Wah Pedal DIY

Written by simon foden Google
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Wah Pedal DIY
The position of the rocker on expression pedal wahs determines the parameters of the frequency range. (PhotoObjects.net/PhotoObjects.net/Getty Images)

Wah is a type of guitar effect pedal, which has an internal signal processor chip which manipulates the frequencies produced by the guitar to approximate the human voice saying "wah." There are two types of wah pedals: Automatic and expression pedal. Both perform the same sonic function, but the method of determining the frequency parameters are different. Automatic wahs have dials that set the range, intensity and speed of the frequency change. Expression pedal wahs are foot operated, and the parameters are determined by the position of the foot pedal.

Skill level:
Moderately Challenging

Things you need

  • Pedal chassis
  • Blank turret board
  • Resistors
  • Transistors
  • Op-amp chip (signal processor)
  • 2 1/4-inch jacks
  • IEC power supply socket
  • Potentiometers
  • Rocker teeth strip (expression pedal only)
  • Phillips screwdriver
  • Wire
  • Wire cutters
  • Soldering iron
  • Solder

Show MoreHide


  1. 1

    Purchase the required parts. You can purchase parts individually or as part of a kit. Using a kit is advantageous because the parts are made to measure and come with a schematic, which is a diagram that details the layout of the components. If you are purchasing your parts separately, you can view wah pedal schematics online.

  2. 2

    Colour-code the board-mounted components. Mark the schematic symbol for the part, the part's location on the turret board and the part itself. Use a different colour for each component and also for components of different values, such as resistors.

  3. 3

    Populate the turret board, which is the blank version of the circuit board. The resistors, op-amp chip, fuses and transistors are mounted here. Fit each part into the correct turret on the board. Push it as far as it will go so that the connector pins stick out of the base of the board. Once everything is in place, place the board facedown, and solder the pins to the metal strips.

  4. 4

    Mount the potentiometers. The location of the pots depends on the type of pedal your are building. For an auto wah, mount them in a row on the top of the turret board. For expression pedals, mount the single potentiometer in the centre of the board, and connect the rocker teeth strip.

  5. 5

    Screw the completed circuit board into the base of the pedal enclosure.

  6. 6

    Mount the IEC power supply socket in the pre-drilled hole on the chassis. The socket that accepts the adaptor protrudes from either the side or back of the pedal, depending on the model. Solder a red and black wire to the output terminal on the power supply socket. Solder the red wire to the positive eyelet on the circuit board, and solder the black wire to the negative eyelet.

  7. 7

    Fit the jacks. Slot these into the holes on either side of the chassis base. Solder a red wire to the output terminal on each jack, and solder the other end to the op-amp chip mounted on the circuit board.

  8. 8

    Enclose the chassis. Screw the chassis lid onto the base.

  9. 9

    Fit dials on to the potentiometer poles if you are making an auto wah.

Tips and warnings

  • Observe your soldering from the side. Looking straight down on to the iron means solder flux can rise up into your face.
  • Never touch the tip of a soldering iron that is turned on.

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