Currently on a creative high – both Life Metal and Pyroclasts from this year have seen career-best reviews – drone metal’s most respected druids seemed determined to level the Queen Margaret Union. With more amplifiers on stage than any act this side of My Bloody Valentine, Sunn O))) (pronounced ‘sun’) use music as a way of eliciting primal responses via repetition and sheer bloody volume. It reverberated around the venue, and inside everyone’s ribcages.

That a band has built a steady and successful career out of – on the surface – playing the same note repeatedly for ninety minutes says something about just how powerful they make that note feel. There are nuances and delicate shifts to their music which reveal themselves progressively as you become attuned to their modus operandi. Some tones are especially drawn out, each member raising their fists on stage, symbolically saluting something while teasing the roar set to come from their guitars. It’s like an EDM drop, the quiet precursor to the pound that follows, the rollercoaster over its apex. Each time it sounds louder, heavier.

That the crowd stands motionless for an hour and a half is a testament to how hypnotic this all is. After twenty minutes, the blue and magenta lights turn to an earthy orange, and it feels immense. The plodding pace has a profound effect on your own ability to notice change, and something like a shift in thematic colour ends up altering the texture of their drone. Where at the start their almost-neon lighting made the barrage sound biblical, this dirty hue turned it into something more grounded, as if it was the sound the Earth made while it was still forming. Smoke machines add to the atmosphere, at one point so densely dousing the venue in a fog that the person in front was a haze, and the band’s music was a formless horror.

Save for a characteristically lengthy trombone solo, there really is little variation across the whole set. After 40 minutes it became patience testing, before somehow becoming captivating again in the last movement. As with much instrumental music, the listener has to contribute something, whether that’s a meaning or a purpose or a feeling. When it all came together to evoke a sense of wonder, or power, or fear, it worked best. If that slips, it can be quite a dumbfounding experience.

From a distance it’s hard not to find the entire concept hilarious. Men in robes play the same thing repeatedly for a long time, and at the end everyone applauds. If the listener isn’t willing to make the effort, they’ll never get past this point. It’s not for everyone, but if subtle texture changes in noise drawn out at a glacial pace sounds like your thing, then a Sunn O))) gig might just be for you.