Charles Bradley’s blooming as a soul singer wasn’t a dream come true, reckons Tommy Brenneck, because Bradley was never in a position to dare to have a dream to hold on to. “His life was full of tribulations that dudes like you and I would never be able to relate to, just from being a poor, uneducated, black man in America,” says Brenneck, the songwriter, producer and guitarist who was at Bradley’s side as he transformed from a Brooklyn handyman to one of the great latter-day testifiers of the classic soul sound.

Bradley had been abandoned by his mother as an infant – he never knew his father – and taken up by her again at eight before he ran away at 14, when he was arrested and sent to a juvenile detention centre. There he learned to cook, for hundreds of people at a time; later he got a similar job at a mental institution in upstate New York. “He cooked for 20 years before hitchhiking across the country to pursue whatever dream he had,” says Brenneck.

‘Pain was very wrapped up in art for him’ ... Bradley in 2014. Photograph: Isaac Sterling

After Bradley returned to New York, in 1996, he awoke one night to hear the sounds of police cars arriving at the nearby scene of what proved to be his brother’s murder. “Pain was very wrapped up in art for him. He didn’t think a singer had soul unless they had experienced some sort of tragedy in their life and they were singing about that. He was 100% right and that’s the difference between an entertainer and an artist.”

From 2002, when Bradley made his first recordings for Daptone Records, until his death from cancer in September 2017, he found a voice that put his life into sound. “He made it look easy because he was a natural,” says country artist Margo Price. “Charles genuinely loved his audience and his fans, and it radiated through him. You could see how happy he was on stage, but you could also feel his pain. I have never cried more tears of joy and sorrow watching someone perform.”

“He had that thing that won’t let you sleep at night if you ignore it or makes your body move in a way you didn’t think it could, to touch the truly raw places of your spirit and let it take you somewhere bigger than you,” says Nathaniel Rateliff.

“I remember how completely blown away I was the first time I heard it,” Ozzy Osbourne says of Bradley’s version of Black Sabbath’s Changes, which Bradley recast as a deep soul waltz. “He showed me the versatility of the song – he took Changes to a new level.”

Ten unheard and rare recordings from across Bradley’s career are now being released as Black Velvet, which captures Bradley propelling across the dancefloor and brooding over ballads. The title comes from the stage name Bradley used when he was singing in bars as a James Brown tribute act, before his career was established. The album, far from sounding cobbled-together, is a fittingly powerful collection.

“When he began pursuing music in New York, creating this Black Velvet character,” says Brenneck, “he didn’t have a dream, so much as a comfort and identity as the local handyman who looked and dressed like James Brown.”

‘He carried weight and anguish every time he sang.’ Photograph: Kisha Bari

“Black Velvet,” explains Gabe Roth, who co-founded Daptone, “was this superhero that helped him transcend all the struggles of his life. ”

Bradley sought out Roth when he decided being Black Velvet wasn’t enough. He turned up at Roth’s door around the turn of the millennium and announced: “I heard you were looking for a singer.” He sang for Roth there and then, and Daptone soon got him in a studio, recording Rodriguez covers, although he didn’t release his first album, No Time for Dreaming, until 2011. In the meantime, he was part of the Daptone family, even helping build the label’s studio.

“When Daptone was being built, I took a ride with Charles to go to Home Depot to buy building supplies, and people were saying to him, ‘What up, James?’ and ‘How’s it going, Black?’” Brenneck says. “People were being nice to him, but you got a glimpse into this real sadness – his whole identity was built on being someone else. No one called him Charles. When he broke out of the James Brown act and took off the wig and became the Charles Bradley we know – and I literally held his hand through that process – we let out this monster of an artist. Every song me and Charles wrote came from somewhere deep, and he carried that weight and anguish with him every time he sang. He would bend over, his face squashed up – and that was before he’d sing a note.”

When Roth introduced Bradley to Brenneck, he found a collaborator who could take the time and effort needed to help him express his talent. Still, it was five years before they became musical partners. Brenneck was looking for a new sound after touring with the Mehanan Street Band and the Budos Band, and happened on Bradley again. “His voice was so compatible with the mid-paced, moody music I was making between tours. It turned out the shit that moved me was really moving Charles. And that’s when our relationship really transformed. He was my guy and I was his guy.”

What defined Bradley’s anguish, Roth says, was not the poverty in which he had spent most of his life, but his personal relationships. “He had lot of issues, from childhood, with his mother. And then his brother being killed. And he had issues with his own sexuality and identity..”

‘He didn’t realise there was power in the lyrics’ … Bradley in 2014. Photograph: Isaac Sterling

Working with Bradley wasn’t always easy. He suffered stage fright, and couldn’t read or write music, so Brenneck acted as his interpreter and transcriber when they wrote together. At first it created problems: he sometimes didn’t learn the lyrics – the power of his voice was enough to sell a song – until fellow Daptone singer Lee Fields persuaded him to start doing so. “The song that really connected was Loving You Baby,” Brenneck says. “There’s a verse in there I completely love and he wasn’t singing it. But when he learned it after talking to Lee, the audiences started responding. And Charles, a very sensitive man, felt that response. He didn’t realise there was power in those lyrics – he thought the power was in his screaming. He learned that people were responding to songs he wrote.”

Bradley was the second of Daptone’s stars to pass away within a year; Sharon Jones had died in November 2016. It left a hole in this tightknit family of musicians.

What Bradley leaves behind is the music, and the memory of an extraordinary performer. “I owe a lot to my performance to watching him,” Price says. “He was so badass. The way he threw out roses to the audience, the way he danced unashamed and unchained, how he jumped down in the crowd and parted the sea of people, touching hands and hugging people. He was fucking brilliant.”

• Black Velvet is released on 9 November on Dunham/Daptone.