Concord, MA 4/1/12 Members of The Harlem Quartet (cq) perform at the Emerson Umbrella Center for the Arts, on Sunday, April 1, 2012. The program includes Turina (cq), Beethoven (cq) op. 18 no. 3, Wynton Marsalis (cq) (Rag, Mating, Hellbound) and A Train. Ilmar Gavilan (cq) (violin) plays a brief solo. Pat Greenhouse/Globe Staff); Reporter: G. Edgers; Section: Arts; Slug: 19quartet