Mesa/Boogie Dual Rectifier
The first of Randall Smith’s famous line of hot-rodded amps started appearing with the Mesa/Boogie moniker around 1970. However, early amps known as “Princeton Boogies”— Fenders that Smith heavily modified—date as far back as 1967. Working in what he called “the Dog House” in Lagunitas, California, Smith started experimenting to see if he could cram a Bassman-like amp into a Princeton-size cabinet.

It worked. The 100-watt, 6L6-powered amps soon garnered attention from such high-profile players as Carlos Santana and Keith Richards, almost immediately establishing Mesa/Boogie as a serious contender in the amp market.

Modern-Day Alternatives

But while Smith’s team released many notable designs thereafter, Mesa’s most influential amp—the Dual Rectifier—came roughly 20 years later, in 1991. Whereas previous Boogies had much in common with Fender circuits, the Dual Rec’s lineage has more British-like origins. R&D guru Doug West made an urgent phone call to Smith from his hotel room one evening late in the ’80s. He’d noticed many guitarists at the time were leaning towards specially modified Marshalls, and he felt it was time for Boogie to respond.

After lots and lots of listening, the company began work on a design with cascading gain sections for more brutal tones. They used a smaller chassis for the prototype, crowding it with tubes, rectifiers, and other components in search of the right sound. Once they’d perfected it, they found transferring the same sound to a printed-circuit-board version was just as challenging. But by late 1990 they’d figured it out.

The Dual Rec on Record

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As its name suggests, one of the keys to the new high-gain Boogie’s sound was its use of two rectifiers. Wall voltage is AC (alternating current), meaning it exits the wall socket as a sine wave. But amps need DC (direct current)—a continuous voltage. All tube amps have rectifiers, either a tube (sometimes two) or solid-state diodes. The latter tend to result in higher voltages and, therefore, more clean headroom at higher volumes.

The lower voltages of tube rectifiers tend to result in earlier breakup and a nice, bluesy distortion. At high volume, tube-rectified circuits also tend to exhibit more “sag”—a pleasing, naturally compressed sound often associated with vintage amps. One of the most intriguing aspects of the new Dual Rectifier was that you didn’t have to choose either one or the other—you could switch between tube or solid-state rectos with the flip of a switch on the back of the amp.

Another Dual Rec innovation was its bias switch, which let users choose which high-gain octal tubes—6L6 or EL34—they preferred. It also featured two footswitchable channels—a handy feature many of us take for granted today, but that was pretty mind-blowing at the time. The amp’s 11 tubes include two 5U4 rectifiers, five 12AX7s, and four 6L6s or EL34s. Why two 5U4s? Just one can’t handle all the current.

When all’s said and done, the Dual Rec—and its many Boogie spinoffs (not to mention hordes of copycat amps)—is most prized for its ability to instantaneously switch from crushing distortion and infinitely sustaining leads to brawny, super-clean sounds. Early adopters included a who’s-who of metal players, including Metallica’s James Hetfield and Kirk Hammett, Dream Theater’s John Petrucci, as well as Tim Mahoney of 311, Dave Grohl, and many, many others.