The Fender Twin and Twin Reverb are guitar amplifiers made by Fender Musical Instruments Corporation. The Twin was introduced in 1952, two years before Fender began selling Stratocaster electric guitars. The amps are known for their characteristically clean tone.
The Twin has seen a number of revisions since its introduction, both internal and external, with its designs sometimes varying greatly from one year to the next. Several variations on the amp's original design have been produced through the years, including the Twin Reverb, the Super Twin, the Twin Reverb II, the Twin Reverb '65 Reissue and the Twin Reverb 68’ Custom Reissues. The Cyber Twin, which combined a tube amp with a digital processor, was introduced in January 2001.YouTube page: "The Fender Cyber-Twin: Full-Length DVD."
Many notable musicians have used Fender Twin amplifiers, including Mark Knopfler, David Gilmour, Chuck Berry, Buddy Holly, George Tomsco of The Fireballs, Mike Oldfield, The BeatlesJohn Lennon and George Harrison of the Beatles both used Fender Twin amps during the recording of Abbey Road and Let It Be; the group also used Twins during their famous Rooftop Concert. Beatles Gear by Andy Babiuk. (1968 Twin Reverb amps using the AC568 circuit), Jimi Hendrix,"The Twin Reverb variant was introduced by the manufacturer in 1963, and Hendrix used one from 1965 to 1966..."; "Eric Clapton prefers old ones..." Jimi Hendrix Gear: The Guitars, Amps & Effects That Revolutionized Rock 'n' Roll pp. 54, by Michael Heatley, Harry Shapiro, Roger Mayer. Eric Clapton, Peter Green, Jeremy Spencer, Danny Kirwan, Keith Richards, Mick Taylor, Steve Jones (Sex Pistols), Jerry Garcia (Grateful Dead), Eric Johnson, Joe Bonamassa, Junior Brown, Kurt Cobain and Tommy Emmanuel.
History The Fender Twin has gone through a number of changes over the years, both cosmetically and electronically.
The 1950s: the Tweed era "Wide Panel" Twin The original version was an all-tube combo amplifier with dual 12" speakers and two 6L6 tubes for a rated output of 25 watts.
"Narrow Panel" Twin
After the preceding looks of the early 1950s (TV front from 1950 to 51/2; wide panel '52–54), Leo Fender changed the cabinet design again, this time opting for no extra wood on the front of the amp, except for the narrow top and bottom panels that hold the baffle board to the cabinet.
The early models of the larger "narrow-panel" tweeds are also remarkable for their refined electronics whose circuit design incorporated dual 5U4 rectifiers in the Twin and Bassman models, another improvement given Fender's quest for a louder, cleaner amplifier. The entire line of Fender amplifiers from 1955 to 1959 (later for smaller models and Bassman) was uniform in this look—tweed or "airline linen" covering with a maroon with gold stripe woven saran grill cloth. The 1×12 Deluxe-Amp, the 1×15 Pro-Amp and the 3×10 Bandmaster are exceptional in dynamics and tone.
Like its predecessors, the narrow panel tweed Fender amplifiers used Jensen Alnico V Concert Series Speakers, for the most part. By the end of the decade, a JBL 15" speaker was available on special order for the Pro model.
"Big Box" Twin It was modified in 1957 for more volume, switching to four 5881 power tubes with the more efficient long-tailed pair phase inverter for a power increase to 80W. This "hi-powered," tweed-covered design continued into early 1960, after the other Professional Series of Fender amplifiers had made the transition to the modern brownface design.
The upgraded 5F8 Twin-amp of 1957 with its complement of four military grade 5881's was briefly rectified with a tall mercury vapor 83 tube and special tube socket. Due to its volatile nature if broken, it was quickly superseded with a GZ34 rectifier but not duly noted on the tube chart until the second production.
The final 5F8-A Twin-Amp version was released in 1958 and produced into early 1960. The 5F series Twin utilized heavy duty Concert Series Jensen P12-N Alnico V blue-dome loudspeakers (conservatively rated in 1957 at only 18 watts apiece). These tweed Twin amps would deliver peaks up to 80 plus watts of power when turned high. With such bursts of volume energy, often these Jensen speakers would fail, and sometimes even burn out (smoke) voice coils. Many well used Twins have replaced speakers today. Keith Richards has used these late model, high-power Twin amps on Rolling Stones tours with his own special design Celestion Alnico (similar to the G12-80) speakers to insure optimum live efficiency. Today, the 5F8 series Fender Twin amps command the highest price of any Fender amp ever built.
The 1960s: the Tolex era Blonde Twin-Amp
The exact plight of the Twin-Amp during the months between January and May 1960, however, remains open to considerable speculation, debate and study. The prevailing explanation is that production was temporarily interrupted during these months as they coincide with the debut of Fender's new "flagship" or top of the line amplifier, the Fender Vibrasonic-Amp. Nonetheless, Fender Musical Instrument Co. kept the image of the Twin-Amp before potential consumers during this short period. The image of the Twin-Amp in the 1960 Fender Catalog has been the subject of considerable scrutiny.
