ORNETTE COLEMAN is best known for having fathered free jazz. But his disdain for conventional tonality wasn't simply a clean break from standard music theory; it also had roots deep within the bent notes and idiomatic harmonies of rural blues. He explored the blues connection in early works such as "Ramblin'," and has returned to it in earnest through the funk-inflected work of his current group, Prime Time. But he hasn't been alone in his efforts; equally interesting work in this vein has been recorded by performers as seemingly unrelated as James Blood Ulmer and David Thomas.

Ulmer's extension of Coleman's ideas seems natural enough, as the guitarist worked in early editions of Prime Time. But Ulmer's most recent recorded work, "Odyssey" and the live "Part Time," finds him actively working out the relationship between this new jazz and those old blues. Crucial to his current sound is the trio format he has adopted, rounding out his electric guitar with Charles Burnham's violin and Warren Benbow's drums.

By dropping the bass from his group, Ulmer simultaneously frees up the drummer, since the rhythmic bottom need no longer be shared, and loosens the music's harmonic axis, as the tonic is implied at best by what his guitar sets down. At the same time, both Ulmer and Burnham have occasion to resort to the older and wider vocabulary of country blues, particularly the practice of using a drone voice while the second player works out melodic variations on the main theme. This lends extra impact, for example, to "Little Red House," particularly the live version, and allows surprising latitude for Ulmer's rethink of "Are You Glad to Be in America?"

David Thomas' debt to Coleman is somewhat more difficult to explain. The singer isn't exactly a jazz musician; his career started with Cleveland art-punks Pere Ubu, and wobbled circuitously from there. Nonetheless there's a decidedly Colemanesque term to his melodic sense, which wavers freely from key to key.

But the most recognizable references to free jazz come courtesy of reedman Lindsay Cooper, who flanks Thomas' capricious harmonic turns with artfully resolute lines that keep the material from toppling into amelodicism. On "More Places Forever," David Thomas & The Pedestrians' latest album, it's Cooper who seems to provide the focus for the performances, not only implying where Tony Maimone's bass should ground the melody, but also seeming to modulate the free-flowing pulse of drummer Chris Cutler. Yet Cooper's management in no way impinges upon the level of expression; indeed, the implied discipline seems to improve Thomas' own performance. Best of all, Thomas, like Ulmer, manages to make connections between the music's past and present that both inform and startle.

JAMES BLOOD ULMER -- "Odyssey" (Columbia BFC 38900) and "Part Time" (Rough Trade 65);

DAVID THOMAS & THE PEDESTRIANS -- "More Places Forever" (Twin Tone TTR 8551); both appearing Saturday at the 9:30 Club.