Dickey Betts, who has died aged 80, was a founder member of the Allman Brothers Band, one of the most influential US “southern rock” groups of the 1970s. The hard-living outfit blazed out of Jacksonville, Florida, in 1969 with a mix of rock, blues, country and jazz that defined the genre, also influencing artists such as Lynyrd Skynyrd, ZZ Top, the Black Crowes and Kid Rock. They scored several platinum and gold albums and were inducted into the Rock & Roll Hall of Fame.

Although the six-piece band was ostensibly led by the blond- haired Allman brothers, Duane and Gregg (guitar and keyboards/vocals respectively), as joint lead guitarist, singer and main songwriter Betts played a crucial role. A larger than life character with his cowboy hats, long moustache and gunslinger good looks, Betts wrote many of the band’s best loved songs, including Jessica, Blue Sky and the 1973 US No 2 smash Ramblin’ Man, inspired by life on the road.

The signature duelling of Betts’s and Duane Allman’s lead guitars rewrote the rule book of how twin guitarists play together - previously one had played lead and the other rhythm. The band’s huge fanbase included President Jimmy Carter, and in 2020 Betts even received the rare accolade of a mention in a Bob Dylan song, when Murder Most Foul contained the line “Play Oscar Peterson, play Stan Getz/Play Blue Sky, play Dickey Betts.”

He was also the inspiration for the rock star character played by Billy Crudup in the former rock journalist Cameron Crowe’s film Almost Famous (2000), the director having been drawn to Betts’s aura of “possible danger and playful recklessness behind his eyes”.

Betts was born in West Palm Beach, Florida, one of the three children of Harold, a carpenter, and his wife, Sarah (nee Brinson), who wrote poetry and played the cornet in a Salvation Army band. Although his father was also a keen fiddler, Dickey’s first instrument was the ukelele, which he started playing aged five, later graduating to the mandolin and the banjo.

He was at West Gate elementary school when he wrote his first song, Seven Years With Pamela, about his sister. He then attended various West Palm Beach schools until seventh grade, dropping out of high school when he was 16, by which time his pursuits included carpentry, hunting and listening to the Grand Ole Opry on the family radio.

Hearing Chuck Berry’s Maybellene in his mid-teens prompted another switch of instrument, as he “started realising that girls like guitars”. He dropped out of high school aged 16 to tour the US with a travelling circus in his first band, the Swinging Saints, but was playing in Second Coming with the bassist Berry Oakley when Duane Allman invited both men to join his new group.

The lineup was completed by the drummer Butch Trucks and – unusually in white-dominated 60s southern rock - a black second drummer, James Lee Johnson, who had previously played with Otis Redding and Percy Sledge.

Although sales of their first two albums were sluggish, Duane Allman’s appearance on Eric Clapton’s 1970 album Layla and Other Assorted Love Songs – which included the classic hit Layla – boosted the heavy-touring Allman Brothers Band’s rising profile. Their 1971 live album At Fillmore East sold 1m copies.

After Duane Allman and Oakley were killed in motorcycle accidents in 1971 and 1972 respectively, Betts led a rejigged lineup. The 1973 album Brothers and Sisters – featuring Ramblin’ Man and the instrumental Jessica, later the theme to the television motoring show Top Gear – topped the US charts for five weeks, while 1975’s Win, Lose Or Draw went into the Top five. By then the band were succumbing to a familiar music industry cocktail of success, drugs, alcohol and feuding.

Betts and Gregg Allman both made solo albums, before Betts felt betrayed when the latter testified against the band’s road manager in a 1976 drugs case and refused to work with him again. Nevertheless, they regrouped in 1978, splitting again in 1982.

A second comeback in 1989 proved more enduring, although in 2000 Betts was fired over his drinking. That third spell in the band had been dogged by alcohol and drug abuse, lawsuits and arrests, and in 1996 he was charged with aggravated domestic assault after pointing a handgun at his fifth wife, Donna (nee Stearns), whom he had married in 1989. The charges were dropped after Betts agreed to enter rehab.

In his later years he returned with his own Dickey Betts Band and played in the band Great Southern with his son Duane. True to his ramblin’ man credentials, he remained on the road to the last, even after brain surgery following a 2018 fall at home, and he released live albums well into his 70s.

He is survived by Donna and his children, Kimberly, Christy, Jessica and Duane.

• Forrest Richard Betts, musician, singer and songwriter, born 12 December 1943; died 18 April 2024