A Sound of Philadelphia music producer’s work sat in the Sigma Sound archives for 50 years. Now Drexel students are bringing it back to life.

Seven thousand audiotapes are stored in the Sigma Sound Studios Collection at Drexel University, neatly shelved in a basement space, each historic session boxed and labeled in black magic marker.

David Bowie, Sly Stone, the Delfonics, Grover Washington Jr., Jerry Butler, Barbara Mason, B.B. King: Names that made Sound of Philadelphia history are written on white cardboard tape boxes. And along with recognizable hitmakers — including Whole Oates, as Hall & Oates called themselves for a Sigma session in 1970 — are artists whose music was never heard, with names not so well-known.

Among those are 10 boxes that document August 1972 sessions with Choice 4 Inc., a vocal group and backing band from D.C., that were recorded by Billy Jackson, the producer whose musical contributions to the Philly sound in the 1960s and 1970s have been underrecognized.

These recordings — credited to Jackson’s Twin Girls production company — play like a time capsule in psychedelic funk and soul, including a trippy, slow jam cover of Bill Withers’ “Ain’t No Sunshine.”

The recordings, made 54 summers ago, have never been issued — until now.

Jackson, who grew up in the Richard Allen Homes in North Philly and died at 77 in Blackwood in 2016, had a long and varied career.

He started out singing with the Revels, his doo-wop group formed at West Philadelphia High School. They scored a 1959 hit with the spooky “Dead Man’s Stroll,” which Dick Clark had renamed to “Midnight Stroll” to not disturb the viewers of American Bandstand.

Jackson cowrote the Tymes’ timeless “So Much in Love” after joining Cameo Parkway Records in 1963 as a staff writer and producer, where he worked with his close friend and Sigma founder Joe Tarsia.

In the 1970s, Jackson produced Ronnie Dyson’s hit “(If You Let Me Make Love to You Then) Why Can’t I Touch You” at Sigma, and worked for Clive Davis at Columbia Records, recording in New York and London with Aretha Franklin, Peter Tosh, Miles Davis, and his wife Betty Davis.

This month, Choice 4 Inc.’s album Clean Up Your Mind was released by Mad Dragon Records, the Drexel label run by students and guided by Monika Julien, a music industry professor at Drexel’s Antoinette Westphal College of Media Arts & Design.

Julien’s students Cole Herrmann, Bella Kaminsky, Adriana Criswell, Harper Risch, and Hayden Clark have overseen all aspects of the Clean Up Your Mind release as a practicum project that began in September. It all started when Julien and music production professor Toby Seay brought them into the Sigma vault to hear the Choice 4 Inc. recording for the first time.

On Saturday, the students will celebrate Clean Up Your Mind with a release party at Milkcrate Cafe in Fishtown. Vinyl LPs will be for sale, Philadelphia DJ Skeme Richards will spin, and Kia Jackson and Kelly Majid, the “Twin Girls” daughters who Jackson named his production company after, are flying in from Atlanta.

“We are so excited about this project,” said Majid. “We are overjoyed.”

Clean Up Your Mind is the second LP Mad Dragon has released from the Sigma Sound collection, made up of tapes donated to Drexel in 2005, two years after Tarsia sold the legendary 12th Street studio, which closed for good in 2014.

In 2019, Mad Dragon put out Laugh to Keep From Crying by Black Power funk and soul group Nat Turner Rebellion. Bandleader Joe Jefferson also wrote hits for the Spinners and O’Jays. He died in 2020.

Julien graduated from Drexel’s music industry program in 2012. She worked as a brand manager in New York before moving back to Philadelphia in 2022 to teach at her alma mater.

A steady stream of archive releases are planned, beginning with Clean Up Your Mind.

“I sat down with Toby and we asked ourselves: ‘How can we take this incredible thing that only Drexel has in the Sigma Sound Collection, and Mad Dragon Records, which has a 20-year legacy, and merge them?’” Julien says.

It’s not as simple as combing the archives and issuing the unreleased music.

First thing, the recordings have to be baked. Quite literally: Reel to reel tapes made after 1968 — the year Sigma was founded — “are all Mylar based,” Seay explains, “which means there’s a magnetic layer stuck on the plastic that breaks down over time. It gets gummy and doesn’t sound very good.”

The solution is to bake tapes at 130° Fahrenheit, then digitize them on first playback. Seay cooks them in an oven in the Sigma storage room.

That’s the easy part, though. “We want to do these kind of releases more consistently,” Julien says, “but there’s a lot of work to do with clearances. We own the archives, but we don’t own the music.”

Choice 4 Inc. has been on Seay’s radar since 2016, when he had a conversation about the recordings with Tarsia, who died in 2022.

“When Toby played it for us the first time, that was really the sparking moment,” says Herrmann.

“We all listen to different kinds of music and some us had more funk-soul in our wheelhouse,” Kaminsky says. “But either way, it was like nothing we had heard before.”

Choice 4 Inc., she says, could be recommended if you like “Stevie Wonder, Bill Withers, Sly Stone. There’s a bit of everything. Jimi Hendrix….”

“Or even Yes,” suggests Herrmann, since Clean Up Your Mind, in keeping with the early ‘70s times, is “a little proggy.” The best contemporary point of comparison, the students agree, is Austin, Texas, psychedelic soul band Black Pumas.

Getting permission was simple, Seay says, because publishing rights to all songs except the Bill Withers cover were controlled by Twin Girls Music, and Jackson’s daughters were fully on board.

Choice 4 Inc. consisted of a four-man vocal group called the Choice 4, teaming with an instrumental backing band who went on to perform as the Jam Band, Pipeline, and Kleeer.

Herrmann said he and his classmates have attempted to contact surviving Choice 4 Inc. members John Maduro and guitarist Richard Lee without success. The marketing challenge has been that they don’t have a credits list of who played on the album, and no pictures of the band.

For the cover, Herrmann, Kaminsky, Criswell, Risch, and Clark came up with a mood board of music-inspired keywords, “Groovy,” “Swaggy,” and “Intellectual” among them. They partnered with Philly graphic design company Dirty Napkin in creating the striking red-and-blue cover.

LPs were pressed at renowned engineer Phil Nicolo’s Studio 4 Vinyl in Coatesville, and Mad Dragon teamed with Philly e-commerce company Mainfactor.

“We knew it was going to be for the active listeners,” says Clark. “For the record collectors.”

So they emphasized an unsung hero of the Philly sound.

“We put the pieces together about Billy Jackson, to tell his story,” says Kaminsky. “I love the sound of the music, but we also all fell in love with the project. It didn’t feel like work.”

“The big thing for me is not only learning about the history of music in Philadelphia, but that we get to be a part of it,” says Risch. “We have become a part of Philadelphia music history, while learning new skills in a way that has brought us all closer together.”

When Jackson died in April 2016, his daughters say, his musical contributions were overshadowed by Philly soul singer Billy Paul and Prince, who both died that same week.

Now, they’re thrilled that their father’s work is gaining renewed attention.

The Choice 4 Inc. “music is awesome,” says Kia Jackson.

“We supported them any way we could,” says Kelly Majid of the students, who Julien said will all get As for their work.

“I just felt like my father was overlooked when it came to how much he contributed to the Philly sound,” Majid says. “It’s great that he’s finally getting the attention he deserves.”

Choice 4 Inc. “Clean Up Your Mind” release party at Milkcrate Cafe, 400 E. Girard Ave., 6 p.m., May 30, milkcratecafe.com.