The mythology of jazz, if the various musics assembled under that name can be said to have anything in common, is founded upon the putatively spontaneous expression of affect, jazz as unbounded freedom, a freedom fundamentally linked to a phenomenological, existentialist understanding of the improvising subject as intentional creator of an (improvised) composition/project. In what follows, I want to argue against this received perception, that musical creation and expression-whether improvised or not-should instead be conceived as the immanent assemblage of asubjective sounding machines that can unleash literally immeasurable potentials for expressivity. In place of the longstanding critical tradition that sees jazz through this lens of a metaphysics of human productivity, a range of actors, both human and non-human, come together in any given musical improvisation to construct a musical experiment. Instead of a protean, subjectbased spontaneity, one discovers instead from this Deleuzian perspective, say, an instrument-club-musician-head-solo-influences-practice-time-mood assemblage.2 In such an ensemble, contingent non-human actors such as a particularly fine reed, a broken valve, an electronic effects system or synthesizer, or the acoustics of
a venue actively participate in musical expression alongside the human subjectbased dynamics of individual imagination or a violent backstage argument.