Freedom, like love and hate, doesn’t mean so much anymore. It’s been stripped of its conceptual gravity, cavalierly used to describe how cars handle, to characterize rollover minutes in cell phone plans and to rally those who love the word to war. But for the two-person bands playing DuoFest this weekend in Durham, freedomspecifically, the freedom to explore music-making outside of typical solo or full-band formatsis key.

But such freedom is an invigorating challenge, too, meaning bands with leaner lineups have to find wayseither through volume, multi-instrumentalists or compositional maneuversto make their music stick. Whether talking the impressionistic folk of Sawteeth McTweedy or the electronic indie pop of Opening Flower Happy Bird, a duo can’t apologize for not being a full band. The open space of a smaller roster leaves room for interpretation, a no man’s land where unconventional methodology reigns supreme.

For The Curtains of Night, a Chapel Hill metal duo, the solution was technology. Guitarist Nora Rogers plays a hulking tube amplifier she built herself. Its bold sound doesn’t give you room to wonder where the other band members are.

“I don’t feel like in a way we’re a typical duo, because Nora’s sound is just so massive,” says drummer Lauren Fitzpatrick, whose own start-stop clatter builds plenty of momentum. “You do have to kind of make up for something that’s usually therenot necessarily something that’s missing, but something that people are used to having.”

Dave Cantwell, a co-organizer of DuoFest, says making compelling music as a duo isn’t all about volume in his bass-and-drums band, The Whole World Laughing. Instead, they just write harder music.

“You have to compensate with compositional density,” Cantwell says. “You have to be able to pack more ideas into one song.”

Durham’s Resist Not, though, is neither complex nor particularly loud. Frontman Aaron Ward says the duo form can be confining because the Hammond organ or five-piece horn section he may hear in his head isn’t on stage, but the stripped-down setup makes the songwriting that much more important. “For me it’s not about musicianship, because I don’t feel like I’m an accomplished guitar player,” says Ward, “but I feel like it lets us focus on song structures and songcraft.”

Eleni Binge co-organizes the festival with Cantwell and plays in duo Beloved Binge with her husband, Rob Beloved. She agrees: “It’s all about the lack of excess, so you’re just down to the basic core: What do you need to make a really good song?”

And once the song is strong, the two members have to find a way to present. Sitting behind the drumkit, Binge not only sets the rhythm but sings, plays keyboards and plays guitar. Like her own motion, Beloved Binge songs are busy, using shifting rhythm and keys and two different verses sometimes sung at once.

“Your limitation is also your asset,” says Binge. “There’s no added weight, so the two members have to each do something that’s not just keeping a standard beat. Usually there’s a lot going on.”

For these bands, the constraints of being a duo aren’t obstacles to overcome, but opportunities to explore a new approach. The level of close interaction between two musicians allows for quirk and style, not just four-piece, four-on-the-floor rock ‘n’ roll. “There’s just such an amazing diversity of artists around here and everybody’s exploring music in their own way,” says Ward. “They’re exploring their own musical interests and musical tastes.”

DuoFest starts at 3 p.m. Saturday, June 7, at Bull City Headquarters. Headliners The Curtains of Night goes on at 12:30 a.m. The preceding line-up, in reverse order, is Opening Flower Happy Bird, Jews & Catholics, Apis Bull, Spacelab, Sequoia, The Whole World Laughing, The Saint Peter Pocket Veto, Beloved Binge, Fortress of Swatches, Speedsquare, The Scientific Superstar, Sawteeth McTweedy, Resist Not!, All Your Science, Horned Goat Cookie Party and 2013 Wolves. Tickets are $5.