When HBO renewed Bill Simmons’ “Music Box” documentary series for a second season in December, it wasn’t exactly surprising. Critics, film festival programmers and audiences were immediately taken with the series of six docs, which launched in July.

But the road to success was a long one. Simmons conceived the series back in 2018. His idea was to make the music version of the wildly successful sports docuseries “30 for 30,” which he co-created for ESPN more than a decade ago. Like “30 for 30,” installments of “Music Box” wouldn’t tell the entire trajectory of an artist’s career, but instead spotlight pivotal moments, creations and creators within the music sector. Also like “30 for 30,” Simmons would enlist A-list documentary filmmakers to make his vision come to light.

Three and a half years later in July, Garret Price’s “Woodstock 99: Peace, Love, and Rage” became the first Music Box film to be released. It was followed by Alison Klayman’s Alanis Morissette documentary “Jagged,” Christopher Frierson’s “DMX: Don’t Try to Understand,” Penny Lane’s “Listening to Kenny G,” John Maggio’s “Mr. Saturday Night” about music entrepreneur Robert Stigwood and Tommy Oliver’s “Juice WRLD: Into the Abyss.”

While the six films in the series delve into an array of topics and explore all kinds of personalities, Simmons says each installment complements the other, and not because they are based in song.

“The throughline that connects each of these six ‘Music Box’ films was their concentration on a window or an event or some sort of condensed timeline that tried to answer a specific question.”

Two examples are Price’s “Woodstock 99,” which examines how the festival eventually collapsed under the weight of its own misguided ambition, and Lane’s “Listening to Kenny G,” which attempts to answer why the best-selling instrumentalist of all time is so polarizing.

“Kenny G makes extremely inoffensive music that nonetheless inspires a great deal of anger and even disgust in certain people,” says Lane, who pitched Simmons the idea for the film. “I thought exploring what it is about him and his music that has made him so wildly popular yet so disdained by the critical class would be an interesting way to get into issues around taste and cultural gatekeeping.”

“Listening to Kenny G,” which premiered at the Toronto Festival, was one of five docs that Simmons commissioned for the series. Frierson’s “DMX: Don’t Try to Understand” was the only film that he acquired.

When Simmons began developing “Music Box,” Morgan Neville and Asif Kapadia had won Oscars for “20 Feet From Stardom” and “Amy,” respectively. But during the three and a half years that it took Simmons and his digital media company, the Ringer, to create, make and deliver the HBO series, documentaries about musicians had blown up. Pink, Taylor Swift and Tina Turner had all followed in the footsteps of Madonna, Lady Gaga and Beyoncé and become doc stars.

There are three music docs on the Oscar shortlist: “The Velvet Underground,” Todd Haynes’ look at the seminal band; “Billie Eilish: The World’s a Little Blurry,” from R.J. Cutler; and Questlove’s exploration of 1969’s Harlem Cultural Festival, “Summer of Soul (…Or, When the Revolution Could Not Be Televised).”

Each singer also had a hand in making the respective documentaries by serving as a producer — or in some cases, the record label served as a producer — which has raised concerns over creative control and whether music docs are artistic endeavors or infomercials.

To be fair, making a music docu without the backing of a pop star or the record label is difficult. Without their blessings there would be no access to talent and the budget for licensing music would mirror a Marvel movie.

Polygram Entertainment and Universal Music Publishing Group executives Jody Gerson and Marc Cimino were key to getting HBO’s “Music Box” off the ground.

“You need a conciliary,” says Simmons. “There’s no way you could do a series like this without people who really get how the music industry works. Marc and Jody were the ones with the relationships.”

While Gerson and Cimino served as series’ executive producers, Simmons notes that Universal Music and the artists behind each “Music Box” film did not have final cut.

Any issues over who was in control of the series’ first season became clear when Morissette distanced herself from Klayman’s “Jagged” in September — days before the doc’s Toronto Intl. Film Festival premiere. The doc captures the singer-songwriter’s 1995 meteoric rise to fame after the release of her breakthrough album, “Jagged Little Pill.” Morissette, who agreed to participate in the film, told the media that the doc included information that was “simply not true” and that the filmmakers had a “salacious agenda.”

“I don’t want to say what happened, but I understand it,” Simmons says. “When somebody’s making a documentary about you and it’s your life and as it gets closer and closer to the premiere date you might get skittish about something. Or you might not like how certain things were portrayed. But I think she’ll be glad at some point that the film exists.”

While HBO won’t divulge the budget of each “Music Box” installment, Simmons says the network licensed all the songs used in the series, which begs the question —how much did they cost? Is HBO paying big money to make “Music Box”? The answer is no.

Veteran documentary executives and filmmakers estimate that each film was made for approximately $2 million-$3 million, which is relatively cheap given how much it costs to license music.

Sheila Nevins, who served as head of HBO Documentaries for 38 years and is the czar of MTV Documentary Films, says quid pro quo allows music-based docs and series to be greenlit.

“I have a docu where a kid sings ‘Let It Be’ and I have to [incorporate] fair use and pay substantially for a little boy to sing this song,” Nevins says. “But if you are making a docu about a band with their cooperation or the record label’s cooperation, you’re basically selling music in the form of a docu because people go out there and buy or download that music after watching the docu. This kid in my film is not going to sell any albums for the Beatles. Whereas in a music documentary, you’re selling the entity. That doesn’t mean it’s not a good doc, but you are selling music.”

Simmons concurs. “It’s a little bit of a revenue stream for [record labels].

“Limp Bizkit, weirdly after ‘Woodstock 99’ [premiered] had a moment for the first time in a while,” he says. “So documentaries have the power to do that because you’re watching them and then you immediately go to your phone — to Spotify — and you start listening. I did that with ‘The Beatles: Get Back.’  I have a Beatles playlist now.”

So what’s in it for HBO besides ratings?

“One of the reasons I was able to talk HBO into [doing this series] was I felt like it’s real intellectual property,” says Simmons. “IP that lives on. I saw it with ‘30 for 30.’ I saw all the different ways ESPN was able to extend this IP that we created for them. They sold it to Netflix. They sold it to Amazon. They made it a signature piece of ESPN Plus when they were launching [the streamer]. It had a sustainability that extended beyond the premiere.”

As for Season 2 of “Music Box,” Simmons plans on developing a slate of six or seven one-offs, which he hopes to announce in the spring. Besides wanting to make a doc about Fleetwood Mac’s hit album “Rumours,” Simmons won’t disclose which topics he wants to explore.

“I don’t necessarily want to give away any secrets because it’s so competitive right now, but there’s a lot of good ideas left out there,” he says. “So, the question for us is how do we keep finding the good ones and then how do we actually make them? You need so much luck with this stuff.”