Boards of Canada redefine the term ‘cult band’. Obscured by shadowy rumour and releasing records with little or no promotion, they have managed to become hugely popular on precisely their own terms. Their latest album, The Campfire Headphase, was released at the beginning of November and has my vote for being one of the albums of the year.

Boards of Canada are Marcus Eoin and Michael Sandison, two Scottish techno producers. Worried that people would automatically compare them to Orbital, the band hid the fact that they are brothers until earlier this year. Their band name was pinched from the National Film Board of Canada – a North American documentary production company, whose films the duo adored as children. And indeed their music captures the grainy, out of focus feel of seventies documentaries and public information films.

The band has been around in one shape or another for about 18 years now, as part of a larger arts collective known as Hexagon Sun, that encompasses video and web work as well as music. Earlier incarnations of BoC have included many different members, but the current set up solidified around 1995 and the release of their Twoism EP. Quietly prolific, they have released three albums on Warp, several EPs, and numerous other releases on their own tiny Music70 label, most of which are virtually impossible to find.

Extremely private, the pair have become the object of much puzzled internet chat over the years. Hexagon Sun, people say, is really a cult and the BoC boys are in fact Satanists. It’s all nonsense, of course, albeit fun nonsense. Listening to their music though, you can see where some of these ideas have come from. Previous albums have slipped in reversed lyrics and references to David Koresh, the leader of the infamous Branch Davidian cult, responsible for the Waco siege of 1993 where eighty people died. The Campfire Headphase abandons all this mucking about, but there remains a distinctly unsettling feeling to many of the tracks on here. It’s beautiful music, but there’s still a sense of something not quite right going on that it’s difficult to put your finger on.

Far less electronic than some of their earlier records, Headphase has a very laid back, organic feel to it. There’s more prominent use of guitars – albeit mangled and detuned – and far less emphasis on vocal samples. The band have said that they were aiming for a cinematic, American feel to the record, and it certainly succeeds on tracks like Chromakey Dreamcoat and the joyful Hey Saturday Sun.

The best track on here, and probably the most accessible piece of music they’ve ever recorded, is Dayvan Cowboy. Beginning with a couple of minutes of faded electronics, it suddenly opens up, transforming into an expansive mix of yearning strings, strummed guitar and what sounds like an infinite number of drums in perfect unison. It’s absolutely awesome.

Even at their most ebullient, however, that wonkilly synthesised sound is still present. It gives the music a harder, darker edge, preventing it from becoming bland Zero 7 chill out fair. ’84 Pontiac Dream in particular, with its weird alarm sound, brings to mind the four minute warning of an imminent nuclear strike. Sherbert Head, meanwhile, is almost destroyed by distortion, but half-heard voices and strangled synths still manage to struggle to the surface.

But that’s BoC’s aesthetic all over, really. This is nostalgic music, but it isn’t rose-tinted or safe. Listening to it is like intercepting some strange, alien music, over the hiss and crackle of a shortwave radio. And while the Boards may not really be as mysterious as their mythology may suggest, their music most certainly is.