For altoist Tim Berne, championing the work of his former mentor, Julius Hemphill, has become something of a part-time job. Lately he's also been performing with trumpeter Baikida Carroll, Hemphill's contemporary in the St. Louis-based Black Artists Group, one of several 1970s collectives inspired by Chicago's AACM. Carroll's name is not as well known as fellow BAG vets like Hemphill and Oliver Lake, perhaps due in part to the era's sax-centricity; Carroll's playing served as a lively and colorful foil to his reed-playing compatriots. He was also temporarily derailed in the late '80s by the onset of Bells Palsy, a condition that causes nerve damage in the facial muscles. This quartet provides Carroll an ideal setting to showcase his vitality and inventiveness, comprising as it does three players with long-running rapport: Berne, drummer Tom Rainey and bassist Michael Formanek, whose name this quartet bore when it hit Philly last year.