Mesa-Boogie 750 User Manual

M

Owner's Manual

ESA

B

OOGIE

Greetings from the Home of Tone

Congratulations on your choice of the Big Block 750 as your Bass amplifier and
welcome to the MESA/Boogie family! As a discriminating player you probably know
that you have purchased the most comprehensive instrument for amplifying Bass that
is available. What you might not realize is that this entitles you to all the experience,
resources and commitment our twenty-five years of service to musicians world wide
has to offer. Our responsibility is to help you sound great! So, if at any time you feel
you need help or direction, we are here for you...a phone call away.

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:

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.

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.

READ AND FOLLOW INSTRUCTIONS OF PROPER USAGE.

Table of Contents

Precautions 0
Overview 1/2

FRONT PANEL:

INSTRUMENT INPUT 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 PAGE 12
DIAGNOSING PRE-AMP TUBE PROBLEMS 13
PARTS SHEET 14

Overview:

Operating Instructions

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

of all-tube preamp experience and

stands firmly on the same soulful sounding ground as all

Simul State™ Power

- which utilizes a tube driver stage feeding a bank of custom designed

M-PULSE

amplifiers, with architecture based on our 30 years

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 harnesses not one, but two power blocks, putting at your immediate disposal ridiculous amounts of transient handling
current produced by the 20 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!

FRONT VIEW: Big Block 750

TM

S I M U L S T A T E B A S S A M P L I F I E R

E N G I N E E R I N G

OVERDRIVE

INPUT TUNER

MUTE

REAR VIEW: Big Block 750

CAUTION

:

Unplug power
before removing fuse or
bolts holding chassis

S

E

U

F

F

U

E

S

POWER FUSE

15A

120 V~

SLO

60 Hz

BLO

15 A

POST PRE

GROUND

LIFT

DIRECT OUTPUT

LEVEL

HANDBUILT IN PETALUMA , CALIFORNIA

GAIN

PASSIVE-MID ACTIVE-MID FREQUENCY

BASS

5 - STAGE VACUUM TUBE AMPLIFIER

M-PULSE BIG BLOCK 750

SIMUL STATE BASS AMPLIFIER

TUBE DRIVEN-MOSFET POWER

EFFECTS

RETURN SEND

FOOT

SWITCH

TUNER

PAGE 1

SLAVE

LEVEL OUT

SPEAKER

OUTPUT

SUGGESTED LOAD

2 OHMS MINIMUM

TREBLE MASTER

O.D.MASTER

AC OFF

OVERDRIVE

Overview:

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.

(Continued)

In addition to this traditional gain stage, the
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
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

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.

BIG BLOCK

delivers its massive power to the ground via the SPEAKER OUTPUT section which offers two types of jacks for

BIG BLOCK

or additional power amplifiers are needed for large (coliseum size) venues. In this scenario the

features an all-tube overdrive stage with its own separate OVERDRIVE

Finally, two punched grille vents serve as exhaust ports for the heat that is forced out of the two mosfet power blocks 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

that is all yours.

. Now let’s get to each of the individual controls and see how they interact to create an individualized sound

PAGE 2