Clockwise from top left: Robert Trujillo, James Hetfield, Lars Ulrich and Kirk Hammett.

By BEN RATLIFF

BUCHAREST, Romania - James Hetfield, Metallica’s mordant singer and guitarist, reported to work first, loudly practicing vocal exercises. Lars Ulrich, the group’s affable drummer, followed him. Then came the band’s long-haired surfers: the lead guitarist Kirk Hammett and the bassist Robert Trujillo .
They were in a guarded outbuilding of Cotroceni Stadium here, several meters beyond the stands. The band needs its 20-minute warm-ups for physical preparation - its members are all in their mid- 40s now. And in the last four years the group has also used the time to write new material, including much of its surprising, vigorous new album, “Death Magnetic.”
“No new songs tonight,” Mr. Ulrich said apologetically . “I’m kind of new-songed out, to be honest.”
The concert would be what most fans probably wanted anyway: music recorded between 1983 (“Kill ‘Em All,” the first Metallica album) and 1991 (“Metallica,” also known as the Black Album), but nothing from the often reviled second half of the band’s career. Metallica will face the present soon enough, when it releases “Death Magnetic” on September 12. The album, produced by Rick Rubin, is far better than anything the group has recorded in the last 12 years . But it may also be seen as a regression, evoking the band’s sound from the mid-’80s.
Metallica’s music was athletic back then, crazy with grim, loud ornament: Mr. Hetfield’s death-fantasy lyrics, songs within songs, strafing and high-pitched guitar solos. But it didn’t stay that way.
There was one apostasy after another: ballads, acoustic-guitar sections, the banning of guitar solos, the cutting of hair. Finally the group hired a performance coach - a therapist, more or less - who played a major role in “Metallica: Some Kind of Monster,” the 2004 documentary about the band’s near-breakup and mending.
Mr. Rubin wanted the band members “to try to erase many years of thinking about either needing to change their sound, or evolve,” he said. “If your marching orders for the first 20 years have been ‘change, change, change,’ then letting go of those preconceived ideas is in its own way a new idea.”
As Mr. Ulrich explained it: “Rick put this mantra over our heads, which was: don’t be afraid of your past. You don’t have to copy it, but it’s O.K. to be inspired by it.”
So what’s this new record about- Innovation fatigue- Nostalgia- Or could it embody a quality that is not usually associated with metal, but probably should be: refinement?
In his first meeting with Metallica two years ago Mr. Rubin gave the band a writing assignment. “I asked them to imagine themselves not as Metallica,” he said. “I said to them, let’s say there was a battle of the bands coming up and nobody knew who they were, and they can’t rely on any of their hits to get them over. What would that sound like?”
He told them that “Master of Puppets,” released in 1986, was the band’s best album. He asked them to imagine that it represented only half the material they owed the record company that year. What would the other half sound like?
Mr. Hetfield said trying to go back in time was “a nice idea, and pretty near impossible.”
“We know too much,” he continued. “You can’t make yourself a virgin again. But I got what Rubin meant.”
“Death Magnetic” bets on the fact that these musicians have matured, and can prove it through music that’s more complicated than what they’ve become used to, but is still theirs. They sound as if they’re pushing, but not straining. As Mr. Hetfield said, Metallica knows more now.
“There’s a little more calmness around our playing,” he said. “We’re not so focused on whether or not we can play it. We’re better.”