Last summer, when founder and first violinist Robert Mann retired, the country’s premier string quartet found itself in a precarious position. On the face of it there was nothing to worry about–Mann’s spot was taken by the quartet’s fine second violinist, Joel Smirnoff, and Ronald Copes, a thoughtful former member of the Los Angeles Piano Quartet, took his chair. Past personnel changes–including the addition of Smirnoff in 1986–had even energized the Juilliard, subtly altering its take on the core literature for the better. But the heart and soul of the quartet had for five decades been Mann, one of the most intense and iconoclastic chamber players ever. It was Mann who fashioned the vigorous, incisive Juilliard style back in the 50s, when a looser, warmer, less probing approach was the norm. He led the quartet in its zealous support of living composers, and is hence arguably responsible for a large chunk of the contemporary quartet repertoire having been written at all. Though he obviously relished a good argument, the other members tended to defer to him, and the sheer force of his will lent an inexorable logic to most of their performances. A new member might emphasize beautiful phrasing or sharpen the rhythm, but no matter what else was brought into the mix a successful Juilliard interpretation was invariably lucid, intense, and intellectually riveting. Upon his departure, Mann left the quartet to vie for attention in a field that, thanks in part to his exemplary leadership, is now crowded with Juilliard imitators and disciples. Reviews of the quartet’s most recent concerts in New York indicate a remarkable continuity, but no matter what happens here, it should be interesting to witness. As part of the venue’s yearlong Beethoven Festival, the Juilliard will play five of Beethoven’s quartets (op. 18, no. 3, and op. 59, no. 3, on Sunday and opp. 74, 130, and 133 on Wednesday) in addition to one each by Berg and Webern. Sunday, 3 PM, and Wednesday, 8 PM, Orchestra Hall, Symphony Center, 220 S. Michigan; 312-294-3000. TED SHEN

Art accompanying story in printed newspaper (not available in this archive): Erich Hartmann-Magnum.