"Fred Hopkins had one of the most forcefully distinctive sounds of any jazz bass player of the last 30 years. Many practitioners of an instrument that has grown in stature since the war were better known. Hopkins rarely led a band of his own and was involved in an exploratory jazz movement that struggled for recognition. Yet to bass players, and listeners who let his music touch them, Hopkins was a musician of remarkable expressiveness and formidable technique.

He was involved with many playing partners and appeared on innumerable recordings, but it was his work with the trio Air (also featuring saxophonist Henry Threadgill and drummer Steve McCall) that showed how inventive and responsive he could be. Air was a mercurial, sometimes aggressive, utterly ingenious ensemble that sprang out of the Association for the Advancement of Creative Musicians, an influential Chicago self-help movement for experimental players developing in the wake of Ornette Coleman and John Coltrane's approach to jazz which made musician-led infrastructures necessary because the mainstream record industry was terrified of it. The band was the perfect setting for Hopkins, with his big sound, maverick approach and boldness of conception.

Like Ray Brown and Wilbur Ware, he had a loud and lustrous sound, reverberating with overtones. But though he could sustain a dark, billowing backdrop for the work of busier partners, he was also capable of astonishing agility, horn-like flurries of improvised melody full of aching, slurred sounds, plucked effects like percussion, cliff-hanging bowing experiments, and sustained low notes that seemed to rise out of the floor like a church organ. He was an ideal foil for the light, restless McCall and the mercurial, emotional Threadgill.

Fred Hopkins grew up on Chicago's South Side, moved to New York in the 1970s, then returned to Chicago for his last years. For his understanding of group improvisation, and his ability to underpin and embroider spontaneous ensemble performance, he was much in demand and his playing partners included the leading figures of the 1960s and 1970s American avant-garde, including Muhal Richard Abrams, Anthony Braxton, Don Pullen and the multi-faceted saxophone hero David Murray, whose groups turned out to be some of Hopkins's most fruitful outlets.

Like many Chicago jazz luminaries, Hopkins was inspired by Captain Walter Dyett's widely respected music programme at Du Sable High School. He also worked in the city's Civic Orchestra, and studied bass with the Chicago Symphony Orchestra's Joseph Guastafeste. He included among his lasting inspirations the classical bassist and conductor Serge Koussevitsky, but it was the Chicago free scene that revealed his potential.

The seeds of Air were sown in a 1971 band with the same line-up, called Reflections, the more lasting version being formed in 1975 as a free-improvising ensemble but one guided by the compositional inspiration of Threadgill, and at times exploring the work of elder statesmen such as Duke Ellington and Jelly Roll Morton.

Fred Hopkins was as forceful, vivid and charismatic as his sound, and followed his own path as a performer. Yet he only took to leading bands in his last years, and it was as a supreme accompanist on an instrument he seemed to make both gentle and thunderously assertive that he was in his element."