Compared to the Raster-Noton label's austere output, most self-described "minimal" techno sounds positively maximal. The laptop-generated oscillator tones and minute, ice-cracking clicks heard on many of the releases by Alva Noto, Byetone, and Frank Bretschneider are often perched on the edge of audibility, suggesting a degree zero of electronic music. But when the three combine their carefully calibrated static as Signal, the sound becomes as deceptively flat — and subtly variegated — as one of Robert Rauschenberg's infamous white paintings. Prepare to commune with the ghosts in the machine.