"Losing J.J. Cale is losing an American musical treasure," Campbell writes. "Always under the radar, he has been, and always will be, a huge inspiration to me and the band."
Campbell notes his admiration for Cale's "magical" guitar tone and "understated" lyrics, while also reflecting on his personal kindness and warmth: "He was always gracious and treated me like a friend."
The Heartbreakers have always been vocal about their appreciation for Cale's music. At last year's Jazz Fest in New Orleans, the band honored Cale by covering his classic track "Travelin' Light," while Petty called him one of his favorite songwriters.