Phil Lesh, one of the founders of the Grateful Dead and an influential…

LOS ANGELES (AP) — Phil Lesh, a classically trained violinist and jazz trumpeter who found his true calling by reinventing the rock bass guitar’s role as founding member of the Grateful Dead, died on Friday at the age of 84.

Lesh’s death was announced on his Instagram account. Lesh was the oldest and one of the longest-lived members of the band that came to define the acid rock sound coming out of San Francisco in the 1960s.

“Phil Lesh, bassist and founding member of The Grateful Dead, passed away peacefully this morning. He was surrounded by his family and full of love. “Phil brought great joy to everyone around him and left behind a legacy of music and love.” Instagram statement partially reads.

The statement did not give a specific cause of death, and attempts to reach representatives for additional details were not immediately successful. Lesh previously survived bouts with prostate cancer, bladder cancer and a liver transplant in 1998, brought on by the debilitating effects of a hepatitis C infection and years of alcohol abuse.

Although he kept a relatively low profile in public life, rarely giving interviews or performing in public, Lesh was recognized by fans and bandmates as a critical member of the Grateful Dead, whose thunderous six-string electric bass lines provided a brilliant counterpoint to the lead guitarist. Jerry Garcia’s soaring solos became the basis of the band’s famous marathon jams.

“When Phil happens, band happens,” Garcia once said.

Drummer Mickey Hart called him the brainiac of the group, bringing the thinking and skills of a classical composer to the five-chord rock and roll band.