An extract from this monumental slab of music, which was recorded live in São Paulo 30 years ago, was issued back in the day on a long out-of-print Impetus LP – but such is the accumulative impact of the Elton Dean Quintet's two improvisations (44 minutes; 33 minutes) that context becomes everything. The instrumentation of Dean's group, with its trumpet, trombone and reed instrument frontline (no piano), invokes a Hot Five of a different era and raw heat is unleashed when the forward motion of a soloist meets the collective interweaving of the ensemble. At the climax of the first improvisation, Dean's intricately unfolding solo is gingerly wrapped in Rutherford and Beckett's two-part counterpoint which feels like a perfect point of arrival; likewise during the second piece, Beckett's piercing, hell-for-leather solo suddenly finds itself floating against clouds of modal gravity from saxophone and trombone. The emotional heat of the music – always blistering – occasionally recalls post-Love Supreme Coltrane, with a clear harmonic centre to which the musicians return after their sorties to the margins. Recorded sound is implausibly good (it's been mastered by Emanem's Martin Davidson), which helps spotlight the itchy energy and supple timbral palette of Liam Genockey's drums. Marcio Mattos' solos scoop block chords and balletic pizzicato out from his instrument – and, heralding an endpoint, he drops anchor with a thunderous bass tremolo that helps guide everyone home.