Howard Wales, the musician Jerry Garcia described as his favorite collaborator, died at the age of 77 yesterday, his family confirmed.

The keyboardist failed an audition for the Grateful Dead in 1970 because his approach didn’t match the group’s. He appeared on their album American Beauty that same year, and Garcia himself kept the relationship going.

“Howard was so incredible, and we were just hanging on for dear life,” Garcia was quoted as saying in the book Garcia: An American Life. “For some reason, Howard enjoyed playing with us, but we were just keeping up. Howard was so outside. For both of us that was a wonderful experience. ... Playing with Howard did more for my ears than anybody I ever played with because he was so extended and so different. His approach was all extensions and very keyboardistic, not guitaristic.”

The pair first met when Wales ran a jam night at San Francisco's the Matrix. Before that, he worked alongside big-name artists like James Brown, Freddie King, Four Tops and others. His final album was released in 2018, but he’s best remembered for the 1970 studio LP Hooteroll? and 1998's live Side Trips, Volume One, which was recorded in 1970. Both records were released under the banner of Howard Wales and Jerry Garcia.

Listen to Howard Wales, Jerry Garcia & Friends' ‘Gypsy Women’

“I didn't know what kind of music [they] would be playing down at the Matrix when I went down," bassist John Kahn once said. "And I still don't know! It was kind of a weird jazz with these other influences – it was mainly Howard's music, all instrumental.”

“We were doing acid jazz when nobody was,” Wales laughed during a 2017 interview. “We were doing stuff that was completely different.”

Looking back across his career, he reflected: “I went on the road when I was 18. … I played with fake IDs and things like that. I was in a group – believe it or not – that had green hair with space suits. … The thing about music with me is that I’ve got a whole swath of all kinds of stuff from these really ‘Why did you do that?' kind of things to incredible stuff. I think that in today’s world you don’t really see that anymore. ... I would say this about the old days: It was a hell of a lot more about love than now. You don’t find too much of the love aspect here. It's really terrible."

There are no details regarding Wales' death, though he had suffered a “medical emergency” on Dec. 6.