The notion of a Ralph Shapey Day must strike its honoree as a bit ironic. After all, for much of his four-decade career the University of Chicago-based maverick was largely ignored by the musical establishment; and the Chicago Symphony Orchestra during the Solti regime paid scarce attention to his provocative compositions. Interest in Shapey's music rose considerably during the 80s, thanks in part to the cachet of a MacArthur "genius" grant. Now, on his 70th birthday and the centennial of both the U. of C. and the CSO, he's at last being feted in style. These two concerts will feature not only his own works but also those by his influences (Beethoven, Edgard Varese, Stefan Wolpe) and students (Jorge Liderman, Lazar Trachtenberg, Fengshi Yang). The master of a style best characterized as "abstract expressionism"--a term usually associated with a group of New York City painters in the 1950s--Shapey is apt to apply broad strokes and bold colors. His music can be ferociously passionate; it can also be tender and spiritual; and it's always psychologically penetrating. Shapey's wife, Elsa Charleston, will sing, and other performers include prominent musicians who have championed Shapey over the years: pianist Gilbert Kalish, conductor Cliff Colnot, and some of CSO's more intrepid members. (Sunday at 5 PM a discussion with Shapey will be moderated by his longtime associate and U. of C. colleague Shulamit Ran.) Sunday, 3 and 7:30 PM, Orchestra Hall, 220 S. Michigan; 435-6666.