There is a certain perversity in calling a three-CD set by twenty-five improvisers "25 pièces sans vide". The title suggests an absence of emptiness, while free improvisation traditionally thrives on precisely the spaces where nothing appears to be happening. And then there is Le UN itself: twenty-five people calling themselves “the one”, which sounds either like a philosophical proposition or the name of a particularly badly organised superhero. In reality, the contradiction is the point. "25 pièces sans vide" is an extended examination of how a crowd can remain a crowd without becoming a blur, and how individual freedom might survive when twenty-five nervous systems are making decisions at the same time.
Le UN began in 2012 through the initiative of double bassist David Chiesa, initially bringing together musicians with very different backgrounds and experimenting with graphic, oral and textual forms of direction. In 2019, the ensemble changed course, concentrating exclusively on free or non-idiomatic improvisation and abandoning scores and formal direction altogether. Its members are involved not only in making the music but also in the organisation of the group, which operates horizontally rather than according to a conventional leader-and-orchestra structure.
That distinction is crucial. Le UN is not simply a large free-improvisation orchestra. It is an attempt to make the organisation of the ensemble itself part of the artistic experiment. The group explicitly treats improvisation as an attitude rather than a genre, and its interest in impermanence extends beyond the music: performances leave traces, recordings, memories and consequences, but cannot reproduce the original situation.
The box gathers five substantial pieces recorded between 2021 and 2022, divided between large-ensemble performances, smaller formations and an outdoor intervention. Across roughly three hours, the scale keeps changing: 45 minutes in Gradignan, nearly an hour in Le Havre, then progressively smaller groups at Cluny before the musicians move into the public space of Place Saint-Michel in Bordeaux. It is less a conventional album than a set of different experiments conducted on the same social organism.
The first disc, "Unité nodale T4S", immediately demonstrates the problem Le UN has chosen for itself. Put twenty-five experienced improvisers in the same room and you have an almost absurd quantity of possible decisions. Somebody can become louder. Somebody else can disappear. A saxophone can interrupt a cello; an electronic texture can undermine a percussion pattern; a piano can suddenly provide a centre of gravity that nobody explicitly asked for. The danger is obvious: collective improvisation can become either a polite soup or an arms race. Le UN generally avoids both.
What makes the large ensemble convincing is its ability to create temporary centres rather than a permanent hierarchy. Sophie Agnel's piano can suddenly become structurally important without becoming “the leader”; percussion can gather momentum without turning into a rhythm section; voices, strings and brass can briefly form recognisable relationships before abandoning them. Electronics from Jérôme Noetinger and Lionel Marchetti do not simply provide atmospheric wallpaper, either. They alter the apparent scale of the ensemble, making acoustic gestures seem larger, stranger or more distant.
The musicians are individually too distinctive to disappear completely. That is one of the group's most interesting characteristics. The lineup includes several generations and approaches to experimental music, from piano, strings, double basses and winds to rotating surfaces, electronics, accordion, voice, hurdy-gurdy, light and physical actions. The challenge is not to suppress these personalities but to prevent them from behaving like twenty-five soloists waiting for their turn. Le UN's own description of its practice places individual singularity at the centre while insisting that it must not obstruct shared space. That sounds suspiciously utopian on paper. Fortunately, the music is more complicated than the philosophy.
"Unité nodale ESJ", occupying the whole of the second disc, makes this especially clear. Its length changes the listener's relationship with concentration. There is no convenient three-minute reset button, no chorus to announce that the previous argument has been resolved. Instead, density accumulates and recedes. Electronics can create broad fields of pressure, while strings, percussion and winds introduce irregular disturbances. At times the texture seems almost geological, as if the ensemble were slowly excavating a sound rather than performing one.
This is also where the title becomes useful. There are “pieces without gaps”, but that does not mean there are no silences or reductions in intensity. The absence of a gap is conceptual rather than merely acoustic. One event remains connected to the next even when the audible material becomes sparse. Listening becomes an exercise in remembering what has just disappeared.
A recent assessment of the set rightly emphasised the unusual ability of the musicians to retain their individual expertise inside the larger aggregate. It also noted the markedly different character of the discs: the first and final pieces combine acoustic and electronic impulses, while the second is more heavily oriented toward electronic waveforms and the two middle pieces on CD3 are predominantly acoustic. The observation is useful because it reveals that "25 pièces sans vide" is not really about one Le UN sound. There isn't one.
The third disc is where the proposition becomes more intimate. "PME postes fixes" reduces the ensemble to a smaller constellation involving piano, rotating surfaces, percussion and electronics. The reduction does not make the music simpler. It makes the relationships more exposed. Every sound has more responsibility because there are fewer bodies available to disguise it. A small metallic gesture can suddenly acquire structural significance; an electronic oscillation can become almost architectural; piano fragments can hover between melody and percussive interruption.
