“What You Won’t Do for Love” went to No. 9 on the Billboard Hot 100 and No. 6 on what was then called the Hot Selling Soul Singles chart. It became a long-term standard and career-defining hit for Mr. Caldwell, who also wrote the song.
The song was covered by artists including Boyz II Men and Michael Bolton and was sampled by rapper Tupac Shakur on his posthumously released song “Do For Love.”
Other Caldwell songs were sampled by hip-hop artists including the Notorious B.I.G., Common, Lil Nas X and Chance the Rapper.
Robert Hunter Caldwell was born in Manhattan on Aug. 15, 1951, and grew up in Miami.
A multi-instrumentalist, he began performing professionally at 17 and got his break playing guitar in Little Richard’s band in the early 1970s. A few years later, Mr. Caldwell played in bar bands in Los Angeles before landing a solo record deal.
Mr. Caldwell would never have a hit that came close in prominence to “What You Won’t Do for Love,” but he released well-regarded albums, including “Cat in the Hat” (1980) — on which he appeared on the cover wearing a fedora — and “Carry On” (1982), on which he was his own producer and played all the instruments.
His song “Open Your Eyes” from “Cat in the Hat” was covered by John Legend and sampled by Common on his 2000 single “The Light.”
In the 1990s, Mr. Caldwell shifted to recording and performing American standards, including songs made popular by Frank Sinatra and Nat King Cole.
Survivors include his wife, two daughters and a stepdaughter.