Fender Custom Shop Prosonic Professional Tube Amp Combo Green Lizard w/ foot switch & custom cover 

Amp is in great condition, never gigged, little use and stored in a climate-controlled room. Fully functional, includes manual, foot switch and custom-made cover. 

Made in USA – Corona, CA

Serviced by Nau Engineering, Rochester, NY

The Prosonic introduced several features that had previously been seldom, or never before, seen in Fender amplifiers. Its most unusual feature is the switchable and power amplifier bias scheme, allowing on-the-fly changes of operating mode and output power (as well as subjective tonal differences). This feature, originally found on Randall Smith's amplifiers, allows the Prosonic to achieve a versatility very rarely seen from mass-market instrument manufacturers. The Prosonic's rear-mounted RECTIFIER/BIAS switch lets the user select from the following three options:

1. Solid-state rectification with fixed bias (marked "S.S. AB2"). Listed at 60 watts .
2. Tube rectification with fixed bias (marked "AB2"). Listed at 50 watts R.M.S.
3. Tube rectification with cathode bias (marked "A"). Listed at 30 watts R.M.S.

Unlike many amplifiers marketed as "Class A", the Prosonic truly functions as a in the "A" position. Class A refers to the amount of current flowing through the power tubes with zero audio signal, with Class A meaning maximum current flow even with zero signal. This makes the tubes run hotter and gives the power section even more gain at the cost of tube life and noise. The Class-A designation for guitar amplifiers is often a misnomer; Few amps outside of the heralded, also with cathode bias, operate in a true Class-A mode [Albeit, it only did so up to 21 watts RMS]. While the Prosonic featured in the Class A mode and fixed bias in the mode, not all class A tube amplifiers are cathode-biased, and not all fixed biased amplifiers are Class AB. Fixed bias amps, however, require lower B+ Voltages to stay within the Plate Dissipation of the power tubes used; Cathode biasing "throws away" this voltage using conventional Higher Voltage power supplies.

Many players praise the Prosonic's clean channel as being "softer," and more prone to break-up and musically desirable distortion, than more contemporary Fender designs. 

The Prosonic also brought levels of gain (distortion) previously unavailable in a Fender amplifier. Taking a major cue from the first generation of Mesa Boogie amplifiers such as the Mark I (itself a modified Fender design), the Prosonic used additional gain stages in the preamp section that cascaded into one another. 

The Prosonic's factory manual states, "Gain 1 functions as a standard gain stage whereas Gain 2 functions similar to a compressor, adding sustain while reducing 'edge' when the volume is increased. This channel produces great high gain sound at any volume—from bedroom to stadium."

While the vast majority of Prosonics were shipped with the standard black covering, some of the initial Custom Shop run were finished in red and seafoam green pebbled tolex, called "lizard-skin" by Fender. Approximately 300 were made in red and 500 were made in seafoam green. The look of the amplifier borrows simultaneously from several eras of vintage Fender design: black "chicken-head" pointer knobs (as used on circa 1950s "tweed" amps), and the silver grill cloth, jewel lamp, and black control plate as used during the 'black face' period (mid-1960s). (Both models came with green jewel lamps).

An all-tube design, the Prosonic uses standard tubes in the preamp sections, and one for the reverb send on the combo model. Output tubes are 5881/WGCs. The rectifier tube is a 5AR4 (GZ34). The spring reverb unit in the combo model also uses a tube.