Wah true bypass mod

Discussion in 'Burnt Fingers DIY Effects' started by bigben55, Jun 29, 2016.

  1. bigben55

    bigben55 Friend of Leo's

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    I had a Vox V847 back in the 1990s. I installed the DPDT Carling switch per the diagram on fulltone's website and remember liking it LESS afterwards.

    Fast forward to now. Thinking of buying another, as I need a cheap wah. I have a killer Wilson wah on a different board btw.

    My question is, should/does modding a wah to True Bypass affect the way it sounds? If so, why, and what can be done about it?
     
  2. bigben55

    bigben55 Friend of Leo's

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    Per the stink foot page,

    When modifying an old Vox or Crybaby (pre 1990) wah pedal to true bypass, you often have to increase the effect level a little. It is as if the true bypass conversion somehow makes the effect quieter. But in reality, it’s the other way around… Old-style pedals – with the hardwire system and no input buffer in the circuit – caused so much signal loss in bypass that the effect output level needed to be slightly lowered, to match the dry signal. When you modify such a pedal to true bypass, you’re suddenly letting the bypass signal through at full strength, meaning the effect suddenly becomes too quiet. In those cases, you will have to increase the output volume a little. But once again, it’s not the true bypass wiring that is the problem…

    SO, what secondary mod (the easier the better, I can solder good but am not an effect builder)do you do to increase the output volume a little?
     
  3. fraser

    fraser Tele-Holic

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    its the first resistor after the input-

    on the modern vox and crybaby wahs, its a 68k.
    you want to use a lower value here.

    take a look at "the technology of wah pedals"
    located here-
    http://www.geofex.com/
     
  4. bigben55

    bigben55 Friend of Leo's

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    I read 33K is a good one to swap to.

    So, I've soldered lots of guitar pickups/electronics. I've soldered speakers into amps. I've soldered other stuff to, like an input jack to the circuit board on a Roland Blues Cube. I've actually replaced the switch on a wah before. What I've NEVER done is mod the circuit board of a pedal.

    Re is the 68K resistor. What's the best way to remove it and replace it? I'm assuming there's holes in the board where the leads on the resistor goes thru to be soldered on the other side.

    Tips? School me
     
  5. fraser

    fraser Tele-Holic

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    [​IMG]

    i think the one you want to change is Rin.

    ive done a bunch of wah circuit board mods.
    i use solder wick (its like a braided copper thing)
    you place clean wick over the solder joint,
    then heat it- it absorbs the solder.

    once the solder is removed the part will come right off,
    might need a little coaxing with your iron-
    i use tweezers or forceps on the resistor to help.
     
  6. bigben55

    bigben55 Friend of Leo's

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    I got desolder braid. That makes sense, I am comfortable doing that. Remove solder, put new resistor in place, trim leads, solder in place, done. Right?

    Do you have to be extra super careful to not overheat the board? And what's the best source of parts online?
     
  7. fraser

    fraser Tele-Holic

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    the board is pretty tough-
    no need to be super careful.
    youre only touching the two solder joints for that resistor.

    i often use smallbear-
    http://smallbear-electronics.mybigcommerce.com/

    but i tend to buy a bunch of different pedal parts at a time.
    if im just after a resistor or something i use a local store.
     
  8. Treynor

    Treynor Tele-Holic

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    Or you could just put a good buffered pedal right before it and do no mods to get rid of tone suck. That was my solution for my V847 when I put my TU-3 tuner in front. I'm very happy with it now.
     
  9. bigben55

    bigben55 Friend of Leo's

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    ^it's that simple? If i go Vox wah>Boss TU2>6 other pedals>amp, I shouldn't have any tone suck?
     
  10. johnnyha

    johnnyha Tele-Afflicted

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    TU2>wah
     
  11. bigben55

    bigben55 Friend of Leo's

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    Eh, due to board space, I can't do TU1>WAH. I kinda want to do the mod, it'll be my first pedal mod.

    Does wah>TU2>everything else do anything positive to my signal?
     
  12. Post-HK

    Post-HK Tele-Meister

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    I had been thinking about modding my Thomas Organ Crybaby for true bypass, but I also noticed that putting it after my TU-3 made the bypass issue MUCH better. Decided to leave it as it - one of the reasons I've turned into a Boss buffer fan of late. Running the Crybaby before the buffer still has all the tone suck.
     
  13. Tom Freeman

    Tom Freeman TDPRI Member

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    I did the true bypass mod to my crybaby. At first I liked it a whole lot, because it sounded much smoother (plus I'd done a bunch of other mods that I was having fun playing around with). However, I quickly realized that I was missing a lot of high end, and the pedal seemed to sound kind of dull. When I put the input buffer back in, the highs I was familiar with were back, but then the pedal sounded harsh and choppy in it's sweep again. I removed the buffer once more, and tweaked a few component values, and now it sounds a bit better, but it still sounds pretty dull to me. Definitely not the classic wah kind of tone I think of (Clapton, Hendrix, theme from shaft, etc.). No percussive whakka-whakka sounds, and it doesn't even seem to boost the highs with the toe down all the way anymore.

    Would putting an output buffer right after the circuit help remedy this? I was already thinking of doing this to help me out when using a fuzz face, but I might get to it even sooner if it can help recover some of the brilliance I expect from a wah pedal.
     
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