Dual AB Box

The artist Jachary requested a pedal to allow him to run both a guitar and a bass through the same pedal board, but send the bass to a bass amp, and a guitar to a guitar amp. I considered building a relay controlled I/0 box, but happened to have all parts on hand to build a fully passive, dual AB box. I placed the two 3PDT switches close enough so that they can both be pressed at the same time, switching both the input and output signals simultaneously. In this way, the output of the first AB box and the input of the second AB box act as a send/return signal for both inputs and outputs.

Furthermore, the “send/return” jacks are switched TS and continue to function if nothing is plugged in. Input B and Output B are also normalled to their “A” counterparts to allow the box to function as a normal single AB box in either AB directions if the user isn’t using both inputs or outputs.

Two red and two green LEDs indicate the switches’ positions, making it clear if you accidentally press only one of the switches.