Chris Trapper would be the first guy to tell you he's always been unhip, even sort of square, when it comes to rock 'n' roll attitude.

''I sang in a barbershop quartet in high school," Trapper says over chocolate cream pie at the Other Side Cosmic Café on Newbury Street,
where he used to wait tables a lifetime ago. That was long before his
Boston-by-way-of-Buffalo pop band, the Push Stars, briefly became major
label semistars and he found himself writing tunes for Cameron Diaz to
cavort to. Back in high school, the barbershop harmonizing got him teased and worse.

''But it made me love a certain style of music that wasn't new -- and
recently, I was asked to play at my high school reunion. So I went from
being the biggest geek to . . . " He smiles, and his voice breaks into a laugh. OK, maybe still kind of a geek, albeit one with a better haircut, fashion sense, an impressive songwriting resume, and fans who cheer rather than jeer the nice guy with the sentimental streak.

Trapper's taste for old-time music has found a new niche in ''Gone Again," his self-released second solo album that features the Wolverine Jazz Band, a crack combo of Dixieland-style players from around New England who bring brassy big-band sound to Chris's light, lovelorn songs about Boston girls, jukebox lights, and old-fashioned dreams. The Wolverines will join Trapper at Harpers Ferry tomorrow night.

In some respects, the material shares the homespun, small-town sensibility Trapper brings to his day job fronting the Push Stars. Except that there's more trombone here than electric guitar.

''I basically worked the last Push Stars record [2004's 'Paint the Town'] to the bone, so the thought of doing another rock record had no appeal to me," says Trapper, 38, who's brainstorming ways to take the seven-piece Wolverines on the road this year, schedules and finances permitting. ''I'm a songwriter, and having a different outlet for my songs is what makes it interesting. I get to learn from some master players, too. [When] you play with the Dixieland horns behind you, all swirling and interweaving, it's incredible."

Trapper first stumbled upon this style of music one night about 15 years ago when, depressed after a long day peddling chocolate chip cookies to tourists at Faneuil Hall, he headed home ''thinking this was not what I wanted for my life." Four musicians who called themselves the Commonwealth Jazz Quartet were performing from a park bench nearby. ''I was really bummed out, and their music had a certain joy that was able to alter my mood immediately," Trapper says. He bought the band's tape, took it home, and forgot about it.

Years later, the Push Stars were tapped to cover the Steely Dan song
''Bad Sneakers" for the soundtrack to the Farrelly brothers' movie ''Me, Myself & Irene." Stumped when he realized he couldn't pull off the lead guitar solo -- and anxious about the fast-approaching recording session -- Trapper hit upon a novel idea while rummaging through his pile of cassettes: tapping the Commonwealth Jazz Quartet for a Dixieland solo break. He called the phone number on the tape, and although he was told the group was defunct, the onetime tuba player suggested Trapper contact a young jazz bandleader named John Clark, who led his own outfit, the Wolverine Jazz Band. Not only did the Wolverines end up playing on the track, the group opened a Push Stars show at the Paradise Rock Club, and both parties have remained friends since.

''Chris is an immensely talented guy," says Clark, 37, a clarinetist who teaches jazz history at Connecticut College, as well as music in the Wellesley public school system. ''He has very open ears to a lot of different styles of music, and his lyrics especially make you think of some of the great lyricists of Tin Pan Alley, like Ira Gershwin -- people who are very sophisticated and witty with interesting wordplay."

Clark points out the influence of traditional jazz among pop and rock artists such as the Beatles, who performed Tin Pan Alley standards during their early years (his own band even covered Lennon-McCartney's homage to the genre, ''Honey Pie," on the Wolverines' 2005 CD, ''Give
Me Some Tempo!").

''Gone Again" is notable for something besides its style. The whole album was recorded almost entirely live in a Needham studio during one marathon session, with the seven musicians playing and Trapper singing
together in one room. Clark says Trapper impressed the jazz veterans by
singing live, and on key, for six hours straight.

''The whole record was done in one night -- no Pro Tools, no computers, all live," Trapper says. ''And I'll tell you, these guys are more rock than anybody. I brought in a bottle of Scotch, and it was gone in, like, five minutes."