Experimental musician Ian Allen has died, aged 56.

The former Negativland member passed away in California on 17 January (15) from "unexpected complications and infections following heart valve replacement surgery", according to a post on the band's Facebook page.

An accompanying tribute reads: "Ian's impact, inspiration, and influence on the group is impossible to overestimate. There would be no group as we know it today.

"Ian struggled with various serious health issues his entire adult life, and while they led to his gradual withdrawal from active participation with the group by the late 80s, he remained a good friend and supporter, attending all of our live shows whenever we performed in the Sf (San Francisco) Bay Area.

"For those who knew him, he was a visionary, magical, impish, playful and eccentric thinker, a true genius who was light years ahead of all of us with his ideas about art, sound, society, and technology. He will be dearly missed."

Allen was a regular contributor to the experimental music band from 1981 to 1987.