Doom metal means many things to many people. Everyone, from ye olde Black Sabbath to the unhinged noise-scrape of Portland's Trees, huddles beneath its raven umbrella, protected from the dark clouds this gloomy music must chase. "Please let me die in solitude," sang Candlemass lead vocalist Robert Lowe during the band's Portland gig in May, pleasing a small gathering of diehards. The line is from the first song of the band's 1986 debut—an album that Lowe himself had nothing to do with. Lowe, who joined Candlemass in 2007, represents another defining characteristic of doom metal: the ability of a band to change its lead singer.

In April, Chicago doom band Trouble played the annual Roadburn Festival in the Netherlands, sharing the main stage with Portland's Danava, among others. Unbeknownst to festival attendees, Trouble agreed it would part ways with original frontman Eric Wagner after returning home. "This was a mutual thing," says founding guitarist Rick Wartell. "Eric knew he really didn't want to continue doing it." The band announced Wagner's replacement—Kory Clarke of Warrior Soul—in the same press release announcing Wagner's departure.

As the news broke, fans were quick to dissect the two singers' styles. Wagner is a higher-pitched Ozzy Osbourne, while Clarke balances alt-metal soul with hard-rock sleaze. Will the umbrella accept the new Trouble? It has accepted vocal switcharoos from Deep Purple, Black Sabbath, Candlemass, and even Sunn O))).

"When I was younger and Deep Purple got rid of Ian Gillan, it killed me," Wartell says. "But then I accepted it once I heard the new singer. It's just the thought of it more than anything that bothers people."

Trouble last toured the West Coast in 1995. Wartell says the band had hoped to sell its new studio album, Simple Mind Condition, on this tour, but the recent collapse of its record label, Escapi Music, has given Trouble no choice but to hawk its own bootlegged concerts—one from 1985—and an acoustic, self-released CD. "But we'll have T-shirts," he laughs. "Lots of T-shirts."