Composers and synth players Paul Beaver and Bernie Krause were among the most high-profile electronic music acts of the late '60s, recording a series of LPs distinguished not only by their groundbreaking studio advances but also by the presence of notables including Gerry Mulligan and Mike Bloomfield. Krause -- a onetime member of the legendary folk group the Weavers -- was working as a staff producer at Elektra Records when he met Beaver, a former jazz musician; under the name Beaver & Krause, they began assembling electronic pieces employing spoken-word passages, acoustic in...