Browne's story songs, old and new, still captivate

Jackson Browne performing at the Orpheum on Tuesday night. (Erik Jacobs for the Boston Globe)

Tuesday night at the Orpheum Theatre, Jackson Browne told his audience that when he compares notes with other classic rockers, they report that they find it tricky to balance new material with old in concert. With a hand literally on his heart, Browne expressed gratitude to a crowd willing to do more than simply tolerate the unfamiliar. And it wasn't just new music, but unreleased music, and lots of it from his forthcoming album, "Time the Conqueror," out next week.

That unwavering attentiveness is a testament to Browne's consistency over the past 35 years. And we're not talking about that ageless pageboy haircut, which, yes, he's still sporting at 59. Or even his warm caress of a voice, which has acquired a welcome touch of grit.

But as a songwriter's songwriter, no matter how long he takes off between albums - in this case six years - or the ruts he has tumbled into periodically, Browne always conjures a few stories and tunes that resonate on each release.

The depth, specificity, and nuance of the songwriting on "Conqueror," often echo Browne's vintage work. And so the nostalgia for his sun-dappled Laurel Canyon youth in the ambling "Off of Wonderland" held up nicely alongside the searching "Fountain of Sorrow" recorded during that period.

Browne is wise, or intuitive, enough to understand that consistency has its limits, however, and that an element of surprise can also pay dividends. He hit the jackpot in the discovery of backing vocalists Alethea Mills and Chavonne Morris. This dynamic duo, whom Browne met in 2001 when they were high school students in LA, pulled focus throughout the night in the most positive way with their powerful, emotional vocals.

They imbued the new and new-ish tunes with vibrancy, testifying with a fervor not normally associated with the mellow golden boy on the jubilant "About My Imagination" and the turbulent protest song "The Drums of War." And they reinforced the timelessness of solid songcraft as they helped reinvigorate well-known toe-tappers "Doctor My Eyes" and "The Pretender" not just with their soulful vocals, but their youthful, hand-waving exuberance.

On the politically charged "Lives in the Balance," Mills and Morris raised their voices in lament, guitarist Mark Goldenberg offered shiver-inducing Spanish guitar licks, and drummer Mauricio Lewak kept an off-kilter beat.

The crowd's enthusiasm and courtesy notwithstanding, a few more hits in the 130-minute show - broken into two sets - would have been welcome as Browne played fewer than a half-dozen of his most familiar songs, including the still-thrumming set closer, "Running on Empty."