When I play live I have a bunch of instruments, including:

• Mandolin: an electric mandolin

• Computer: a custom MIDI mapper driven by keyboard, foot drums, and breath controller.

• Bass whistle: a whistle-controlled bass synthesizer

I also have some effects, primarily a talkbox and an audio-to-audio synth pedal. Normally I route the mandolin into the effects, but I've recently been wanting more options:

• The computer effects are a lot of fun routed through the talkbox.

• If I set the bass whistle to emit just a sine wave, and pipe that into the synth pedal, I can control professionally-designed sounds:

The thing that makes this tricky is that I want to be able to play mandolin direct (which goes via the talkbox output) at the same time as playing bass whistle (which goes via the pedals output). I sketched a lot of options:

And eventually realized I only needed something simple:

This lets me switch between two modes:

• Mandolin goes to talkbox, whistle goes to pedals.

• Mandolin goes to pedals, computer goes to talkbox.

I wired something up with a 3PDT switch, five 1/4" jacks, and a couple wagos, in a a small case:

The 1/4" jacks are very slightly too big for the case, so I needed to make them very slightly smaller. Which I did (not recommended) by melting away the offending region with the soldering iron.

I tested it with my mandolin pretending to be each instrument, and it seems to work! The main risk is that the volumes of the input instruments aren't in the right range, which I won't know until I combine all three instruments. If that's the situation I think I can add some resistors to balance it out.

If the levels are decent, though, I'll give it a go at Porchfest tomorrow!