Owsley “Bear” Stanley, who supplied LSD to the 1960s flower power generation and worked closely with psychedelic band The Grateful Dead, died in a car crash in Australia, his family said.

Mr Stanley, who was 76, started as a sound engineer for the band and is credited with developing hifi technology which is now taken for granted, such as on-stage monitors for bands to hear themselves while playing.

But he was more remembered for the pure form of LSD he manufactured, fuelling the flower power counter-culture which exploded out from San Francisco in the mid to late 1960s.

Mr Stanley died when his car swerved off a road and slammed into a tree, media reports said. Queensland police said a 76-year-old died at the scene while his female passenger was taken to Cairns Base Hospital with minor injuries. “We are extremely saddened to report that Owsley “Bear” Stanley, our beloved patriarch, died in an automobile accident near his home in Far North Queensland Australia,” a family statement said.

“The family asks for privacy while we deal with this tragedy,” added the statement, issued by former Grateful Dead tour manager Sam Cutler.

The grandson of a former governor of Kentucky, Stanley was the original LSD “cook” who produced large quantities of LSD at his lab in San Franciso. He was arrested several times for drug making.

He briefly managed the Grateful Dead and oversaw their live sounds at a time when little thought was given sound systems in public arenas. His tape recordings of Dead concerts were turned into live albums.

Stanley reportedly became an Australian citizen in 1996 and lived near the northeastern Australian city of Cairns, where he worked as an artist, making gold and enamel sculptures.