Steve Reich will be 80 this year – a landmark date that will no doubt encourage some to reflect on an extraordinarily consistent body of music spanning over 50 years, where each composition is seen to build and develop on a fully formed stylistic language and clear musical vision. Generalisations only speak half-truths, of course, and while it is possible to trace a largely continuous line through Reich’s oeuvre, the differences that appear from one ‘phase’ to the next are sometimes more revealing.

Two recent recordings show up some of these differences. Ensemble Signal under Brad Lubman focus on two recent chamber works: the energetic, engaging Double Sextet (2007) and darker, more reserved Radio Rewrite (2012). While both pieces build on Reich’s interest in combining multiples of the same (or similar) instruments, they also dispense with the regular 12 beat rhythmic grid that forms the foundation for so many of the composer’s earlier works. In fact, Double Sextet starts with a 22 beat pattern based on 6+4+5+7, while Radio Rewrite uses even more irregular groupings in its opening movement. Such unpredictable patterns not only force the listener out of his or her comfort zone but also demand supreme focus and concentration from each performer.

Ensemble Signal’s playing in Double Sextet is so crisp and precise that it’s easy to forget its rhythmic and contrapuntal complexities. At the same time the harmony’s slightly gritty qualities are preserved, and just the right amount of articulation given to the sustained pitches and chords, which quite literally bind each section together. Their performance of Radio Rewrite makes a little more of the contrasts between the work’s five sections than Alan Pierson and Alarm Will Sound’s excellent recording (Nonesuch, 12/14), with rhythms punched out nervously at the beginning and more weight and emphasis added to the central movement, where the work’s indebtedness to the rock band Radiohead (from whose songs it quotes) is at its most obvious.

Like Signal, the LSO are by no means newcomers, and here their percussion ensemble casts its net further back to the more percussion-heavy and rhythmically steady-state Reich of the 1970s. Pairing together Clapping Music (1972) and Music for Pieces of Wood (1973) certainly makes sense as the latter quotes from the former’s rhythmic pattern. More similarities than differences lie between these works, for sure. Pieces of Wood is given an excellent rendition on this live recording, as if the precise mechanism of a complex clock had been carefully deconstructed before being pieced back together. The LSO percussion’s performance of Sextet (1985) also builds up in energy and momentum to a quite thrilling climax; but, perhaps inevitably for music that demands such high levels of precision and accuracy, a few anomalies appear during the rhythmic transitions of the first movement.