The Bad Plus and Joshua Redman shine in rare collaboration

Over their 15 years together, the Bad Plus has developed a distinctive and recognizable sound: irreverent, florid, a juggling act of jazz, rock, and classical influences. This is, after all, a band that has covered both Stravinsky's Rite of Spring and Kurt Cobain's "Smells Like Teen Spirit." Rare in jazz, it's a band in the truest sense, never allowing substitutions on the bandstand and always speaking in a collective voice.

All of which makes the addition of a fourth voice an intriguing notion, especially one as well-defined as that of saxophonist Joshua Redman, who has enjoyed his own successful career for more than 20 years.

Although Redman is a gifted and fluid improviser, his own sound has always fallen more firmly into traditional jazz channels. As restless as he's been, he's steered between post-bop and groove poles, with respectable diversions such as an orchestral album.

As the appropriately named Bad Plus Joshua Redman, the collaborative quartet played World Café Live on Saturday night to an enthusiastic crowd. Redman has stepped into the trio's world for this project, but the move into relatively unfamiliar territory is an inspired one, revealing a more intense and fiery side of his playing.

The set covered nearly all the quartet's debut album, released last month, with a few older Bad Plus tunes added.

The evening began in a melancholy mood with pianist Ethan Iverson intoning mournful chords, leading into bassist Reid Anderson's "Love Is the Answer" from the trio's 2001 debut. When Redman entered with a keening tenor melody it was as if he'd belonged there all along, like a singer adding his voice to instrumental tracks. Iverson welcomed the new addition with dissonant piano, clashing with the opening lines of the saxophonist's solo, instantly shifting the ground under his feet and spurring him in unexpected directions.

The Bad Plus has always delighted in music that comes from provocation, evidenced on the mechanical funk tune "As This Moment Slips Away." During solos, Iverson might begin to stutter the melody, Anderson subvert time with an unexpected pause, or King interject sudden eruptions. Redman welcomed the challenges inherent in this band of provocateurs. Whether unraveling synchronized cascades with Iverson on "Faith Through Error" or wending elusive figures through drummer Dave King's lovely "Beauty Has It Hard," he fit in more like a long-lost brother than a special guest.