Raphael Saadiq's endless inventiveness is all over soul. As a producer, he guided the slow-burning neo-soul of D'Angelo's “How Does It Feel,” the yearning, string-laden affirmations of Solange's “Cranes in the Sky,” and the nostalgic, 808 drum-machine grooves of Erykah Badu's “Love Of My Life (An Ode to Hip-Hop).” Meanwhile, his memorable chorus on The Roots' “What They Do” proves his vitality as a backing singer.