Now in its 10th year, this showcase of local and regional jazz acts features free concerts Saturday and Sunday. Also, on Saturday at 2 p.m., a free jazz improv workshop aimed at teens (sign up at a2jazzfest.com). Tonight: the Elvin Sharp Quartet (6 p.m.), a young jazz ensemble, led by tenor saxophonist Sharp, that plays funky original compositions along with classics from the hard-bop and post-bop catalog. The Alex Hoberty Quintet (7:30 p.m.), a young jazz ensemble led by bassist Hoberty, an MSU jazz studies student. Junk Jazz (9 p.m.), a Detroit experimental jazz trio which has influences as varied as funk, punk, and Brazilian. Rabbit Hole (Sat.), 608 E. William, & Ravens Club (Sun.), 207 S. Main. Tickets $50 (Fri.) & free (Sat. & Sun.). Donations accepted. (734) 769–2999, a2jazzfest.com.