Home Forums GuitarPCB Build Support Muff OpAmp Mod (answered)

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    I’m starting work on my 3rd pedal project, but first one from GuitarPcb. The other two were kits, so there were pretty straight forward. Now I need more of a challenge. I’ve ordered the Muff OpAmp pcb and I like to add the Tone Bypass and Diode switching.  I have a couple of question though

    Tone Bypass – can I use the DPDT board? If so, how do I populate the board and connect it to the Tone and Volume?

    Diode Switching – If I use the DPDT board, how do I get 6 diodes to each side? I want to use the 1N914 for the BOM on one side and try 1N34A on the other. I am planning on using sockets on the 1N34A, since it is an experiment. I just don’t know how properly place the 6 diodes on each side.

    Link to build doc: https://guitarpcb.com/wp-content/uploads/2018/06/BD_BMP-OP-AMP-v2.pdf

    Thank you



    RTFM.  There is a diagram in the Build Doc that shows how to wire the TONMANN tone bypass.  There is also an instruction for wiring a Tone TwEQ in place of the stock tone stack.

    If you want to string 6 diodes onto one side of a DPDT, you will need to solder three together facing one direction and stack the  2 ends onto the DPDT next to another three facing the other direction.  Obviously, the middle diode in each string is not touching the board.

    When adding diodes in a string, you will increase the Forward Voltage, Fv, which will increase the signal level that the string passes.  Since 1N34A are germanium that pass a lower Fv than the 1N914, you may wish to use 6 on the 1N34A side and only 4 on the 1N914 side of the DPDT.  This will result in a closer signal level between the 2 positions of the switch.



    Since you are new, new I would state that RTFM is what we lovingly refer to as Read The Fantastic Manuals. The main build document aside you can also learn a ton from our RTFM pages  also known as the Guides Pages which I am certain you will find helpful.

    You will even see a diagram showing how to wire a DPDT board with examples but also check out all the PDF Guides up top as well.


    Thanks for the answers.





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