Every musical genre needs a ground zero. It may not be its exact point of origin, but it’s the time and place at which all of the possibilities and future branches seem to coalesce, with the following decades left to add footnotes. Rock and roll has Sun Studio in Memphis. Punk rock has CBGB. And for hip-hop, though the genre might have its official birthplace at Kool Herc’s 1520 Sedgwick Ave., its commercial watershed can be traced to the NYU dorm room of Rick Rubin, where in 1984 the enterprising young producer, his business partner Russell Simmons and a teenage Queens rapper named LL Cool J fully launched Def Jam Recordings.

Following the 1985 release of the Platinum-selling “Radio,” LL’s debut and Def Jam’s first full-length pressing, Rubin would go on to produce for acts as varied as Slayer, the Beastie Boys, the Dixie Chicks, Metallica and Adele. Simmons would develop a vast, multifaceted empire that established the gold standard for hip-hop entrepreneurship. And LL would release seven more Platinum albums, star in several films and long-running TV shows, win a pair of Grammys and will receive a star on the Hollywood Walk of Fame on Jan. 21.

Now 48, LL still remembers Rubin’s old phone number and the address of his college dorm room. He got them from the back cover of T La Rock’s “It’s Yours,” the Rubin-produced 1984 single, which was the first recording to sonically capture the rough-edged, beat-heavy primacy of NYC street rap onto record. “Radio” went one step further, stripping hip-hop of the last vestiges of its disco roots. With nothing but a beat and LL’s inimitably charismatic delivery, it launched the 17-year-old as the genre’s first crossover sex symbol and bona fide pop star, his Kangol hat becoming just as distinctive a fashion accessory as Run-DMC’s Adidas.

FROM KING TO QUEENS: LL Cool J onstage in the U.K. in 1987, top, and back home on the bus in Hollis in 1985.
Left: Normski/PYMCA/Shutterstock; right: Josh Cheuse/PYMCA/Shutterstock

If LL’s name no longer provokes the sort of immediate reverence that rap nerds hold for his Golden Age contemporaries like N.W.A, Eric B & Rakim, or onetime labelmates the Beastie Boys, it’s possibly just because his career has extended long enough for him to be taken for granted. Even considering his longevity, it’s remarkable how many landmarks LL can claim for his genre. He took part in one of hip-hop’s highest-profile battles, with Kool Moe Dee. He staged hip-hop’s first comeback act with 1990’s “Mama Said Knock You Out.” His track titles have been referenced in song by everyone from Jay Z to Mos Def, the Notorious B.I.G. and Sonic Youth, and he gave Rock the Bells, long hip-hop’s premier annual festival, its name. For a genre in which debut records often serve as de facto greatest hits albums, LL’s ability to transcend the decades is much easier said than done.

“There’s a tension, sure,” LL says of hip-hop’s youthful obsession. “The difference with hip-hop is that, relatively speaking, it’s still a very young genre, especially compared to jazz, rock and roll, country. So the tension comes in when people start asking if it’s possible to grow up and mature and be an adult and still do hip-hop. So many guys are nervous about the idea of doing it. A lot of guys who worry, if I’m not doing a song that 14-year-olds like, then somehow it’s not relevant. I don’t think that’s true. The music is growing, the industry is maturing, and you have to be like fine wine and just keep doing it from the heart.”

In concert with his pin-up good looks, LL was also the first rapper to breach the pop charts with a full-on love song, 1987’s brazenly sentimental “I Need Love” off his second album. The heartstrings-rending rap ballad has become such a staple of the genre that there’s essentially an entire Grammy category dedicated to it, but at the time it was about as daring a move as a subculture known for bluster and machismo could countenance.

“I don’t have to be a juvenile to make cool records. I don’t have to be on the pop charts to be relevant. I’m a cool artist because I’m LL Cool J.”
LL Cool J

“Rick and I had, not exactly a falling out, but a total disagreement about that song,” LL remembers. “He was like, ‘Man, if you’re so confident about it, why don’t you put it out first.’ Back then, people really had this idea that if you were from the hood making rap records that you’ve gotta do nothing but edgy stuff. People are a little more comfortable now with the idea of a rapper being a creative artist, but back then, they didn’t look at us like that. It was like, if you’re not drinking Ol’ English and screaming, what are you even doing? How dare you talk about some sensitive stuff?”

The song reached No. 14 on the Billboard Hot 100 — and became one of the earliest Top 10 hip-hop hits in the U.K. — breaking open a foothold for LL’s follow-up loverman tunes “Around the Way Girl” (No. 9 in 1990) and “Hey Lover” (No. 3, 1995). As successful as this side of the rapper proved, it also forced him to face that hurdle that has bedeviled crossover rappers ever since: Maintaining his lyrical cred while still servicing the pop charts.

“I could show you every record where I had real aggressive songs — maybe it just came across that way because of what the hits were,” he says. “I love aggressive music. But radio was so different at that time, that the labels started catering more to my ballads after ‘I Need Love.’ I had the harder records still, but they were servicing more of the softer, ‘Around the Way Girl’ side of things.”

But if he ever ran the risk of being grouped into the Tiger Beat crowd, LL’s most iconic televised performance made sure he’d be remembered for the unblinkingly intense live performer he is. Taken from the first hip-hop installment of MTV’s “Unplugged” series, LL’s live rendition of “Mama Said Knock You Out” became a staple of the channel, with the shirtless, sweaty, screaming LL giving suburban America a taste of just how powerful and immediate rap could be when stripped down to its most basic level, his hardest-working man in hip-hop aura nodding to James Brown, from whom the head-knocking beat of “Mama” was taken.

BIGGER AND DEFFER: The rapper, performing in Philadelphia in 2012, has long maintained a steady performance schedule in addition to his film and TV work.
Owen Sweeney/Shutterstock

LL makes the comparison explicit. “My thing has always been not to see how profound I can be,” he says, “or to make my songs sound like an audiobook. I’m not making literature. The idea was to make something you could feel. You think about someone like James Brown, he was never about songwriting per se, it was about vibe, and what the music makes you feel.”

A career as long as LL’s could hardly be expected to be free of missteps: Some fans were wary of his embrace of the then-dominant gangsta rap aesthetics on 1993’s “14 Shots to the Dome,” and more recently, his collaboration with Brad Paisley for country-rap hybrid “Accidental Racist” accidentally raised the hackles of the Internet’s outrage machine.

Yet both clearly came from the rapper’s desire to try something new, and it’s that impulse that saw him notch his first No. 1 single 17 years after his debut, with his first No. 1 album coming only two years earlier.

LL professes little desire to chase trends as he enters his fourth decade in music. After 12 studio albums with Def Jam, he released 2012’s “Authentic” through indie outfit S-BRO Records, and he clearly finds a degree of freedom in his elder statesman status.

“People back in (the 1980s) really had this idea that if you were from the hood making rap records you’ve gotta do nothing but edgy stuff.”
LL Cool J

“If I put out more music, it’ll be just because,” he says. “It’s not to try to compete. I don’t have to be a juvenile to make cool records. I don’t have to be on the pop charts to be relevant or be a cool artist. I’m a cool artist because I’m LL Cool J and this is what I do. And that’s just coming from a place of confidence, not hubris or arrogance.

“But (what’s great) is that the only thing that’ll stop me from making music is me. No one’s got a gun to my head now. There’s nothing stopping me from making music and working with the producers I want to work with. So if I don’t, it’ll only be my fault.”