It is here that Le UN's approach begins to resemble chamber music without adopting chamber music's usual manners. The players listen closely, but there is no obligation to be elegant about it. Sounds can scrape, interrupt, hover, stutter or simply refuse to develop. The intimacy is therefore not cosy. It is closer to being in a room with several people who are all paying extremely close attention to one another and none of whom has been given the authority to settle the argument.
"PME cordes" goes further by reducing the acoustic palette largely to strings, accordion and voice. Three double basses, two cellos and two violins create a fascinating vertical tension between low resonance and high-frequency fragility. The result is almost a study in how little is required for strings to stop sounding “beautiful” in the conventional sense. Bow pressure, friction, scraping, resonance and interruption become as important as pitch.
The voice and accordion introduce another layer of ambiguity. The human voice can suggest language even when no language is being used, while the accordion is capable of sounding simultaneously mechanical and organic. Together they create the impression of an improvised miniature theatre in which nobody has bothered to write the script. This is perhaps the most persuasive argument for Le UN's insistence that improvisation is not a genre. The music does not need to sound like a particular tradition because its subject is the act of negotiating what happens next. Then the musicians leave the stage.
"Brigade d'Intervention Légère PSM", recorded at Place Saint-Michel in Bordeaux, places the ensemble directly inside public space. Here the environment is no longer a neutral acoustic container. Voices, ambient noise and the unpredictable behaviour of the surrounding square become part of the material. The distinction between performer and audience becomes less secure, which is precisely what Le UN has been questioning throughout its practice.
This is more than an interesting recording trick. Playing outdoors introduces a different kind of risk. A concert hall can be controlled, at least in theory. A public square has traffic, conversations, weather, pedestrians, distractions and people who did not consent to becoming an avant-garde audience. The world is allowed to interrupt the musicians. In such circumstances, improvisation stops being a purely musical negotiation and becomes a negotiation with reality itself.
That interest in displacement is fundamental to Le UN's broader activity. The ensemble has explored streets, rivers, caves, exhibition spaces and acousmatic situations, deliberately placing improvisation in environments that disturb the conventional separation between performer, listener and location. The point is not simply to find exotic places in which to record unusual sounds. It is to discover how much of the music depends on the idea of a stage in the first place. The answer, on "25 pièces sans vide", seems to be: less than we might assume.
There is also a subtle political dimension to the ensemble's method, although it wisely avoids turning the recordings into an ideological lecture. Twenty-five people sharing responsibility without a conductor is not a metaphor for harmonious society. Quite the opposite. It exposes how difficult collective life actually is. Someone has to listen. Someone has to leave space. Someone has to accept that their excellent idea is not going to happen. Someone else has to make a noise at precisely the wrong moment and discover that it was, accidentally, the right one. That tension is what keeps the music alive.
The set is not uniformly easy listening, and it should not be. The extended "Unité Nodale ESJ" can become deliberately dense, with electronic textures occupying enough space to test the listener's patience. A recent review of the set found this concentration less convincing than the more varied acoustic sections, noting the tendency of the long second-disc performance toward sustained electronic density. That criticism is fair, but the slight imbalance also makes the box more revealing. A project genuinely committed to collective risk should occasionally produce results that are less immediately persuasive. Otherwise the “risk” is just good branding.
What ultimately distinguishes "25 pièces sans vide" is therefore not technical virtuosity, although there is an extraordinary amount of it. Nor is it simply the spectacle of twenty-five musicians improvising simultaneously. Its real subject is attention: how individual attention can become collective without becoming uniform, and how a group can construct temporary form without deciding in advance what that form should be.
The three-CD format makes that question physical. You do not consume this music like a playlist. You spend time with it. The box comes with a twenty-page bilingual booklet containing texts by Le UN, Joël Pagier, Jean-Philippe Pierron and Nate Wooley, reinforcing the sense that the release is intended not merely as documentation but as an account of an ongoing practice.
And perhaps “documentation” is the wrong word anyway. The ensemble itself insists on the distinction between traces and proof. A recording can tell us that something happened. It cannot give us the situation in which it happened, the glances between musicians, the physical acoustics, the audience's reactions, the accidental noise outside the room or the precise instant when one player decided to enter and another decided not to.
That missing information is not a defect. It is the residue that makes the recordings worth hearing.
"25 pièces sans vide" ultimately presents improvisation as a strange form of collective architecture. Nothing is fixed, yet structures appear. Nobody is officially in charge, yet decisions accumulate. Individual voices remain audible, yet something larger occasionally emerges from their interference. And the “one” in Le UN never becomes a single voice. It becomes a temporary agreement between many.
Twenty-five people making one music without making themselves one person: humanity has spent millennia failing to solve that problem politically. Le UN at least gets a few hours of excellent noise out of it.