Mesa-Boogie Rectifier Stereo User Manual

M

ESA

Owner's Manual

OOGIE

B

Hello from the Tone Farm...

YOU, the smart player and all around intuitive human, have put your trust in us to be
your amplifier company. This is something we do not take lightly. Our reward is that
we've made a classic amplifier and by choosing this amplifier, you have become part of
the MESA family...Welcome! Our goal is to never let you down. Your reward is that you
are now the owner of our most popular selling power amp, the 2:100. Bred of fine all
tube amp heritage...benefiting from the many patented pioneering MESA/Boogie circuits
that led to the refinement of your new instrument. Feel confident, as we do, this product
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 CONTROLS & SWITCHES

LEVEL CONTROLS 2

PRESENCE 2

POWER ON 3

STANDBY 3

MODERN 3

REAR PANEL - SWITCHES & JACKS

INPUTS A / B 4

BIAS SWITCH 4

GROUND LIFT 5

SPEAKER JACKS 5

TUBE BAY 6

DRIVER TUBES 12AX7A 6/7

AC RECEPTACLE 7

LINE FUSE 7

TUBE MAINTENANCE

DIAGNOSING POWER TUBE FAILURE 8

DIAGNOSING PRE-AMP TUBE FAILURES & PROBLEMS 9

Feature Article by Randall Smith On Bias Adjustment 10/12

SPEAKER HOOK-UP GUIDE & IMPEDANCE MATCHING 13/14

POSSIBLE HOOK-UP SCHEMES - Amplifier to Speaker Cabinets 15/18

WIRING EXAMPLES USING THE SIMUL-CLASS 2:100 19/20

Feature Article By Randall Smith On How Tubes Work 21/23

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: 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.

Be sure to have the warranty card filled out by the store at which it was purchased and return to

Mesa/Boogie.

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.

READ AND FOLLOW INSTRUCTIONS OF PROPER USAGE.

Operating Instructions

Overview:

MESA/Boogie

. Here the stunning performance of the

Head

when the

Dual

Congratulations on your choice of the

Family. This 2 rack space unit is born of legendary stock and traces its lineage to the mighty

Dual

RECTIFIER STEREO 2:100

as your power amplifier and welcome to the

Dual Rectifier Solo

is faithfully recreated in a stereo format that duplicates the power section exactly

is set to its Silicon Diode rectifier setting. Rectifier tubes were not included in this package, as their size did not permit
inclusion along with an overall consensus among players asked, that those needing 200 watts of this type of aggressive power would
require the tighter, faster response of the silicon diodes. The eight 6L6 power tubes (4 per side) are fan cooled and kick out 100 watts
of all-tube power per channel. Three 12AX7s’ make up the driver section and these are housed inside the unit. Preamp tubes used in
this manner rarely wear out as there is little or no exposure to excessive vibration and they are operating under minimal gain require­ments .

RECTIFIER STEREO 2:100

The
to a trigger pulse sent by either of its companions, the

is a “smart” power amplifier as it contains the MODERN Switchable Voicing feature. It responds

Rectifier Recording Preamp

or the

TriAxis Programmable Preamp

.

When a cable is connected to the MODERN trigger port and this feature is switched via any tip-to-ground type logic, the negative

2:100

feedback in the power section of the

Triple Rectifier Solo Heads

FRONT VIEW

2:100

and has become the most recorded sound in heavy modern rock.

is reduced, unleashing a sound of true ferocity. This is a trademark sound in the

E N G I N E E R I N G

LEVEL A LEVEL B

MODERN

ONON

Dual

and

REAR VIEW:

WARNING

:

To reduce risk of fire or

electric shock, replace fuse with

same type and rating only. Do not

I
N
P
U
T
S

RECTO INPUTS RECTO INPUTS

CHAN. B CHAN. A

SPEAKERS

expose this unit to rain or moisture.

BIAS

SWITCH

NORMAL

6L6

EL34

MUST MATCH TUBES SEE OWNERS BOOK

8

OHM

4

OHM

E N G I N E E R I N G

POWER FUSE

120 V~

60 Hz

6 A

MODERN

2:100

WARNING

:

To reduce risk of fire or electric
shock, Do not remove cover. No user­serviceable parts inside. Refer
servicing to qualified personnel.

GROUND

SWITCH

LIFT

6 A

SLO

BLO

GROUND

NORMAL

OHM

8

SPEAKERS

4

OHM

PRESENCE

I
N
P
U
T
S

STANDBYPOWER

PRESENCE

S

E

U

F

F

U

E

S

PAGE 1

Overview: (Continued)

most commanding sounds in rack-mount history as

Without further delay, connect up your favorite preamp and get ready to experience one of the

Recto

power goes stereo for the first time in this amazing package.

