In the early 1960s, when rock was swallowing popular culture and jazz clubs were taking few chances on the new thing as the developing avant-garde was then known Mr. Dixon, who was known for the deep and almost liquid texture of his sound, fought to raise the profile of free improvisation and put more control into musicians hands. In 1964 he organized “The October Revolution in Jazz," four days of music and discussions at the Cellar Cafe on West 91st Street in Manhattan, with a cast including the pianist-composers Sun Ra and Cecil Taylor, among others. It was the first free-jazz festival and the model for present-day musician-run events including the Vision Festival.
Soon after that, he established the Jazz Composers Guild, a cooperative organization intended to create bargaining power with club owners and build greater media visibility. Mr. Dixon played hardball: he argued for a collective strike on playing in jazz clubs and hoped for the support of John Coltrane, the wave floating most boats of the new thing. The strike never happened, and the Guild fractured within a year.
William Robert Dixon was born in Nantucket, Mass., on Oct. 5, 1925. His family moved to Harlem when he was about 7; he first aspired to be a visual artist and studied commercial art in high school. (He continued to paint throughout his life.) In 1944 he enlisted in the Army, eventually serving in Germany during the last few months of war in Europe.
After his return he attended the Hartnett Conservatory in Manhattan and then started performing around town alongside, among others, Mr. Taylor, whom he met in 1951; the bassist Wilbur Ware; and eventually the saxophonist Archie Shepp, with whom he formed a quartet.
On records including “Intents and Purposes" (1967) and the two-volume “Vade Mecum," recorded in 1993, Mr. Dixon displayed a fascination with whispered notes and the lowest, darkest ends of a bands sound. He used delay and reverb on his trumpet, in long, floating tones and scrabbling figures; his music got closer to the ideal of pure abstraction than that of many of his colleagues.
In the late 1950s, he was raising a family and working during the day as a secretary at the United Nations. By 1959 he was booking the new music into West Village cafes, including the “Phase 2" and “Le Figaro." Thus began a long-running role as bootstrap activist and outspoken critic of nearly all the systems of jazz: how it is presented, taught, promoted, recorded and written about.
In 1968 he began a career in academia at Bennington College in Vermont. Hired simultaneously with the dancer Judith Dunn, with whom he collaborated in all his work for a six-year stretch, he worked first in the dance department and eventually in music. In 1973 he established the Black Music Division, a performance-and-theory curriculum of his own devising.
During the 1980s his recording career picked up: small-group music, orchestra pieces and a sideline of solo trumpet works, eventually released as a self-produced six-disc set, “Odyssey."
In experimental jazz, where the most successful tend to be the most prolific, Mr. Dixon's output looks comparatively scant. But most of his albums, even up to last years Tapestries for Small Orchestra, have a profound and eerie center, and his influence among contemporary trumpeters is clear.
“When I play, he told the journalist Graham Lock in 2001, whether you like it or not, I mean it."
