The Marshall Plexi: Icon of Rock Tone
While tens of thousands of guitar amps have been produced in the pantheon of music equipment, the true lifeblood of rock ‘n’ roll is formed with the tributaries of just a handful of amps. Because much of the entire recording industry owes gratitude for this small grouping of amps, the price of them shot through the roof—each at their own pace, of course, with different inflection points that sent interest and price surging. One such amplifier is the Marshall Plexi.
“Plexi”, like so many influential pieces of gear, isn’t the official model name, but rather referring to the acrylic panel that covers the control surfaces on the front and back of the amps. For the most part, the “Marshall Plexi” covers amps made by Marshall from 1965 up until the ‘70s, and are 100-watt machines. Of course, not all Plexis feature such a wattage, but most. These amps served up a decent feature set for their time, but Spartan by today’s standards, with no modern amenities of which to speak. Two channels with two inputs each, along with knobs for presence, a three-band EQ and volume knobs for each channel was all anyone got, and customers of the time couldn’t have been happier.
Those happy players were so ubiquitous in the Plexi’s heyday that it might be easier to list big names that didn’t play one instead of those who did. Hendrix, Clapton, Page, Van Halen, Townshend, Angus Young, Johnny Ramone and quite literally hundreds of others relied on these amplifiers to hew their crafts. The release of the Plexi culminated with the surging popularity of rock music in 1965, a time when musicians hungry for distorted leads were starting to require more power at bigger venues. Before the days of a carefully-curated PA system, rock musicians needed loud amps to fill huge concert halls without leaving those in the cheap seats wanting for more. Pete Townshend recognized the need for such an amp after a show in which he could hear audience members talking to each other even as the amplifiers roared. Marshall doubled down on this business opportunity by inventing modular stackable speaker cabinets for even more volume, creating what today’s musicians still refer to as a “full stack”.
If there’s one thing to be known about the gear industry back then, it’s that consistency is nonexistent. There is no one “official schematic” for the Plexi model, and attempting to open your own and create a schematic is an exercise in futility. Marshall’s engineers simply used what they had on hand and made it work, tweaking each one to sound its best even if one of the parts bins ran a little dry. As Marshall began selling more and more, this approach slowly became less and less practical from a dollars-and-cents (or maybe pounds-and-pence) perspective, and Marshall ended up relaunching the series with the most definitive change in the line—Marshall moved away from handwiring each amp and into PCB construction.
The "Plexi” models are considered by some to be the pinnacle of British amp designs and purists have been known to spend some serious duckets acquiring one. At one point we were one such collective purist, using an actual Plexi as a reference for our Dirty Little Secret MKIII. Unlike prior iterations of our flagship foundation overdrive, the DLS MKIII was engineered to be a part-for-part distillation of this circuit, using a bit called a “mu-amp” that sounds strikingly similar to real vacuum tubes. In the 12 years since its original launch, many Marshall pedals have come and gone, but for our money, the DLS still stands alone at the top. Featuring an exacting recreation of that legendary preamp, our DLS can essentially toggle between 50- and 100-watt models simply by increasing the operating voltage from 9 to 18 volts. Stacking pedals into the DLS is just like using the amp; run all your drives and fuzzes before the DLS and watch it handle the whole chain like a champ. And with an internal switch to toggle between Super Lead and Super Bass modes, nothing gets you closer to the real thing than the Dirty Little Secret.