Unreleased songs recorded by Jimi Hendrix between 1968 and 1970 will be released next year.

Experience Hendrix and Legacy Recordings announced on Wednesday that they will release Hendrix’s Both Sides of the Sky on March 9, 2018. The 13-track album includes 10 songs that have never been released.

Hendrix died in 1970 at age 27. The new album is the third volume in a trilogy from the guitar hero’s archive. Valleys of Neptune was released in 2010, followed by People, Hell and Angels in 2013.

Eddie Kramer, who worked as recording engineer on every Hendrix album made during the artist’s life, said in an interview that 1969 was “a very experimental year” for Hendrix, and that he was blown away as he worked on the new album.

“The first thing is you put the tape on and you listen to it and the hairs just stand up right on the back of your neck and you go, ‘Oh my God. This is too [expletive] incredible,” said Kramer. “It’s an incredible thing. Forty, 50 years later here we are and I’m listening to these tapes going, ‘Oh my God, that’s an amazing performance’.”

Many of the album’s tracks were recorded by Band of Gypsys, Hendrix’s trio with Buddy Miles and Billy Cox. Stephen Stills appears on two songs: $20 Fine and Woodstock.

“It sounds like Crosby, Stills & Nash except it’s on acid, you know,” Kramer, laughing, said of $20 Fine.

“Jimi is just rocking it,” he added. “It’s an amazing thing.”

Johnny Winter appears on Things I Used to Do; original Jimi Hendrix Experience members Mitch Mitchell and Noel Redding are featured on Hear My Train A Comin’; and Lonnie Youngblood is on Georgia Blues.

Kramer produced the album alongside John McDermott and Janie Hendrix, the legend’s sister and president of Experience Hendrix. Kramer said though Both Sides of the Sky is the last of the trilogy, someone could find new Hendrix music in an attic or a basement, which could be re-worked.

He also said they have live footage of Hendrix, some just audio and some in video, which they plan to release.

“It was amazing just to watch him in the studio or live. The brain kicks off the thought process - it goes through his brain through his heart and through his hands and onto the guitar, and it’s a seamless process,” Kramer said. “It’s like a lead guitar and a rhythm guitar at the same time, and it’s scary. There’s never been another Jimi Hendrix, at least in my mind.”