The nucleus of the Byrds formed in early 1964, when Jim McGuinn, Gene Clark, and David Crosby came together as a trio. All three musicians had a background rooted in folk music, with each one having worked as a folk singer on the acoustic coffeehouse circuit during the early 1960s. In addition, they had all served time, independently of each other, as sidemen in various "collegiate folk" groups: McGuinn with the Limeliters and the Chad Mitchell Trio, Clark with the New Christy Minstrels, and Crosby with Les Baxter's Balladeers. McGuinn had also spent time as a professional songwriter at the Brill Building in New York City, under the tutelage of Bobby Darin. By early 1964, McGuinn had become enamored with the music of the Beatles, and had begun to intersperse his solo folk repertoire with acoustic versions of Beatles' songs. While performing at the Troubadour folk club in Los Angeles, McGuinn was approached by fellow Beatles fan Gene Clark, and the pair soon formed a Peter and Gordon-style duo, playing Beatles' covers, Beatlesque renditions of traditional folk songs, and some self-penned material. Soon after, David Crosby introduced himself to the duo at The Troubadour and began harmonizing with them on some of their songs. Impressed by the blend of their voices, the three musicians formed a trio and named themselves the Jet Set, a moniker inspired by McGuinn's love of aeronautics.