Fender Prosonic
The Fender Prosonic guitar amplifier was produced by Fender Musical Instruments from 1996 to 2002. Available in head and combo versions, the Prosonic featured several departures in design from traditional Fender amplifiers such as the Bassman, Twin Reverb, and Deluxe Reverb. Designed by Bruce Zinky as a project for the Fender Custom Shop, the amplifier later had a non-Custom Shop production run at the Fender facilities in Corona, California. (Most contemporary Fender amplifiers are produced in Mexico). Initially priced to compete with buyers in the so-called boutique amplifier market who were seeking more distortion than any previous Fender had ever offered. It is believed that high list prices, and deviations from established Fender amplifier designs, swayed many buyers away from the Prosonic. It developed a cult following among serious guitarists, aided by the rise of musician-centric internet communities.
Innovations and sound
The Prosonic introduced several features that had previously been seldom, or never before, seen in Fender amplifiers. Its most unusual feature is the switchable rectifier 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 Mesa Boogie 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:
- Solid-state rectification with fixed bias (marked "S.S. AB2"). Listed at 60 Watts R.M.S.
- Tube rectification with fixed bias (marked "AB2"). Listed at 40 Watts R.M.S.
- Tube rectification with cathode bias (marked "A"). Listed at 30 Watts R.M.S.
The Prosonic is generally regarded as a "Class-A" amplifier, although this is not technically accurate. While the three settings give a different feel to the Prosonic, the labels can be misleading, as all choices result in Class AB2 operation of the power amplifier stage. The Class-A designation for guitar amplifiers is often a misnomer, as heralded amps such as the Vox AC-30 also do not operate in a true Class-A mode. Furthermore, pushed into power amp distortion, even true Class A amplifiers become, electronically speaking, Class AB. Aside from warmer sound, the major benefit of keeping the amp in "A" mode is that users can change tubes without needing to bring it to an amplifier technician to have it rebiased. This obviously is very useful if a tube is blown during live playing, as a new one can simply be popped in.
A channel-switching amp, the Prosonic offers a clean channel that features a blend of traditional Fender sounds with the influence of Vox amplifiers, frequently attributed to the Class A mode. 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. Detractors view this trait as an apparent "darkness" in tone, and perceive this lack of the typical Fender "sparkle" as merely an undesirable lack of clean headroom.
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. Although Fender had been designing amps with some facility for built-in distortion/overdrive since at least the late 1960s, never before had they arrived at a sound so readily usable for modern high-gain styles of music, and far removed from what many players consider to be archetypical Fender tones. 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."
Configurations and cosmetics
Prosonics were available first from the Fender Custom Shop, and later from Fender Musical Instruments, and for each production run, combo amplifiers featuring dual Celestion 10" speakers, and head versions were available. (Zinky's initial combo versions, some of which made it to stores, used two 12" speakers.) Although the circuitry is identical, users with experience playing both production runs claim the Custom Shop run is of a higher quality. The combo version featured a tube-driven, Accutronics spring reverb unit. This unit has been said to have the largest (i.e., longest) reverb tank ever featured in a Fender amp, enabling it to yield very long durations of reverberation (echo). The head version omitted the reverb tank.
While the vast majority of Prosonics were shipped with the standard black tolex covering, some of the initial Custom Shop run were finished in red and seafoam green pebbled tolex, called "lizard-skin" by Fender. Approximately 500 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). (Green tolex mmodels came with green jewel lamps; red tolex models came with a red one.) Head versions have a flat script logo reminiscent of the short-lived "brownface" designs (of the early 1960s), while combo models have a more common raised/rounded Fender logo variety.
Specifications and electronics
An all-tube design, the Prosonic uses standard 12AX7A tubes in the preamp sections, and one for the reverb send on the combo model. Output tubes are 5881/6L6WGCs. The rectifier tube is a 5AR4 (GZ34). The spring reverb unit in the combo model also uses a 12AT7 tube.
Although the Prosonic is a channel-switching amp, both channels share the same active-EQ section. Defying conventional logic, the Prosonic offers independent master volumes for each channel, or rather, on the clean channel, simply one volume control. The drive channel features the aforementioned dual cascading-gain controls, plus an additional master volume.
Two outputs for speaker cabinets are provided, (with switchable 4/8/16 ohm operation on the head version). The back panel also provides for a line-level effects loop, as well as an input for the (one-button) footswitch.
Design quirks and lack of sales
Towards the end of the 1990s, poor sales relegated many of the existing stock of Prosonics to closeout sale status. Theories abound as to why it was never a great success with players; foremost was its high price. Originally listing at nearly $2000 and commonly retailing for $1300-1600, it was simply perceived as too much money despite innovative design and glowing reviews. The Prosonic also suffered from something of an identity crisis; the cosmetics suggested classic Fender tones, and many players desiring an amp for Blues/Country playing, for example, were put off by the over-the-top lead channel. Conversely, the demographic for high-gain amplifiers, generally the domain of practioners of heavy metal and the fledgling nu-metal genre, and dominated by products from Marshall and Mesa Boogie, had long written off Fender as incapable of producing amplifiers catering to their style. The combo's 10-inch speakers, though specially designed & voiced for the Prosonic to handle huge amounts of power, were seen as too small by players favoring 12-inch speakers. The mechanical relay-based channel switching, designed to provide a more pure signal path, produced a large pop upon channel switching at low volumes, unlike other electronically buffered designs- this deliberate design choice was nonetheless perceived as the premier 'design flaw' among players. Several of the Prosonic's other quirkier design elements, such as the shared EQ and line-level effects loop, were designed for studio use and weren't ideal for live playing. Understandably, buyers were attracted to the amp's flexiblity, and when used on-stage, these studio-friendly features were perceived as design flaws. Like many other high-powered combo amplifiers, the Prosonic's weight, at 60 lbs, was another less-than-popular characteristic.
Influence on future products
In 2006, Fender introduced the Super-Sonic model, which draws heavily on elements of the Prosonic. Available in head and 1x12" combo forms (as opposed to the Prosonic combo's 2x10" form), the Super-Sonic also features the pre-Silverface voiced clean channel paired with the cascading-gain drive channel as pioneered on the Prosonic. Absent is the switchable rectifier or facility to run the amplifier in Class A mode, but a 2 channel EQ has been added to the clean side, as well as a "voicing switch" offering tones inspired by the classic Fender Vibrolux and Fender Bassman models.
References
- Fender Australia. "Prosonic Combo".