Danny Federici

Every band has a member known as "the quiet one", a musician who chooses not to share the limelight and thus runs the risk of being overlooked when the plaudits are distributed. Danny Federici, who has died of melanoma aged 58, was so quiet that his employer, Bruce Springsteen, often introduced him as the Phantom, or Phantom Dan. But Springsteen, like all hard-core fans of the E Street Band, knew that his fellow New Jerseyite made a vital contribution to their success during a collaboration that lasted almost 40 years.

Federici played the accordion part that so memorably coloured the song Fourth of July, Asbury Park (Sandy), a highlight of Springsteen's second album, The Wild, the Innocent & the E Street Shuffle, in 1974. His rampaging Hammond organ solo provided the climax to Kitty's Back when the band arrived in London the following year, by which time his use of a keyboard-operated glockenspiel had added a special piquancy to the arrangement of Born to Run, the song that would become Springsteen's signature tune. And to Hungry Heart, one of the leader's best loved songs, Federici added an organ solo so perfectly melodic and appropriate to the spirit of the piece - an ineffable mixture of exultation and sorrow - that it is engraved on every fan's heart.

Federici's membership of the band, which ceased operations in 1988, reformed for a year in 1999, came together again for a Vote for Change tour (an attempt to stave off the re-election of George Bush) in 2004 and reconvened again last year, was finally disrupted by the onset of skin cancer three years ago. When the band visited Europe last Christmas, the organ bench was occupied by Charlie Giordano, who had performed with Springsteen on the Seeger Sessions tour a year earlier. Speaking of a change he hoped would be temporary, Springsteen described Federici as "one of the pillars of our sound". It was the finest of tributes that Giordano performed his predecessor's parts to the last note.

After lengthy treatment, Federici returned to play a single show at the Conseco Fieldhouse in Indianapolis on March 20, when Kitty's Back, Spirit in the Night and other old favourites were included. Announcing his death last week, Springsteen said: "He was the most wonderfully fluid keyboard player and a pure, natural musician. I loved him very much."

Born in Flemington, New Jersey, Federici started to learn the accordion at the age of seven, was soon performing polkas on local radio shows, and was still in his teens when he made his way to the thriving boardwalk clubs of Asbury Park, where he hooked up with Springsteen in 1969. Having made his first recording with a local singer named Bill Chinook, whose sidemen included the bass guitarist Garry W Tallent and the drummer Vini Lopez, two future E Streeters, he and Lopez formed their own heavy metal band, Child, and invited Springsteen - "a skinny guy with long hair and a ratty T-shirt" but "an incredible guitar player and a good singer," in Federici's recollection - to join them.

By 1970, in order to avoid confusion with another local band, they had changed their name to Steel Mill and were receiving complimentary reviews for shows in San Francisco, with a repertoire broadened to include songs by Bob Dylan and Muddy Waters. They played their last gig in Asbury Park in February 1971, after which Springsteen formed his own group, at first known as Dr Zoom and the Sonic Boom, in which Lopez and Tallent were joined by guitarist Steve Van Zandt and pianist David Sancious, who displaced Federici.

Although Federici played no part in the recording of Greetings from Asbury Park, NJ, Springsteen's first album, he was back for the tours that accompanied the album's release in 1973, and for the sessions that produced its sequel. By the time they recorded Born to Run, the approach of the E Street Band had coalesced around Max Weinberg's thunderously upright drumming, Tallent's solid bass, the rhapsodically arpeggiated piano decorations of Roy Bittan (replacing Sancious, with whom Federici had a poor relationship), Clarence Clemons' R&B-drenched saxophone and Van Zandt's flamboyant presence. But no single contribution was more fundamental than that of Federici on the Hammond B3, with which he evoked the sound of soul music, and the glockenspiel, whose tintinnabulations recalled the teenaged innocence of Phil Spector's hits with the Crystals and the Ronettes.

During the lengthy periods when the E Street Band was out of commission, Federici remained active in the recording studios. He accompanied Joan Armatrading, Graham Parker, Garland Jeffreys and Gary US Bonds, and recorded two solo albums of jazz instrumentals: Flemington (1997) and Sweet (2005). After his illness was diagnosed he set up the Danny Federici Melanoma Fund to raise money for research at the Sloan-Kettering hospital in New York City, where he died. He is survived by his wife, Maya, a son and two daughters.

· Daniel Paul Federici, musician, born January 23 1950; died April 17 2008