NOTE: BEFORE YOU MOUNT THE

with one of the above mentioned
you need, you may find one of the more forgiving

Class2:90

more suited to your style or application. Save the packing material and keep the amplifier in perfect condition and you

2:100

IN YOUR RACK! This is an extremely aggressive and powerful amplifier intended for use

MESA

preamplifiers in large venues. If after trying it you feel you may have chosen more amp than

MESA

strereo power amplifiers such as the

Stereo 2:50

or the

Stereo Simul-

should be able to return it to the place of purchase for full credit toward one of the less aggressive models that might perhaps better
suit your needs. If this stunning, agressive power well suits your playing style and needs, congratulations and by all means rock on.

And now on to the controls and features of
it will prove to be quite worth while in the end and will help you to enjoy

your

new

2:100

. Please take some time along the way and read this operating manual,

your

new amplifier to its full extent.

FRONT PANEL CONTROLS

LEVEL CONTROLS:

pre-amp, try a setting of 2 as a starting point. If the amp is being fed by lower-level signals such as those from (minus) -20db type
effects units, etc..., you may need to raise the Levels as high as 2:00 or 3:00.

Each channel of the

2:100

has its own LEVEL Control. If the amplifier is being fed by signals from a typical

E N G I N E E R I N G

LEVEL A LEVEL B

MODERN

PRESENCE

PRESENCE CONTROLS:

ONON

STANDBYPOWER

Each channel on the

NOTE:

nected to a speaker or load resistor!

either channels’ LEVEL Control is dialed to anything other than zero.

to comply to this procedure can cause serious damage to your
section.

PRESENCE

Remember to turn the LEVEL Control to zero on any channel not con-

A Load must be present at all times when

Failure

2:100’s

2:100

has its own “active” PRESENCE Control. These controls provide a boost

power

in the upper mid-range/lower Treble zone, which are the frequencies that tend to get obscurred in the energy of live performance; use

them when you need to cut through a “loud mix.”

Use these PRESENCE Controls with discretion as they can make for some ear

E N G I N E E R I N G

LEVEL A LEVEL B

MODERN

PRESENCE

ONON

STANDBYPOWER

PRESENCE

damaging, almost harsh sounds if set too high - especially if the TREBLE Control
on your pre-amp is dialed up extremely high.

PAGE 2

FRONT PANEL CONTROLS: (Continued)

POWER SWITCH & POWER UP:

First remove the protective covers from the tubes (plastic webbing) before con-

necting the A.C. cord to a power receptacle.

Make all necessary connections including pre-amp, effects, speakers and instrument before

E N G I N E E R I N G

VEL A LEV

MODERN

ENCE

ON

POWER

ON

STANDBY

PRE

neglected by the user.) But ignoring this procedure everytime the amplifier is used will shorten the tubes toneful life.

Never remove any of the power cords terminals. All three terminals of the A.C. power cord must be connected and always check
that the power receptacle has the proper voltage present. Also, make sure that the power cord is inserted all the way in when
connecting to a power receptacle.

STANDBY SWITCH:

Perfect for set breaks...this toggle switch also serves an even more important purpose. In the standby

position the tubes are at idle so that during power up they may have a chance to warm up before being put to use.

E N G I N E E R I N G

VEL A LEV

ON

MODERN

ON

you flip the STANDBY switch to its ON position. AC power is turned on via the POWER switch
and indicated by the pilot lamp. Before switching on the power, place the STANDBY switch into
its Standby position and allow at least 30 seconds of warm-up time before switching the STANDBY
switch to the ON position.

This start up procedure helps extend tube life by preventing a high voltage turn-on surge. (How­ever, all of our amplifiers are tested to withstand this extra stress, just in case this procedure is

Before the power is switched on, make sure the STANDBY switch is in the standby position.
And as mention above, wait at least 30 seconds before changing to the ON position.

ENCE

POWER

MODERN:

STANDBY

This jack is the trigger port for the auto-tracking MODERN feature. This jack can receive a trigger pulse from the
corresponding jack on the
modifies the amount of negative feedback in the power section when the MODERN mode in Channel 2 of the

PRE

MESA Rectifier Recording Preamp

or

Triaxis Programmable Preamp

. This smart power amp auto-

Recto Preamp

is

selected or switched to via the Footswitch. The Front Panel LED indicates when the feature is active and negative feedback has been

reduced.

E N G I N E E R I N G

MODERN

If used with the

ONON

jacks and store under a user preset. This reshaping is crucial to the

Triaxis

- use one of the 4 programmable switch

sound of the MODERN mode and using this feature duplicates the

STANDBYPOWER

circuit and the performance of this punishing mode in the

Dual &

Triple Rectifier Solo Heads.

