Rafael Toral's Wave Field (currently out of print) and Violence of Discovery and Calm of Acceptance (Touch) are two of the most gorgeous ambient guitar discs ever recorded, so you'd hardly blame the guy if he made a few more just like them. In fact the Lisbon-based sound artist's latest stateside release, a one-sided vinyl picture disc called Harmonic Series 0 (Table of the Elements, 2003), weaves a similarly dense drone from electric guitar and analog instruments; the biggest change there is that he's added a computer to his setup. But since then Toral has decided that a job well done needn't be redone. The pieces he'll perform here represent a radically new paradigm, which he's dubbed the "Space Program." It reverses Toral's relationship with his raw material: instead of patiently sculpting a constant stream of sound, in his new work he manipulates signals from homemade or hacked-into hardware to draw attention to the silence that surrounds them. He's explained to me that there will be no drones, no loops, and no self-sustaining background processes: "I'm playing it all," he says, "manually, live and solo." (He says this approach has given him "a level of technical dexterity and a capacity for listening and concentration" beyond anything he's known before.) In "Space Study 1" Toral will employ a gestural interface--a pair of gloves he's outfitted with sensors--to control computer-generated sine waves. And in "Space Study 2" he'll cover similar territory using feedback from a hot-wired toy Marshall amp. This is his first local appearance in more than three years. Saturday 9, 9 PM, 6Odum, 2116 W. Chicago, 312-666-0795, $12. All ages.