The Fender Pro was an instrument amplifier manufactured by Fender Electric Instruments from 1946 to 1965. It was characterized by its dual 6L6-family power tubes and single 15" speaker, with output power increasing from 18 watts up to 40 watts over its production run. The Pro was replaced in the Fender lineup by its offspring the Pro Reverb.

History

Woody

The Professional was the largest of the three amplifiers

Leo Fender Clarence Leonidas Fender (August 10, 1909 – March 21, 1991) was an American inventor known for designing the Fender Stratocaster. He also founded the Fender Musical Instruments Corporation. In January 1965, he sold Fender to CBS, and later foun ...

produced at the launch of his company in 1946. It was built in small numbers on a special-order basis, and used the same circuitry and even the same chassis as the Model 26 (

Deluxe Deluxe may refer to: Corporations * Deluxe Corporation, check printers * De Luxe Motor Car Company, an American automobile manufacturer Media and entertainment * DeLuxe Color, a brand of color photography used in motion pictures, especially t ...

), with "Model 26" on the control plate scratched out and 6L6 tubes and larger transformers driving a 15-inch field coil speaker. The distinctive rear-panel cabinet was uncovered hardwood (maple, mahogany or walnut), with red, gold or blue grill cloth and vertical chrome bars in the center.

Tweed

In 1948 the Pro-Amp was part of Fender's revamped lineup in top-panel cabinets covered in luggage twill (miscalled "tweed") with redesigned electronics. The first version (1948–53) had a small, round-cornered speaker aperture and is known as the "TV-front;" this was followed by the "wide-panel" (1953–55) and "narrow-panel" (1955–60) cabinets. The circuit over this time evolved considerably, from 6SC7 (or 6SL7) grid-leak biased preamp tubes and paraphrase inverter driving a cathode-biased 6L6G push-pull output section (model 5A5) to a more advanced 12AY7 cathode-biased preamp and

12AX7 12AX7 (also known as ECC83) is a miniature dual-triode 6AV6 vacuum tube with high voltage gain. Developed around 1946 by RCA engineers in Camden, New Jersey, under developmental number A-4522, it was released for public sale under the 12AX7 ident ...

cathodyne inverter driving fixed-bias 6L6GBs with

negative feedback Negative feedback (or balancing feedback) occurs when some function of the output of a system, process, or mechanism is fed back in a manner that tends to reduce the fluctuations in the output, whether caused by changes in the input or by othe ...

and

filter choke In electronics, a choke is an inductor used to block higher-frequency alternating currents while passing direct current (DC) and lower-frequencies alternating current (AC) in an electrical circuit. A choke usually consists of a coil of insula ...

(model 5E5-A); while headroom was increased and distortion reduced, output power remained around 25 watts.

Brownface

From 1960–63 the Pro along with Fender's other combo amps received a cabinet with front-mounted controls covered in brown

Tolex Tolex is a trade name for a flexible, waterproof, vinyl material used as a cover material for books, upholstery, guitar amplifiers, cases, and other products. Tolex was filed as a trademark on August 30, 1945 by the General Tire, and was register ...

; it shared its circuit with the other members of the "Professional Series",Pro,

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Bandmaster A bandmaster is the leader and conductor of a band, usually a concert band, military band, brass band or a marching band. British Armed Forces In the British Army, bandmasters of the Royal Corps of Army Music now hold the rank of staff ...

Twin Twins are two offspring produced by the same pregnancy Pregnancy is the time during which one or more offspring develops ( gestates) inside a woman's uterus (womb). A multiple pregnancy involves more than one offspring, such as with t ...

Concert A concert is a live music performance in front of an audience. The performance may be by a single musician, sometimes then called a recital, or by a musical ensemble, such as an orchestra, choir, or band. Concerts are held in a wide variet ...

, Showman and Vibrasonic incorporating the architecture of the 5F6-A Bassman ( long-tailed-pair phase inverter), separate bass, treble and volume controls on each channel and a complex "harmonic vibrato" tremolo circuit (6G5 and 6G5-A). The Pro, like many of the Professional Series, became solid-state rather than tube- rectified, eliminating rectifier sag; output was now pushed up to 40 watts through a pair of

5881 6L6 is the designator for a beam power tube introduced by Radio Corporation of America in April 1936 and marketed for application as a power amplifier for audio frequencies.J. F. Dreyer Jr."The Beam Power Output Tube" New York: McGraw-Hill, ''Ele ...

s or 6L6GCs. The earliest brownface Pro Amps featured prototype aluminum knobs; these models primarily contain parts from 1959.

Blackface

In late 1963 the Fender amplifier line was reclothed in black Tolex with black-painted control panels. The Pro circuit (AA763) was largely the same as its predecessor, but reverted to tube rather than solid-state rectification and dropped the costly "harmonic vibrato" for a simpler electro-optic tremolo circuit. The Pro was joined in 1965 by the Pro Reverb, essentially the same amplifier with

spring reverb A reverb effect, or reverb, is an audio effect applied to a sound signal to simulate reverberation. It may be created through physical means, such as echo chambers, or electronically through audio signal processing. Echo chambers The first r ...

and 2×12" speakers; the non-reverb Pro was discontinued the following year.

References

{{Fender Instrument amplifiers