Browse Helix Models and Effects

Recorded with an American Telecaster in the middle pickup position. Dynamic Room reverb added for ambience.

The Mark IV was launched by Mesa/Boogie in 1990 as a three-channel 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). The "crunch" channel is designed for use by hard rock and heavy metal rhythm guitarists. There were two versions of this amp. Mark IVs built from the start of production until about September 1993 are referred to as version A; amplifiers made from late 1993 until the end of production in 2008 are known as version B. Early Bs 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. Another distinct difference in the "B" version, is the low voltage power supply. This section is susceptible to catastrophic failure. It is a result of electrolyte leakage, from the filter capacitors Mesa used in the low voltage PSU. The leakage will cause erosion of PCB traces and component leads. The close proximity of these components, to the power amplifier bias resistors, can result in failure of power tubes and it's associated components. The repair process is extremely difficult and time consuming. Even with these shortcomings, the Mark IV's are in terms of sound, one of Mesa's best. Both versions are highly regarded; production of the Mark IV ceased in 2008.

This model is for the amp's "Rhythm 1" clean channel.

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