When a musician leaves a band, it recalibrates and fills the void; when a musician dies, that's an absence with long-lasting presence. For this S.F.-based instrumental act, the passing of trumpeter Jeff Jacobs irretrievably altered the band's dynamic. The Drift found its voice on 2005's sophomore release Noumena, and honed it to a fine point with 2008's excellent Memory Drawings, building on steely interplay between Jacobs' horn and Danny Grody's guitar. With a solid rhythm section pounding out propulsive beats, the band carved out post-rock space between Tortoise's percussive grooves, Do Make Say Think's guitar-rock shades and trumpeter Rob Mazurek's jazz-dub Chicago Underground collective. Much of that remains, but with Jacobs gone, the remaining trio has to rely more on hypnotic riff repetition, with bassist Trevor Montgomery especially stepping up. The mood is, not surprisingly, more somber, though no less revelatory at times. Opener "Dark Passage" sounds like Black Heart Procession's slow nihilism kicked into overdrive by Neu!; the dusky guitar lines on "Horizon" build up momentum until they could be Ennio Morricone as rendered by Pinback. "Fountain"'s 12 minutes incrementally unfurl into transcendence when Grody's guitar noise eventually drifts into a simple and graceful piano pattern. Still, Jacobs' absence is felt: on "Luminous Friend," the keys approximate trumpet to strong effect; on "Continuum," a similar attempt falls flat. This band is coming to terms with a devastating loss, and for the most part honoring their friend in compelling new ways. But it's also an ongoing process. Things have changed, and forever. That takes getting used to.