[MrSandMan]

The Mesa Boogie Mark IIC and IIC+ are treading the reputation in vintage enthusiasts across the world as the holy grail Boogie, along with the classic Mark I, due to their glorified rhythm channels, and lead channels.

The Mark IIC features a silence footswitching system and a new modification to the reverb circuit. The reverb was noisy on the Mark II, a similar problem persisted with some IIB models as well. The correction Mesa Engineering came up with simply involved a resistor swap and an alter to the ground lead placement. And this mod is still written as one of the 'official' mods, and is sent to Mesa Boogie authorized techs (it runs about $50.00 for this mod). Mesa/Boogie no longer do this mod at the factory.

The Mark IIC+ was the last of the Mark II series, but certainly not the runt. It featured a more responsive and useful lead channel, more importantly, an enhanced circuitry fix in the effects loop. Unlike earlier Mark II models, the footswitch could be used without the signal overloading the inputs. However, the volume pedal on the Mark IIB cannot be implemented on Mark IIC+s.

Many owners, dealers, sellers often say the "+" refers to the amp having a graphic EQ, but they are mistaken. The misunderstanding may have been created in the mid 1980s, when Mesa Boogie released the Studio .22 model and then changed the name to Studio .22+, which featured enhanced wiring, etc. All Mark II models could be made with EQ as an option, but not all of them were built with the EQ. However, a Mark IIC+ could, for example refer to a 100 watt amp without an EQ or reverb.

Anyone could easily tell if a particular amp is a "+" by looking for a hand-written black "+" mark directly above where the power cord attaches to the back of the amp. Many dealers and sellers will increase the price on a Mark IIC+, however, some often don't know anything about what the "+" signifies - they often don't know where to find the "+" mark. Indeed, the “+” mark itself can be forged. An owner can call Mesa/Boogie to verify the serial number against the records. Mesa Boogie only made approximately 1,400 Mark II amps before going to the Mark IIC+.