This is a library of perfboard and single-sided PCB effect layouts for guitar and bass. I'm not an electrical engineer by any stretch of the imagination, just a DIY'er who likes drawing layouts. It is meant for the hobbyist (so commercial use of any of these layout is not allowed without permission) and as a way to give back to the online DIY community.

Monday, August 10, 2015

Electro-Harmonix Big Muff π

I got a request for a layout of the Big Muff that could be used to build the Triangle, Rams Head, Green Russian, or NYC versions. While it shouldn't be that hard to take one of my previous layouts of the BMP and make the value changes, I thought I'd make a more detailed project than I normally do. First, let's start with the schematic. This is the basic circuit used by pretty much every variation of the Big Muff (excluding the IC Big Muff):



The only difference between versions is a handful of component values. Generally, the circuit was tweaked to work with whatever Mike Matthews had on hand. As a result, there are about 18 different variations produced by Electro-Harmonix. Now, not all of those variations sound all that good. But over the years several really good sounding Muffs have been traced and their component values posted on the web (mostly on Kit Rae's awesome Big Muff site). The 4 versions specified in this project seem to be some of the most popular and best sounding Muffs.

The component names in the schematic above correlate to this layout:



For a full BOM for all 4 versions, download the file linked below. In addition to the BOM, it contains scaled transfers for etching your own circuit board, as well as a scaled drilling template for building the effect into a Hammond 1590B enclosure.


If a BMP variation you want to build isn't specified in this project, use the above schematic and compare it to the schematic of your desired version to figure out what components go where.

Updated Sept. 2, 2015 to correct schematic, placement of Tone pot, and drilling template.

18 comments:

  1. This is such a awesome work! Thank you so much for share this proyect with us. I'm sure that this will be so useful for a lot of people.
    Keep doing it like this! Cheers from Chile!

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  2. Awesome project. I would only mention that on the schematic, C7 and C10 are kind of on the wrong side of the clippers. Dont think it would affect. On the leyout it follows the original schematic but if you check whith the one you show it messes that place. Awesome project again!

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    Replies
    1. C7 and 10 can be on either side of the clippers. There are several iterations of the BMP with it either way. It has no real effect on the sound. The layout predates the schematic I drew up. Apparently I was just following a schem that had it differently.

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  3. Hey guys,i've just finished BMP version and it works and sounds fantastic)Tnx for awesome project)

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  4. Big Muff pi, Triangle Big or Muff 77 OpAmp for David Gilmour sound?

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    1. He's used a couple different ones over the years. I think Kit Rea's Big Muff site has a whole write up on what he used. I think he used a Ram's Head and Civil War. Probably a few others too.

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    2. thanks brother, nice info.

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  5. Hello you would not have the layout of Pharaoh Fuzz, to provide for us? I have the scheme How can I send you? Thank you man

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    Replies
    1. I'm actually in the middle of laying that one out, so stay tuned!

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    2. ok thank you , I follow every day the Blog, sensational

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  6. Hi, im doing the nyc, the resistor omit it's just a jumper? and on the 1u Caps should i use polyester or ceramic?
    Greetings.

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    Replies
    1. Don't use a jumper, just leave that spot empty. And it's up to you on what kind of caps. EHX has used both kinds over the years. I would probably go with ceramics as they'll probably fit better on the board. Good luck!

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  7. This big muff ... is 1/2 Watt or 1 watt ... polyester or ceramic ??

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  8. Wow awsome ,sorry for my question.

    But how to do an bypass? simple put a switch in front of the input, and switch it direct to output?

    And another question is. Why there are 3 ground points?
    And where to put the "-" from the 9v battery?

    Sorry for my dump question but iam complete new to that kind of stuff.

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    Replies
    1. Lots of ways to do bypass switching. There's a simple way that's shown in the General Layout Note tab at the top of the page, and many more can by found with a google search. The extra ground pads are just to have extras.

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  9. Hi, could you tell me the dimensions of the pcb layout?

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