Reggie Griffin played the bass line into an ”Oberheim DSX sequencer which was hooked up to a Minimoog via CV and gate: pre-MIDI“
He had to play it correctly at least all the way through each section. He would then chain the sections together in “Song Mode” on the DSX and it as recorded on a 24-track tape using a sync tone on the tape. “As I remember, it had to stay in sync from beginning to end: There was no punching in.”
After the bass line they did the synth chords, which doubled a chord sound that was already there in the verses. ”I had just gotten a Yamaha DX1 [their flagship FM synth at the time] imported from Japan and everyone was excited to hear it recorded. It turned out to be not too much more than two DX7s in one box with a weighted keyboard–though that was rare at that time.”
They used this to make the chordal decaying pad sounds on throughout the song. They had elements of DX7-style piano and string/vocal pad elements.
He did a fast, single-note, clarinet sounding synth part under the rap in the middle of the song, and the bells on the breakdown.
”Arif asked me to do something crazy in that section so I used the DX1 in programming edit mode and moved the various FM modulating sine waves around.
Frequency Modulation synthesis on the Yamaha DX instruments worked via a fundamental tone (sine wave) modulated by other sine waves, so I tweaked the modulating waves while playing some notes on the keyboard.”
Those are the sound affects you hear, and it was all recorded live to tape.
I was in the studio another day and watched Arif editing half-inch tape and flying in the “tape scratching” sound affects you can hear on the breakdown. He worked on perfecting that for many hours. Arif Mardin was a brilliant musician and producer. He and Reggie Griffin made a huge forever hit out of a good basic song.
Studio
Mel did his rap at Sugarhill Studios in Houston, Texas.
The repetition of Chaka Khan at the beginning of the song was a mistake made by the producer who decided to keep it.