Philly Soul was one of the most popular forms of soul music in the early '70s. Building on the steady groove of Hi Records and Stax/Volt singles, Philly soul added sweeping strings, seductive horns, and lush arrangements to the deep rhythms. As a result, it was much smoother -- even slicker -- than the deep soul of the late '60s, but the vocals remained as soulful as any previous form of R&B. Philly soul was primary a producer's medium, as Kenny Gamble & Leon Huff and Thom Bell created the instrumental textures that came to distinguish the genre. That isn't to short-change the vocalists, since the Spinners, the O'Jays, Harold Melvin & the Blue Notes, and the Stylistics were among many fine soul singers with distinctive voices, but the sonic elements that made Philly soul distinctive were the creation of the producers. Gamble & Huff worked with the Delfonics, Archie Bell, Harold Melvin & the Blue Notes, and the O'Jays; Bell produced the Spinners and the Stylistics, among others. The highly produced sound of Philly soul paved the way for the studio constructions of disco and urban contemporary R&B.