Mod-able Wah Project notes Revision 02 June 2004 Thanks to Gerben Koopman for this wonderful project! I have slightly enhanced his original project and created an improved pcb mask. The idea of this project is to use an exsisting wah and replace the circuit board add a couple rotary switches and have a "super wah"! The PCB has 3 different ways to change the sound: 1. different trimpots to change the 'timbre' of the Wah 2. different capacitors to select the range over which the filter works 3. selection of 1 of 2 inductor or 2 inductors in series. Trimpots -------- You can measure the trimpots before you install them. Using a ohm-meter you can tune the trimpot into the original value of the resistor it is replacing and mark that spot on the trimpot. This will give you a reference for tuning the trim pots once the project is up and running. 1. Gain-50K-pot (R1b). This gives, together with the 22K, the original 68 K for the input resistor. Lowering the value gives more gain and a bit more bass. This pot can be used to make the wah uni-gain or to give a small volume boost. 2. 'Saturation'-5K-pot (R2). This replaces the 1K5-resistor. To my ears it gives more mid/saturation when raising the value. Go easy on this one or the sound will get to muddy. 3. Q-50K-pot (R7b). The original 33K is still in place. Changes the the Q of the filter. Raising this pot gives a more peaky wah sound. 4. 'Honk'-1K-pot (R4). This replaces the original 510/470 Ohm-resitor. Lowering this one gives more 'Honk' to my ears. Capacitors (C2a-f) Bigger value caps = lower frequency range Suggested values; 5n6, 8n2, 10n (original), 15n, 22n and 33n. Try and see what you like. Use a 6PDT rotaryswitch with 'break-before-make' contacts. You can place a 1M-resistor over every pole on the switch stop the popping (which is really loud!) when switching when the wah is in use. Inductors. Using 2 inductors in series gives a really fat sound which is different than switching the 'range-capacitor'. The Fulltone-inductor gives my main-sound and I use the original Vox-inductor in series for the 'fat'-sound. Note that the diagram shows wiring for a rotary switch, you can also use a 4PDT on-on-on toggle switch if you can find one. Copyright 2004 JD Sleep http://www.generalguitargadgets.com