A couple of years ago, Dr. John's granddaughter tried to turn him on to the Black Keys. The album she gave him sat on his bedside table for a year, but when the New Orleans R&B great finally gave it a spin, he was blown away. "I thought it was very mystical," says Dr. John, leaning on his cane – which is adorned with trinkets, including his backstage wristband from 1976's Last Waltz concert – in the control room of Easy Eye Sound, Keys frontman Dan Auerbach's Nashville studio. "I didn't know how old those guys were in years, but I knew they got old souls."
Around the same time, Auerbach and a friend were discussing their mutual affection for Dr. John, who was inducted into the Rock and Roll Hall of Fame last year. "He was like, 'Man, you should make a record with him,'" Auerbach recalls. "I said, 'Good idea!'" Auerbach reached out to John's management, and now, two years later, the pair are preparing to release Locked Down – a gritty brew of New Orleans R&B, psychedelia and voodoo that recalls John's greatest LPs, like 1968's GRIS-Gris and 1974's Desitively Bonnaroo. "In the material world, shit don't be connected," John says. "But in the spirit kingdom, it connects, and if you let that roll, some shit happens that wouldn't ever happen."
The duo met in New Orleans last year, and Auerbach was impressed by the 70-year-old's fully intact musical mojo. "He played on this out-of-tune piano, and when he sits behind that fucking instrument, it's magic," says Auerbach. "Then he went off on some conspiracy theories – he's still into that weird shit he put into the lyrics on his first few records."
This fall, Auerbach assembled a band at Easy Eye that included the Black Keys' touring bassist Nick Movshon and keyboardist Leon Michels – plus Auerbach himself on guitar for several tunes. When John arrived, they had no songs and no expectations. "Expectations always lead to disappointments," says John, smiling. "That's an old saying, and sayings don't get old unless they true."
Auerbach suggested that John – whose friends call him by his real name, Mac Rebennack – lay off the piano and play Wurlitzer or Farfisa organ instead. "Mac's catchphrase for the whole session was 'Don't matter,'" says Auerbach. "'Hey, Mac, you mind playing the Farfisa?' 'Don't matter.'"
In just nine days, the group tore through the album's 10 basic tracks. Auerbach pushed John to get more personal with his songwriting, which resulted in intensely emotional lyrics like the ones to "My Children, My Angels" and "God's Sure Good," where he growls, "God's been good to me/Better than me to myself."
Other highlights of the set include "Eleggua" and "Ice Age," swaggering jams born of both musicians' love for African rhythms. "Mac's level of musicianship is off the charts," says Auerbach. "All the parts he came up with were right on point, right behind the beat where you wanted to hear it. So I knew right away there was no waiting around on Mac. We were all pushing forward."
This story is from the March 1st, 2012 issue of Rolling Stone.