Peter Brötzmann found this tape by chance, usefully labelled with recording date (16 October, 1997), city (Osaka, Japan) and venue (the Blue City club), in what he calls his ‘chaos-box’. But if you're fearing that a 70-minute saxophone/trombone duo might test the limits of your listening patience, the boundless variety of these improvisations – timbrally, harmonically and melodically – aspire to the dimensions of ensemble music. Recent sightings of Brötzmann at Cafe OTO have been grimly determined affairs, with the German free-jazz master nonchalantly throwing his weight around, and it is pleasing to hear him deriving so much obvious pleasure from a gig and the mood throughout is informal, more like a salon evening for friends than a formal club night. A 30-minute opener called ‘Name That Thing’ is fuelled, in place of a rhythm section, by pure testosterone and there are jokey blokey pranks for us all to enjoy as one player abruptly grinds to a halt, leaving the other dangling over a structural cliff edge. Johannes Bauer's tendency is to steady the ship with guileless and uncomplicated lines and gestures – unadorned loops of modal patterns, or bonkers chromatic banana skins – which allow Brötzmann to do his thing. There's some unexpectedly honeyed clarinet playing to be heard too, but even at his most ‘out’ Brötzmann's saxophone lines are carefully weighted and concise. But a pity they called the album Blue City – Chaos Box is a title waiting for an album, surely?