This tutorial describes how to recreate David Gilmour’s “Sound on Sound” effect. David uses a dual amp setup on Shine On you Crazy Diamond to achieve an infinite sustain over which he can play solos. Check out this article for a more detailed explanation and a video of the effect as used in concert.
Download the Ableton Live set here, MIDI map an expression pedal to the same controls as shown in the tutorial video, plug in a guitar and “shine on you crazy diamond.”
For more info on my Ableton Live centric guitar rig, here is the series and collected articles.