The re-emergence of the Twin-Amp in mid 1960 revealed a new aesthetic design that would become prominent among Fender's top of the line amplifiers, with the exception of the Vibrasonic-Amp. By 1961, the Bandmaster, the Bassman and the newly debuted Showman were all covered in the new look exemplified by the late 1960 Twin-Amp: blonde tolex and maroon or "oxblood" grille cloth. The Twin-Amp of this period (late 1960–1963) was manufactured with a variety of speakers including Jensen, Oxford and JBL designs. This variation lends support to the idea that the 80-watt circuit was beyond the power handling capacity of the speakers of the late 1950s. After a slight change in appearance, from the rough blonde tolex and maroon grille appearance to a smooth blonde tolex with a gold grille cloth, the Twin-Amp was replaced with the Twin Reverb-Amp in 1963.
Blackface Twin Reverb
During the blackface era of Fender amplifiers from 1963 to 1967, the amps had black faceplates, black tolex covering on the cabinet, and neutral to slightly amber tinted silver sparkle grill cloth with a small ribbed rectangular pattern. The Twin now had an onboard spring reverb tank and was renamed the Twin Reverb. The Fender Twin Reverb is considered a standard model for players seeking a clean sound, and it is especially known for the quality of its built-in spring reverb.
Two transition prototype 1963 Twin Reverb amps have been found in both brown and blonde Tolex covering. The brown one still had the harmonic tremolo and early Vibroverb reverb circuitry with an extra tube and rear dwell control. The blonde Twin Reverb Leo gave to steel player Red Rhodes for testing purposes at the famous Palomino Club (North Hollywood). Performing in the house band with band leader Gene Davis, Red played his Pedal 1000 steel and Twin Reverb live, and on some popular TV shows including Cal's Corral (I'll eat a bug! Cal Worthington), Star Route, and Country Music Time.
Fender's 1963 product flyer featured a flat logo, black Tolex amp, while their 1963 full-line catalog showed a raised logo amp on the cover, both with a grey Saran grill. The first production Twin Reverb models used an unusual 7355 power tube (weaker cousin to the 6L6) as with their concurrent smooth blonde, blackface Fender Showman amplifier.
During this time the amplifier's output was rated at 85 watts into a 4-ohm speaker load. The circuit used is commonly known as the AB763 circuit. Fender Twin Reverb amplifiers use four output tubes, of the 6L6GC type. They use six preamp tubes, consisting of four 7025/12AX7 typesThe 7025 is a lower-noise version of the 12AX7. and two 12AT7 types. All Twin Reverbs feature a solid-state rectifier.
The Fender Twin Reverb has two independent channels, labeled Normal and Vibrato. The control have black-skirted knobs numbered from 1 to 10. The Normal channel has two inputs, a "bright" switch (which compensates for loss of brightness through the volume control when the control is set lower than about "6" on its 1–10 scale), a volume control, treble, middle and bass tone controls. The Vibrato channel has a duplication of the same controls as the normal channel, plus the addition of reverb, vibrato speed and intensity controls. Reverb is accomplished with a tube/transformer driven low impedance spring reverb tank (made by the Hammond company) or its spin-off company Accutronics. The addition of the reverb circuit requires an additional "gain" stage in the preamp, and as such, the Vibrato channel is capable of a bit more distortion when the volume is set high. Vibrato (tremolo) is accomplished with what is known as a "vibrato bug" by Fender amplifier repairmen. The vibrato bug is a four-wire device consisting of a neon tube and light-dependent variable resistor, packaged in a short section of black tubing. It resembles a water bug, with slender wispy legs. The tube generated vibrato oscillator pulsates the neon light, which varies the resistance on the resistive element. That variable resistance is applied to the audio signal on the Vibrato channel, creating a pulsating increase and decrease of that channel's volume. The speed controls varies the rate of the oscillator. The depth control limits the amount of application the variable resistor has on the audio signal.
The front panel also has a bright red pilot light lens (better known as "pilot lamp jewel" for its multiple triangular-shaped facets), covering the pilot light (made by the Chicago Miniature Lamp Co.). Other color schemes (amber, white, green, purple and blue) are also available. Rear panel controls include a 2.5-amp "slo-blo" fuse, an accessory AC outlet, an earth ground selection switch, on/off and standby switches. Additionally there are two speaker output jacks, and jacks for footswitches to activate/deactivate the reverb and vibrato effects. The black faceplates of the "blackface" era Twin Reverb will say either "Fender Electric Instruments" (FEI) or "Fender Musical Instruments", (FMI) depending on the date of manufacture. Units made before the takeover of Fender by CBS in 1965 will be marked Fender Electric Instruments, and be worth a bit more on the collectors market.
The more common speakers found in Fender Twin Reverb amps include Jensen C12Ns, Oxford 12T6s, JBL D-120Fs (an upgrade at the factory), Altec Lansing 417-8Cs, Utahs and, in later years, CTS and Eminence models. Some Twins were fitted with EVM 12L variant speakers known as EVM 12Fs. Unlike most Electrovoice speakers, they were fitted with metal dustcovers like the JBL D-120Fs.
Twin Reverb amplifiers came standard with "tilt back legs" which allowed the amplifier to be tilted at an angle backwards, so the speakers faced at a more upward angle, promoting better distribution of their output to an audience when placed on a low stage.
Silverface Twin Reverb In 1967 the Fender amplifier line switched from the original black faceplate to a new brushed aluminum faceplate with light blue labels (except the Bronco, which has red) and changed the color of the grillcloth from silver grey to silver with sparkling blue threads embedded within it, ushering in the Silverface era. Other blackface cosmetic features were retained. The first silverface Twins used the blackface AB763 circuit until May 1968, when Fender switched to the AC568. Since the tube complement was the same, Fender just used up their stock of printed tube charts saying AB763 until they ran out.