By Kimberly Chun

EVEN AT 46 , mellowed, and years away from his days as a music writer, Yo La Tengo guitarist-vocalist Ira Kaplan continues to lay down the blueprint for indie rock nerd-dom. He looks like a less doughy Albert Brooks. He sounds like an academic – precise in his word choice and dry in his humor, and he's elusive as a rare species of misanthrope or bookworm. So am I wrong to assume that he'd want to cut loose when he leaves Hoboken, N.J., and goes on the road – maybe indulge a little, act out a bit, take a bite out of the ass of life?

Yes, I'm wrong. It's 8:30 a.m., too close to my early morning bedtime, and I'm rambling like some kind of cockamamie rooster. Kaplan is cordial, even when I ask him what kind of naughty high jinks he's cooking up for Yo La Tengo's present tour, which comes to the Fillmore June 18 and 19.

"So are you planning on getting in a lot of reading or hibernating on this tour, or will you be participating in all those classic rock 'n' roll activities depicted in The Dirt, the Mötley Crüe biography?" I babble, brain firing erratically because of caffeine and sleep deprivation.

He laughs. "You know, I didn't read that book, so you'll have to let me know what those activities are," he says patiently, like a parent talking to a slow child. "Run a check list by me and I'll tell you which ones we're planning and which ones we're not."

For some reason The Dirt's details – the rat-infested Crüe quarters, the shit-stained socks, Razzle R.I.P. – temporarily escape me. "Um, busloads of groupies?"

"Probably not."

"Heroic amounts of heroin?"

"Probably not."

"Porn cameos?"

"No, probably not," he says, then sighs. "No, I guess we failed."

He doesn't seem too unhappy about not living up to my early morning jones for tales of half-assed cross-dressing, car crash fatalities, lousy songs, serial infidelity, and poor hygiene. In fact, Kaplan is in a pretty good mood. He likes Yo La Tengo's 12th album, Summer Sun (Matador). He chuckles a lot. He sounds like he had a full night's sleep after playing a show at the Academy of Music in North Hampton, N.H. He's been happily settled in the same band for about 19 years with his wife, Georgia Hubley, and for the past 12 years with James McNew. In fact, Kaplan comes off a hell of a lot happier than the last time I talked to him, two years ago, when he was putting together a score for a program of Jean Painleve shorts at the San Francisco International Film Festival.

There's only a friendly but firm undercurrent of curmudgeonliness that will not be stemmed. Kaplan refuses to give up the dirt on Summer Sun willingly. You have to come and get it.

"So how would you describe this album?" I ask.

"That's your job?" Kaplan says in a weird, high-pitched, querulous voice he probably saves just for these occasions. He sounds like he's part asking, part telling, part grousing, and then he adds good-naturedly, "Basically, you tell me what you think, and I just say, 'I disagree.' No matter what you say, I'll disagree."

"It doesn't make for a scintillating interview," he continues later, laughing a little. "But I think I'm very distrustful of people who explain their record, that say, 'Oh, yeah, we were really depressed when we made this record.' I think, really? It takes three months to make a record – you were depressed the whole time? You're just saying that, you know. It just comes out of life, and life is a very varied experience."

As you can tell, the guy is overflowing with good vibrations. He's made his summer album, and it sounds nothing like the Beach Boys – or the backing tracks to an MTV spring-break party. It's less Smile than it is a breezy flash of bared teeth and breathy jazz-fusion lite – that's the spelling-challenged, streamlined, dumb as a fox, and willfully oblivious lite. Because it would have been easy to go dark and bleak during the time Yo La Tengo were making Summer Sun: the period extending from the Afghan conflict to the war in Iraq, from summer 2002 through their annual Hanukkah shows that same year. They chose lite rather than night – the kind of lite you embrace when you put on the pounds and reach for a diet incarnation of the toxic pop you once mainlined with impunity on a regular basis. The same kind of lite you get from a band that would dub its universally lauded 1992 album May I Sing with Me (Alias). Little wonder the collective Yo La Tengo entity confesses, on the band Web site, to listening to lite jazz on a regular basis.

Summer Sun has that same smooth, unruffled, even tasteful quality, which is why it might have slightly annoyed me at first. It goes down easy but starts out slow, even somnolently, downplaying grabby hooks yet resuming familiar melody lines and ideas – foregrounding the ambient, electronic touches of 1997's I Can Hear the Heart Beating as One (Matador) and resuming the moody suburban dreamscape of 2000's And Then Nothing Turned Itself Inside-Out (Matador). The album sounds at times like a naive pop volley toward interplanetary jazz travel ("Beach Party Tonight," "Nothing but You and Me"), at others like the wistful, whimsical YLT that embraces the softer side of the Velvet's Loaded.

In some ways, Summer Sun is as lazy and loose as that fat, hot orb, rolling with the straight-faced scat-touched funk of "Moonrock Mambo" or chugging along with a rhythm that mimics the dry husky song of crickets, accompanied by echoey piano and deep-sixed guitar on "Don't Have to Be So Sad." Yet it's an album that's also haunted by all that's come before: their old songs, other people's standards, their own film scores, remixes by Kit Clayton and Nobukazu Takemura, and instrumental recordings with Other Dimensions in Music's Roy Campbell Jr., Daniel Carter, and Sabir Mateen, who've played with them live and join them on Summer Sun, along with William Parker (Cecil Taylor, David S. Ware) and Paul Niehaus (Lambchop), among others. The band's heart now seems to be beating along to their quietly locked-in jazz instrumentals ("Georgia vs. Yo La Tengo") and more freeform miasmas ("Let's Be Still") rather than their kinda wanna-be pop hits. After interpreting other songwriters' tunes on Fakebook and on a continuing basis at shows, and hearing their own tunes taken apart and reassembled by others, they seem ready to shine a light on old ideas and reflect on what they've done before, last summer. And here they almost seem to be covering themselves, interpreting their own catalog, impersonating a band called Yo La Tengo as they once aped the Velvet Underground in I Shot Andy Warhol.

It's a natural step, says McNew, 34, who recently put out his own "coming-of-age" solo album, A Grown-Ass Man (Shrimper). "I think they are ideas and sounds and moods that could have appeared on virtually every record we've ever made except maybe that they're receiving a different emphasis now or they're just being expanded on. It doesn't feel like much of a departure. It feels right," he says on the phone from North Hampton.