The Allegheny Choirs, under the direction of James D. Niblock, will perform a free concert at 3:15 p.m. Saturday, April 8, in Shafer Auditorium. The Allegheny College Chorus, Chamber Choir, Women’s Ensemble, Men’s Ensemble, and College Choir will each perform several works, and the groups will collaborate to close the performance as a choir of 111 voices. The concert is free and open to the public.