Request: Foxrox Wah Retrofit Buffer

Here’s a small utility circuit that can be of help if you want to place your wah in front of your fuzz. Simply stick this one between the two.

As is usually the case I haven’t given this a try myself yet, so let me know if you do.

Update (06.10.2012): Thanks to G5120fx for verifying this one as working.

Update (08.10.2012): An on-board trimmer for the volume was requested so here’s a quick update on the original layout. Give it a try and let me know if it works.

Update (11.10.2012): Thanks Jacob for verifying that the layout with on-board volume also works.

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16 thoughts on “Request: Foxrox Wah Retrofit Buffer

  1. Hi, I’ve built this circuit but it’s generating a lot of static, I used a tl071 and when turned on initially i get the guitar output but gradually the static builds up and cuts out the guitar sound. I’ve tried another ic and same result. I’m testing the circuit out side an enclosure so wondering if this circuit is susceptible to emf interference and if boxed in a ground enclosure it should go away. Thanks Vman

  2. I just installed this (with external volume pot) into my BBE Ben Wah Clone and it works perfectly! I tried another vero layout from the internet but it didn’t work well, was missing a few components 100 ohm resister, diode I think. This thing rocks! I used TL071 as it is a lot harder and more expensive to source a legit LF351. Thanks Harold for this layout!

  3. Gus, do you have a schematic for the wah? I have no experience with this one, but I was under the impression you just splice it in between the output signal wire and the output jack tip?

  4. I recall building something similar for a friend a while back. I’m not sure it had the final mixing stage, but at least there was two individual boost/cut channels. Let me dig around on my computer and see if I can find it.

  5. Yes, your exactly right on what I was hoping to do. I would like to be able to plug two guitars into a single input amp and be able to boost or cut each input to equalize the volumes for different pickups. I wanted to check out the foxrox buffer with one of my wahs, so I built two so I could try the mixer idea.

    Thanks again for everything,

  6. Hi Mike,
    I don’t have any experience with this circuit myself, but I don’t think it was meant for what you want to use it for. It’s a unity gain buffer with optional attenuation of the input signal and no boost.
    I suppose you could modify this by swapping out R1 with a higher resistance, but it’s not an ideal solution. And you might need to also add a mixing stage to add the two circuits together.
    What are you looking for exactly (what problem do you want to solve)? Sounds to me like you want a box with two inputs and one output, where each input takes a guitar signal through an active boost/cut stage and the two stages are mixed to one output at the end. Correct?

  7. I would like to combine the outputs of two separate “foxrox buffers with volume” to make a two channel mixer (for two guitars). When I combine the outputs, the output level drops so that no boost is available. Is there a way to restore the output level so I can add a little boost?

    Thank you very much for sharing your time and knowledge!

  8. Hi Jacob. I see what you mean. The volume control is there, but as an off-board pot and not as a trim pot. I’ll see what I can do since this is an easy addition.

  9. Hey Harald! So, when you look at the FoxRox retrofit picture (, we see a trimpot and 4 wires coming off of it, any chance of updating this layout to include the trimpot that sets the boost circuit’s volume? Or just ways to make it closer to the original in general? He’s got some good install guides on the site now too.

  10. Hi Harald!
    Just wanted to say, this vero is verified! Thanks, i needed one for my modded wah!

  11. Oh thank you Harald a lot! I was the one to request it and you did it you great old chap. Cheers!
    Will verify this asap

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