Léo Dupleix return to Black Truffle with Round Sky, following the enchanting Resonant Trees (BT119). The composer here performs on analogue synthesizer, harpsichord and spinet as one member of Asterales, a group that brings together four important figures in the international community of musicians working with just intonation: Dupleix, Jon Heilbron (double bass), Rebecca Lane (quarter-tone flute) and Frederik Rasten (guitars). The quartet perform three recent pieces by Dupleix, each of which is like a different view on the same landscape of unruffled calm, where the unique harmonic events made possible by just intonation flicker across melodies and harmonies like light on the surface of water.

The first side is dedicated to ‘Poème d’air’, composed while Dupleix was immersed in the music of 14thcentury ars nova composer-poet Guillaume de Machaut. A sustained study of the ‘sonic possibilities of low-pitched sounds in just intonation’, it begins with a long, rumbling pitch from Heilbron’s bass, soon joined by the organ-like tones of the composer on synthesizer. The piece is made up of cycling sequences of chords, each of which is repeated for several minutes before the music either freezes on a single harmony or silently pauses before the next episode begins. These structures are initially dominated by the bass and synthesizer, with Lane’s pure vibrato-less flute tone and Rasten picked harmonics adding flashes of colour. As the piece develops, flute and guitar become more prominent and the bass climbs to higher registers. The development culminates in a stunning episode around fifteen minutes in where the texture thins out, casting a spotlight on a melodic figure exploiting the uncanny sound of Lane’s quarter-tone flute.

On the second side we are treated to two briefer pieces, closer to the sound of Resonant Trees as they return harpsichord and spinet to the foreground. ‘Ghosts’ centres on a harpsichord melody that slowly expands as it repeats, growing from a haunting six-note cell to a flowing succession of notes whose shape become increasingly difficult to perceive. Alongside this melodic development, an increasingly lush accompaniment grows, with long tones from bass, flute, e-bowed guitar and synthesizer holding notes picked out the harpsichord melody in a swaying harmonic cloud. Dupleix notes that the concluding ‘Round Sky’ was written in the countryside in spring, a circumstance that seems far from irrelevant to the impression the piece makes when its euphonous spinet arpeggios emerge from a gentle synthesizer drone like a flower from a bud. Performed as a duo with Rasten, with both instrumentalists also singing, this title piece exemplifies what makes Dupleix’s music so unique: grounded in a rigorous application of just intonation principles yet as open as Harold Budd or Andrew Chalk to an uncomplicated, intuitive experience of beauty.