The Dirty Three brews dark melodies

Rock instrumentalists will surprise you, as they should. The Dirty Three does, colliding indie rock with old-timey folk, weaving feedback and violin into an unexpected sound both graceful and abrasive.

At the Australian trio’s 90-minute concert Thursday at the Henry Fonda Music Box Theatre, fans crowded against the stage to absorb waves of lilting melodies that would turn dark and emotional. Dozens of others were slumped against the walls, but the Dirty Three was too explosive to be chill-out music for long.

The title song from the band’s newest album, “She Has No Strings Apollo,” began slowly and accelerated in tempo and intensity. The band was a more powerful unit live, not just from the volume of jagged guitar and violin, but also from a deeper rumbling that shook the room and the swaying fans to their fiber.

The trio occasionally became the filthy four whenever joined by bassist Zak Sally (of the band Low). Always at the center was violinist Warren Ellis, a frequent collaborator with Nick Cave, playing with his back to the crowd but also stepping up to the microphone for an occasional introduction between songs.

His rambling explanations for the instrumentals were almost literary, rooted in life experience and cultural observation. The emotional content needed no embellishment, sending Ellis into fits of release: kicking up his heels, pacing in a circle, falling to his knees to pluck the strings with his teeth and even screaming into the microphone pickups on his instrument. And maybe surprising even himself.