What began with analog stomp boxes in the early 1980s, and maybe a Frippertronics style setup for looping, eventually turned into something that back then would have seemed like science fiction. The electric guitar is still a sound source today even in the most extreme kind of setup, but it is also a midi controller that can trigger any kind of sound, and the humble analog stomp boxes were either replaced by digital stomp boxes today, housing little computers, or directly by computers running some kind of sound software. Today’s digital guitar sound worlds are limitless.
I currently use a hybrid system of relatively ancient stomp boxes and multi-effect floor pedals in combination with a Windows laptop and an iPad. The computer runs a Canadian software called Plogue Bidule, a modular system with virtual patch cords (similar to MAX/MSP) that can be used to create just about any kind of setup made out of sound sources, sound manipulation, loops, and sound/midi signal paths.
All concerts with this system are entirely improvised.