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Adding a "blend" knob to an effects pedal.

Discussion in 'Effects [BG]' started by cjgallen, Oct 7, 2003.


  1. cjgallen

    cjgallen

    Oct 19, 2001
    How would I go about adding a knob to blend the wet and dry signal on an effects pedal?

    I've attempted this by simply adding a wire from the input to the output with a pot in between, but it made some strange feedback noises, so I'm guessing that wasn't right :p

    Anybody? Also, what's a good size pot to use? 500K? 1Meg or more?
     
    youshouldverun likes this.
  2. Jazz Ad

    Jazz Ad Mi la ré sol Gold Supporting Member Supporting Member

    It will be different on each circuit.

    Instead of modding the pedal, I'd use (actually, I do use) a loop pedal such as a Loooper or a Boss LS-2.
     
  3. cjgallen

    cjgallen

    Oct 19, 2001
    I built a Looper box. How would I add a blend knob to that?

    It seems like a blend knob on the effect pedal would be the same thing as one on the loop box. The only difference would be the instrument cable in between?
     
  4. cjgallen

    cjgallen

    Oct 19, 2001
    AHA! As soon as I saw a schematic I was like "DUH!"

    Wet signal goes to one end of the pot, the dry signal to the other end, and the center goes to the output.
     
  5. Jazz Ad

    Jazz Ad Mi la ré sol Gold Supporting Member Supporting Member

    Um, no.
    WHat you described won't work.
    A blender pot is actually 2 volume pots, stacked and wired backwards.
     
  6. cjgallen

    cjgallen

    Oct 19, 2001
    WRONG, I just did my method, and it works beautifully :D
     
  7. Corwin81

    Corwin81

    Mar 18, 2003
    Ames, IA
    wanna post a schematic? I'm thinking of building a Big Muff with a blend pot, yet still having true bypass
     
  8. the low one

    the low one

    Feb 21, 2002
    UK
    Now that is something I would be interested in. As good a distortion as the Big Muff is it kills your tone.
     
  9. cjgallen

    cjgallen

    Oct 19, 2001
    The Big Muff is exactly what I'm working on now. I'm also fiddling around with my recently aquired Morley Power Wah. I've already made both of them true bypass :D makes a world of difference.

    On the Big Muff I'm adding a "Body" knob to control the mid range scoop/bump, as well as the blend knob.

    I'm going to add a volume and blend knob to the power wah as well, and I might try making a frequency control like the white Dunlop.

    The Tone Stack Calc is a handy app. It let's you modify values in the Big Muff tone circuit and shows you the wave output.

    I'll probably write up a little how-to guide and post it when I'm all done.

    I attached the schematic for the Green Big Muff, and the changed values for the Black russian version are boxed in.
     
  10. isnt the morley power wah already true bypass? cause i turn it off and unplug it and the sound still goes through it
     
  11. cjgallen

    cjgallen

    Oct 19, 2001
    No, not exactly. It was wired in a similar manner as the big muff. If you look at the schematic you see that when "bypassed" the entire wah circuit is still connected to the input. True bypass removes the circuit completely so there is only one path from input to output.
     
  12. Corwin81

    Corwin81

    Mar 18, 2003
    Ames, IA
    any schematic made for the blend yet?
     
  13. I'm very interested in the schematic for the Big Muff too. The blend and tone knobs you were talking about sounds very interresting. Please post a 'how-to' guide when you're done

    Thanks
     
  14. cjgallen

    cjgallen

    Oct 19, 2001
    Mwahahah, it's so awesome!!! :D Added a volume and "Q" control to the power wah as well. I can finally dial in that Burton growl. Sounds so close to Call of Ktulu it's scary. I finally have a wah that I don't want to sell!

    Gonna work on a little how to guide for both. I'll probably post it here first.
    [​IMG]
     
  15. please post schematics and how to's if you can!!!
     
  16. I'm curious to know exactly how you did your "Body" knob mod, too.

    As for adding a blend knob to any effect, you may not always luck-out and be able to get away with just using a pot, like on the Big Muff. I built this box so I could blend in some clean signal to any effect, or chain of effects. It's really kind of like a little mixer, wet/dry balance and output volume controls:
    http://www.moosapotamus.com/paraloop/paraloop.htm

    ~ Charlie
     
  17. Corwin81

    Corwin81

    Mar 18, 2003
    Ames, IA
    wow, that's pretty much what I was looking for moosapotamus. Muchas gracias!
     
  18. cjgallen

    cjgallen

    Oct 19, 2001
    Here's my schematic.

    The blend knob makes some squealing noises when you crank the volume up too far, but I have no idea what exactly causes this. If anyone knows, please let me know so I can correct it.

    Other than that it's fairly straightforward. I put in the "Millenium Bypass" diagram as well. Works with the existing DPDT switch.
     
  19. can you make the morley true bypass and q control only schematic cause if the blend knob does squellys i dont want it or does the blend knob make squeally noises on the wah as well? thanks.
     
  20. cjgallen

    cjgallen

    Oct 19, 2001
    I didn't add a blend to my Power Wah, just the q control and a simple volume knob. No squealing at all on that.

    I'll whip up a schematic really quick...