American singer-songwriter Jason Isbell recalls spending time with David Crosby during the recording of his 2020 album Reunions, where the late musician "got really stoned" and showed him the 'secret' tunings Joni Mitchell was so well-known for.

"I wish I knew how to tune a guitar the way Joni Mitchell does," Isbell says in the latest issue of Uncut. "Nobody really knows, but David Crosby did. He knew every single one of them." However, Isbell recalls that "One night he got really stoned and we talked him into showing us all those Joni tunings."

In all but a few of Mitchell's guitar songs, she utilises multiple alternate tunings. Instead of writing these out using notes, Mitchell preferred a system of one letter and five numbers to describe each tuning. The letter refers to the note name of the bottom string, and the numbers represent the frets at which you play one string to be able to tune the next open string. Using this system, it's easy to understand why Mitchell's tunings were somewhat elusive.

"He just sat there for hours retuning his guitar over and over and over and showing us what notes they were supposed to be," Isbell says of Crosby, "I couldn't do a single one of them, but Crosby knew them all."

While some musicians (via JoniMitchell.com) have identified up to 80 different tunings that Mitchell used when taking into account the use of a capo, it's widely thought that the actual number of "distinct essential patterns" is lower. By organising songs into groups that use the same essential pattern, it's more like 45 - still a hell of a lot more tunings than the average artist would have down pat.

Isbell first met Crosby at Newport Folk Festival, where the two performed The 400 Unit's Ohio as well as Crosby Stills Nash's Wooden Ships. It was after this that the duo collaborated on Reunions, where Crosby contributed his unmistakable harmonies on the tracks What I've Done To Help and Only Children.