modern true-bypass or you can still with the original type of wiring. The only potential downside to the original wiring scheme is that the input to the pedal is always tapped into the circuit. The switch is basically toggling between the pedal output or the input output. The original pedal used a DPDT switch as well (not for my wiring) although smart people can adapt the wiring to achieve using a DPDT.



I hope you enjoyed this series and learned something from it!

-Ryan

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7 Comments


David Gordon
David Gordon
Nov 02, 2023

Hey Ryan. I just wanted to say thank you for putting together this learning series. I thoroughly enjoyed following along from start to finish. I went the route of designing my own board and have ordered a few for myself. I can't wait to build one. I've built your few of your other pedals and they all sound great!

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The link above for the solid organic polymer filter caps is for the 22uF variety. I failed to double-check the value and bought the wrong parts by mistake. No worries, I had some mere mortal 100uF caps on hand and will swap them out with my next Mouser order.

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Ryan
Ryan
Oct 02, 2023
Replying to

Oh no! You're right. I'll have to dig and find a real part then. The 22uF would be ok too but the 100uF would be more proper. Thank you for bringing this to my attention!

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Looking forward to building another one of your projects. The footswitch location in the drill file is off-center. Is anything in the way if we set X to zero?