A little over a month ago, J Records, a new label helmed by former Arista Records honcho Clive Davis, sent select members of the music press a sampler of five tracks from the then forthcoming sophomore album by the Top 40 trio LFO. It came with a letter penned by LFO’s 25-year-old frontguy, Rich Cronin. The letter didn’t waste any time with coy introductions or cute hellos. Cronin cut right to the chase. “It’s a little-known fact,” he began, “that I personally wrote the singles ‘Summer Girls’ and ‘Girl on TV’ from our first LFO album.” That’s right: Cronin, a local boy who grew up on the South Shore before making his way down to the teen-pop mecca of Orlando and hooking up with ’N Sync svengali Lou Pearlman’s Trans Continental Entertainment juggernaut in the mid ’90s, actually did have a hand in writing both of those summer-of-’99 singles. And that’s front-page news, because in the singles-driven teeny-popper circles that LFO are nominally tied to, most careers would be in the critical-care unit if not for the efforts of some of the best pro song doctors in the Top 40 business.

Cronin, who confirms he’s got a way with a hook and a pen on the new Life Is Good . . . (J), shares the LFO spotlight with a pair of more trad boy-band types (i.e., they sing a bit, they dance a bit, but mostly they just look good in the clothes), Devin Lima and Brad Fischetti. But his most important collaborators over the past few years have been Dow Brain and Brad Young, a pair of unassuming thirtysomething producer/engineer types who spend most of their afternoons hidden away in a modest two-room recording studio across the tracks from the commuter-rail stop in Needham. Their names appeared next to Cronin’s on the writing credits of LFO’s breakthrough hit (“Summer Girls”) as well as on four of the other better tracks from 1999’s LFO (Arista), including the single “Girl on TV.” And owing to their apparent knack for getting the goods out of Cronin, they were retained for Life Is Good — the album features five cuts co-written by the duo and recorded and produced by them at Underground Productions in Needham.

Underground Productions dates back to the pre-teen craze days of alterna-rock’s Nirvana-led emergence as a commercial player. But the “Underground” Brain and Young had their eyes on even in the early-’90s had nothing to do with the rock scene. “I know Boston’s very much known for being a rock city,” Cronin explains over the phone from a tour stop in Milwaukee, “but Brad and Dow are the pioneers of the hip-hop cause in Boston — they have worked with every hip-hop artist in Boston in the past 10 years.” Indeed, the duo got their start creating tracks for aspiring local rappers out of a small, “closet-sized” room in Allston. “We didn’t have any gear for vocals,” Young recalls. “All we had,” Brain continues, “was a Mac Classic computer, a sampler, and a drum machine. We’d connect with people and just bring them in to do beats for their rhymes.”

Both Brain, who grew up in Cambridge, and Young, who’s from Connecticut, had played in bands themselves: Brain was briefly part of local alterna-rock singer/songwriter Tracy Bonham’s band, and they were both members of a local reggae group called the I-Tones. Gradually they took on a more active role in their studio work with artists in terms of constructing and in some cases co-writing backing tracks. At the same time, they began testing the industry waters by working out speculative development deals with certain artists and releasing local hip-hop singles on their own DBK label (in 1995 they released a CD compilation of DBK singles by Punch, Dif Productions, and Polecat). Although they had some minor successes along the way, even those were tempered by the kind of frustrating disappointments that are endemic in the music business.

“We had an artist we got signed to Polydor — a rapper named T-Max,” Young details. “This guy was so good. We did the whole record — it was mastered, the artwork was done, everything was ready. Then PolyGram acquired the Def Jam roster and they decided to shelve T-Max. It was tragic. And we did this single with Polecat that was supposed to come out on some label. They had somebody do a remix, and all the guy did was put a Kool and the Gang sample on it. They couldn’t come to terms with the financial thing to get the rights for the sample, so that never came out either.”

