Pedal Hacker Projects - True Bypass Loops

There are times when you want to add true bypass switching to a pedal without re-housing and re-wiring the pedal. You can make a true bypass loop pedal cheaply and easily to accomplish this. Here are some wiring diagrams that you can use to make your own loops with various features.

True Bypass Loop, No LED Indicator

As simple as it gets, four jacks and one switch. This circuit accomplishes a true bypass loop with the minimum of parts. Plug the input signal into In, the output to Out, the In of the pedal you want to bypass to Send and the Out of the pedal  you want to bypass to Return.

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True Bypass Loop with LED Indicator

Add a few more parts to the previous design and you have a loop with an LED indicator.

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True Bypass Loop with LED Indicator and a Feedback Mixer

This is another variation on the loop circuit. This one uses a potentiometer to act as a passive mixer to send signal from the output back into the input. The feedback mixer is great for making fuzz or dirt boxes oscillator or generate larger than normal amounts of gain. You can also use it with modulation effects like chorus, delay and phasing to get some very neato sounds. The circuit simply taps off of the output to a SPDT switch (you could use a SPST switch also), routes the signal through the potentiometer, and then back to the input through the Send jack.

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True Bypass Loop with LED Indicator and a Volume Control

What if you want to add a volume attenuator to your loop? For example, you have a pedal that provides an unwanted volume boost when engaged? You can add a simple passive volume control to the true-bypass loop to attenuate the signal in the return path. In this example, we wire a 100K audio taper pot as a simple voltage divider.

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