Mr.Gumby wrote:
There are other electronic options as well, I have, for example, seen Andy Irvine use pedals that produce a hum to fill out his sound when playing solo.
Just did a quick search and yeah, it looks like EDM and "ambient guitar" styles have made a market for drone pedals. I had no idea this stuff was out there. It's been a long time since I paid attention to electric guitar FX.
Here's one example, the "Electro Faustus Drone Thing." Skip ahead to 5:00 to start hearing what it does:
https://www.youtube.com/watch?v=YnuNWD2uevQAmong several drone pedals I skimmed through on a quick search, that sounded the most like a set of pipe drones on some of the less extreme settings. It's an independent sound source, not an inline effect that requires an instrument input. Too fussy to adjust during a performance, but you could get two or three pedals and tune each one to a different fundamental pitch for playing in different keys/modes. Then run 'em through a switch box, put it all on a pedal board and you're set.
Since you're playing with a piper, another cheap, dirt-simple idea would be to record the drone from your piper, then run it through an audio editor to change the pitch. Output audio files at the pitches you want, then play that as a loop through the PA.
Me, I'd still go for a shruti box, for the "authentic acoustic" vibe and looks. Something else I discovered back when I was fooling around with a looper, was that an audience likes to see what's producing the sounds. "Hidden" effects like loops or pre-recorded sounds don't go over as well as when the audience sees you working an instrument to produce the sounds. With a shruti box, they can see what's happening.