True Bypassing My Vintage CryBaby Wah Pedal

By Paul Marossy

Last Updated 06/04/05

A lot of guitar players complain that when their wah pedal is bypassed, it "sucks tone", meaning that it dulls the sound of the bypassed guitar. This due to the fact that the footswitch is a SPDT switch, so when the wah circuit is bypassed, it is always loading down the "bypassed" signal. There are two ways to get around this. One way is to install something like an FET input buffer, so that when the circuit is bypassed, it will not load down the signal. This is in fact how the new manufacture CryBabys are designed - the SPDT switch is still used and the buffer keeps the tone sucking at bay. The other way to do it is to true bypass it. This is the route I chose to take. Here are some details on what I did to modify my wah to true bypass.

	This the shell with bottom cover removed. This is a new manufacture wah that I bought, but the circuit is vintage CryBaby, with a TDK inductor. In spite of that, I think this one sounds pretty good myself.
	This is a closer view of the PCB. It uses carbon comp resistors and 2N5117 silicon transistors. The caps appear to be polystyrene. I added the parallel 100uF power filter caps and 1M pulldown resistor for use with a power supply, before I converted it back to strictly battery powered.
	This is a close up of the pot and the rack & pinion assembly. The pot is a heavy duty type made by Allen-Bradley. I'm not sure how old it is, but it doesn't make any scratchy noises at all.
	This is the new bypass switch, a 3PDT switch in lieu of the original SPDT switch. One of the poles is unused, and someday I may put in an LED indicator. I didn't install the LED mainly because I was concerned that it might create a popping noise when it was activated. The 100K 20-turn pot is to adjust the input resistance value to my liking. I kept the pot internally mounted because it's not something I want to adjust ever again, nor do I want any possibility of the setting from inadvertently being changed.
	This is the original input jack, made by Carter. To true bypass the pedal, the original SPDT switch must be removed. The green wire from the input jack goes to the new DPDT or 3PDT switch and the green wire going to the circuit board will now be reconnected to the new switch. The blue wire carrying the output signal (connected to the pot and PCB) will go to the new bypass switch and the white wire connected to the output jack will now be reconnected to the new bypass switch. See this diagram for details on the bypass switch wiring.
	In place of the DC power jack on the shell, I installed a power switch to interrupt the power to the circuit. This way, since I hate plugging in and unplugging cords all the time, I can just flip the switch. I did this mainly for use on my pedalboard and it also lets me just flip the switch to de-power the circuit. This is the only thing on my pedalboard that requires me to manually switch the power on/off.