There was no original input signal being processed, simply the feedback hum generated by plugging the original chain of pedals back into itself. However, when Stapleton went near the pedals he found the sound changed in accordance with his proximity to the various pedals and units.
No original input signal was present for processing; rather, a feedback hum resulted from reinserting the initial sequence of pedals into themselves. Nonetheless, as Stapleton drew nearer to the pedals, the sound changed according to his proximity to different components.