Early Mesa/Boogie Mark Series amps were something of a sensation, but even with the line now having stretched all the way to the massively featured Mark V, many fans of these powerful little beasts feel the evolution peaked at the end of the Mark II range, with the Mark IIC+.

Though at the time they were simply the next step along the line – a tweak to the Mark IIC, which was just a relatively minor twist away from the Mark IIB before it, and so forth – players soon noticed (often in hindsight) that these “+” amps sounded fantastic. Not only did they have a revised lead channel that issues delectably creamy, bright, high-gain lead tones, but their cleans were often hailed as sweet and superior, too. So revered is the Mark IIC+, in fact, that good ones often command up to twice or more the price of the Mark IIC and Mark III amps that immediately preceded and superseded them.

So, given that this wasn’t an entirely new amp by any means, what was the big deal about that Mark IIC+ circuit? Depending on how you look at it, the answer can be “a lot” or “just a little.” Technically speaking, the Mark IIC and IIC+ used a slight modification of the same circuit board found in the Mark IIB. Mesa Engineering never officially distinguished the “+” in the literature at the time, either; it was simply the latest iteration of the “C” line, which itself was the last of the Mark IIs. Externally, the Mark IIC+ is recognized by the “+” sign added by hand in black marker above the power-cord entry point on the back of the chassis, and by a slight change in the front control panel, which says “Pull Deep” above the Master 1 control, rather than “Gain Boost” (some amps originally built as IICs might have had the “+” added when returned to the factory later for upgrade, but should generally have “Pull Gain” above Master 1).

Much of what was different about the Mark IIC+, therefore, was begun with the Mark IIC, itself an upgrade that cured the Mark IIB’s noisy reverb circuit (on the amps that had reverb at all, of course) and “popping” lead/rhythm channel switching. What inspired the good folks at Mesa Engineering to tweak things a little further, though, and to add that hand-inked “+” to the chassis, seems to have been a staff member’s own quest for the ultimate shred tone.

While the original Boogie is the brainchild of Randall C. Smith (who is still head honcho at Mesa to this day), staffers Doug West and Mike Bendinelli appear to have been the evil geniuses behind the “+” revisions. According to information compiled by Edward P. Morgan through direct chats with West and Bendinelli (much of which has been published in his informative entries on the Boogie Board forum, where he posts as “Boogiebabies”), the pair dug their hands into the Mark IIC lead circuit in late winter of 1983, while Smith was attending the Musicmesse trade show in Germany. Bendinelli, an engineer, pushed the gain further and further, also voicing it for West’s request to make it brighter, adding another gain stage to the already toothsome cascading-gain lead circuit for which Boogies have long been famous. Upon his return, Smith approved the revisions and the Mark IIC+ went into production in February of ’84. The run, however, was short, and the “+” went out of production surprisingly quickly, as the new Mark III – with added a crunch channel – was brought in circa March of ’85. Many Boogie players will tell you that certain iterations of the Mark III (again, there are several, designated by the color of marker stripe, or lack thereof, above the power cord entry point) achieve a lead tone that’s almost indistinguishable from that of the Mark IIC+. Aficionados of the latter, though, usually dispute this. Wherever your tonal preferences lie, the Mark III used a different and more affordably produced printed circuit board, as well as a less-formidable power transformer, so there were significant changes in production between Mark IIC+ and Mark III, however you slice it.

Like the Mark amps before and after them, Mark IIC+ Boogies were available with a range of options. To the base 60-watt head or combo you could add reverb, graphic EQ, 100-watt output stage with SimulClass (a simultaneous use of Class A and Class A/B tube pairings, or one or the other independently), an export power transformer, an upgraded Electro-Voice or Altec speaker, and an exotic hardwood cabinet with wicker grille. Our featured amp, owned by Todd Duane, is a rare example of a rare breed, with all the extras other than the export transformer (pointless in and of itself, unless you plan to tour outside North America). It’s a major looker, too, in outstandingly clean and original condition, with a luscious Bubinga cabinet. Of its tone and performance, Duane tells us this “is one amp that can really do all styles exceedingly well. I’ve used mine for country, worship, and Top 40 classic rock gigs. You can do it all; metal (Metallica ‘Master Of Puppets’), progressive rock (Dream Theater), whatever you want to dial in. The clean channel is a great warm-blackface-type clean, while the gain channel has an awesomely warm, squishy and chewy rhythm/lead tone.”

Further to Mark IIC+ lore, the marker scrawl below the power cord intake on the back of the chassis is most often “MB” for Mike Bendinelli, not because he designed the revisions (although he did), or even built all the amps (which he didn’t), but simply because he performed most of the final checks before each Boogie went out the door. Some amps might even display “RCS” for Randall Smith himself, who occasionally stepped in on final check duties. And while any “+” or scribbled initials in marker can obviously be forged by unscrupulous Mark II owners looking to add value to their non-“+” amps, there’s another well-publicized test to reveal the hallowed lead circuit, short of sending it to Mesa Engineering to open up and verify. This so-called “loop test” simply requires that you plug a guitar into the “Return” jack of the effects loop, switch the amp to Lead, play a sustained note, and change the Lead Drive and Volume 1 controls while the note decays. If these knob twiddlings can’t be heard in the sustained note – no change of volume or tone – the amp has the “+” lead circuit. Ka-ching!

This article originally appeared in VG September 2014 issue. All copyrights are by the author and Vintage Guitar magazine. Unauthorized replication or use is strictly prohibited.