Whatever you call Miles Davis’ music on Bitches Brew (billed as “Directions in Music by Miles Davis”), it was not exactly a subtle shift in course: the wild, surreal cover art, the menacing title, the marathon explorations, the prominent doses of psychedelic rock and heavy soul. Drawn to the primal expressiveness of rock and soul, Davis created his own sound of great ferocity and chaos, of quiet beauty and deep grooves, and when he went into the studio for three days in August of 1969 — in the immediate fallout of Woodstock — he was fortunate enough to have a slew of first-class musicians help him execute his vision: his core band of Wayne Shorter, Chick Corea, Dave Holland, and Jack DeJohnette, augmented by the likes of John McLaughlin, Bennie Maupin, Joe Zawinul, and Larry Young. The two side-length tracks, “Pharaoh’s Dance” and “Bitches Brew,” are winding jams with shifting moods and tempos; the many musicians dance gingerly around each other at times, then stomp and flail with abandon. “Spanish Key” offers intense, impenetrable funky rhythms and showcases McLaughlin’s rough-edged guitar and some rather aggressive trumpet from the leader. “Miles Runs Down the Voodoo” is a filthy, snaking, late-night R&B vamp while “Sanctuary” mixes introspective passages with a few dense bursts of activity.