Blues harmonica player Carey Bell, who performed with both Muddy Waters’ and Willie Dixon’s bands, died Sunday in a Chicago hospital of heart failure. He was 70.

Mr. Bell’s trademark sound worked well on funky up-tempo songs, but he also was also capable of great expression and sustained melodic work in ballads. He emerged at the forefront of blues harmonica in the 1970s after touring and recording with Muddy Waters and Willie Dixon, particularly as part of Mr. Dixon’s Chicago Blues All-Stars.

Born November 14, 1936, in Macon, Mississippi, Bell wanted a saxophone but his family could not afford one. Instead, his grandfather bought him a harmonica.

He was playing the harmonica by age 8, and in 1956, at age 19, he moved to Chicago with his godfather, pianist Lovie Lee.

Soon, he was supporting himself as a professional musician, playing on the street for tips.

He met and learned from Marion “Little Walter” Jacobs and Sonny Boy Williamson II, but found a special fatherly mentor in Big Walter Horton

Bell never planned too far ahead, would show up for gigs in suspenders, and had a missing front tooth he never replaced. He had little formal education, and his reading and writing skills were limited.

“He was just such a sweet, gentle guy, with a huge ability to laugh at himself,” Bruce Iglauer, president of Alligator Records, which released several of Bell’s albums, said. “And he took great pleasure in bringing joy to other people. When he’d play harmonica and people applauded, he just loved it, he glowed.”

Bell is survived by 10 children, including blues guitarist and vocalist Lurrie Bell, with whom he recorded the 2004 album “Second Nature.”