Even though Boston didn’t have the best rep as a rap town in the ’90s, Brain and Young say they had no problem staying busy with local work. “I don’t know if the hip-hop thing here was really a secret or not, because in our circle it seemed like everybody was rapping,” Young recalls. “There just wasn’t really an outlet for it in the clubs. Basically, they were doing it at our studio and maybe one or two other places.”

Cronin’s introduction to Underground Productions came through former New Kid on the Block Danny Wood, who’d gotten involved in the local underground hip-hop scene himself in the ’90s. “I was on a mission to get connected,” Cronin admits, “and I met Danny through a friend who was a friend of his brother. To me, when New Kids were big, they were the biggest. When I saw them blow up the way they did, I really felt that local kids like me could do it. It made me realize that this doesn’t have to be a dream. If anyone says to me that this doesn’t happen to regular people, that’s bullshit, because they were regular people. If New Kids never happened, I would have believed that you had to travel to Hollywood or something to make it. And when I finally met up with Danny, I realized how normal he was, and I really related to him. And that made me want it even more.”

Although the LFO style swings heavily toward the pop end of the spectrum, with brisk acoustic-guitar strums and tailored vocal harmonies providing a solid melodic foundation, songs like “Summer Girls” wouldn’t be possible without a rhythmic sensibility informed by hip-hop. And even Cronin’s singsongy flow owes a good deal to rap. In fact, Cronin came from a hip-hop background and only later discovered the joys of pop. “We were basically doing hip-hop for a while. I used to rap all the time with Akrobatik back when he was called Stud B and he had a group called the Soul Squad — to this day I think some of the music he made back then was the best shit I ever heard. But I started realizing that I dig these old Tom Petty records and the Lemonheads and stuff. That’s why my music has this pop-rock hip-hop vibe to it.”

All that came together one afternoon in ’98 when Cronin, who’d already inked a deal with Arista, wandered into Underground Productions with an idea for a summery song about girls. Brain and Young came up with a breezy acoustic-guitar riff and looped a rhythm track, and by the next day the trio had the song that would launch LFO’s career. “I think he played it for the label, but it wasn’t the direction that they were looking for,” Young remembers. “The album was mostly done at that point,” Brain continues, “and they weren’t even planning to include ‘Summer Girls.’ ” Cronin pretty much remembers it the same way: “Everyone around me liked it, but it was never a song I intended to release. I mean, I wrote it in a couple of hours and we recorded it in a couple of hours. It was just a song that I liked — sort of a yearbook blurb, a song dedicated to me and my friends.”

All that changed in ’99, when a DC-area radio programmer got his hands on a demo of “Summer Girls” from LFO’s manager and put it into heavy rotation. Before long, Cronin and his cronies were back in the studio rushing to put the finishing touches on an album that, as its centerpiece, would feature “Summer Girls” and go on to sell more than two million copies. Now Cronin is going out with Jennifer Love Hewitt. Brain and Young are still in Needham, but these days they get calls to produce tracks on discs by artists like Eden’s Crush and Mulberry Lane. And they’re happy with where they’re at.

“We’ve been told that we have to be in New York if we want to be serious,” Young admits. “And if you’re not there every day, then it is a little bit of a disadvantage. But for us I think it’s a lifestyle choice. The people I know who are there doing this in New York are so engrossed — it’s all they do all the time. I think we both like the balance of working and having other interests, which you can actually do here.”

Meanwhile, Cronin is hoping that as one of the few teen-pop stars who does write his own songs, he’ll be able to bring some of his old fans along and find some new ones as his writing begins to reflect his growing maturity. “It’s not like I’m intentionally trying to be more mature on the new album — I don’t buy into that stuff. But I’ve been through a lot of things and learned a lot about life and about music in the last couple of years. And if you’re not writing about yourself and what you know, then you’re not writing about much. So that’s what I write about. Sometimes it’s just girl problems. Sometimes it’s problems in life. In that respect it probably is a little more grown up, because I’m more grown up.”