You might not know its name, but if you tuned into episodes of Soul Train in the '70s, you knew "TSOP (The Sound of Philadelphia)," the jaunty song that kicked off every episode - and was indeed the No. 1 song in America on April 27, 1974.
"TSOP" was the biggest hit for MFSB, the ad-hoc house band for the Philadelphia International Records label. (Their name was short for "Mother, Father, Sister, Brother.") By this point, the Philly sound, as overseen by label founders Kenny Gamble and Leon Huff, had blown up in a big way thanks to chart-toppers like Billy Paul's "Me and Mrs. Jones" and The O'Jays' "Love Train" in 1972 and 1973.
While Soul Train wasn't from the City of Brotherly Love - host and creator Don Cornelius was from Chicago - the up-and-coming music variety show, which had been nationally syndicated since 1971, recognized the power of the Philly sound. So Cornelius commissioned a new theme from Gamble and Huff. With backing vocals from The Three Degrees, the newest members of the P.I.R. roster, the stirring track was just what Cornelius wanted - although he famously asked that the group not name the song after the program, or even include the show in the lyrics to the song. (They're heard in the version on the show but not on the single.)
"He was like, 'I don't want anybody else to have my brand but me,' " Gamble told Billboard after Cornelius' passing in 2012. "We said, 'But that's YOUR theme song.'...So we called it 'TSOP' and it became a No. 1 record, and every time we'd see him after that he'd say, 'Dumbest move I ever made.'"
While the original recording only served as the theme for two years, "TSOP" is forever connected with Soul Train and its joyful presentation of Black music on television. A remake by George Duke would be used to introduce the show between 1987 and 1993.