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Fender Twin Reverb

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Title: Fender Twin Reverb  
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Fender Twin Reverb

The Fender Twin is a guitar amplifier made by Fender. It 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 Twin Reverb II, and the Twin Reverb '65 Reissue. The Cyber Twin, which combined a tube amp with a computerized processor, was introduced in January 2001.[1]

Many notable musicians have used Fender Twin amplifiers, including The Beatles,[2] (1968 Twin Reverb amps using the AC568 circuit),[3] Jimi Hendrix,[4] Eric Clapton,[4] Keith Richards from The Rolling Stones, Jerry Garcia and Eric Johnson.


The Fender Twin has gone through a number of changes over the years, both cosmetically and electronically.

"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.[5]

"Narrow Panel" Twin

After the preceding looks of the early 50's (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, although a JBL 15" speaker was available on special order for the Pro model.

Tweed Twin

It was modified in 1958 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 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.

Blonde Twin-Amp

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 silver grille cloth, the Twin-Amp was replaced with the Twin Reverb-Amp in 1963.

Fender Twin Reverb

The Fender Twin Reverb is an all-tube guitar amplifier with two 12", 8-ohm speakers made by various suppliers. The more common speakers found in Fender Twin Reverbs include Jensen C12Ns, Oxford 12T6s, JBL D-120Fs (an upgrade at the factory), 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. The Twin Reverb is frequently shortened in conversation to 'Fender Twin' or simply 'Twin', though it should not be confused with the Tweed or Blonde era Twin amplifiers which had vastly different circuits and no 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. All Twin Reverbs feature a solid-state rectifier.


The Twin Reverb was first introduced during the blackface era of Fender amplifiers which was from 1963 to 1967. During this time the amplifier's output was rated at 85 watts into a 4-ohm speaker load.

The so-called blackface amplifiers have black faceplates, black tolex covering on the cabinet, and neutral to slightly amber tinted silver sparkle grill cloth with a small ribbed rectangular pattern.

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.

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 types and two 12AT7 types. The 7025 is a lower-noise version of the 12AX7.

The Fender Twin Reverb has two independent channels, labeled Normal and Vibrato. The controls 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.[6] 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 colour 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. Those units made before the CBS take over of Fender in 1965, will be marked Fender Electric Instruments, and be worth a bit more on the collectors market.


In 1968 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.

The Twin Reverb, along with all other silverface models, had an aluminum frame (trim) surrounding the sparkling blue grillcloth from late 1967 to 1969. Early silverface amplifiers made between 1967 and 1968 had black lines on the brushed aluminum control plate, still retaining the '60s "tailed" design. This feature was offered on models produced prior to the "tailless" period in 1973. Some later models came with an unusual silver grillcloth with sparkling orange threads ("orange sparkle"); a black grillcloth was even fitted on some production runs. During the silver face period, the Twin Reverb's chassis and AA769 circuit was shared by the Dual Showman Reverb, effectively producing the Twin Reverb in a head form.

The rating of the amplifier's output power was also upgraded to 100 watts, and between 1977-1982 the power was increased to 135 watts.

Twin Reverb II

In 1982 the Twin Reverb II was introduced to compete with Mesa Boogie's very successful products; it had an output rating of 105 watts and a return to Blackface era cosmetics albeit with a different, channel-switching cascading gain circuit with a more modern mid-range voicing and without the 'traditional' vibrato. The Twin Reverb II was produced until 1986, and was available as a head (amplifier alone) or 2×12 combo. The circuits for this series of 1982 Fender amplifiers were designed by amp guru Paul Rivera; the 60w Concert amplifier was by far the most successful in terms of sales, but all models in this range and the next are now becoming highly sought-after by collectors and players.

"Red Knob" Twin

The Twin Reverb II was replaced by The Twin, commonly referred to, though incorrectly as, the "Evil Twin" (Fender has only referred to the "TWIN AMP" or the '94 Twin Amp as being the "Evil Twin", NOT the red knob twin) due to the addition of both a separate gain channel and a switchable overdrive on the clean, in 1987. It featured a dual output switch, allowing the user to select either 25 watts or 100 watts of output. The Twin was designed for maximum versatility for live or studio use with features like speaker jacks with selectable impedance, Low-z/XLR output, a "Power Amp Thru" feature that bypassed the preamp circuit and a buffered effects loop. Both clean and overdrive channels could be activated simultaneously and reverb could be turned on/off for each channel. Earlier Twin Reverb amps were known among musicians to be best suited for loud, "clean" tones. The "Red Knob Twin" was made until 1994; it has since been succeeded by "Twin Amps" of Fender's current Protube line.

'65 Reissue

In 1992 Fender introduced the '65 Reissue, with blackface cosmetics and circuitry, an output rating of 85W RMS and 8Ω Jensen C-12K speakers. It should be noted, however, that the '65 Reissue is constructed with a printed circuit board and new 1/4" phone jacks for the footswitch pedal replacing the older RCA design of the vintage originals. Fender's original intention was to issue only 300 of this model, but it was continued due to its success in the market. The '65 Reissue is also available with a single 15 inch speaker, called the '65 Twin Custom 15.[7]

'68 Custom

In 2013, Fender introduced a redress of the '65 reissue dubbed the '68 Custom Twin Reverb. It came with silverface cosmetics, altered negative feedback circuitry, and a "Custom" channel which utilizes a modified tone stack derived from the Fender Bassman. The output remains at 85W, unlike the Twin Reverb of 1968.[8]

See also

List of Fender Amplifier users


  • Kelly Industries Audio Gear Review
  • Unofficial Fender Amp history page
  • The Brown Twin Page
  • Kelly, Martin, Foster, Terry & Kelly, Paul (2010) Fender: The Golden Age 1946–1970 London & New York: Cassell ISBN 1-84403-666-9.
  • Linden, Paul, "The Myth of the 1960 Small-Box Brown Fender Twin," The Tone Quest Report, March 2005, vol 6, no. 5.

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