By JON PARELES QUEBEC

QUEBEC - The Arcade Fire - a self-guided indie-rock band grown popular enough to sell out arenas ? recently played to a crowd of 45,000 people at the Festival d’Ete de Quebec, the band’s largest crowd yet as a headliner.

It’s a scale that the band is learning to deal with, intent on doing the right thing amid the confusion and tacky temptations of the 21st-century music business. The seven-member band is simultaneously a throwback to a more heroic age of rock and a glimmer of hope in a digital era that forces musicians to fend for themselves.

It prizes the sounds and methods of a disappearing era: hand-played instruments, analog recording, albums made to be heard as a whole. The band is well aware of the possibilities opened up by the Internet. “Hope that something pure can last,” Win Butler, the band’s main singer and lyricist, sings on the band’s new album, “The Suburbs” (Merge). The Arcade Fire’s songs, credited to the whole band but largely written by Mr. Butler and his wife, Regine Chassagne, mingle the punky and the symphonic, the cryptic and the emotional, the self-doubting and the anthemic, often with surging crescendos that make the tunes optimistic despite themselves.

It’s both a stomping rock band and a mini-orchestra, complete with string section, accordion or medieval hurdy-gurdy as needed. The group performs in a hyperactive rumpus. Even as it brings out the details of its elaborate, multipart songs, it maintains what Will Butler ? Win’s younger brother, and the band’s vintage-synthesizer expert ? calls “that amateur sheen, that nonprofessional sheen that I treasure.” Despite its size, the Quebec concert was just part of a warm-up tour for the band’s new album, “The Suburbs,” which was followed by two shows at New York’s Madison Square Garden the first week of August.

The Garden shows are another conquest for a band that has barely been heard on commercial radio stations yet had its previous album, “Neon Bible,” make its debut at No.2 on the Billboard album chart in 2007. The band’s 2004 debut album, “Funeral,” recently passed 504,000 copies - a megahit for an indie- rock band. The Arcade Fire built its following both in the time-tested way - incessant touring that carried it from house parties to giant festivals - and through the 21st-century word of mouth that multiplies across the Internet . Calmly and stubbornly, the band is an old-school holdout in a digital world.

“All of us had powerful experiences of pop music that was meaningful and had something real about it,” said Win Butler, 30. ” The Arcade Fire is determined to maintain the album as an artistic format, a physical object and an emotional experience. On “The Suburbs,” as on the band’s two previous albums, the songs cross-reference and comment on one another, gathering depth and resonance as a whole.

On “The Suburbs” the band ruminates on memory and modernity, and about childhoods spent, like the Butlers’, in featureless, interchangeable suburbs: their family lived near Houston. “I’m not going to stop making albums because of some fad of digital distribution,” Mr. Butler said. “The idea that you just have to make bad cheap stuff and sell it cheaply because the format changes, to me, is crazy. It’s more important than ever to me to have the artwork and the recording be as great as they can be.”