The Art Ensemble of Chicago generated such an irrepressible momentum that it’s sometimes easy to forget that it was essentially a mutation of the Roscoe Mitchell Sextet, which recorded the epochal and wildly experimental Sound album in 1966. Even in the Ensemble’s most exuberant years Mitchell never joined in with the face-paints and costumes, always seeming a more serious figure, slightly aloof and self-contained. So, it’s unsurprising that, when leading dates like this one, Mitchell was keen to ditch the pan-African percussion and ritualistic theatricals of the Ensemble, and get back to his serious work overlaying elements of the European classical avant-garde onto improvisation. There’s a sense of careful patience and composerly intent in these somewhat sparse constructions, with the unconventional instrumental line-up encouraging a harmonic disjunction that’s all the more stark for a lack of drums. Still, there’s room for individual voices to emerge: the clipped grandiloquence of AACM founder Muhal Richard Abrams’ piano, and the brash trombone burps of the 23-year old George Lewis making his recording debut. Moreover, a previously unreleased version of Coltrane’s ‘Naima’ – reduced to the barest melodic skeleton – reveals a deceptively tender intimacy underpinning the whole set.