For about six months now, a series of mysterious signs have clung to the 9:30 Club's walls. They've been plastered outside, where fans line up for shows, and inside, on the same bulky black doors as posters for acts such as GoldLink and Drive-By Truckers. "Be aware," the laminated paper has read in black-and-white."Tonight's show is being recorded."

These signs didn't reveal much. That was the point.

The recordings aren't meant for a commercial or some band's tour DVD. The untold story behind these signs is that 9:30 Club has recorded about 40 performances for a modern music variety show premiering on PBS stations in April.

Each one-hour episode of "Live at 9:30" will showcase concert excerpts from several bands, interspersed with comedy, interviews and short film segments. In its first iteration, Garbage will share run time with MisterWives (an indie pop band from New York), El Vy (a new venture from Matt Berninger of the National), Ibeyi (French-Cuban twins who sometimes sing in Yoruba) and Hannibal Buress, the stand-up comedian who brought attention to the sexual assault allegations against Bill Cosby. The 12 episodes will be released monthly.

For the 35-year-old 9:30 Club, creating a television show meant balancing its hip, gritty vibe with mass marketability. The 9:30 has fostered up-and-coming talent, while also booking Bob Dylan and Willie Nelson. Smashing Pumpkins, R.E.M. and Moby played there before they made it big, but owner Seth Hurwitz once declined to book Demi Lovato because he thought she wasn't cool. "It's a proper rock-and-roll venue," said Shirley Manson, the lead singer in Garbage. "It's not sort of a corporate atmosphere."

Though it may lack a corporate feel, the company behind the 9:30 Club is by no means a small operation. Over the last five years, the Hurwitz-chaired I.M.P. Productions has experienced significant growth, and now operates the historic Lincoln Theatre while presenting shows at U Street Music Hall, Jammin Java and other venues. In October 2017, an ambitious I.M.P.-run 6,000-capacity venue will debut at the Wharf, a new development at the Southwest Waterfront. "We created a venue where the patrons are closer to the artists than just about any other concert hall," said developer Monty Hoffman. "We had some corporate alternatives but I liked Seth."

With the TV series, the creators hope to introduce the 9:30 to the millions who can't cram inside the 1,200-capacity club. But Hurwitz said he doesn't have plans to replicate 9:30 in other cities. "I don't do things I already have," he wrote in an email.

The decision to peg the show as variety comes with some risks. Replicating the format of established music TV shows like "Austin City Limits," which feature full-length performances, might have been a safer route. But instead the show follows a model that's like an inverted "Saturday Night Live," with 80 percent music and 20 percent everything else.

To the creators of "Live at 9:30," variety is what will keep viewers hooked. But are today's audiences — who ingest "SNL" in five-minute viral YouTube clips — too fragmented for this to work?

"Our attention spans are much shorter than they used to be," said David Inman, author of the book "Television Variety Shows: Histories and Episode Guides to 57 Programs." "If I wanted to see a rock group on 'The Ed Sullivan Show,' I had to sit through three or four shows I didn't want to watch. Now you don't have to buy the CD to listen to the particular song you like. You buy it on iTunes."

For years, producers have pitched Hurwitz on the idea of filming a TV show at the venue. They wanted to shoot behind-the-scenes glimpses into what goes on backstage, but Hurwitz thought the reality TV premise would distract viewers from what was going on onstage.

If a series was going to work, the club would have to be involved from the start. In 2013, Michael Holstein, an executive at the production company the Content Farm, had a chance encounter with 9:30 communications director Audrey Fix Schaefer. Holstein was discussing a music show with another venue, but he and Schaefer decided to band together with Hurwitz for a show at the 9:30 instead. "If you're going to do a TV show about music," Schaefer recalled saying, "you have to work with me."

To make the program special, Hurwitz proposed the variety-show format. Comedic bits (Buress arguing why Donald Trump would beat Hillary Clinton in a freestyle rap battle) and intimate moments (Grace Potter taking a shot with her band before stepping onstage) would expand the show's appeal.

Showcasing a legendary rock band alongside an unknown one could attract a wide audience while maintaining the club's street cred. "We want something for everybody," Holstein said. "Maybe you'll tune in because you love Garbage, and you'll discover Ibeyi."

But working with a big network would mean commercials would interrupt the show. The relationship might also come with baggage. Placing a soda company's logo onstage didn't sound appealing. Neither did including certain artists because the network owns their record label, a demand Holstein said could arise. So they decided to go with public television.

The creators spent about a year and a half trying to find sponsors. In three instances, they thought they were finally close, but were let down when their contact moved to a new company.

In May, a sales contractor working for the show pitched Chris Paul, a vice president at the content management system Squarespace. Two main points sold Paul: the variety format, and the fact that he once had played in a D.C. band called Northeast Corridor and dreamed of booking the 9:30 Club.

"I'm nostalgic for that myself," Paul said. "Right now a lot of music discovery is happening through digital means. You don't often get to have that experience of the live show."

Shinola, a retailer from Detroit, and Destination D.C. followed. 

To find their musical acts, the club approached artists that were already slated to play there: the Jesus and Mary Chain, Tove Lo, MS MR, Youth Lagoon, Leon Bridges, Lianne La Havas. Contributors and hosts, like stand-up comic Ralphie May and writer-actress Jill Kargman of Bravo's "Odd Mom Out," were sought out separately. Wayne White, a designer for "Pee-wee's Playhouse" and art director for Smashing Pumpkin's "Tonight, Tonight" video, was tapped to create the opening credits and graphics along with his son, Woodrow. Lorne Michael's entertainment company was called in for post-production and sound design.

"Live at 9:30" launched a new relationship between the club and contributors like Kargman and White. In other cases, it solidified age-old connections. Garbage had shot parts of its video, "Sex Is Not the Enemy," thereBob Boilen, host of NPR's All Songs Considered, was a member of Tiny Desk Unit, the first and last band to play at 9:30's old venue on F Street NW, before it closed. In "Live at 9:30," he leads an interview segment called "Boilen Points," featuring casual conversations with the artists.

"There's an awful lot of people who are going to turn on the television set and not know anybody who's on the show," Boilen said. "The intent is to be somewhat inclusive."

But maintaining a genuine concert experience would be difficult if fans encountered a full film crew.  That's why the creators decided to film clandestinely. "This TV show gets it," Hurwitz wrote in an email. "It's about this special magic that happens" there between the bands and the audience.

Shakey Graves and Yonder Mountain String Band strapped GoPros onto their guitars. Garbage's Butch Vig had one on his drum set. And Kargman as host took things even further. While the English Beat performed, she strapped one onto her forehead.

This post has been updated.