Mr. Jansch had a notable solo career that spanned five decades and nearly two dozen albums, drawing admirers on both sides of the Atlantic for the flawless technique and harmonic color he brought to the guitar.
Rolling Stone magazine named him as one of the top 100 guitarists of all time, and he opened for Young on concert tours in recent years. Young once called Mr. Jansch his favorite acoustic guitarist and “as much of a great guitar player as Jimi Hendrix was.”
Led Zeppelin guitarist Jimmy Page was also among his staunchest followers, with Zeppelin’s instrumental “Black Mountain Side” featuring a similar guitar pattern as Mr. Jansch’s 1966 version of the folk song “Blackwaterside.”
Mr. Jansch was still in his teens when he emerged in the Edinburgh folk-club circuit as a guitar prodigy. He cemented his early promise with his 1965 self-titled album, which included a dazzling cover of Davey Graham’s “Anji” and the haunting and raging “Needle of Death,” which Mr. Jansch wrote for a friend who died of a heroin overdose.
Later, Young told Guitar Player magazine that his own song “Ambulance Blues” was “almost like a note-for-note cop” of Mr. Jansch’s “Needle of Death.”
The topicality of Mr. Jansch’s music, his virtuosic guitar work and his brooding good looks brought him acclaim as Britain’s answer to Bob Dylan.
While never fulfilling that degree of public renown, Mr. Jansch enjoyed a successful solo career before forming Pentangle in 1967 with his then-roommate, guitarist John Renbourn. The two had previously recorded the well-received albums “Jack Orion” and “Bert and John.”
As Pentangle, they were joined by other young musicians — drummer Terry Cox, singer Jacqui McShee and double bassist Danny Thompson — who had coalesced around Les Cousins, a nightclub in London’s Soho district.
Pentangle was heralded in live performances and several albums (including the best-selling “Basket of Light”) for music that incorporated ideas from modern jazz and American country blues into English and Celtic folk music. Mr. Jansch called it a “progressive jazz folk band.”
To its most devoted fans, the style was compelling, intricate and introspective. Occasional detractors considered the music predictably solemn and interchangeable.
Pentangle’s exhausting tour schedule, heavy boozing and financial disputes with its music production company led to the group’s collapse in 1973. Mr. Jansch owned a sheep farm in Wales and formed various short-lived bands. His final album was “The Black Swan” (2006), which featured singers Beth Orton and Devendra Banhart.
Pentangle reunited periodically, with changing lineups, but it was Mr. Jansch’s tours with Young over the past several years that brought him renewed attention.
In December, music critic Ben Ratliff wrote in the New York Times that Mr. Jansch retained a powerful allure despite the ravages of ill health.
“His singing,” Ratliff wrote, “once handsome and presentable, has become gnarled and ugly-beautiful, not impressionable at all. He phrased lyrics as he wanted to, cutting off words and singing through grimaces, flying toward a note and swerving away. And his playing merged pattern-picking and slides and pull-offs, extended harmony and bent notes on top of strong chords. But it was simplified into a unified, original style; it sounded hungry and forceful without blowing smoke.”
Herbert Jansch was born Nov. 3, 1943, in Glasgow, Scotland. After his father left, he was raised in Edinburgh by his mother and sister in what he called a strict and sheltered Protestant family.
His infatuation with music began when he was 8. “Our teacher brought in a Spanish guitar for us to look at, and we had never seen anything like it to actually touch,” he told a Liverpool newspaper. “I have been obsessed with it ever since.”
Largely self-taught, he soaked up American blues and jazz influences. As a teen, he became a gangly presence in local folk clubs, earning income from busking and dates at bars and cafes. For a period, he hitchhiked around Europe and North Africa.
Mr. Jansch settled in London at 20 a mature musician but a fretfully bad businessman. He signed away rights to his first album for 100 pounds; it went on to sell millions of copies. He was not regretful, or so he said, and claimed never to have been motivated by commerce. He added for good measure, “I could never see the point in taking orders.”
Mr. Jansch’s marriages to Lynda Campbell and Heather Sewell ended in divorce. Survivors include his wife, the former Loren Auerbach, and two sons, Kieron and Adam. A third son, Robert, died in 2008.
Mr. Jansch continued to exert a strong influence on other musicians; British guitarist Gordon Giltrap released the album “Janschology” (2000) in his honor. Despite the acclaim that befell him, Mr. Jansch was self-effacing in most interviews. “I’m not one for showing off,” he told London’s Guardian newspaper last year. “But I guess my guitar-playing sticks out.”