Few bands have been as misrepresented as Melvins. A cursory Google search might imply a single-minded aesthetic of slow, super-heavy sludge, but over the last 30-plus years, their 20-plus albums have yielded a dizzying array of styles and approaches. A single Melvins album will often cover more ground, with more energy and invention, than most bands manage in an entire career.

Pinning down what – or, indeed, who – Melvins actually are is becoming even more difficult. Arguably, the last 'proper' album with a stable lineup was 2010’s The Bride Screamed Murder. Yet they’ve been as prolific as ever, with an all-star covers project, one-off ensembles with members of godheadsilo, Fantomas and the Butthole Surfers, and a resurgence of their 1983 lineup. The latest offering, Basses Loaded, features six bassists, including Steve McDonald from Red Kross and Off!, who’ll be rumbling guts on the upcoming tour.

'Houdini [1993’s MTV-bothering album] had almost as many bass players – we just didn’t point it out back then,' says drummer Dale Crover. 'The title is a play on an American baseball term and the fact that all of our bassists are loaded on performance-enhancing drugs.'

Given the band’s enormous back catalogue, what can we expect to hear on this tour?

'Old stuff, stuff from the middle period and a couple of new songs. We’ll also be doing a bunch of covers, and at least one song that’s pretty obscure. We do as much as we can, but if we played a song from each record, we’d be here until 5am. When you love a band but they play too long, it’s… urgh.'

From the outside, it seems like Melvins are increasingly indefinable. Does it feel that way on the inside, too?

'It definitely keeps it interesting. We’ve never been afraid to try something. I don’t feel like we’re one thing or another. You don’t have to have a bunch of songs that sound this way or that way. It’s punk rock, man. Or jazz. Take your pick.'

Basses Loaded is out now via Ipecac Recordings. Melvins are on tour until Thu 23 Jun.