Mesa/Boogie Mark Series

The Mesa Boogie Mark Series is a series of guitar amplifier made by Mesa Engineering (more commonly known as "Mesa/Boogie"). It was Mesa's flagship product until the introduction of the Rectifier series, and the amplifiers are very collectable.

Mark I

The very first Mark I was made in 1969, when Smith, as a joke, modified Barry Melton's (Country Joe and the Fish) Fender Princeton amplifier. He removed the standard 10 inch speaker and modified the chassis to fit the larger transformers that were needed by the 4-10 tweed Fender Bassman, the circuit that he had added into the 12 watt Princeton. Finally, mounting a 12 inch JBL D-120, a popular speaker of the time, Smith had created what would be the first Boogie.

Randall Smith took the "hot-rodded" Princeton into the front store. Coincidentally, Carlos Santana was present and "wailed through that little amp until people were blocking the sidewalk." Impressed, Santana told Smith, "Man, that little amp really boogies!", thus providing the current name for the amplifier and the company.

The first Boogies are referred to as Mark I's, though they were not given this name until the Mark II was released. They were 60 or 100 watt combo amps with a 12-inch speaker, primarily Altec-Lansing 417-8H Series II. The Mark I had two channels: The "Input 2" channel, voiced like the Fender Bassman, and the high gain "Input 1" channel, which produced the overdriven "Boogie lead" sound used most notably by Carlos Santana on Abraxas, and by The Rolling Stones' Keith Richards and Ron Wood, who used the amps live and in the studio from 1977 until 1993.

This amp in its original form is very collectable. Reverb was optional, and not present on many early Boogies. Later, Mark I models were available with reverb and/or graphic EQ.

Early models have "slave out" and "reverb" labeled on the back with Dymo stick; they do not have any "pull lead" capabilities on the volume controls. Later models had "Pull Bright" and "Pull Boost" on the volume controls. The front panel controls were Volume 1, Volume 2, Treble, Middle, Bass, and Master. These early models are fairly inconsistent, since many of them were "custom" models, made-to-order for various buyers.

Mesa/Boogie has stated the original and the reissue have a "looser" lead sound because the first two preamp stages occurs before the tone controls. In the later Mark II and III models, there is only one gain stage before the tone controls. This signal chain is an issue of some dispute among Boogie owners.

S.O.B. (Son of Boogie)

The S.O.B. was introduced sometime during the Mark II era. This was Mesa/Boogie's first attempt at having a reissue of the Mark I. It had 2 inputs and its controls were Volume 1, Volume 2, Master, High, Middle, Low, Limit or Presence (depending on the version).

Mark II

Mark IIA

The Mark II introduced channel footswitching, and wasn't referred to as the "Mark IIA" until the Mark IIB was issued. It was also available as a head, which could be hooked up to a number of different speaker combinations, although a 1x12 cabinet was typical. However, the reverb circuit is considered noisy and the footswitching made a popping sound when used; both of these features were later improved on the Mark IIC. The preamp gain on the Mark IIs occurs after the tone controls and so, according to Mesa/Boogie, the IIA has a "tighter, more focused sound" than the Mark I.

The IIA and IIB, and some late-model Mark I amps, used a silicon device called "fetron" in place of one of the 12AX7 preamp tubes, and included a switch for configuring the amp for either fetron or 12AX7 operation. The reason for using a fetron was to address some of the problems associated with microphonic 12AX7 tubes in a high-gain situation; its use was later discontinued.

Mark IIB

The Mark IIB introduced an effects loop and an expanded control panel, featuring both a lead drive and a lead master dial. More importantly, it marked the introduction of Mesa/Boogie's "simul-class" system, where two of the power tubes (always 6L6s) run in class AB pentode while the other two tubes (either 6L6s or EL34s) run in class A triode. In a simul-class amp, running all four tubes generates approximately 75 watts RMS of power; running only the class A tubes produces about 15 watts. Also available were non-simul-class Mark IIBs in both a 60 watt version and a 100 watt version that allowed shifting down to 60 watts by turning off a pair of power tubes.

The two input jacks on the front panel are marked "Input" and "Foot Switch." The front panels read Volume, Treble, Bass, Middle, Master, Lead Drive and Master. It has "Pull Bright" on the Volume, "Pull Shift" on the Treble, and "Pull Bright" on the Master.

Mark IIC & IIC+

The Mark IIC featured a quieter footswitching system and a new mod to the reverb circuit. According to Sacks, "The reverb was noise-ridden on the Mark II, a problem which persisted with some IIB models as well. The solution Mesa came up with involved resistor swaps and a change in ground lead placement. That mod[ification] is still on the books of 'official' mods, which they send to their authorized techs; it runs about $50." Mesa/Boogie no longer does this modification at its own factory.

The Mark IIC+ was the last of the Mark II series and featured a more sensitive lead channel and, more importantly, an improved circuitry in the effects loop. Unlike earlier Mark II models, pedals could be used without the amp's signal overloading their inputs. However, the volume pedal option on the Mark IIB cannot be implemented on Mark IIC+s.

Some owners/dealers/sellers say the "+" refers to an amp having an EQ, but they are mistaken. The mistake may have originated in the mid 1980s, when Mesa/Boogie issued their Studio .22 model and then changed the name to Studio .22+, which featured improved wiring, etc. All the Mark II models could be made with EQ as an option, but not all of them did. A Mark IIC+ could, for example, refer to a 100 watt amp without EQ or reverb.

One can 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 increase the price on a Mark IIC+ but often don't know anything about what the "+" means--they often don't even know where to find the "+" mark. Indeed, the mark itself can be forged. An owner can call Mesa/Boogie and ask them to check his or her serial number against their records. Mesa/Boogie only made about 1,400 Mark II amps before going to the Mark IIC+.

The Mark IIC and IIC+ are gaining reputations in vintage circles as the best Boogies, next to the classic Mark I, due to their much-praised rhythm channels, and to a lesser degree their lead channels.

Mark III

The Mark III was launched by Mesa/Boogie in 1985. It introduced a third channel, a "crunch" rhythm sound right in between the rhythm and lead channels. This amp has a dual footswitch system: one footswitch alternates between the current rhythm mode and the lead mode, and the other selects either the clean rhythm mode or the crunch rhythm mode. The two rhythm modes share all of their controls, while the lead mode only shares the rhythm modes' tone stack, featuring independent gain and master volume controls. The Mark III ceased production in 1989.

Mark IV

Mesa Boogie Mark IV

The Mark IV was launched by Mesa/Boogie in 1990. Is was the state-of-the-art Mesa/Boogie three-channel combo amp, with independent controls for all three channels, except bass and mid, which are the same for both Rhythm 1 (clean) and Rhythm 2 (crunch). There were two versions of this amp. Start of production until about September 1993 Mark IV's are referred to as version A; amplifiers made from late 1993 until the end of production in 2008 are known as version B. Early B's have an attached power cord, like the A version. Some differences: version A has no footswitch for reverb or stereo effects loop, and the lead channel is much like the Mark IIC+'s. Version B has switchable reverb, a single switchable stereo effects loop, and an output to drive another power amp. Its voicings are altered slightly. Both versions are highly regarded; production of the Mark IV ceased in 2008.

Mark V

Mesa/Boogie unveiled the Mark V on 15 January 2009 at the 2009 Winter NAMM Show. It features many of the sounds and features made famous by previous Mark series amps, in addition to more recent features such as voicing switches, silicon/tube rectifier, contour function, etc.