Mesa Boogie Big Block 750 User Manual
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Greetings from the Home of Tone
...You, smart player and intuitive human, have put your trust in us to be your amplifier
company. This is something we do not take lightly. By choosing this instrument to be a
part of your musical voice, you have become part of the Mesa family...WELCOME!
Our goal is to never let you down. Your reward is that you are the new owner of an amp,
bred of fine all tube heritage...benefiting from the many pioneering and patented Mesa
circuits that led to the refinement of your new model. We feel confident, this amp will
inspire many hours of musical satisfaction and lasting enjoyment. It was built with you in
mind, by players who know the value of a fine musical instrument and the commitment it
takes to make great music. The same commitment to quality, value and support we make
to you...our new friend.
Table of Contents
Precautions
Overview _________________________________________________________________________________________ 1-2
FRONT PANEL:
INSTRUMENT INPUT _________________________________________________________________________________ 3
PASSIVE/ACTIVE SWITCH ____________________________________________________________________________ 3
TUNER ____________________________________________________________________________________________ 3
CONTROLS:
OVERDRIVE ______________________________________________________________________________________ 3-4
GAIN ______________________________________________________________________________________________ 4
BASS ____________________________________________________________________________________________ 4-5
PASSIVE MID _______________________________________________________________________________________ 5
ACTIVE MID ________________________________________________________________________________________ 5
FREQUENCY _______________________________________________________________________________________ 6
TREBLE ___________________________________________________________________________________________ 6
MASTER ___________________________________________________________________________________________ 6
O.D. MASTER _______________________________________________________________________________________ 7
POWER SWITCH ____________________________________________________________________________________ 7
REAR PANEL:
FUSE ______________________________________________________________________________________________ 8
A.C. RECEPTACLE ___________________________________________________________________________________ 8
GROUND LIFT, POST/PRE, DIRECT OUT _______________________________________________________________ 8-9
EFFECTS LOOP: Send & Return _______________________________________________________________________ 9
FOOTSWITCH_______________________________________________________________________________________ 9
TUNER ___________________________________________________________________________________________ 10
SLAVE ____________________________________________________________________________________________ 10
SPEAKERS ________________________________________________________________________________________ 10
FACTORY SAMPLE SETTINGS ________________________________________________________________________ 11
PERSONAL SETTINGS ______________________________________________________________________________ 12
DIAGNOSING PRE-AMP TUBE PROBLEMS _____________________________________________________________ 13
PARTS SHEET _____________________________________________________________________________________ 14
PRECAUTIONS & WARNINGS
Your MESA/Boogie Amplifier is a professional instrument. Please treat it with respect and operate it properly.
USE COMMON SENSE AND ALWAYS OBSERVE THESE PRECAUTIONS:
READ AND FOLLOW INSTRUCTIONS OF PROPER USAGE.
YOUR AMPLIFIER IS LOUD! EXPOSURE TO HIGH SOUND VOLUMES MAY CAUSE PERMANENT HEARING DAMAGE !
No user serviceable parts inside. Refer service to qualified personnel. Always unplug AC power before removing chassis.
EXPORT MODELS: Always insure that unit is wired for proper voltage. Make certain grounding conforms with local standards.
WARNING: EU: permission from the Supply Authority is needed before connection.
WARNING: Vacuum tube amplifiers generate heat. To insure proper ventilation always make
certain there is at least four inches (100mm) of space behind the rear of the amplifier cabinet.
Keep away from curtains or any flammable objects.
WARNING: Do not block any ventilation openings on the rear or top of the amplifier. Do not
impede ventilation by placing objects on top of the amplifier which extend past the rear edge of
its cabinet.
WARNING: Do not expose the amplifier to rain, moisture, dripping or splashing water. Do not
place objects filled with liquids on or nearby the amplifier.
WARNING: Always make certain proper load is connected before operating the amplifier.
Failure to do so could pose a shock hazard and may result in damage to the amplifier.
Do not expose amplifier to direct sunlight or extremely high temperatures.
Always insure that amplifier is properly grounded. Always unplug AC power cord before changing
fuse or any tubes. When replacing fuse, use only same type and rating.
Avoid direct contact with heated tubes. Keep amplifier away from children.
Be sure to connect to an AC power supply that meets the power supply specifications listed on
the rear of the unit. Remove the power plug from the AC mains socket if the unit is to be stored
for an extended period of time. If there is any danger of lightning occurring nearby, remove the
power plug from the wall socket in advance.
To avoid damaging your speakers and other playback equipment, turn off the power of all related
equipment before
making the connections.
Do not use excessive force in handling control buttons, switches and controls. Do not use
solvents such as benzene or paint thinner to clean the unit. Wipe off the exterior with soft cloth.
