The harp, whose lineage can be traced to the time of the pharaohs, is enjoying a revival of sorts these days. Revered by many folk cultures, it's been snubbed for almost two centuries by most European composers, who preferred the volume and versatility of the similar-sounding harpsichord (although a few Romantic composers like Berlioz employed it now and then for color). The current interest in early music has given the harp a new lease on life. At this week's confab of the Historical Harp Society in Evanston, a variety of topics--from genealogy to performing practice--are on the docket, but for those uninterested in scholarly minutiae the Saturday recital promises to be the most interesting. The performers are some of the world's finest pluckers: Mara Galassi of Milan is an expert on the Italian double harp, popular during Monteverdi's time, which sports two rows of strings, allowing for chromatic flourishes; Judit Kadar of Berlin specializes in 14th- and 15th-century harp repertoire; William Taylor and Ann Heymann are virtuosos of the clarsach, a triangle-shaped Gaelic harp plucked with fingernails; and Ron Cook and Cheryl Ann Fulton are harpists with expertise in medieval music. Saturday, 7:30 PM, Lutkin Hall, Northwestern University, 700 University, Evanston; 275-2824 or 708-584-5259.