Mr. Cosey’s best-known work for Chess was on Muddy Waters’s album “Electric Mud” (1968) and Howlin’ Wolf’s “Howlin’ Wolf Album” (1969).
Both records were released on a Chess subsidiary, Cadet Concept, founded to focus on heavier and more psychedelic sounds. They put two of the greatest blues voices into a harder blues-rock context, including long, vivid solos by Mr. Cosey. Both Muddy Waters and Howlin’ Wolf disliked the results, but the records made their point: over time they were defended and eventually celebrated.
Meanwhile, Mr. Cosey was working widely. He was a member of the Association for the Advancement of Creative Musicians, the cooperative Chicago organization devoted to experimental improvisation; he toured with Aretha Franklin and the jazz saxophonists Gene Ammons and Sonny Stitt; he played with Philip Cohran and the Artistic Heritage Ensemble in 1968, on the album “The Malcolm X Memorial,” a cult classic of soul jazz.
In the spring of 1973, Mr. Cosey joined Miles Davis on tour. At the time, Davis was looking for “a deep African-American groove, with a lot of emphasis on drums and rhythm,” as he put it in his autobiography. Mr. Cosey, he wrote, “gave me that Jimi Hendrix and Muddy Waters sound that I wanted.”
That only partly describes Mr. Cosey’s sound and strategies. Sitting in a chair behind a row of guitar pedals, with dark glasses, tall Afro and long beard, he used original tunings, sometimes on a 12-string guitar, chopping through the dense rhythm with wah- wah and downstrokes, pushing his solos toward ghostly delicacy or scrabbling arias striped with reverb and feedback. (His playing influenced other guitarists working around the outskirts of both rock and jazz, including Vernon Reid, Henry Kaiser and Arto Lindsay.) He can be heard on the Miles Davis albums “Agharta,” “Pangaea,” “Get Up With It” and “Dark Magus,” some of the most experimental and confrontational records of Davis’s career.
In later years Mr. Cosey appeared on Herbie Hancock’s 1983 album, “Future Shock”; briefly played in the band Power Tools with the drummer Ronald Shannon Jackson and the bassist Melvin Gibbs; formed a band in 2001 called Children of Agharta with other members of the mid-’70s Davis group; and performed in the band Burnt Sugar on the album “The Rites,” an improvised version of Stravinsky’ “Rites of Spring” conducted by Butch Morris.