Keith Olsen, the producer/engineer whose work with Fleetwood Mac in the mid-‘70s would make him one of the most in-demand producers of the era, has died.

Scorpions wrote Monday on their Facebook page: "We just learned about the passing of our dear friend and producer Keith Olsen. Keith produced many iconic albums, including our album Crazy World. Keith was a wonderful guy, and the making of Crazy World was such an inspiring journey, containing outstanding songs like 'Wind Of Change' and 'Send Me An Angel,' which had the Keith Olsen touch, on every single note. Our hearts and prayers go out to his family. RIP, Keith. You live on in the music."

Details on his age—he was believed to be either 74 or 75— cause of death and location have not been announced. Olsen lived in Arroyo Canyon, Calif.

A bassist who made his way from Minnesota to Southern California in the 1960s, eventually getting a job as an engineer at the Sound City studio, Olsen was best-known for his work with the Lindsey Buckingham-Stevie Nicks edition of Fleetwood Mac. He signed Buckingham-Nicks as a duo in 1973 to his Pogologo Productions company, producing their debut album which Polydor released.

Once they joined Fleetwood Mac, he stayed on as the band’s producer, overseeing the multi-million sellers Fleetwood Mac and Rumours. His success led to him working with The Grateful Dead on Terrapin Station and Shakedown Street, Foreigner on Double Vision, Pat Benatar’s Crimes of Passion and Precious Times and Rick Springfield’s Working Class Dog.

By his count, Olsen produced more than 120 albums over 25 years, 24 of which were certified platinum; 14 are multi-platinum. His work appeared on more than 500 albums, including albums by The Babys, Whitesnake, Ozzy Osbourne (pictured above) and Sammy Hagar.