If you’re talking power drone, Sunn0))) is the band to mention to impress your hipster pals–really the only band you can mention, seeing as the duo coined the term. (And if you are going to mention it, remember that it’s pronounced “sun,” named after the amplifier brand.) In the last few years, Stephen O’Malley and Greg Anderson (also members of Khanate and Goatsnake, respectively) have gained a gaggle of followers drawn, inexplicably, to their bone-rattling, arrhythmic sonic earthquake drones. Altar finds Sunn0))) collaborating with Japanese sludge-metal trio Boris, and although the raucous energy of the latter hasn’t done much to lighten the pitch-black mood of Sunn0)))’s other recorded work, Altar is easily the most varied and accessible album ever to bear the triple end parenthesis.


    The cover art for Altar shows the five collaborators dressed in Sunn0)))’s customary black hooded robes, and it’s an important clue as to who’s at the helm on the album. Though the bands conceptualized and wrote Altar together, O’Malley and Anderson cede far less of their signature sound than does Boris. The album begins with the expected monolithic, drum-free guitar and bass drones that suffocate the air and swallow the light, and it ends exactly the same, with absolutely no tension relieved by album’s end. “N.L.T.” is pregnant with gongs, sampled cymbal screeches and a bowed bass so ungodly low that it’s more felt than heard–new satin lining on the same old coffin for Sunn0))), but Boris fans are gonna be seriously wigged out.


    That feeling that the members of Boris are deferring more than necessary wouldn’t be so distracting if the more Boris-y parts of Altar weren’t so damn great. The drums of Boris’s Atsuo come crashing through a few minutes into “Etna,” and his tom and cymbal rolls sound like someone who’s been buried alive, frantically scraping from within the tomb. When Anderson, Atsuo and Boris’s guitarist Takeshi unite for a gigantic tyrannosaurus riff mid-song, feedback sirens shrieking all around them, you wonder why Sunn0))) doesn’t channel Sabbath more often.


    Altar may very well be Sunn0)))’s Supernatural, loaded as it is with guest stars both familiar and new to longtime fans. Joe Preston (Melvins/High on Fire) turns the dirge-like “Akuma No Kuma” into a spacey funeral dirge with his heavily vocodered vocals, matched by a synthesized horn-section homage to Star Wars that borders on parody. Ex-Soundgarden guitarist Kim Thayil is submerged somewhere in the indulgent fifteen-minute closer “Blood Swamp,” clearly the classiest guest spot he’s made since the first Presidents of the United States of America album. The most impressive cameo comes on “The Sinking Belle (Blue Sheep),” wherein Jesse Sykes’s deathly alto drifts over a gorgeous dream-pop lullaby, as straightforward and beautiful a track as Sunn0))) has ever cut.


    Sunn0))) has loosened its impenetrability ever so slightly, and in exchange Boris has embraced free-form sound experiments. There’s plenty to love on Altar for drone classicists and open-minded listeners alike, but it could have gone even further. Consider Altar a blackened crystal ball, promising tantalizing future directions for both bands involved and, by default, the entire power-drone genre.