Emerson String Quartet: True teachers never quit

12:15 p.m. today, South Mecklenburg High School auditorium. Four brave young string players from Providence High School perform the last movement of a Mozart quartet before a couple of hundred peers, having learned it shortly before the performance.

Onto the stage come two members of what may be the premiere string quartet in America: The Emerson, which plays a concert tonight at 8 p.m. at Halton Theatre. (Tickets are still available here for the Charlotte Concerts season-opener, though it's almost sold out.)

Violinist Phil Setzer and violist Larry Dutton warm the crowd up with a couple of gentle jokes: The other two members of their quartet, violinist Gene Drucker and cellist Paul Watkins, haven't arrived yet. If they're unavoidably delayed, could the Providence players work up tonight's program and sit in?

Dutton mentions that neither of his parents played classical music, and a chance exposure in third grade to a school concert made him want to take it up. "It's important that we learn about music in public schools. It doesn't mean everyone's going to be a professional musician, but they'll know this great repertoire."

Then, gently, they begin to make suggestions. Dutton repositions the young musicians, so they can see each other better and project sound more efficiently. Setzer suggests new fingering for one player and helps him work on bowing. They explain how a string quartet has to give the illusion that it's a tiny orchestra by using dynamic contrasts, though its loud-to-soft range will be less than that of a symphonic group.

Some folks in the audience have simply come to hear the group play. They'll get their wish in a bit; when all four players reach the stage, the Emerson plays one movement from each of the three pieces on the bill tonight (Mendelssohn, Britten, Beethoven). Yet nobody's talking or distracted during the teaching moments, because they're hearing sound basic advice from masters of the craft.

South Meck music teacher Marc Setzer is Phil's brother, and Marc's wife teaches at Providence. So some special pleading may have been involved to get this 75-minute event to happen, though Charlotte Concerts regularly asks touring musicians to spend time in the community while they're here.

But you can see that these quartet players, who are in residence at State University of New York-Stony Brook, are having a good time. They love talking about the sound of the music, the mechanics of the music, the ideas of the music.

Globe-trotting and Grammy-winning though they be, they are teachers at heart. Performing matters to them, of course: That's how they make a very good living. But if you watched them at South Meck, you got the sense that sharing what they know matters just as much.