I was adding a battery holder to my Plumbutter and decided to dress the wiring.  It’s not a necessity, but I think it’s good to twist a ground with a signal wire for some shielding effect.  The first and easy step was to twist the wires going to the eight quarter-inch jacks.  These have two wires, signal and ground, but they aren’t twisted.  Remove the jack by unscrewing the hand-tightened nut, gently twist the wires, and replace the jack.  The second step was to add a ground wire to be twisted with each signal wire going from the main board to the mixer.  I made up twisted pairs of #24 stranded wire and replaced the existing solid wires with these.  I soldered one end of the ground wire (white for visibility) to a pad clearly meant for this use next to each of the outputs on the board.  The mixer end of the ground wire is left unconnected.  I used red/white for modules on one side and black/white for those on the other side.

The battery holder mounts in the hole the original battery leads went through.   I drilled a new hole for the battery leads between it and the power inlet.  Radio Shack supplied the the battery holder and power clip.  The clip’s wiring comes out of the short edge, which is just right for this.

I also twisted a ground wire with existing leads going from the snare hit noise output over to a capacitor on a prototyping area and back to the mixer. You can see it running parallel to and one inch to the left edge of the mixer.  Now all the signal wires have some shielding.