Mesa/Boogie MARK IIC+ - Presence

To connect your Processors via the Eects Loop:
1. Connect the SEND to your processor’s INPUT.
2. Connect the RETURN to your processor’s OUTPUT.
NOTE: If your processor has Stereo OUTPUTS – or is Stereo IN and OUT ¬– connect the Mono Inputs of the
processor to the IIC+’s Loop’s SEND and RETURN. Most Stereo processors provide a Mono option on the Inputs
and Outputs and most times, though not always, the Mono signal is processed in the LEFT Channel. In some
cases, you may be able to connect the additional (output) channel of a stereo processor to another amplifier
to achieve a stereo eect.
NOTE: Keep in mind that connecting two amplifiers in the above manner (Stereo via the Eects Loop) can result
in ground loops and unwanted noise from the amplifiers having diering Ground references. This is sometimes
remedied by lifting one of the amplifier’s circuit to chassis Ground, and depending on the amplifiers, this might
be a switchable feature. DO keep the Mark IIC+ Grounded in this scenario (don’t disconnect the Ground prong
on the Power Cable) as it needs to remain grounded to help prevent the risk of shock. Alternatively, there are
buers and isolating devices on the market, including some made by us here at MESA, that can help with these
types of grounding issues. Call your local music retailer to investigate your options should you experience these
unwanted noises when connecting two amplifiers in this manner.
Cabling: It is always best to use the shortest cable lengths possible when patching in your processors. If you
intend to run very long cable lengths, use a buer. Even though the amplifier’s Eects Loop IS buered, there
can be some minimal sonic penalty the longer the cable length becomes. Always use shielded, high-quality
cables to connect your processors to the Eects Loop.
Levels and Compatibility: One way to check the quality of your processors and also match the levels, is to do
this simple test: Set up a sound without processors in the Loop. Listen to the sound and observe the feel. Insert
your processing into the Loop and do the same.
Next, remove the SEND and RETURN cables from the IIC+’s Loop, and if the sound gets better, or the level
jumps up, you will know that either your processor’s levels are set too low and need adjustment, or perhaps
the processor’s output section is in question or just not a good match.
If unplugging the cables from your Eects Loop reduces the signal level, simply lower the Input and/or Output
Levels on the processors. Repeat the test until there is no – or very little – dierence in levels when the Eects
Loop patch cables (processors) are inserted and removed from the Eects Loop.
PRESENCE
The PRESENCE is a Tone control of sorts located in the later part of the signal chain in the power section. It
adjusts the mix of a predetermined (high) frequency relating to the negative feedback circuit in the power
section. It is a very powerful control, and its setting can give the impression of opening the sound up and adding
brightness and attack, or clamping it down, compressing and darkening it. These characteristics, in turn, aect
how you perceive dynamic content, as brighter sounds appear as faster while warmer sounds feel slower and
more relaxed.
This addition ¬– or removal – of top end with the PRESENCE control can seem to move the sound forward and
back (near or far) in the musical landscape (mix). It also has an impact on our perception in the time domain
and helps define whether the sound feels either “tight-tracking” and “fast” or “slow” and “behind the beat.”
Clean sounds handle higher PRESENCE settings well to a point, then things can become too forward in the top
end. Overdrive sounds usually call for lower to medium PRESENCE settings. Overly high settings of the PRESENCE
there can quickly lead to unfocused, and at real extremes, even buzzy top-end characteristics, especially with
single note lead playing, which is rarely good. Some Crunch Rhythm and Heavy chording sounds can tolerate
added cut and sizzle from the medium to higher range of the PRESENCE, but how much usually depends on
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