When it comes to drone, there’s a fine old line between the brilliant and the banal. It’s a genre of music where an unchanging chord, or a continuous noise, can either be a joy to behold or a complete chore to listen to. Some artists get it completely wrong, but then there’s a group of acts making drone music that you know you can completely rely on to get it right. Whether it’s the kings of repetition like Philip Glass and Brian Eno, or acts like Grouper and Fennesz, with these artists you know you’re in safe hands.

Following the release of their third album (and first for Thrill Jockey) Choral, the duo of Mountains deserved to join the ranks of the trusted droners. That record was their most coherent to date, a well-judged amalgam of analogue and electronic instrumentation and a warm and welcoming listen. This sonic template was furthered on their first proper studio-recorded album, Air Museum; while more experimental it didn’t better the music on Choral but it did allow Brendon Anderegg and Koen Holtkamp the chance to further their work away from the synthetic, and the culmination of this pursuit comes in the form of their new record, Centralia. It’s a meticulously constructed release, with the duo layering the separate acoustic and electronic sounds without the aid of computer manipulation, to create a kind of 21st century folk record.

The two names that come to mind with the music Mountains is currently making are Terry Riley and John Martyn. Riley of course has long been an influence on Holtkamp and Anderegg but all the more in the passing years as the acoustic elements of their music gain some much-deserved clarity; and it’s the playing of Martyn (and Roy Harper too) that informs the sound of the more guitar-heavy tracks on Centralia. But before that, it’s the chimes and flutterings of epic opening track ‘Sand’ that charms with its primarily electronic burbles and higher-pitched drones, calling to mind TNT-era Tortoise, before it seamlessly floats into a beautiful outro of subdued cello. This is followed by the shorter doom-folk of ‘Sand’ which is powered by circular acoustic guitar picking and layered with gorgeous synth washes, before ‘Circular C’ introduces jazz-tinged piano and fuzz over ten wonderful minutes.

‘Tilt’ is the track that most points towards the folk genre, with fast-paced plucking mixing effortlessly with the subtle electronica. This is again one of the shorter tracks, and leads into the album’s centrepiece, the twenty minute meditation of ‘Propeller’. Ostensibly a live track (as is the following shimmer of ‘Liana’, whose mood is only disturbed by a surprising burst of electric feedback), it’s been given some added studio instrumentation, but nothing which takes away from its organic feel. Over the course of its running time Mountains visit extremes of light and shade, emotion and noise as organs hum and modulate to create one warm haze of music. Closing track ‘Living Lens’, though essentially fine, feels like something of a letdown after that double salvo but does succeed in maintaining the tone of the album as a whole.

It’s probably fair to say that if you’re not a fan of drone or ambient music then Centralia is unlikely to change your perception of the genres. However as a document of the music of Mountains, it’s their finest work to date and a testament to their singular vision of how analogue and electronics can best be combined.