Mesa/Boogie Mark Series: every version
Every version, how to tell them apart, how to date one, and what to check before you buy. 9 versions, Early 1970s on.
The Mark series started with the original Boogie of the early 1970s, the first amp with a cascading high-gain preamp, and every Mark since has added switching, channels or options on top of it. Serial numbers run in sequence through each model, so the number, the faceplate labels and a few rear-panel markings identify most Marks. The Mark IIC+ is the one to be careful with: its “+” is a marker-pen stroke, and Mesa upgraded many IICs to C+ spec.
The versions, in order
Mark I (the original Boogie) (Early 1970s–1978)
Original
The first Boogie: a cascading high-gain preamp in a small combo, sold simply as a “Boogie”.
How to spot one
- Serial number starts with the letter A (roughly A1 up to the low A2000s on the last examples from 1978).
- Its cascading high-gain preamp was the first to offer a true lead-style overdrive from the preamp.
- Options included a five-band graphic EQ, reverb, and hardwood or snakeskin-covered cabinets.
- Later originals have pull switches for bright and gain on the control knobs.
Specs
| Power tubes | 6L6 (60 W and 100 W versions) |
|---|---|
| Rectifier | Solid-state (silicon diodes) |
| Phase inverter | Long-tail pair |
Mark IIA (1978–1980)
Mark II
The first Boogie with footswitchable Rhythm and Lead modes, each with its own gain and master.
What changed from the Mark I (the original Boogie)
- A footswitchable Lead mode with an extra gain stage and its own gain and master controls.
How to spot one
- Originally sold as the Mark II; the “A” was added later to tell it apart from the Mark IIB.
- Footswitchable Rhythm and Lead modes, each with its own gain and master volume.
- Mode switching is done with a relay, which can pop when you switch.
- No effects loop: that arrived with the IIB.
- Serial numbers roughly 3000–5574 on 1×12 amps.
Specs
| Power tubes | 4 × 6L6GC |
|---|---|
| Rectifier | Solid-state (silicon diodes) |
| Phase inverter | Long-tail pair |
Mark IIB (1980–1983)
Mark II
The Mark II with a tube-buffered effects loop, and Simul-Class power as an option.
What changed from the Mark IIA
- A tube-buffered effects loop.
- Simul-Class power became an option.
How to spot one
- An effects loop on the rear panel: the first tube-buffered loop on a production guitar amp.
- Rhythm/Lead switching is still by relay; the Pull Lead switch on the Lead Drive knob does the same job as the footswitch.
- Optional Simul-Class power (with a Class A / Simul-Class switch), or a 60/100 W power switch on non-Simul amps.
- Optional five-band graphic EQ and reverb.
- Serial numbers roughly 5575–11000 on 1×12 amps.
Specs
| Power tubes | 4 × 6L6GC |
|---|---|
| Rectifier | Solid-state (silicon diodes) |
| Phase inverter | Long-tail pair |
Mark IIC (1983–early 1984)
Mark II
Quieter switching and a reworked reverb, with “Gain Boost” on the Master 1 pull switch.
What changed from the Mark IIB
- The noisy relay switching was replaced with a quieter system.
- The reverb circuit was reworked to cut noise.
How to spot one
- Quieter mode switching replaces the relay that popped on earlier Mark IIs.
- A reworked reverb circuit cures the noisy reverb of earlier Mark IIs.
- The Master 1 pull switch is labelled Gain Boost (the IIC+ changed it to Pull Deep).
- Serial numbers roughly 11001 to about 12400.
Mark IIC+ (1984–1985)
Mark II
The most sought-after Mark: a revoiced, higher-gain lead circuit, built for only about 14 months.
What changed from the Mark IIC
- The lead circuit was revoiced with more gain from a second cascading drive stage.
- The effects loop was improved so pedal-level effects no longer overload it.
- EQ Auto was added to the graphic EQ switch.
- The Gain Boost pull on Master 1 was replaced by Pull Deep.
How to spot one
- A hand-written “+” in marker on the rear of the chassis above the power cord, usually with the final tester's initials below it.
- Pull Deep is printed above the Master 1 knob instead of Gain Boost.
- The graphic EQ switch has an Auto position that turns the EQ on automatically in Lead mode.
- Factory-built examples start at serial numbers around 12,400–12,500.
- Built for only about 14 months, with fewer than about 3,000 made.
- Chassis codes such as SRG, HRG or DRG describe the build: S = 60 W, H = 100 W, D = Simul-Class, R = reverb, G = graphic EQ; an added X means an export transformer.
Specs
| Power tubes | 4 × 6L6GC |
|---|---|
| Rectifier | Solid-state (silicon diodes) |
| Phase inverter | Long-tail pair |
Mark III (1985 to the late 1990s)
Mark III
Three footswitchable modes (clean, crunch, lead), with revisions marked by a coloured stripe.
What changed from the Mark IIC+
- A third mode (Rhythm 2 crunch), selected by a pull switch on the Middle knob or a second footswitch.
How to spot one
- Three footswitchable modes: Rhythm 1 (clean), Rhythm 2 (crunch) and Lead.
- Rhythm 2 is turned on by the pull switch on the Middle knob or by a separate footswitch.
- The revision is shown by a coloured marker stripe above the power cord: none or black, then purple, red, blue and green.
- Presence and reverb knobs sit on the rear panel of short-chassis amps.
