The foursome of John Butcher, Christian Kobi, Hans Koch and Urs Leimgruber is called S4, with that letter S indicating that all the members play soprano saxophone. Immediately, that throws up the question of whether S4 could rightly be called a saxophone quartet; the argument in favour hinges on the fact that it is a quartet in which all four play saxophones, while the counter argument cites the varied instrumentation of other saxophone quartets (of which there are many!); for example, the archetypical World Saxophone Quartet featured two alto/soprano saxophones plus one tenor and one baritone, while the improvising sax foursome that recorded Propagations (Potlatch, 2007) consisted of one soprano, two altos and one tenor. In fact, the only realistic precedent for S4 seems not to be a foursome at all but the soprano threesome of Lol Coxhill, Steve Lacy and Evan Parker that recorded Three Blokes (FMP, 1994). Maybe S4 is best thought of as four blokes....

Studio-recorded in Zurich, in January 2015, Cold Duck consists of nine improvised tracks, ranging in length from just over a minute to just over twelve, a total of forty-eight minutes altogether. The track titles are the Roman numerals from I to IX. The comparative brevity of the tracks is not an issue as they follow on neatly from one other, with no awkward jump-cuts, giving the album coherence and making it flow smoothly. Alongside conventional passages, the tracks feature a variety of extended playing techniques including breathy under-blowing, reed popping and scraping, percussive key sounds, sustained bent notes and high-pitched squeaks; none of these outstays its welcome and none is included for novelty value but all are well-integrated into the totality, keeping the soundscape fresh and interesting by giving it depth and variety.

With four soprano saxophones involved, it is not always possible to differentiate exactly who is playing a particular contribution, so credit for the album's success must go to all concerned rather than individuals being particularly singled out — a collective triumph. Although there are some absolutely thrilling passages in which all four are blowing flat-out together — most notably on "V" — it is far more common for different players to fade in and out over the course of a piece, thus creating an ever-shifting, multi-textured sound that is rich and highly appealing. Some of the more fascinating music is also some of the sparest, that variety adding to the album's appeal. Cold Duck is an auspicious first album from S4, and we must hope that more follows soon.