The young Bar-Kays had already been through plenty. Stax had hoped to groom them as the next Booker T. and the MG’s, the house band that had broken out as a headliner in its own right. But only months after their song “Soul Finger” became a hit, four of the Bar-Kays perished in the same 1967 plane crash that killed Otis Redding. The group’s 20-year-old trumpeter, Ben Cauley, was the sole surviving passenger; the bassist James Alexander, 19, had not been on the flight.
With their manager, they began rebuilding. The drummer Willie Hall, who was 17 at the time, and the guitarist Michael Toles, who was only 15, joined, and they rushed to release an album under the group name. Mr. Hall said the band was as green as goose droppings, though he used more colorful language. “We didn’t know anything,” he said, “but the company needed something out there before the sympathy died.”
Credit Bob Smith, via Concord Music Group
It wasn’t long afterward that Hayes began sitting in with the group at Memphis club gigs, and leading the musicians through chord changes while he rhapsodized at length. By the time they were backing him in the studio, a musical intuition had formed. Mr. Alexander’s relentlessly agile bass lines bandied with Mr. Hall’s stop-time rhythms; Mr. Toles’s finger-stretching guitar figures cut through Hayes’s thick organ.
“We recorded ‘Hot Buttered Soul’ in two days,” Mr. Alexander said. “He gave you a creative direction, maybe a line to play, and we kept going.”
When the guitarist Harold Beane stopped by the studio for a mixing session, Hayes asked him to improvise freely.
“He told me, ‘I want to take it out of the box,’ so I turned on the fuzz tone and turned up the tremolo,” said Mr. Beane, whose lengthy “Walk on By” solo evokes both buzz saws and Morse code. “Then I took my guitar, and I slid it up and down the microphone stand. The arranger in Detroit heard that, and he matched that sound with strings.” Mr. Beane then began playing in Hayes’s touring band, before joining Funkadelic.
Credit Houston Cofield for The New York Times
“Hot Buttered Soul” became a sensation, and, thanks to the stubbornly long running times of its four songs, carved out a place for album-oriented black radio. Mr. Toles and Mr. Hall left the Bar-Kays band (which had hired a lead singer and begun moving toward more dance-oriented funk on its own very popular albums). Adding a second guitarist, Charles Pitts, known as Skip; the keyboardists Mr. Snell and Sidney Kirk; and horn players, including the trumpeter Mickey Gregory, the group was rechristened the Isaac Hayes Movement.
The band members worked hard for their $75-a-week salaries, and Hayes kept the players on their toes. The first time Mr. Snell played with Hayes was in front of 70,000 people, he recalled, with no set list or rehearsal. Hayes opened with a song Mr. Snell had never heard before.
“It was fast,” Mr. Snell recalled. “Chords coming, and here comes the breaks, and it’s got all kinds of stops. And then right in the middle of that, the tune breaks down into ‘Oh mama let me light your fire. …’ I’m like, what? Then it comes back to going fast again, then into triplets, now totally ripping. That’s the first tune. The rest, I knew.”
Credit Houston Cofield for The New York Times
Recording could be similarly unpredictable. “He was a night owl,” Mr. Hall said of Hayes. “He’d say, ‘Hey, man — session tomorrow night at 7.’ But then he may not show up until 11, depending on which chick had just flown into town.” If the musicians started to get sleepy rehearsing ballads in the wee hours, Hayes would dispatch his assistants to take attractive women to the studio.
“At that point, all the crooked backs straightened up, everybody’s got their hips shaking, and grinning, and boy, now you got something going on,” Mr. Hall said.
By whatever means, Hayes was able to coax out sounds that could shift from slippery syncopation to dizzying, psychedelic crescendos. “The Spirit of Memphis” includes a cover of Bill Withers’s “Ain’t No Sunshine” that begins with a musical quotation from Jimi Hendrix’s “If 6 Was 9” before evoking the sounds of both the Meters and Wes Montgomery. Even as Hayes was studying the orchestrations of the Carpenters, Mr. Hall said, “we were leaning toward rock. Blood, Sweat and Tears, Cream — just drop a tab of acid, and go crazy.”
The jaw-dropper on the boxed set is the recently unearthed 33-minute version of “Do Your Thing,” from 1971. With its swirling organ, boogaloo fugues and aggressively atonal guitar bursts, this extended improvisation suggests a musical showdown between the jazz guitarist Sonny Sharrock and the avant-garde German group Can.
That spirit of discovery couldn’t last forever. After “Shaft,” Hayes began a drift toward acting, bankruptcy and rote disco. Mr. Alexander dedicated himself fully to the Bar-Kays, who would amass their own series of Top 10 R&B singles. By the end of the 1970s, the members of the Isaac Hayes Movement had found other work.
“We didn’t have any kind of uniformity other than following our leader,” Mr. Hall said. “What you hear on those recordings is a reflection of the energy between all of us. We loved each other.”
The former members of the Movement continue their contributions to the Memphis music scene today. Mr. Beane, Mr. Toles and Mr. Gregory have all played with Elmo and the Shades; Mr. Hall joined the Bo-Keys, along with Mr. Pitts, who died in 2011.
Mr. Alexander is shepherding the Bar-Kays into their sixth decade. They’re holding auditions for a singer.