NOTE: Use unshielded cable of good quality when connecting the

MODERN

trigger port to your preamp or master switching unit.

I
N
P
U
T
S

RECTO INPUTS RECTO INPUTS

CHAN. B CHAN. A

WARNING

:

To reduce risk of fire or

electric shock, replace fuse with

same type and rating only. Do not

expose this unit to rain or moisture.

BIAS

SWITCH

NORMAL NORMAL

POWER FUSE

6L6

120 V~

60 Hz

EL34

MUST MATCH TUBES SEE OWNERS BOOK

8 OHM

E N G I N E E R I N G

6 A

MODERN

6 A

SLO

BLO

WARNING

:

To reduce risk of fire or electric
shock, Do not remove cover. No user­serviceable parts inside. Refer
servicing to qualified personnel.

GROUND

SWITCH

LIFT

GROUND

8 OHM

I
N
P
U
T
S

Shielded cable will also work ,but is unnecessary.

PAGE 3

REAR PANEL FEATURES:

REAR VIEW:

WARNING

:

To reduce risk of fire or

electric shock, replace fuse with

same type and rating only. Do not

I
N
P
U
T
S

RECTO INPUTS RECTO INPUTS

CHAN. B CHAN. A

SPEAKERS

INPUTS:

inputs for pre-amps and/or effects, depending on how you have your system wired. You may drive the

expose this unit to rain or moisture.

BIAS

SWITCH

NORMAL

6L6

EL34

MUST MATCH TUBES SEE OWNERS BOOK

8

OHM

4

OHM

Located on the Rear Panel, these two 1/4” jacks are the Channel A and Channel B inputs for the

E N G I N E E R I N G

POWER FUSE

120 V~

60 Hz

6 A

MODERN

2:100

WARNING

:

To reduce risk of fire or electric
shock, Do not remove cover. No user­serviceable parts inside. Refer
servicing to qualified personnel.

GROUND

SWITCH

LIFT

6 A

SLO

BLO

GROUND

I

N

NORMAL

P
U
T
S

OHM

8

SPEAKERS

4

OHM

2:100.

2:100

These are the

with your pre-amp

S

E

U

F

F

U

E

S

directly or choose to come from the last effect in a chain and drive the power amp this way. Either way is fine and up to your

preference. The amplifier is stereo, offering two separate channels of

WARNING

:

To reduce risk of fire or

electric shock, replace fuse with

same type and rating only. Do not

expose this unit to rain or moisture.

I

N

P

U

NORMAL

BIAS

SWITCH

6L6

T
S

RECTO INPUTS RECTO INPUTS

EL34

MUST MATCH TUBES SEE OWNERS MANUAL

E N G I N E E R I N G

POWER FUSE

120 V~

60 Hz

6 A

6 A
SLO
BLO

WARNING

:

To reduce risk of fire or electric
shock, Do not remove cover. No user­serviceable parts inside. Refer
servicing to qualified personnel.

GROUND

SWITCH

LIFT

GROUND

NORMAL

amplification. If you wish to use only one of its channels, it is neces­sary to: 1 ) Make sure a speaker (or load resistor) remains con-

I

nected to a speaker jack on both channels, including the unused

N
P

one; or 2 ) Turn the LEVEL Control of the unused channel to zero.

U

(This is necessary because an amplifier channel receiving any amount

T
S

of signal at its input will require a “load” at its output - or damage will
most likely result.)

MODERN

the signal path between preamp and power section as it occurs in the
a driver tube responsible for the effects return stage and all related circuitry in the

The RECTO INPUTS are wired such that when the companion

tifier Recording Preamp

Dual

and

Triple Rectifier Heads

is used, the circuit remains exactly true to

. To achieve this duplication,

2:100

must be removed and this includes the

Rec-

LEVEL Conbtrols as they are part of this circuitry. As a result, when using the RECTO INPUTS, you will use the Recto Pre LIVE
OUTPUT Control as your overall final master level control.

TUBE BIAS:

2:100

of the

Your

2:100

was designed with versatility in mind. The BIAS SWITCH allows you to adapt the power output section

in order to use the other classic pentode power tubes, the British style EL 34. These tubes are largely responsible for the

signature sound of many immediately identifiable and wonderful sounding amps created in Great Britain

WARNING

:

I

N

NORMAL

P
U
T
S

RECTO INPUT

To reduce risk of fire or

electric shock, replace fuse with

same type and rating only. Do not

expose this unit to rain or moisture.

