By Will York

SAY WHAT YOU will about neo-folk, hairy psych-rock bands, or Wolf Eyes – the strangest recent development in underground rock has to be the doom- and drone-metal phenomenon. It's not the music itself that's new, but the acceptance and critical respect it has gained outside the metal community is unprecedented and downright weird. Bands like Sunn O))), Khanate, Boris, and Earth, who perform at this week's Days of Darkness fest and have been making obscure and difficult music for years, have recently come to be accepted by tastemaker publications such as Arthur and the Wire not as ass-kicking headbangers, but as through-the-backdoor avant-garde artistes.

How did this happen? Is drone metal simply riding the coattails of the "new weird America" hype, or are we really experiencing a renaissance of "thinking person's metal"? And if the latter is true, is that really such a good thing? Maybe it's just a case of years of hard work and toil paying off, together with a little help from the mystique (and shrewd marketing tactics) of key labels Southern Lord and Hydra Head.

I imagine some of the bands are equally perplexed, but regardless, they're taking the ball and running with it. The past few months have seen new releases by all the above bands, including an out-of-retirement comeback album by Earth, as well as extensive touring on the part of some otherwise fairly reclusive acts. While all the albums sound completely different, each one offers an answer to the same question: Where do you go after you've created music that proclaims the end of rock – and metal – as we know it? Or, to paraphrase Spinal Tap's Nigel Tufnel, "What's after the end?"

Blacker, better

Sunn O)))'s answer, it seems, is to keep digging till you get to the next layer of hell. The new Black One (Southern Lord) is their sixth album and their most hellish yet, as if to challenge listeners who only recently hopped on board. True to its title, Black One could be called Sunn O)))'s homage to black metal, and it features guest appearances by such scary dudes as latter-day black-metal purists Xasthur and Leviathan. Here, Sunn O)))'s patented subwoofer drones mix with frostbitten Scandinavian-style riffs and lo-fi, shrieking vocals, some of which were recorded from inside the back of a hearse. I enjoyed Sunn O)))'s apocalyptic Flight of the Behemoth (Southern Lord) a few years back, but even I need to take a walk in the park after a few tracks of this stuff.

Khanate's Capture and Release (Hydra Head) is equally uncompromising and just downright ill. As with Sunn O))) – guitarist Steven O'Malley's other band – Khanate takes a certain frame of mind to properly appreciate on an emotional level, and I'm not there these days. Objectively, I can appreciate the studied dissonance of O'Malley's guitar anti-riffing and the force of James Plotkin's wall-rattling bass guitar, as well as the discipline involved in putting together a 25-minute monstrosity such as "Release," the second of two tracks here. Subjectively, though, C&R is a bitter pill to swallow.

Instead of trying to out-gun the current wave of doom specialists, Earth mastermind Dylan Carlson has turned in an album of plodding post-rock instrumentals that are a far cry from the proto-Sunn O))) drones of 1993's infamous Earth 2 (Sub Pop). The recent Hex: Or Printing in the Infernal Method (Southern Lord) is an interesting diversion, almost like doom metal's answer to Ry Cooder's Paris, Texas soundtrack. I've heard this described as a country album, which is absurd, but there is a surprising amount of twang and shuffle to these otherwise morbid tunes. It's not spectacular, but don't blame Earth for not living up to the hype and hyperbole that's been built up around them in recent years – it has nothing to do with the music Carlson and company are making now.

The new album from Japan's Boris, a three-piece who took their name from an old Melvins song, is also unexpectedly spacious and low-key. Done in collaboration with Japanese noise artist Merzbow, Sun Baked Snow Cave (Hydra Head), is yet another departure for a band, who, like the Melvins, is known for making departures. Like their 1996 album, Absolutego (reissued in 2001 on Southern Lord), the disc comprises a single track that goes on for more than an hour. Unlike that full-length, which marked a new extreme in terms of slow-motion, cymbal-crashing doom – Cave is a journey into drumless space full of gentle acoustic guitar plucking, swelling feedback and electronic noises, and sampled insect sounds, but it's also thankfully devoid of the New Age-isms that plague so many bands reaching for this sort of blissed-out transcendence. You could call it ambient music for the intelligent bong wielder, but that's not quite doing it justice.

Borrowed bitterness

Speaking of the Melvins, they're likely the one band all these groups would agree on as an influence. For years doom metal was defined by groups trying to sound like Black Sabbath, but anyone looking for a blues-based Tony Iommi riff among these albums is bound to come away feeling parched and wearied. You could say that each of these bands has taken some aspect of the Melvins' sound – whether it's the bitter, blackened guitar tones or just the slow tempos – and then carried it to an extreme end point. What they've left behind, for better or worse, is the obnoxious humor of a band that sometimes frustrates listeners but avoids taking itself too seriously. If anyone ever called the Melvins' music "thinking person's metal" to their faces, he or she'd get laughed at, and rightfully so.

As for the Melvins themselves, they're still churning out new releases at a rapid rate. Their recent collaboration with Jello Biafra, Sieg Howdy!, is a not-so-welcome follow-up to last year's Never Breathe What You Can't See (both Alternative Tentacles). Was that first CD really such a rousing success? The Melvins turn in some respectably workmanlike hard rock here, and the cover of Alice Cooper's "Halo of Flies" is enjoyable enough, but otherwise, Biafra's shoehorned lyrics and obvious political commentary are tough to take, however well-intentioned.

More bearable is The Monkees' Uncle (Ant Acid Audio), the new album by Altamont, drummer Dale Crover's side project. Crover trades off guitar, drum, and vocal duties with a few of his pals, and the lack of pretension, or any sort of hallowed reputation to uphold, makes it easier to enjoy this album for what it is – a casual side project with a few nifty songs and lots of references to '70s hard-rock à la Cooper (again), Slider-era T. Rex, and Raw Power-era Stooges.

One more band that's worth mentioning amid all this hubbub is Thrones, the solo project of Joe Preston, who over the years has managed the hat trick of playing with the Melvins, Earth, and Sunn O))). (As if that weren't enough, he's now playing bass for local stoner-metal juggernaut High on Fire.) Day Late, Dollar Short (Southern Lord), an odds-and-ends compilation released earlier this year, is just the second Thrones full-length, even though Preston has been making this kind of music since 1994.

If nothing else, Day Late, Dollar Short proves you can cover the Residents and Rush, employ "lead bass," and still not sound anything like Primus. Not everything works, but there's some twisted brilliance here. Preston's lumbering yet triumphant version of the 2112 deep cut "Oracle" is worth the price of admission, as is the strangely blissful, vocoder-drenched "Obolus." There's a mad scientist element at work in Preston's music – with its unwieldy drum machines, antique synths, and outmoded sequencers – that gives it as much in common with, say, Quintron as it does Preston's Southern Lord label mates. In comparison to Black One or Capture and Release, Day Late, Dollar Short comes off like comic relief. And that's saying something.

Days of Darkness, including Exhumed, Ludicra, Graves at Sea, Kalas, Saros, and Stormcrow, takes place Sat/29, 8 p.m., Elbo Room, 647 Valencia, SF. $10-$12. (415) 552-7788.

Sunn O))), Boris, and Thrones play Mon/31, Slim's, 333 11th St., SF. $13-$15. Call for time. (415) 522-0333. For advance tickets, go to www.ticketweb.com.

Melvins play with Jello Biafra at the "Alternative Tentacles Bat-Fest," Mon/31, 8 p.m., Great American Music Hall, 859 O'Farrell, SF. $16. (415) 885-0750.