Thom Bell, the legendary producer who revolutionized Philly Soul in the 1960s and ’70s, has died, Rolling Stone and The Philadelphia Inquirer report. Bell co-created “The Sound of Philadelphia” alongside songwriter Leon Huff and producer Kenny Gamble, who were known as the Mighty Three. Together, they founded Philadelphia International and crafted some of the most beloved records of the era. Some of Bell’s most renowned works include “La-La Means I Love You” by the Delfonics, “Backstabber” by the O’Jays, “Mama Can’t Buy You Love” by Elton John, and “Rubberband Man” by the Spinners. A cause of death has not yet been revealed. He was 79 years old.

Bell was born in Jamaica in 1943, but his family relocated to West Philadelphia where he was raised alongside nine brothers and sisters. Both of Bell’s parents were musicians, and Bell followed suit: As a child, he played drums studied classical piano. In his teenage years, he played alongside Gamble in the Romeos, and, by his early twenties, he’d taken a job a staff writer and touring conductor for Chubby Checker. In the late ’60s, Bell began working as a producer for the Delfonics—a collaboration that would result in hits like “La-La Means I Love You” and “Didn’t I Blow Your Mind.”

Bell’s classical background informed his work as an arranger and producer, and he employed instruments and techniques that were considered unconventional at the time. His lush signature sound could include everything from sitars to orchestral strings to bassoons, but his notation was not always traditional. “The very first time I wrote music out for my strings, I wrote a figure and put above it: ‘pluck,’” Bell told Pitchfork’s Jayson Greene in 2013.

He continued: “The musicians said to me, ‘Hey Bell; what’s this ‘pluck’ business? What are you talking about, man?’ I was like, ‘You know, [mimes plucking strings with fingers].’ They just looked at me and said, ‘You mean pizzicato!’ They still send me Christmas cards teasing me about that.”

In 1975, Bell won the Grammy Award for Best Producer of the Year, and, in 2006, he was inducted into Songwriters Hall of Fame. Earlier this year, a new documentary focusing on the work of Bell, Huff, and Gamble was announced.

As the news of Bell’s death circulated, Gamble wrote in a statement (obtained by Rolling Stone): “Tommy and I have been best friends for over 60 years. When we first met, we decided to start writing songs together and form a singing duo ‘Kenny and Tommy’ and then our band the Romeos…. He was a great talent and my dear friend. Rest in peace, buddy.”

Huff Added: “Thom Bell was my favorite musician, arranger, songwriter, and music producer of all time! It was my esteemed honor and pleasure to work with him creatively and as a business partner. Rest in peace.”

Speaking in the same 2013 interview with Pitchfork, Bell reflected on his writing process. “Every melody I ever wrote, I worked hard on,” he said. “And once I deliver it, that’s it. There’s nothing else I can do. I had one rule: You cannot change that melody. You don’t know why it’s right, but you know it is. You take a pencil and you put it in the pencil sharpener and you sharpen it and sharpen it and sharpen it—once it reaches its point, it’s done. Once it gets to where it’s supposed to be, that’s where it’s supposed to be. After that, it breaks.”