While watching this spring’s moving documentary Let the Fire Burn, which tells the haunting story of the 1985 MOVE bombing in Philadelphia, I recently thought about my cultural relationship to that brotherly town. From the pioneering gangsta raps of Schoolly D, the soothing voice of voice of radio personality Dyana Williams, Rocky running up the stairs of the Philadelphia Museum of Art, the arty hip-hop of the Roots and Jill Scott singing rough as an Afro puff, the city has always offered many artistic delights.

But years before any of that was on my radar, my eyes fondly focused on the olive green label glued to every Philadelphia International Records release that crossed the threshold of my Harlem apartment when I was a kid in the ’70s.

Although a few years before the Cooley High era, Motown and Stax ruled the airwaves, as 1972 musical collaborators and business partners Kenny Gamble and Leon Huff propelled Black music to the next level.

The Sound of Philadelphia became a joyful noise built of smooth lyricism, lush textures, stirring strings and a driving beat. Combined with the meticulous horn and string compositions of collaborators Thom Bell, Bobby Martin, Jack Faith, Norman Harris and Bobby Eli, the collective created a sound that still sounds fresh more than 40 years later.

Gamble and Huff first met as session players at Philly’s famed Cameo-Parkway studio. Gamble explained to writer Tony Cummings in the book The Sound of Philadelphia: “I suppose we started together because we had the feeling, the second sense, that told us we had something special to give each other. We knew the kids weren’t buying the old, primitive kind of R&B anymore; they wanted something more sophisticated. So we were using strings, vibes and big orchestrations. But it took us some time to find the right blend.”

Launched as a joint venture with Columbia Records, the duo received a $75,000 advance for 15 singles and a few albums. Signed by music man supreme Clive Davis, whose own legacy includes discovering Sly Stone, Gil Scott-Heron, Whitney Houston and Alicia Keys, it was a masterful move designed solely to get Columbia in the Black music race. In Davis’s first autobiography Clive, he wrote: “Not long after signing, Gamble and Huff blew up. Within nine months, they sold 10 million single records.”

Recording at Sigma Sound Studios, the musical wonderland where most of their classic sides were constructed and recorded, the right blend occurred a few months after the label’s formation when Gamble and Huff records recorded “Back Stabbers” with a male trio, the O’Jays. “That track helped us develop our sound,” Gamble told me a few years back. “I think we did it in three or four takes, five at the most, and we put everything into it.”

Like the Motown musical assembly line that Berry Gordy perfected, the Gamble and Huff team were no slouches when it came to producing records quickly. “There were times when we could record a whole album in three weeks,” Gamble says. “The O’Jays would go into the studio and put leads on four or five songs in one night. Songs like ‘Stairway to Heaven’ and ‘Family Reunion’ were recorded in one night. Those fellas were from the heart singers, and we tried to pull everything out of them.”

Leon Huff added, “We had patterned Philly International after Motown on the business side. But when it came to the sound, we knew we had to be unique. We always had the best songwriters and arrangers, but when it came to singers you had to be more than good. You had to have an edge.”

Perhaps the most edgy singer on the imprint, Teddy Pendergrass began as a drummer for Harold Melvin & the Blue Notes before the group’s leader recognized his vocal prowess. Stepping to the mic with swagger, Teddy belted his way through powerful hits with the group that included “The Love I Lost,” “Where Are All My Friends” and “Wake Up Everybody.”

Smiling at the memory, Gamble said, “Teddy’s voice was like a demon. He’d attack a song and spit them out.” But after a while, Teddy was tired of fronting the group and wanted to go solo. “That was Teddy’s decision. It happened right after ‘Wake Up Everybody,’ which he basically sang by himself. Groups go through changes, but it all worked out.”

Of course, back in those days, if one was to have a great label you had to record at a great studio. In the tradition of Muscle Shoals (Aretha Franklin, the Staple Singers) and Chess (Etta James, Muddy Waters), the Philly folks used Sigma Sound.

Owned and operated by recording engineer Joe Tarsia, the studio soon became the home for the Gamble & Huff house band MFSM, as well as the amazing roster that included Billy Paul (“Me and Mrs. Jones”), Lou Rawls (“See You When I Get There”), the Three Degrees (“When Will I See You Again”) and many others.

“We developed a relationship with Joe, who supplied so much technical knowledge and gave us a quality sound, which became the Philly sound,” Gamble recalls. “It wasn’t just about good songs, musicians or singers, it was also about the sound. Sigma had the best fidelity and quality. Not a lot of pops and hisses.”

Inspired by what Gamble & Huff achieved at the Sigma Sound factory, David Bowie went there in 1974 and recorded his “plastic soul” masterpiece, Young Americans. “A lot of people wanted to get that sound,” Huff added. The following year, Bowie sang the title track on Soul Train, whose 1973-75 theme song was a Gamble and Huff composition. “Don [Cornelius] flew in one Sunday afternoon, and we cut two or three versions. After the session, we would just bring the tapes back to the office and groove to what we did.”

As the decade went on, Philadelphia International continued doing their thing. The songwriting duo McFadden & Whitehead became platinum selling artists in 1979 with “Ain’t No Stopping Us Now” and the Jackson 5 left Motown to get down with their sound. Yet as the 1980s began to dawn, the sounds of blackness, as well as Black radio, began changing.

“Technology changed music for us,” remembers Gamble. “Our roots is live music, but when computers took over, we knew it was time for us to do other things.”

Forty-one years after Philadelphia International ruled with its distinctive sound, Gamble and Huff songs are still relevant. Used in countless commercials and television programs, their songs have also been sampled by rappers Jay Z, French Montana, Gang Starr, Rick Ross and others.

Roots keyboardist and Erykah Badu producer James Poyser told me once, “For me, Gamble and Huff’s sound was funk music that wore nice shoes and a tux. They knew how to be funky, but they were also classy. With their mostly positive lyrics and their love for community, their music has definitely put its stamp on us.”

Kenny Gamble once explained to me that a song should be able to take a person on a journey. Years later, we’re still flying.

Cultural critic Michael A. Gonzales has written cover stories for Vibe, Uptown, Essence, XXL, Wax Poetics and elsewhere. He’s also written for New York and The Village Voice. Read him at Blackadelic Pop and follow him on Twitter @gonzomike.