The Nashville police said he had died of a self-inflicted gunshot wound. Don Aaron, a spokesman for the police, said Mr. Welch apparently had health problems and left a suicide note.

Mr. Welch was with Fleetwood Mac from 1971 to 1974. After leaving, he formed the rock group Paris, but when its two albums had limited success, he went solo. His version of “Sentimental Lady” — on which Christine McVie and Lindsey Buckingham of Fleetwood Mac sang backup (it had earlier been recorded by the band) — was a Top 10 hit in 1977. His“Ebony Eyes” reached No. 14 on the Billboard singles chart the next year. He had four Top 40 singles between 1977 and 1979. He later moved to Nashville, where he pursued songwriting.

Mr. Welch was born in Los Angeles — on July 31, 1946, according to some sources; on Aug. 31, 1945, according to others — the son of Robert Welch, a producer for Paramount.

Bob Welch was living in Paris when he joined Fleetwood Mac, which at the time was primarily a blues band. During his tenure, largely because of the influence of Mr. Welch and Ms. McVie (who had joined a few months earlier), the band developed more of a pop sound and its following grew, especially in the United States.

But Mr. Welch left and was replaced by Mr. Buckingham and Stevie Nicks shortly before Fleetwood Mac had its greatest success in the middle and late 1970s with the albums “Fleetwood Mac” and “Rumours.” When Fleetwood Mac was inducted into the Rock and Roll Hall of Fame in 1998, Mr. Welch was not included in the group.

Mr. Welch’s survivors include his wife, Wendy.