AC OFF
S I M U L S T A T E B A S S A M P L I F I E R
TM
PASSIVE-MID ACTIVE-MID FREQUENCY
FRONT VIEW: Big Block 750
INPUT TUNER
OVERDRIVE
GAIN
BASS
TREBLE MASTER
O.D.MASTER
OVERDRIVE
5 - STAGE VACUUM TUBE AMPLIFIER
CAUTION
:
Unplug power
before removing fuse or
bolts holding chassis
POWER FUSE
15A
SLO
BLO
120 V~
60 Hz
15 A
F
U
S
E
F
U
S
E
GROUND
LIFT
EFFECTS
SPEAKER
OUTPUT
RETURN SEND
SUGGESTED LOAD
2 OHMS MINIMUM
REAR VIEW: Big Block 750
HANDBUILT IN PETALUMA , CALIFORNIA
SIMUL STATE BASS AMPLIFIER
TUBE DRIVEN-MOSFET POWER
M-PULSE BIG BLOCK 750
POST PRE
DIRECT OUTPUT
LEVEL
FOOT
SWITCH
SLAVE
LEVEL OUT
TUNER
PASSIVE
ACTIVE
Operating Instructions
Overview:
Congratulations on your choice of the M-PULSE BIG BLOCK 750 as your amplifier and welcome to the MESA/Boogie Family!
First we would like to thank you for choosing us as your amplifier company. This is something we never take for granted and you will
come to find that we are here to help you sound your best should you ever need help. We feel confident that your new amplifier will
bring you many years of rewarding inspiration and create for you a newfound freedom to express through your music.
This mighty powerhouse joins the innovative band of M-PULSE hybrid bass amplifiers as the heavyweight king of headroom with its
urgent big venue tone. It represents the ultimate marriage of simplicity and versatility and will surprise you daily with its fundamental
musicality and tone.
The BLOCK stands firmly on the same soulful sounding ground as all M-PULSE amplifiers, with architecture based on our 30
years of all-tube preamp experience and Simul State™ Power - which utilizes a tube driver stage feeding a bank of custom designed mosfet output devices. This design seamlessly integrates the best sonic qualities of old-world tube circuitry and modern high
power mosfet technology to arrive at a stunning blend that is both musical and powerful. In the BIG 750’s case, that is doubly true.
This monolith of tone puts, at your immediate disposal, ridiculous amounts of transient handling current produced by the 12 heavy
duty custom designed mosfet devices. This means when you want to say something with your instrument, your voice will be heard
with accuracy, both harmonically and in the time domain. Every bassist knows how important that is!
PAGE 1
Overview: (Continued)
Looking at the Front Panel, it is apparent how logically the controls are laid out before you, creating a simple and intuitive platform
for expression. However, don’t let this simplicity deceive you as to the incredible shaping power of this preamp. The tone controls
are voiced such that minimal shaping is needed to achieve a warm musical blend, yet should you want to create your own signature
sound, they can take you anywhere you wish to go quickly and effortlessly.
This tone control stack features two MID controls. A wide band passive MID works magically with the wide-band active BASS and
TREBLE controls to create a balanced, spatial blend, while a semi-parametric MID allows frequency specific shaping over a wide
range that covers low, mid and high mid/low treble frequencies. This array is simple to use, yet provides all the shaping power you will
need while keeping the tweaking to an inspiring minimum.
In addition to this traditional gain stage, the BIG BLOCK features an all-tube overdrive stage with its own separate OVERDRIVE
and MASTER controls. This footswitchable mode brings everything we’ve learned building high gain guitar amplifiers over three decades to focus on bass guitar and creates an incredible new frontier of truly usable overdriven bass sounds.
The Rear Panel neatly showcases all the features you would come to expect in a amplifier of this caliber and ensures all your interfacing needs are covered.
A balanced XLR DIRECT OUTPUT captures the entire preamp signal and features both PRE and POST options while its dedicated
DIRECT LEVEL control allows you to match levels to all types of consoles. There is also a GROUND LIFT switch for the DIRECT
circuit to help ensure a quiet signal when connecting to consoles that may have different ground references.
A dedicated TUNER circuit with both Front and Rear Panel Outputs features a footswitchable MUTE function for silent tuning when
the footswitch is connected in stage or studio environments.
Outboard processing is handled through the series EFFECTS LOOP which is activated when cables are inserted into the SEND and
RETURN jacks.
A SLAVE OUTPUT and dedicated LEVEL control are provided for capturing the entire sound of the preamp and power section. This
is useful when another BIG BLOCK or additional power amplifiers are needed for large (coliseum size) venues. In this scenario
the SLAVE is the perfect feed signal because it will pass on everything you do to the sound and give you control over the signal
strength.
The BIG BLOCK delivers its massive power to the ground via the SPEAKER OUTPUT section which offers two types of jacks for
cabinet interfacing. Standard jacks allow connection under any scenario with any cable, while the heavy duty NEUTRIK SPEAK-ON
connectors lock the cable in place for speaker enclosures that incorporate this system as a design feature.
Finally, two punched grille vents serve as exhaust ports for the heat that is forced out of the mosfet power block by the dual cooling
fans. NEVER BLOCK THESE VENTS!
NOTE: BLOCKING THE EXHAUST VENTS WILL CAUSE OVERHEATING AND LEAD TO INTERRUPTED PERFORMANCE OR
EVEN DAMAGE TO YOUR AMPLIFIER.
That wraps up the Overview, which has covered the controls and features briefly to familiarize you with the power and possibilities of
the BIG BLOCK 750. Now let’s get to each of the individual controls and see how they interact to create an individualized sound
that is all yours.
PAGE 2
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