Mesa-Boogie 50 CALIBER PLUS User Manual

MESA/BOOGIE

MESA/BOOGIE

.50 CALIBER PLUS
OWNER OPERATING INSTRUCTIONS

CONGRATULATIONS! You've just become the proud owner of the boldest sounding, easiest
operating 50-watt amplifier there is… and you're sure to enjoy it!

The Spirit of Art in Technology

GREAT SOUND
special, high-gain "personality". We tuned (and retuned) its preamp section to make it capable of
monstrous, fat lead tones while still offering plenty of crystal-clear headroom for rhythm. Its power
section has been fitted with 6L6 tubes in a specially modified (and patented) circuit that offers fluid
dynamic response with plenty of “give”. And a custom-designed vintage Celestion speaker - made
exclusively for MESA/Boogie - provides a perfect blend of full-bodied clarity and warm “crunch”.

GREAT SIMPLICITY
It's nearly impossible to come up with a bad sound or a wrong setting. And here to help you get
started is a brief explanation of your new amp's features and controls.

FRONT PANEL

INPUT JACK This ¼” guitar jack is the instrument input to your amplifier. Patented “Dual Mode”
circuitry makes this single jack work for both Rhythm and Lead… providing very high headroom for
sparkling clean Rhythm, and super high gain for monstrous Lead playing. Be sure to use a
good-quality, shielded guitar cord.

. Many months of patient, painstaking R&D were spent in developing the .50 Plus's

. One of the .50 Caliber's greatest virtues is its incredible simplicity of operation.

FEATURES

FOOTSWITCH JACK
provided. When the red LED on the footswitch box is illuminated, the .50 Caliber is in the Rhythm
mode… red equals Rhythm. Stepping on the button switches the amp into the Lead model and the
LED goes out.

Should you lose or forget your footswitch you can activate the Lead mode by pulling out the "Pull
Lead" switch on the Volume knob.

VOLUME (GAIN)
overall sensitivity to your guitar's output, and must be mixed in conjunction with the Master(s). In the
Rhythm mode, the maximum clean setting is usually around 6 (varies with stronger or weaker
pickups) and most players find their favorite cleanest, brightest spot between 3 and 5. But if you want
some breakup in the Rhythm mode, turn the Volume up high.

This ¼” jack connects to the Lead/Rhythm footswitch via the unshielded cable

This control is active in both Rhythm and Lead modes. It establishes the amplifier's

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In the Lead mode, the Volume knob is intentionally less sensitive so that there is no need to reset it
when switching between the two modes. With most guitars, distortion begins around 2 with a real
nice sounding blues-type tone reminiscent of old Fenders turned up loud. Settings above 3 or 4
produce the more modern and monstrous distortion sounds. Gain and distortion increase slowly as
the Volume setting is increased, often producing the tightest, best-sounding heavy crunch tones
between 7 and 9.

To prevent undesirable squealing, noise and feedback, the Volume should be reduced as playing
loudness - via the Master and Lead Master - is increased.

MASTER This control regulates the power amplifier level and the actual overall loudness. (In Lead
mode, the Master and the Lead Master work together “in series” to perform this function.) If you run
the Volume at 10 and both Masters below 2 (in Lead mode), Grandma can nap in the next room
while you annihilate Manhattan with monstrous metal performance! You'll still get the sound and feel
of big amps cranked way up.

Turning up the Master begins to reveal the .50 Caliber's incredible sound-per-watt capability… it's
noticeably louder than other comparably rated amps! The maximum performance for loud, clean
Rhythm and hot, high-gain Lead playing comes around 5 and 4 on the Volume and Master, with the
Lead Master set between 3 and 4. This puts the amplifier right in the middle of its range for great
sound and easy footswitchability. The taper of the two controls is gradual enough so that dialing in
both great Lead and great Rhythm sounds is quite easy to do.

However, the taper of the Master control gets radical above 5 and begins to unleash the maximum
from your .50's power section. And this power amp has been designed to deliver its greatest crunch
when turned up smoking loud! But you must turn down the Volume as you increase the Master, to
avoid excessive squealing.

When you want to turn down to soft playing levels and continue to footswitch between Lead and
Rhythm, merely turn down the Master. This will preserve the volume balance between the two
modes.

LEAD MASTER

This control affects only the Lead mode; it operates in series with the regular Master
to determine the loudness of the Lead mode in relation to Rhythm. It should generally be adjusted
after setting the Volume and Master controls. Since the Lead Master is located “before” the Effects
Send jack (and the regular Master) in the signal path, it also acts as an effects send level for the
Lead mode.

TREBLE This is the most powerful of the three rotary tone controls. At high settings (7 ½ and
above) it will appear to minimize the effect of the Bass and Middle controls. But they will become the
stronger controls when the Treble is set below 5. For those who split hairs tonally and want the very
best, most bubbly and funky clean tones, you should find the exact spot on the Treble where all three
tone controls are balanced. This will usually be somewhere between 5 and 7.

When playing hard-core crunch, especially at very soft practice volumes, the 50 will usually sound
better with the Treble and Presence set quite high. This will help produce sustain and harmonic
jumps at soft playing levels.

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For silky, warm and round jazz tones, run the .50 Caliber in the Rhythm mode with the Treble set low
and the Bass and Middle turned up higher. Add sparkle with the Presence control.

BASS, MIDDLE

You've already read our recommendations for these settings in the TREBLE section

above, and because the tone controls are interactive, all three must be set together.
That "sweet spot" setting for maximal funky clean tones also depends on the right amount of Bass

and Middle. Settings of 4 to 6 for both of these controls will usually provide 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 reverb, and
all-tube send/return electronics. Tonal quality is outstandingly good. NOTE: If both Reverb and
Master(s) controls are set extremely high, acoustical feedback between the speaker and the reverb
springs 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 Masters 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 sound “warmer”. Season to your liking ... most players run the Presence between 5 and

9.

GRAPHIC EQUALIZER

This feature is fun to use and definitely expands the tonal flexibility of the .50
Plus. (But for those who opt not to use the Graphic - don't worry! All of the R&D for tonal performance
was conducted without using the Equalizer… so that it wouldn't be necessary for obtaining good
tone.) The three-position EQ Switch selects either “EQ IN” (bottom position); “EQ AUTO” (which
automatically activates the EQ whenever you switch to the Lead mode); or EQ OUT (the unlabelled
center position). If you are using the optional EQ Footswitch to control the Equalizer remotely (via the
rear panel “EQ Footswitch” jack), the front panel switch should generally be set to its center EQ OUT
position, since the footswitch cannot override the “EQ IN” mode (although it can be used to turn on
the EQ when you're in Rhythm mode with "EQ AUTO" selected).

Although there are hundreds of ways to set the Graphic, there is one setting that's particularly useful
and popular - the classic “V”! Move the first and last sliders about three-fourths of the way up. Move
the second and fourth sliders two-thirds of the way up. Move the center slider about three-quarters of
the way down… then fine-tune your sound using just this center slider. (You'll hear how a slight
adjustment at the 750 Hz position makes a dramatic difference in the sound, whether you're playing
with moderate distortion, heavy distortion, or perfectly clean.) This “V” setting makes the amp sound
even bigger, bolder, fatter and “hazier”… especially at very soft playing levels.

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