“There’ve been four or five times where someone quit the band because a terrible show turned into a fight after,” says singer-guitarist Josiah Johnson of the Seattle nu-folk phenomenon The Head and the Heart, whose highly-anticipated second album, “Let’s Be Still,” comes out Tuesday and will be a featured item at Starbucks nationwide. “Then the next morning everyone’s like ‘OK, never mind.’ ”

Johnson and THATH fiddler Charity Rose Thielen are sitting at a picnic table at Golden Gardens on an implausibly gorgeous fall day, the Olympics “out” in all their glory.

“That’s the reality of a band,” says Thielen. “If you can’t quit and then move through it, you aren’t fit to be in a touring band.”

Spoken like a seasoned professional — which Thielen and her bandmates surely are now, after nonstop touring (200 dates in 2012), nearly 300,000 sales of the band’s first album, raves in Rolling Stone and USA Today, a cover story in Billboard magazine and rafts of late-night TV appearances, including a return appearance on “The Late Show with David Letterman,” scheduled for this Wednesday.

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Unlike the group’s first album, which celebrated togetherness, “Let’s Be Still” reflects nostalgia for lost “alone time,” and is peppered with unfulfilled relationships, melancholy and even a little self-consciousness.

But it’s also a triumphal, poppy studio production, painted with thick sonic textures unaffordable to the band in its infancy.

“They’ve sort of come into their own,” says Stuart Meyer, who signed the group to Seattle’s Sub Pop Records back in 2010. “They have much more sense of self now and what they can be. And what they don’t want to be.”

What The Head and the Heart does want to be is a fiercely democratic band. Idealistic, romantic and unjaded, they are of a piece with the earnestness projected by another Seattle act, rapper Macklemore.

What they don’t want to be is “cool kids” picked by tastemakers like the website Pitchfork (which hated the band’s first record) or part of the “hierarchy of hipness,” as Thielen puts it, of Seattle’s notoriously fickle alternative-music press.

“We want to make good music, and we care about songwriting and we care about creating an experience in our live shows, and that’s what matters … for people to be moved in some way by what we do.”

Anyone who saw the band at Sasquatch two years ago, where a spontaneous line of swaying, locked-armed sing-a-longers from ages 15 to 55 erupted spontaneously across the width of the amphitheater during THATH’s set, knows it can do that.

“They have that magic,” says manager Matt Shay, of San Francisco’s Zeitgeist, which also handles Seattle’s Death Cab for Cutie.

Though often lumped in with the folk revival (Avett Brothers, Mumford and Sons) THATH is really a singer-songwriters’ band with a rock background. Johnson and Thielen become animated when they talk about songwriting, not bluegrass or Woody Guthrie.

The Head and the Heart came together in 2009, when Johnson, raised in Orange County, Calif., hit it off with singer-songwriter Jonathan Russell at an open mike at the Irish bar Conor Byrne in Ballard. Russell had come out with drummer Tyler Williams from Richmond, Va. Seattleite Chris Zasche, tending bar at the club, was recruited to play bass; Californian Kenny Hensley, piano; Thielen, from Lake Forest Park, violin.

Johnson and Russell are the principal composers, though Thielen is beginning to shine. The band used to write songs together, says Johnson, an intense, handsome 29-year-old with an analytical mien. This time, each writer brought in songs fully formed.

“When you’re on the road together day and night,” says Johnson, “the last thing you want to do is sit down and write a song together.”

Johnson’s tune “Fire/Fear,” slow and thick, depicts a marriage gone sour from an imbalance of power.

“It’s not about a marriage that I’ve had,” he says. “And it’s not even about a marriage that I’ve watched … but I do know the feeling of being that person that’s taking the other person’s hard work for granted and not giving as much as I’m giving.”

Johnson’s musical influences include Radiohead, Bon Iver and Damien Rice. But even when the band’s music is darkly textured, as on Russell’s funereal title tune — “the world’s just spinning a little too fast,” he complains — or his ironic “Homecoming Heroes,” which skewers the fickleness of fame, there is a curious optimism, buoyed by Hensley’s clanging piano.

That optimism may also be driven by the fact that Johnson and Thielen both grew up in Christian households. Thielen’s beautiful “These Days Are Numbered,” though it deals with death, is underscored with an intense faith that would not be out of place in a George Herbert poem.

Unpretentious and quick to laugh, Thielen, 27, went to Shorecrest High School. Her mom, an orchestra teacher, exposed her to classical violin (Suzuki lessons at 6) and Christian music. But after hearing Willie Nelson at 16, Thielen bought a guitar and started singing. At the University of Washington, she started jamming on violin.

“I’ve never seen you playing your violin backstage,” says Johnson to Thielen. “You’re always asking if you can borrow my guitar.”

Johnson taught himself to play guitar in high school and played in several bands at the University of California, Irvine before moving to Seattle for grad school at the UW.

From the start, The Head and the Heart agreed to split everything equally. That means that even though Thielen wrote and sings “These Days Are Numbered” by herself, everyone else gets an equal share.

The Eagles started out that way, too, but it didn’t last. If THATH’s second album debuts in the Billboard Top 10 and pulls the first one into gold record territory (500,000 sales), as it very possibly will, can this idealism last?

“We revisited that on the road,” says Johnson. “But our lawyer, Ed Pierson, who is magnificent, I remember him saying, ‘You guys don’t realize that one of the best decisions you made was deciding to split everything.’ I think we relearned that on tour.”

The Head and the Heart has taken its share of road knocks — airport all-nighters, 14-hour van drives, 3 a.m. wake-up calls, even waiting out Hurricane Irene in a basement — but Johnson modestly dismisses all that.

“ ‘Oh, my life is so hard, I make a living playing music,’ ” he says mockingly, knowing he is living the dream.

Somehow you get the feeling that even if he or Thielen threatens to quit, in the morning they’ll just say, “OK, never mind.”

Paul de Barros (206-464-3247 or pdebarros@seattletimes.com) covers music at blogs.seattletimes.com/soundposts/ or follow him on Twitter @pdebarros