"Source of Uncertainty," Featuring Morton Subotnick, at Schimmel Center New music has always been a central component of the River to River Festival, but for breadth and variety the festival has outdone itself this year. Though most of its contemporary offerings put a spotlight on composers working with conventional instruments and voices in several styles, there were also two concerts, both called "Source of Uncertainty," that focused on electronic music. Ian Douglas for The New York Times Source of Uncertainty Morton Subotnick performing at the Schimmel Center for the Arts as part of the River to River Festival. Specifically, the concerts explored analog synthesis: music made on synthesizers built of modules that produce and modify sound waves, rather than on the computers that have largely supplanted them. Or had. Just as vinyl LPs are back in vogue, analog synthesizers are having a resurgence. The second "Source of Uncertainty" program, on Saturday evening at the Schimmel Center for the Arts at Pace University, was devoted mainly to a hero of analog synthesis, the composer Morton Subotnick. It would be inaccurate to suggest that Mr. Subotnick, at 79, is clinging to an antique instrument as the world has moved on. He is still fond of the Buchla modules (or updated versions of them) on which he made his classic scores of the 1960s and "70s, and had a Buchla setup with him onstage. But he had a laptop too, and used it - along with a software program by Ableton - to expand, shape and control the Buchla's sounds. Mr. Subotnick offered a single, seamless performance built on two very different works. He began with an excerpt from "Silver Apples of the Moon," a seductively tactile score he created for Nonesuch Records in 1967, and morphed it into "Song and Dance," a new, improvised work commissioned for the occasion. For anyone smitten with electronic music in the late 1960s Mr. Subotnick's conjuring in "Silver Apples" yielded many richly nostalgic moments. Tones that sounded like a cross between dripping water and percussion instruments; sliding, high-pitched notes that melded the impulsive chatter of a birdhouse with effects from sci-fi space epics; and distant sirens that arose from within a dense, smooth chord were all shaped into a blossoming narrative essay. In this version Mr. Subotnick used surround-sound technology, allowing the work's evocative strands to move freely around the theater. Was it dated or gimmicky? Compared to the sounds produced by computer composers today - and to the slicker timbres and cross-rhythms of "Song and Dance," in which heavily processed live vocalizations by Mr. Subotnick were woven into flexible, quickly morphing textures - some of the buzzes and chirps could seem quaint. But they are of their time; you might as well argue that Bach's concertos are quaint once you're heard Beethoven's. Mr. Subotnick's performance included live video by Sue Costabile, working under the name Sue.C, that matched the music's impulses to evolving shapes, colors and (mostly metallic) textures. The program also included a tape work, Richard Lainhart's brash, muscular "Orchestra of the Damned." The River to River Festival runs through Sunday at various sites in downtown Manhattan; (212) 219-9401, rivertorivernyc.com.