Knoxville is a jam session. A jam session performed in-concert at the Big Ears Festival in, you guessed it, Knoxville, by three men (Christian Fennesz, David Daniell and Tony Buck) who had never before performed or even rehearsed together.

Thrusting three strangers on stage and recording their output is an approach to making music which comes with some obvious limitations. No matter how talented the artists, or how complementary their styles, it is always going to be a matter of someone picking a chord and a rough tempo and just letting things evolve.

Now let there be no doubt, these are three very talented musicians, with very complementary styles. The piece of music that they have created (split into four movements by cutting at the quiet bits) makes for a remarkably coherent 31 minutes of music given the circumstances. As you might expect each section builds organically with simple melodic movements breeding and multiplying into waves of feedback with Fennesz’s trademark ambient guitars and keyboards providing a strong foundation from which the songs build.

There are some moments of quite enchanting beauty, particularly Antonia, the third and by far the most peaceful movement of the EP, Buck’s light cymbals act as a gentle rainfall on the oceanic stirrings of endlessly reverberating strings and sine waves. The effect is one of a constantly changing body of sound, but one of a very carefully defined nature, a soothing, predictable progression of noise and melody.

Perhaps making soothing ambient music is easy, and making challenging experimental thunderstorms is difficult, but the grace of Antonia highlights many of the shortcomings of the piece as a whole. The progession of each movement is generally of a dynamic and not a tonal nature. Occasionally Fennesz or Daniell will add a counter-melody on guitar but for the vast majority of the album the music is in a single constant droning key. Daniell’s guitar, often at the forefront of the mix, particularly on opening movement Unuberwindbare Wande, soars above the maelstrom of sound at times, but when it gets there at times loses its way and proceeds to walk up and down the fret board aimlessly. But it is Buck’s percussion which ultimately dominates the album. He plays the drums like a hurricane shaking palm trees or your dad rummaging through the garden shed trying to find the right type of screwdriver. Don’t expect any ‘kick, snare, kick, snare’ here. Instead expect a surprising number of arrhythmic taps, crashes and shimmers all very near the high-end of the conventional drum kit’s register. At times, particularly when the movements are in their playful lulls between storms, Buck’s meanderings are engaging and potent like creatures lurking in the shadows, but when the dynamics pick up the sound of endless cymbal crashes become grating, almost unlistenable.

For devoted aficionados of experimental improvisational post rock this recording will come as a master class in the potency and power that can be summoned almost off-the-cuff by today’s best experimental musicians. But for the casual listener, someone with a couple of Tortoise records and a copy of Fennesz’s Venice or Black Sea, this is a recording to be admired from a distance; background music that refuses to stay in the background; or immersive music which may rub a nerve on closer inspection.