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45 Degrees of Tone: The JTM45 Roundup

Mojave Ampworks Special Edition Plexi 45

Anyone familiar with the JTM45 would surely be jealous of Victor Mason. Not only has he seen more than his fair share of vintage Marshall, Vox, Hiwatt and other rare treasures come through his shop, but Victor recently acquired 26 of the all-time greatest JTM45s ever assembled via the Kronemyer collection, and he’s got the pictures to prove it! This is just one of the factors contributing to the obsessive nature of Mojave (and the associated Plexi Palace). Having been around for over a decade on the internet, Vic has been repairing, restoring, buying and selling vintage Marshalls for quite some time now. Stemming from his early desire to find out how EVH created the classic brown sound, Victor embarked on his journey through countless hours of digging into vintage amps and learning where their strengths and weaknesses lay. Mojave now offers an entire line of amps to serve the classic Marshall tones and well beyond with innovative features and designs. The Mojave Plexi 45 also has two very unique features over a stock JTM45. First is a simple feature to allow volume control by way of throttling the power level. Second is a line level output, which is adjustable and incorporates a ground lift.

Standing apart cosmetically from the rest of the amps, the Special Edition Plexi 45 is built on the same footprint as the Coyote and Scorpion designs, with a white-and-black color scheme and chrome hardware. The head is built with an open grille cage that allows for maximum airflow to keep the set of completely NOS glass cool. The 45 supplied for the roundup consisted of a pair of 1970 NOS Genelex KT66s, 3 Mullard 12AX7s and a Mullard GZ34. Like the Germino, the Plexi 45 is based on the R/S transformers, which are custom wound by Mercury Magnetics.

The chassis is a thing of beauty; the .09” thick aluminum, with a high tensile strength and welded edges and seams will ensure it will not flex, bend or develop fatigue, like the early, folded, softer chassis, and will prevent the heavy transformers from causing the chassis to sink in and sag. Mojave deviates from the original JTM45 by using modern, tight-tolerance parts. Custom manufactured caps and metal film resistors allow each amp to sound as close to the one built before it as the one after it. Consistency is something that Vic definitely strives for, and it shows in the build quality and attention to detail, and the desire to add convenient functionality to his amps.

We found in testing that not only did the amp have an extremely low noise floor, but that it was an authoritative and powerfully voiced amp. There was definitely something different in the tone of the Plexi 45; it was cleaner sounding, but still very bold. Having been to Vic’s shop, I was fortunate enough to play one of the 26 JTM45s he had acquired, and I’m positive that the experience with those amps had more than a little to do with the design of the custom R/S transformers made for his Special Edition model. The amp is built like a tank.

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