“He is one of the greatest singers ever, one of the greatest voices ever,” says 32-year-old rapper-producer Tyler, the Creator, who places Wilson in the echelon of Stevie Wonder and Donny Hathaway.

When you hear Wilson’s voice, “there’s something that draws you in,” says Dave Grohl, of Nirvana and Foo Fighters. “And I think that’s because there’s this comfortable nature to it, where you just feel like you’re being sung to.”

“Like a train hitting me,” is how singer-songwriter and producer Babyface recently described Wilson’s voice.

“It makes everything just sound like love,” says Tyler, who adds that Wilson’s vocal style has “been passed down through the likes of Justin Timberlake, Brian Alexander Morgan, Pharrell Williams, and it went through me.”

But even if you know the voice, you might not know the story behind it.

The voice was forged in church pews and rose from the wreckage of Tulsa’s dark past. It exploded on party anthems of the 1970s and ’80s, and brought Wilson fame but little fortune. And it was nearly lost to years of drugs and alcohol that left Wilson sleeping behind dumpsters in Hollywood.

What brought Uncle Charlie back — and what’s made him better than before?

The second time Wilson recognized his vocal power, he was around 5 years old and imitating his preacher father in their Oklahoma church. “He had authority over his congregation,” says Wilson.

Wilson found his own authority by belting out gospel hymns. If he ever sang timidly, his mother would turn around from the church piano and give him a look that said, “Boy, get straight.”

“I had to turn it out,” Wilson says. Singing at full force became second nature.

“I didn’t know all these people were doing all these records,” Wilson says. “I was young and didn’t understand.”

Still, the Gap Band’s funk and R&B sound helped give rise to an entirely new genre of music: hip-hop. Their samples appear on tracks by Nas, Dr. Dre, Kendrick Lamar, N.W.A. and more.

The Gap Band’s sound influenced other genres, too. Grohl, as a kid growing up around Washington, D.C., heard the Gap Band on the radio around the time he was learning to play guitar and drums.

“This snare-slam-kick pattern that goes waapo-baapoo-bapoo-bap — that’s kind of the most perfect precursor to a chorus ever in the history of music,” Grohl says. “They were probably the first funk band I heard hitting those hard slams and I was like, ‘Oh God, that’s perfect, man.’” He’d go on to incorporate that kind of funk drumming on Nirvana songs like “Smells Like Teen Spirit” and “Come as You Are.”

The Gap Band would also become the soundtrack for multiple generations. Their songs accompanied family reunions, weddings and car rides to school.

“Growing up in a Black household, there’s certain music that’s just played around the house,” says Tyler, the Creator. “And Charlie Wilson’s voice is definitely a staple in that.”

But here’s the thing about those Gap Band records: For the most part, Wilson’s vocals were first takes. He was searching for a melody, with only lyrics in hand.

“It came out of my head, in the spur of the moment,” Wilson says. “I didn’t know what the melody was going to be.” He’d opened his mouth, the sound came out, and that was often the version they used.

He hated that. Those first takes were great enough to make hits, but not good enough for him. “I wanted to be able to work it and get it right,” he says. He wanted to sing it with more authority.

But that’s also the reason Wilson sounds even better now. Our point of comparison is a first take, and now he’s worked that vocal for decades.

Wilson’s manager, who is also his son-in-law, pulls out his phone at the kebab restaurant, and plays an NPR segment from that morning. It’s about songs for “Dry January,” and it features music critic Sasha Frere-Jones talking about battling alcoholism and how he first heard Wilson’s “I’m Blessed” while hospitalized in a psychiatric ward. The lyrics seemed too cheerful for an addict in recovery, but Wilson’s voice imbued the light message — “Riding clean/living dreams” — with gravity and power.

“I love his voice so much,” Frere-Jones said on NPR. “I had to just sort of get over myself, and absorb it as a song. And I was sort of like, ‘Yeah, I am blessed.’”

The segment ends, and Wilson says: “That’s amazing.” He sees himself in Frere-Jones, and his struggle with addiction. “I know what it was. I was a piece of s— on the side of the road.”

After the hits stopped hitting, in the early 1990s, Wilson sunk into heavy substance abuse: namely cocaine and alcohol. Sometimes he’d stayed awake for days. Other times, he slept outside — by bushes, under cars, in alleys — around Hollywood.

