Randy Cain: Founder member of the Philly soul group the Delfonics

The falsetto soul hits "Didn't I (Blow Your Mind This Time)", "La-La (Means I Love You)" and "Ready or Not Here I Come (Can't Hide from Love)" by the Delfonics are so evocative of the early Seventies that they regularly feature on the soundtracks of films like Quentin Tarantino's blaxploitation homage, Jackie Brown. Yet the records made by the Philadelphia vocal trio still sound fresh and distinctive and have been covered by Aretha Franklin, The Jackson 5, Todd Rundgren and Prince. The grooves and melodies devised by producer Thom Bell have proved so infectious that they have been sampled on myriad hip-hop and R&B releases by Notorious B.I.G., Missy Elliott and the Fugees.

The second tenor Randy Cain played an important part in creating the Delfonics' distinctive blend of three-part harmonies with Wilbert Hart – lead and baritone – and his older brother, William, whose swoop from aching tenor to falsetto made listeners swoon and became the group's trademark. William "Poogie" Hart co-wrote most of the group's hits with Bell and remains its de facto leader to this day. Cain was a mainstay from 1965 to 1971, the year the Delfonics won a Grammy Award for Best Rhythm & Blues Vocal Performance by a Duo or Group for "Didn't I", and he also helped the band to score three Top 40 hits in the UK. In 1973, he had a hand in the formation of Blue Magic, the Philadelphia group whose US hit "Sideshow" became a Top 3 single for the Jamaican singer Barry Biggs in Britain in 1976.

Born Herbert Randal Cain III in 1945, he joined his school friends, the Hart brothers, when their vocal group – originally called the Veltones, then the Four Gents, and eventually the Orphonics – lost one member to the church and another to the draft. They loved recreating the doo-wop sound of Little Anthony and the Imperials and Frankie Lymon and the Teenagers in the Harts' basement and became good enough to play colleges and high schools and enter local talent shows.

In 1966, they acquired as manager and promoter Stan Watson, who suggested a name-change to the Delfonics. He introduced them to Bell, working as pianist and arranger at Cameo Parkway, the Philadelphia label famous for Chubby Checker, Dee Dee Sharp and The Tymes. William Hart and Bell wrote "He Don't Really Love You", with the studio musician turned producer playing most of the instruments on the track.

The following year, they released "You've Been Untrue", another Bell-Hart composition, but the partnership really delivered in 1968 with the smooth ballad "La-La (Means I Love You)" which reached No 4 in the US. The same year the Delfonics played Vegas with Sammy Davis Jnr and were supported by the Jacksons in Chicago (Cain loved telling the story of a 10-year-old Michael Jackson bringing them tea and honey in the dressing room and telling everyone they were his favourite group).

With Bell's gift for melody and orchestration, the Delfonics ushered in the era of slick, sophisticated, symphonic Philly Soul, and helped define the genre with three excellent albums – including 1969's Sound of Sexy Soul – and a run of singles which crossed over from the R&B to the pop charts including "Break Your Promise", "I'm Sorry", "Funny Feeling", "Somebody Loves You", "When You Get Right Down To It" and "Over and Over".

By 1971, they had broken through in the UK as well, and appeared on Top of the Pops, but Cain either became ill or fell out with the Harts, depending on whose account you believe. He was replaced by Major Harris of the Jarmels. In 1973, Cain, then working for WMOT Productions (the initials stood for We Men of Talent), suggested that the singer and songwriter Ted Mills get together with a quartet called Shades of Love. As Blue Magic, they scored a No 1 R&B hit with "Side-show" and also placed "Three Ring Circus" in the US Top 40 in 1974.

Cain rejoined the Delfonics for a while in the '80s, and again recently, though in the intervening years both he and Wilbert Hart had filed and won civil suits against William Hart, the sole owner of the name, and Arista Records/Sony BMG, the owners of the Delfonics' catalogue, for back royalties.

Pierre Perrone

Herbert Randal "Randy" Cain III, singer: born Philadelphia 2 May 1945; died Maple Shade Township, New Jersey 9 April 2009.