The Rickenbacker 4001 is a bass guitar that was manufactured by Rickenbacker as a "deluxe model" of the 4000 between 1961 and 1981 before being replaced by an updated version, the Rickenbacker 4003. There are several models of the 4001, such as: The 4001, 4001S, 4001LH, 1999 (European model), 4001V63 (reissue), and the newer 4001C64S C Series recreation in honor to Paul McCartney´s lefty 4001s bass with reversed headstock.

The Rickenbacker 4001 was designed with the "crested-wave" body shape, much like the other basses of the 4000 series. The 4001 model features a neck-through construction, a full-wood body, fret board with metal strings (originally flat-wound, though many players replaced them with round-wounds), twin truss rods, triangle inlays, two pickups, two volume and two tone dials, selector switch, and wiring for Rick-O-Sound (standard in models post-1971). Rickenbacker also produced six-string, and short-scale versions of the 4001 model.

The 4001S (and 1999) model varies in its use of dot inlays, and unbound neck construction. The Rickenbacker 4003, which replaced the 4001, differs mainly in the truss rod system, other features being quite similar to its forebear.

Rickenbacker International Corporation, also known as Rickenbacker, is an electric and bass guitar manufacturer based in Santa Ana, California. In 1932, the company became the world's first to produce electric guitars and continues to produce a range of electric and bass guitars to this day.

The company was founded in 1931 as the Ro-Pat-In Corporation (ElectRo-Patent-Instruments) by Adolph Rickenbacher and George Beauchamp in order to sell electric Hawaiian guitars. These instruments had been designed by Beauchamp, assisted at the National String Instruments Corporation by Paul Barth and Harry Watson. They chose the brand name Rickenbacher (later changed to Rickenbacker), though early examples bear the brand name Electro.

Nicknamed "frying pans" because of their long necks and circular bodies, the instruments were the first solid-bodied electric guitars, though they were a lap-steel type. They had pickups with a pair of horseshoe magnets that arched over the strings. By the time production ceased in 1939, several thousand "frying pans" had been produced.

Christopher Russell Edward "Chris" Squire (born 4 March 1948), is an English musician, known as the bass guitarist and backing vocalist for the progressive rock group Yes. He is the only member of the group to appear on every album. He is widely regarded as the dominant bass guitarist among the early seventies British progressive rock bands, influencing peers and later generations of bassists with his incisive sound and elaborately contoured, melodic bass lines.

He was born in Kingsbury, a suburb of northwest London, in England. His father was a cab driver, and his mother a housewife. He was trained in the St Andrew's church choir as a young boy, beginning his musical career with a group called the "Selfs", along with his friend Andrew Jackman who played the keyboards. The band had their own venue at the St Andrew's church hall where on Friday nights they played at their own club, called appropriately, the "Graveyard Club". This was run by a group of local Grammar School boys which included Jonathan Angell, Bill Mesley, Chris Mann and Colin Mallett.

Sir James Paul McCartney, MBE, Hon RAM, FRCM (born 18 June 1942) is an English musician, singer-songwriter and composer. Formerly of the Beatles (1960–1970) and Wings (1971–1981), he has been described by Guinness World Records as "The Most Successful Composer and Recording Artist of All Time", with 60 gold discs and sales of over 100 million albums and 100 million singles. With John Lennon, George Harrison, and Ringo Starr, he gained worldwide fame as a member of the Beatles, and with Lennon formed one of the most celebrated songwriting partnerships of the 20th century. After leaving the Beatles, he began a solo career and later formed the band Wings with his first wife, Linda Eastman, and singer-songwriter Denny Laine.

According to the BBC, his Beatles song "Yesterday" has been covered by over 2,200 artists—more than any other song. Wings' 1977 release, "Mull of Kintyre", became one of the best-selling singles ever in the UK, and he is "the most successful songwriter" in UK chart history, according to Guinness. As a songwriter or co-writer, he is included on thirty-one number one titles on the Billboard Hot 100, and as of 2012 he has sold over 15.5 million RIAA certified units in the United States.