Eventually Wilson made it to rehab. It’s also where he met his future wife. Mahin left her job as a drug counselor, and they soon married. “She’s my 24-7 rehab,” he says, now 29 years sober.

But as he was emerging from such hard living, doctors told him he wouldn’t be able to sing like before, that his vocal cords were frozen and ruined by drug residue.

“I said, ‘Lord, is this it for me?’” Wilson says. “And I heard a voice: ‘No.’”

Wilson credits the resurrection of his voice to the entity he believes created it. “I was praying by that time,” he says, “and I was just leaning on God for what I needed to do.” He brushed aside doctors’ assessments, lived more cleanly and exercised his vocal muscles. His voice returned, and now he always includes a praise break during his live shows, giving a testimony fit for church about how God rescued what he almost lost.

Still, like any muscle, vocal cords weaken with age. But for Wilson, the further away he gets from those years of substance abuse, the closer his voice gets to its original form.

“It’s sounding better because I don’t put anything on it,” he says. “I don’t drink alcohol, I don’t smoke cigarettes, I don’t snort cocaine. No more. So, it’s a pure voice again.”

Something else miraculous happened for Wilson: a second act, in middle age.

It started with Snoop Dogg, who grew up hearing Gap Band at home and gave him the name Uncle Charlie. Snoop was eager to have Wilson sing on his 1996 album, “Tha Doggfather.” Wilson, newly sober, had to be careful stepping back into the world of hitmakers.

“One is too much, and a thousand is never enough,” he says. One hit of something, “and my life is over.”

Enter: his wife. Mahin pulled Snoop aside at Death Row Records and talked to him like a mother: “Nobody can smoke if Charlie is in the studio,” she said. So Snoop’s crew stopped.

Wilson accompanied Snoop on the 1997 Lollapalooza tour, where he took the younger rapper under his wings “and showed me showmanship,” Snoop recalled during the unveiling of Wilson’s walk-of-fame star. But Wilson has also served as a true uncle in Snoop’s life, counseling him on his marriage and even getting him to stop smoking weed for a short time.

With his wife and a support system to keep him on the right track, Wilson started finding success in the early aughts as a solo R&B artist. He now has had nine No. 1 songs on Billboard’s adult R&B charts, the most of any male artist. Wilson became Uncle Charlie to everybody. He shares his wisdom with younger artists — about the perilous allure of drugs, and the alluring perils of the music industry.

His audience includes boomers who partied to the Gap Band, and young people, born after his first solo hits, who immediately recognize him when they hear his signature “ohh-wee!” and “shabadaba twee twee twee” on certain tracks. He often gets asked by younger fans to talk to their moms and aunties on the phone.

Two days after that early birthday lunch, Wilson and Mahin sit in the green room at the MGM National Harbor Hotel & Casino, outside of Washington. An assistant hands him a cup of warm water with honey. This, and a 10:30 p.m. bedtime, is what keeps his voice in top shape.

At rehearsal, he tried to conserve his voice, and promised the band he wouldn’t sing through the set. Then the music started. “I gotta sing,” he said. “I can’t help it.” He had to leave rehearsal, because he was too tempted to turn it out.

For many years, he performed gigs every weekend. He’s only pulled back in the past year after two back surgeries, and arthritis, which left him moving much more slowly. He’s also reduced the physicality of his live show. Before the MGM show, he got his muscles stretched out for about an hour.

But he has no intention of retiring. He’s got about 20 to 30 unreleased songs, and never wants to stop recording. A gospel or Christmas album could be in his future.

When the lights go down in the MGM theater, Wilson is no longer a 71-year-old with a bad back. He is Uncle Charlie. He struts across the stage as he sings his new single, “Superman.” He pounces backward as he jumps into the Gap Band classic “Burn Rubber,” which pulls the crowd to its feet, as if they’re at church in Tulsa. When he gets to “Outstanding,” he points the mic to the crowd.

His music conjures memories and transports people to the past. But when he performs, he roots himself in the present moment. Wilson plants himself onstage for the final run of “Charlie, Last Name Wilson,” his first hit as a solo artist. And he launches the rocket in his throat, crossing nine syllables in one breathe.

“That’s why I’m introducing myseeeeeeeeeelf,” he belts, though we know the voice so well. “First name Charlie, last name Wilson.”