John Alec Entwistle was born in Chiswick, a London suburb, in 1944 and attended Acton County Grammar School. He joined the Middlesex Youth Orchestra and his initial music training was on trumpet, french horn, and piano, all three of which would feature in his later rock playing. In the early 1960s, he played in several traditional jazz and dixieland outfits. He formed a duo called The Confederates with schoolmate Pete Townshend, and later joined Roger Daltrey's band The Detours, playing a major role in encouraging Townshend's budding talent on the guitar, and insisting that Townshend be admitted to the Detours as well. After changes in personnel, Daltrey had fired all members of his band with the exception of Entwistle, Townshend, and the drummer, Doug Sandom, although it was only because he hadn't yet found a drummer with sufficient talent to replace him. Upon the entry of Keith Moon to the band, Daltrey relinquished the role of guitar to Townshend, becoming frontman and lead singer in the band, while the band considered several changes of name, temporarily performing as the High Numbers, and finally settling on the name The Who.
Entwistle picked up two nicknames during his tenure as a musician. He was nicknamed "The Ox" because of his strong constitution and seeming ability to "eat, drink or do more than the rest of them." Bill Wyman, bassist for the Rolling Stones, described him as "the quietest man in private but the loudest man on stage." Entwistle who was one of the first to make use of Marshall stacks, in an attempt to hear himself over the ruckus of his bandmates, who famously leapt and moved about on the stage, with Townshend and Moon smashing their instruments on numerous occasions. (Moon even employed explosives in his drum kit during one memorable performance). Pete Townshend later remarked that John started using Marshalls in order to hear himself over drummer Keith Moon's rapid-fire drumming style, and Townshend himself also had to use them just to be heard over John. They both continued expanding and experimenting with their rigs, until (at a time when most bands used 50-100 W amps with single cabinets) they were both using twin Stacks with new experimental prototype 200 W amps. However, no matter what was taking place on stage, Entwistle stood by calmly and quietly, while plucking the strings very fast, in what was later described as his "typewriter" technique of playing, which earned him the name "Thunderfingers" by his bandmates and some fans of the Who. The band had a strong influence on their contemporaries at the time, with Cream and the Jimi Hendrix Experience both following suit. Although they pioneered and directly contributed to the development of the "classic" Marshall sound (at this point their equipment was being built/tweaked to their personal specifications), they would only use Marshalls for a couple of years. Entwistle eventually switched to using a Sound City rig in search of his perfect sound, with Townshend following suit later as well. Townshend points out that Jimi Hendrix, their new label mate, was influenced beyond just the band's volume. Both Entwistle and Townshend had begun experimenting with feedback from the amplifiers in the mid-1960s, and Hendrix had not begun destroying his instruments until after he had witnessed The Who's "auto-destructive art".
Entwistle's wry and sometimes dark sense of humour clashed at times with Pete Townshend's more introspective work. Though he continued to contribute material to all of The Who's albums, with the exception of Quadrophenia, his frustration with having his material recorded by the band, only to relinquish the position of vocalist to Daltrey, was a large part of the reason he became the first member of the band to release a solo record, Smash Your Head Against the Wall (1971). The only member of the band to have had formal training, he contributed backing vocals and performed on the French horn (heard in "Pictures of Lily"), trumpet, bugle, and Jew's harp, and on rare occasions, lead vocalist, (usually on his composition), the only exceptions being the first verse of "Happy Jack" and Ivor's part on "A Quick One, While He's Away". Examples are on Tommy, ("Cousin Kevin", "Fiddle About"), on the live favourite "Heaven and Hell", and on Who's Next ("My Wife"). He layered several horns and performed all pieces to create the brass as heard on songs such as "5:15", among others, while recording the Who's studio albums, and for concerts, arranged a horn section to perform with the band.
Entwistle also experimented throughout his career with "bi-amping," where the high and low ends of the bass sound are sent through separate signal paths, allowing for more control over the output. At one point his rig became so loaded with speaker cabinets and processing gear that it was dubbed "Little Manhattan," in reference to the towering, skyscraper-like stacks, racks and blinking lights.
His "full treble, full volume" approach to bass sound was originally supposed to be captured in the bass solo to "My Generation". According to Entwistle, his original intention was to feature the distinctive Danelectro Longhorn bass, which had a very twangy sound, in the solo, but the strings kept breaking. Eventually, he recorded a simpler solo using a pick with a Fender Jazz Bass strung with LaBella tapewound strings. This solo bass break is important as it is one of the earliest bass solos (if not the first) captured on a rock record. A live recording of The Who exists from this period (c. 1965), with Entwistle playing a Danelectro on "My Generation", giving an idea of what that solo would have sounded like.
Entwistle's technique ranged from using fingers, plectra and tapping to utilizing harmonics in his passages. He would change the style of play between songs and even during songs to change the sound he produced. His fingering technique would involve pressing down on the string hard and releasing in an attempt to reproduce a trebly, twangy sound. Note, however, that he would change his thumb position from pickup, to the E string and occasionally even allowing his thumb to float near the pickup. His plectrum technique would involve holding the plectrum between his thumb and forefinger, with the rest of his fingers outstretched for balance.
Entwistle's playing style was rarely captured well in the studio. He was better heard in concert, where he and guitarist Pete Townshend frequently exchanged roles, with Entwistle providing rapid melodic lines and Townshend anchoring the song with rhythmic chord work. Indeed, Townshend noted that Entwistle did the rhythmic timekeeping in the band, doing the role of the drummer. Moon, on the other hand, with all his flourishes around the kit, was like a keyboard player. In 1989, Entwistle pointed out that, according to modern standards, "The Who haven't a proper bass player."
Entwistle also developed what he called a "typewriter" approach to playing the bass. It involved positioning the right hand over the strings so all four fingers could be used to tap percussively on the strings, causing them to strike the fretboard with a distinctive twangy sound. This gives the player the ability to play three or four strings at once, or to use several fingers on a single string. It allowed him to create passages that were very percussive and melodic. He used this approach to mimic the fills used by his drummers in band situations, sometimes sending the fills back at the drummers faster than the drummers themselves could play them.
This method is unique and should not be confused with the hammer-on tapping techniques of Eddie Van Halen and Stu Hamm or the slapping technique of Larry Graham, and in fact pre-dates these other techniques. A demonstration of this approach to bass playing can be seen on a video called John Entwistle - Master Class, part of Arlen Roth's Hot Licks instructional series, as well as Mike Gordon's film, Rising Low. Demonstrated in Mike Gordon's film, Rising Low is John's tendency to use his fore, middle and ring fingers on his right hand when playing. This would allow him to create "clusters of notes" in his bass lines, as well as play triplets with relative simplicity. Notable in his left-handed technique is his use of slides, positioning the left hand for octaves and his use of the pentatonic scale.