From Zeros to heroes... the rise and rise of a superband

Alexander Ebert's preoccupation from a young age with founding a community, a "posse", or a group of his own, has found a harmonious home. The singer has stopped worrying. The 33-year-old Los Angeles musician now finds himself at the helm of the 10-piece musical collective known as Edward Sharpe and the Magnetic Zeros, a 1960s-inspired folk-pop band that is rapidly achieving cult status.

Likened to Arcade Fire and The Polyphonic Spree, Ebert's ensemble of musical minstrels first made it mainstream in 2009, appearing on David Letterman's chat show in the US with their aptly titled first album, Up from Below. The free-spirited gang has since headlined festivals across the country, being handpicked earlier this year by the actor Kevin Spacey to perform five shows in London's Old Vic Tunnels, all of which sold out. On Tuesday they are set to play a sold-out gig at London's Shepherds Bush Empire. And all this without having yet achieved major conventional chart success.

Yet as they stand on stage at Paris's Rock en Seine festival, their tambourines shaking, accordions vibrating, and Ebert's voice resonating across the crowd, they are still surprised when the foot-stamping French audience echoes their lyrics back perfectly. The European music industry has not always been quite sure what to make of the self-defined "Edward Sharpe Experience" of euphoric songs that spread the earnest messages of hope, love and joy, accompanied by, banjos, horns, whistles and handclaps.

Ebert has his own theory. "When we first came over here two years ago, the climate in general was snarky, pessimistic, and cynical – all rock'n' roll in that sort of sense," he says, during a quiet moment away from the rest of his group. "While they appreciated us, there was a real disparity in vibe between the two continents. Now I feel, there has been a slight cultural shift in Europe. It feels more pure-hearted and open-minded. It seems less about pessimism and more about embracing something new."

While the frontman performs shoeless, Ebert was not always so carefree. His band might now be driving the folk revolution, but it "started in a place of desperation", when the songwriter could not handle his drug and drink addictions any longer and his former band, Ima Robot, signed by Virgin, felt sterile. It was around this time in 2008 that he met bandmate Jade Castrinos, 25, fell in love, bought a second-hand touring bus and piled in with a group of artists he knew, to start singing "for fun".

London-born guitarist Christian Letts, 33, has known Ebert since he was four. Practising in a studio flat in Echo Park, Los Angeles, for years, Letts says the creation of the band "evolved naturally". He adds: "We have never set out an idea of what we are or what we are going to be. It has always evolved in a natural way." Accordion player Nora Kirkpatrick, 26, from Iowa, says the band has made it through "working out" its own "groove".

Three weeks into their sold-out European tour and Edward Sharpe – named after a fictional messianic figure dreamed up by Ebert who could manipulate music "as if pulling on strings" – insist they provide an authentic experience in an industry often criticised for the absence of it. Seeking the community he has sought since childhood, Ebert, whose grandfather, Carl Ebert, co-founded Glyndebourne Festival Opera, says he wants to make music "devoid of any sense of irony".

"I had a South African teacher at school, a sort of hippie who played the acoustic guitar while us five-year-old kids would sing along, playing our tambourines and recorders in unison," explains Ebert. "It was just this deep sort of atmosphere, you know, of not taking it too seriously, but feeling a sense of community while playing the music. That's partly where this all comes from – I'm acting like a five-year-old and it's impossible to bullshit at that age."

Perhaps it is this unashamed honesty that convinces the initially hip-swaying French fans to join Ebert in a dance-off as he frantically jumps about the stage and then into the cheering crowd. Vocalist Castrinos says the band focuses "intently on the present", offering listeners in that moment something that "can give them strength of feeling, an emotion, even for the length of one song". It appears to hit the mark. As they launch into "Home", which professes "my home is nowhere without you", the audience responds by singing back "Maison" to the band, in unified agreement. Ebert remains adamant his band can embrace success without losing the DIY appeal that has made them so popular. "Everybody has the power to stay true to themselves," he says.

On the eve of their British tour and with an eagerly awaited second album imminent, the band is enjoying an increasingly popular sense of community. Ebert's "crew" has "fallen together like puzzle pieces", says Kirkpatrick. "I don't think any of us could ever have expected it, but it's true."