Rear Panel Features - Mesa/Boogie .50 CALIBER SERIES Owner Operating Instructions

That "sweet spot" setting for maximal funky clean tones also depends on the right amount of Bass and
Middle. Between 4 and 6 for both these controls will usually give the best balance against "that perfect
Treble setting" where the tone is springy and bright but not hard sounding.
The Bass and Middle response has been very carefully designed to allow fatness in the Rhythm mode
while avoiding tubbiness or flab when footswitching to a crunch, lead or metal tone.
REVERB The .50 Caliber amplifier includes a 3-spring miniature Hammond-Accutronics unit and all tube
send/return electronics. Tonal quality is outstandingly good. Note: If both Reverb and Master controls are
set extremely high, acoustical feedback between the speaker and spring may occur. This does not
indicate a fault or malfunction with the amplifier, and is only caused by an inappropriate and unnecessary
combination of settings. Should this "reverb howl" begin to occur, turn down either the Master or the
Reverb.
PRESENCE This control lets you dial in your exact choice of extreme high frequencies and sets up the
basic brightness of the overall tone. Brighter tones generally sound clearer and cleaner while less bright
tones are "warmer". Season to your liking... most players run the Presence between 5 and 9.

REAR PANEL FEATURES

FUSE Should your .50 Caliber Boogie blow its fuse, be sure to replace it with a similar amperage,
slow-blow type. Should the fuse repeat its blowing, check for a bad power tube. Often it will light up red
hot all over the large metal plate inside. Repeated instantaneous fuse blowing indicates a bad rectifier
diode or a shorted filter capacitor. Any of these events is very uncommon in the .50 Caliber Boogies.
GROUND This switch is often helpful in reducing buzzes which originate in the AC power wiring outside
the amplifier. Leave the switch in its center OFF position unless position A or B definitely helps. This
usually occurs only when the ground pin on the AC plug is being defeated via a ground-lift adapter at the
wall socket. In the center OFF position your Boogie cannot be the source of annoying "ground shocks" to
the microphones, etc.
DIRECT This feature provides a variable strength signal output originating right from the speaker jack.
Thus, good tone is supplied, all Effects and Reverb are included, and there is absolutely no loss of the
Boogie's tone when running from the Direct to a mixing board or another amplifier. But bear in mind that
speakers themselves exert a tremendous coloration to the tone, -primarily by rolling off the highs very
steeply above 5 to 6 kilohertz. Consequently, many players will still prefer the recorded sound of a
microphone "listening" to the speaker.
In some sophisticated set-ups, players run the Direct into their effects rack and then from the last effect
device into other external amplifiers. This is the Steve Lukather/Bob Bradshaw hookup. But such a
set-up cannot route the last effect output back into the original Boogie. Also note that a speaker or load
resistor must remain plugged into a speaker jack when using the Direct. Otherwise the amplifier will
operate improperly and damage may result from running without a load. Suggested value of the load
resistor is 8 ohms, 50 watts minimum.
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