When Dan Charnas began his research for Dilla Time, his ambitious, definitive tome on the journey, legacy and sound-shifting innovations of late hip-hop producer and MC James Dewitt Yancey, aka J Dilla, he faced a Herculean task; how does one pen an exhaustive, 400-page opus on a deeply private man who, while today is celebrated by loyal fans, musicologists and famous artists as the most consequential composer of his era, remains an obscurity? You go deep.

“Nobody was really talking about the music,” says Charnas of the work of the prolific production visionary and master of the MPC3000. Dilla, who died in 2006 from complications of lupus, expanded the boundaries of time signatures in rap and beyond.

Friend and frequent collaborator Questlove and others have described him as a sheer genius who took sampling and beat composition to unconventional heights. The Slum Village member’s studio excursions with hip-hop and R&B stalwarts The Pharcyde, A Tribe Called Quest, Janet Jackson, The Roots, De La Soul, D’Angelo, Common and Erykah Badu have propelled him to legendary status among music historians. Dilla is even featured in a music exhibit at The Smithsonian’s National Museum of African American History and Culture.

His ascent to hip-hop deity did not happen by accident; J Dilla put in the work. “People identify that drunken, limping, stumbling kind of production with Dilla and mistakenly say it happened because he just didn’t quantize,” continues Charnas, alluding to the MPC digital setting that allows users to correct rhythmically imprecise drum patterns and loops. “When people talk about Dilla, they talk about him as this sort of musical mystic. Like, 'He had a great feel.' It’s all this godlike, otherworldly language but almost no deconstruction of what he was doing. Most of those really exaggerated beats you're hearing are the result of Dilla’s programming. He used a completely new time field that did not exist before him.”

Released 2/1, Dilla Time: The Life and Afterlife of J Dilla, the Hip-Hop Producer Who Reinvented Rhythm joins a growing list of hip-hop books that have hit shelves over the last two years that go beyond the boilerplate biography—Bring That Beat Back: How Sampling Built Hip-Hop (Nate Patrin); The Marathon of Don’t Stop: The Life and Times of Nipsey Hussle (Rob Kenner); The Motherlode: 100+ Women Who Made Hip-Hop (Clover Hope); and Promise That You Will Sing About Me: The Power and Poetry of Kendrick Lamar (Miles Marshall Lewis).

Coming in May is It Was All a Dream: Biggie and the World That Made Him, by Justin Tinsley, senior culture writer at The Undefeated. Dilla Time is the first comprehensive book on the influential Detroit producer. Tinsley's subject, on the other hand, is a Roll & Roll Hall of Famer who's been the subject of seemingly countless books, documentaries and shows since his 3/9/97 death.

Says Tinsley of the moment he realized what he was in for: “I was like, ‘Oh, shit—what the hell can I tell people about Biggie that they don’t already know? The book can’t just be 'Christopher Wallace was born in Brooklyn, sold some drugs, signed to Bad Boy and became a star, beefed with Tupac and got killed.' I wanted to know what drove his mother, Voletta Wallace, to come from Jamaica to the Bronx and then to Brooklyn.”

It Was All a Dream connects the dots. Along with interviews with friends and loved ones, including Biggie’s son, Christopher “C.J.” Wallace, there are passages about President Richard Nixon and the legislation he signed that affected the financial structure of New York in the ‘70s, prompting the city's near-bankruptcy.

“That impacted the educational system and took the arts out of the schools,” Tinsley explains. “It stripped so many neighborhoods of their resources that we saw the rise of hip-hop along with the boom of crack cocaine. Then you start talking about that from a national standpoint, then funnel it down to St. James and Fulton St. in Bedford-Stuyvesant, Brooklyn, and how that impacted a young Biggie. When you read the book, you go probably 200 or so pages before it even gets to ‘Juicy.’”

It Was All a Dream pierces the gangsta “King of New York” armor of Biggie Smalls with anecdotes like the time a seven-year-old Christopher retreated to his mother’s room to sleep with her after having a nightmare from a movie he'd watched earlier. There’s a story from Biggie’s friend and Junior Mafia member Michael “Chico Del Vec” Abrahams (who introduced B.I.G. to selling crack) of a 200-pound teenage Wallace breakdancing in his cramped bedroom.

For fans wanting an insider’s view of what it was like for Biggie to be hustling in North Carolina and freestyling at Southern clubs before meeting Bad Boy label head Sean “Puffy” Combs, it’s all there. Nor does Tinsley shy away from Biggie’s alleged physical abuse of protégé and future rap legend Lil' Kim.

“He had regrets about how he'd treated people in his life,” Tinsley says. “Biggie was more excited about fatherhood than he was about releasing his third album.”

Charnas is a professor at NYU's Tisch School of the Arts and he at times takes an academic approach to Dilla's story, including obsessively detailed rhythm diagrams of his production work. But he, too, bring his hero—who died three days before his 32nd birthday—back down to earth.

He does some particularly revelatory myth-busting. “I wanted to go beyond the trope of Dilla being this humble dude,” he says of the driven talent who struggled for mainstream notoriety. “No, Dilla wasn’t humble; he was quiet and furious, quiet and competitive and quiet and fed up.”

Indeed, while Dilla embraced the respect and love he received as part of the all-star Soulquarians crew, he grew frustrated that his groundbreaking work on such classics as A Tribe Called Quest’s “Find a Way,” Busta Rhymes’ The Coming and Common’s Like Water for Chocolate was attributed to the collective. When he received an early vinyl copy of D’Angelo’s 2000 masterpiece Voodoo, to which his contributions are more than conspicuous, he was disappointed that he didn’t receive proper credit. And contrary to hip-hop folklore, Dilla did not create his magnum opus, the 2006 instrumental album Donuts, from his hospital bed.

Charnas believes the history of hip-hop deserves more meticulous storytelling. “That's the commonality I feel I have with Justin Tinsley,” he says. “I'm interested in the world that made James Yancey. I'm interested in explaining to the world, and even to Dilla’s world that may not understand it, that this is why James was super-important."

Just as their two subjects pushed the boundaries of hip-hop, the authors of these two books have significantly expanded the narrative about the form.