Description

MESA Boogie Mark IIb 100/60w 150w speaker

Currently needs some attention and possibly new tubes - the clean channel is working but the gain channel is not working at all. Could need a decent service where they reset the bias as well as replace tubes.

5? x 12AX7 preamp tubes;
2 or 4 6L6 power-amp tubes (like a big Fender)
for 60w or 100w (switchable).
EV Black Shadow 150 watt speaker - dubbed "the greatest guitar speaker ever built"!

I will throw in the original hard-case with rollers for the new owner, because it's quite heavy without the wheels.

Mark IIB:

The Mark IIB is credited as the first guitar amplifier with a tube-buffered effects loop. However, the loop was placed between two critical gain stages, and tended to overdrive some instrument level effects, and also caused volume pedals to act as remote gain controls for the lead mode. Mesa later implemented a mod that caused the effects loop to become more transparent, and smoothed out the lead channel, similar to the IIC+'s lead channel. 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 Mark IIB's front control panel is identical to that of the IIA. 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. The Rear control panel was altered to accommodate the FX Send and Return jacks.