- Simul-Class amps have a Class A / Simul-Class switch and use EL34s in the outer sockets and 6L6s in the inner pair.
- Serial numbers run from about 15,000 to about 28,400.
Specs
| Rectifier | Solid-state (silicon diodes) |
|---|---|
| Phase inverter | Long-tail pair |
Mark IV (A and B) (1990–2008)
Mark IV
Three true channels, each with its own gain and volume. Version B adds a stereo loop and a reverb footswitch jack.
What changed from the Mark III
- The three channels got their own gain and volume controls instead of shared ones.
How to spot one
- Three channels (Rhythm 1, Rhythm 2, Lead), each with its own gain and volume controls.
- Version A was built until about 1993; Version B from about late 1993 to the end of production.
- Version B has a stereo effects loop, a footswitch jack for reverb and a satellite output; Version A has mono loops and no reverb footswitch.
Specs
| Rectifier | Solid-state (silicon diodes) |
|---|---|
| Phase inverter | Long-tail pair |
Mark V (2009–2023)
Mark V
Three channels with three modes each, including Mark I, IIC+ and IV modes, and 90, 45 or 10 W per channel.
What changed from the Mark IV (A and B)
- Each of the three channels got three switchable modes, including recreations of the Mark I, IIC+ and IV.
- A per-channel choice of 90, 45 or 10 W.
How to spot one
- Three channels with three modes each: Clean/Fat/Tweed, Edge/Crunch/Mark I, and Mark IIC+/Mark IV/Extreme.
- Power switchable per channel between 90 W Simul-Class, 45 W and 10 W single-ended Class A.
- Four 6L6s with a bias switch for EL34s, plus a 5U4 rectifier tube used in the lower power settings.
- A channel-assignable five-band graphic EQ.
Specs
| Power tubes | 4 × 6L6 |
|---|---|
| Rated power | 90 W / 45 W / 10 W |
Mark I Reissue (1989–2008)
Reissue
A reissue of the original Boogie with reverb, an effects loop and a Tweed power setting.
What changed from the Mark I (the original Boogie)
- Adds an effects loop, spring reverb, a Tweed power setting and a 100/60 W switch.
- Drops the pull gain and pull bright knobs of later original Mark Is.
How to spot one
- 100 W with a half-power switch that drops it to 60 W.
- A Tweed power setting that lowers internal voltages for a softer feel.
- An effects loop, which original Mark Is don't have.
- Spring reverb on board.
- No pull gain or pull bright knobs, unlike later original Mark Is.
Specs
| Power tubes | 4 × 6L6 |
|---|---|
| Rectifier | Solid-state (silicon diodes) |
| Phase inverter | Long-tail pair |
| Rated power | 100 W / 60 W |
Mark series buying checklist
Date it
- Mark series serial numbers run in sequence through each model, so the number places an amp within its model's run.
- Rough serial ranges: Mark I with an A prefix (up to the A2000s); Mark IIA about 3000–5574; Mark IIB about 5575–11000; Mark IIC about 11001–12400; Mark IIC+ from about 12,400–12,500; Mark III about 15,000–28,400. Ranges overlap near the changeovers.
- Mesa keeps factory records and can look up an amp's build date and original spec from its serial number.
- Technicians often hand-wrote dates or codes on the chassis during inspection, which can also help date an amp.
Check it’s original
- The “+” on a IIC+ is a marker-pen stroke, so it can be faked; a serial number in the right range and the Pull Deep faceplate label are better signs.
- The loop test checks for C+ circuitry: plug the guitar into the effects return, select Lead, and turn Lead Drive and Lead Master. On a C+ they have no effect.
- Mesa converted many earlier IICs to C+ spec for their owners, so a “+” on a lower serial number can be a genuine factory upgrade rather than a fake.
- On a Mark III the stripe is a marker line above the power cord; no mark or a black dot means an early (black stripe) amp.
- A Simul-Class Mark III should have EL34s in the outer sockets, 6L6s in the inner pair, and a Class A / Simul-Class switch on the back.
What usually needs work
- Relay switching on the Mark IIA and IIB can pop or chatter when changing modes.
- Opto (LDR) switching parts are a known failure point on 1990s Mark IVs: dim or flickering channel LEDs, footswitch faults, popping, gain loss or volume drops.
- Most noise, crackle and loss-of-gain problems come down to tubes: try swapping preamp tubes (V1 first) before anything else.
- Reverb faults are usually the reverb tube (V4), or the reverb tank and its cable connections.
Questions buyers ask
How can I tell a real Mark IIC+ from a IIC?
Look for a serial number from about 12,400–12,500 up, Pull Deep above Master 1 (not Gain Boost), and do the loop test: with the guitar in the effects return and Lead selected, Lead Drive and Lead Master should do nothing.
What do the Mark III stripes mean?
They mark circuit revisions. A coloured marker line above the power cord shows the version: none or black first, then purple, red, blue and green.
What is Simul-Class?
A Mesa power section where one pair of power tubes runs Class AB and the other closer to Class A, so the amp can run all four tubes for full power or just the Class A pair for less.
Mark IV A or B: how do I tell?
The B has a stereo effects loop, a reverb footswitch jack and a satellite output on the back. The A has mono loops and no reverb footswitch.
Is there a new IIC+?
Yes. Mesa released an official Mark IIC+ reissue in 2024.
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