Venerable old-school DJ Chuck Chillout and his rapping partner Kool Chip run a graduate class in hip-hop tradition on Masters of the Rhythm, a solidly entertaining party record that skirts rugged language and any ideas more serious than “Rhythm Is the Master.” Over modest beats that sample Kool and the Gang, Cameo, Herbie Hancock and Talking Heads’ “Once in a Lifetime,” the duo drops energetic rhymes on familiar topics (with relevant soundbites from Public Enemy, the Fat Boys and Run — DMC), reliving rap’s recent past with engaging enthusiasm.