The act of creation in art is fascinating in the way you can potentially go from nothing to something of value in a very short space of time. In the field of improvised music, it's easy to just make a mess, but sometimes, you can make magic too. Hans Joachim Irmler and Jaki Liebezeit are past masters at the mysterious and tantalising game of improvisation, with both Faust and Can creating much of their most renowned work by simply playing together and seeing what happened. So when Irmler and Liebezeit convened last year to rehearse for a series of live shows, they soon found themselves jamming instead and creating something new – Flut is the result.

The Faust Studio, where these recordings were made, is situated in an ex-factory beside the Danube, and the accompanying press release makes much of the two artists contemplating the implacable force of the river between takes, the swirls and eddies of its current flowing ever onwards, but never in the same way twice. It's an apposite image, particularly as Liebezeit's drumming on this album tends to anchor the music as much as drive it along, while Irmler's "prepared" organ changes in tone throughout, sounding variously like guitar, strings, horns and synth – in fact, it's sometimes hard to believe that just two people are making this complexity of noise in real time.

'Amalgam' starts the album with brooding waves of organ underpinned by a measured circular canter of drums, before a volley of horror show Hammond stabs recall the dark cosmic emanations of Pink Floyd circa A Saucerful Of Secrets. You can literally hear the space of the factory building in which it was recorded, and also imagine this playing in the background of some grimy art installation in the early 70s. Irmler's instrument crackles and sputters like a broken, over-driven machine, and elicits that strange sense of joy that comes from hearing certain types of mechanical noise. 'Golden Skin' begins with a hypnotic loop of high organ to which Liebezeit responds with a bhangra beat on his toms. There's a jazzy, Soft Machine vibe to the improvisation that follows, with moody patterns woven into the sound by Irmler's bass pedals. 'Ein Perfektes Paar' is based around a sparse, skeletal beat that threatens to get funky, while a grooving 'Autobahn'-ish bassline emerges at times from beneath Irmler's layers of crunching fractal scree.

The second set of improvisations use a series of simple arpeggios as their foundation (achieved, I assume, by combining the organ with a basic sequencer). On 'Sempifernity', a shadowy drone pushes the arpeggio slowly into the background, where it continues to pulse nervously like an ignored car alarm in fog. Irmler riffs around in the gloom at leisure, peaks and troughs in the sound occurring as potential themes are tried out and then abandoned. A faster arpeggio drives 'Washing Over Me', with Liebezeit imbuing the track with an urgent energy. The dirty distorted organ sound is like the buzzing of an engine, Irmler never soloing exactly but flexing his fingers restlessly over the keyboard. 'König Midas' maintains the faster tempo, and of all the tracks on Flut sounds most like a sketch for a more fully worked-out piece, its relatively simple phrases almost flirting with conventional melody.

None of these pieces are perfect, but it's the sense of the unknown, the apparent misstep leading to a new path, that makes them so compelling. "Musical bars are like prison bars," says Liebezeit. Flut is a fine example of what can happen when music is allowed to go free.