BIAS

SWITCH

6L6

EL34

MUST MATCH TUBES

E N G I N E

POWER

120 V~

60 Hz

6 A

and used on some of the best recordings to date. The nature of their sound is usually brighter in the
extremely high frequencies...some players find this almost thin at first. However, aficionados of the EL34
sound know that nothing has the lushness of harmonics or spread like a power amp using EL34’s. In
truth EL34’s do focus in on a region of upper harmonics that 6L6’s reproduce, but not really enhance, in
the same way the EL34’s do.

This characteristic is sometimes preferred for sounds that range from a soft clip that would be used for
chording or soloing, to an all out high gain crunch or lead sound. Players that use mostly these types of sounds may prefer the EL34
clip to the 6L6’s that come standard in the
you will likely prefer the stock compliment of 6L6’s that the

2:100

. If you need a variety of sounds and rely on a clean chording sound much of the time,

2:100

comes fitted with. We feel the 6L6 is a more balanced sounding
tube that produces plenty of harmonic lushness, while at the same time delivering the rich lows that are crucial to both a warm clean
sound and huge, tight high gain crunch sound.

PAGE 4

REAR PANEL

(Continued)

TUBE BIAS: (Continued)

We recommend the 6L6 for reliability: In our many tests and continued use of the currently

available EL34 type power tubes on the market today, we regret to say that they do not appear to be as rugged in construction as the

2:100

available 6L6. This is another reason why your

was shipped with 6L6 power tubes. If you plan to use the EL34’s we suggest
that you keep a full set of tubes and extra fuses with you during all performances in the event of a tube failure occurring when using
the currently available EL34’s.

GROUND LIFT:

This mini-toggle switch is extremely useful in reducing the hum and buzz caused by ground loops which occur in

rack installations. Ground loops occur when there is more than one path for grounds between electronic units. There are three main

type of ground loops; each one contributes its own trademark component of buzz or hum. The three
types of ground loops are:

I

N

1 ) Grounds being connected via the ground lugs of the power cords on the units. The rule-of-thumb here

P

is that one and only one unit in a rack should have a connection to the AC power ground; all the other

U
T

units in the rack should have their grounds lifted by using 3 to 2 adaptors on their AC plugs. We suggest

S

grounding the Power amp (no adapter).

E R I N G

FUSE

6 A
SLO
BLO

WARNING

:

To reduce risk of fire or electric
shock, Do not remove cover. No user­serviceable parts inside. Refer
servicing to qualified personnel.

GROUND

SWITCH

LIFT

GROUND

NORMAL

2 ) Ground loops occuring because of two or more audio cables connecting two components. The most common solution is to
diconnect the shield from the sleeve connection at one end of some of the inter-connecting cables, so that only one cable between
each device has an intact ground shield. Some experimentation is required to find which cable is best for conducting the ground, and
which cables are best suited to have the special “clipped ground.” We recommend trying the intact-ground cables for the signal path
which flows, say, from an Effects Send jack to an effects unit; and trying the clipped-ground method on the cable which connects the
effects output back into an Effect Return.

3 ) Ground loops created by the physical contact between the metal chassis of the components and the steel rack rails. It is for this
third type of ground loop that the GROUND ISOLATION Switch was provided. This switch effectively lifts the electronic circuit ground
from the metal chassis ground (which otherwise must be done manually by disconnecting a wire inside of the amp.) Here again, the
rule is that one device in your system - and usually only one - needs its circuit ground connected to its metal chassis ground; all others
should be lifted (in other words, disconnected) for quietest operation. (Some effects units provide similar switches; some are con­structed such that the input ground and the output ground are permanently separated; in other cases, the method used to isolate the
grounds is unclear.) Again, some experimentation is vital to discovering which combination of “lifted” and “grounded” works best in
your rack...and our GROUND ISOLATION Switch makes this process much easier.

NOTE: If the

2:100

is operated outside of a rack installation, the switch should generally be set to the Normal position, or squealing,

buzzing and oscillation may occur. Always check this switch before thinking that something has gone wrong with your amp!

SPEAKER OUTPUTS:

The

2:100

provides one 8 Ohm and two 4 Ohm speaker outputs for each channel. When using a single

8 Ohm speaker or 8 Ohm cabinet on a channel, connect the speaker or cabinet to the 8 Ohm jack. If using two 8 Ohm speakers
(assuming they are wired in parallel) or cabinets on a channel, plug them both into the 4 Ohm jacks. ( The logic here is that two 8 Ohm

loads connected in parallel add up to a 4 Ohm total load.) Mismatching of speaker

CHAN. B CHAN. A

SPEAKERS

8 OHM

4 OHM

8 OHM

4 OHM

SPEAKERS

impedance will not cause damage or severe loss of power. (Extreme mis-matches
will decrease tube life, however.)

MESA/Boogie

4x12 and 4x10 cabinets come

standard wired to 8 Ohms and are wired in series-parallel.

Some Non-

MESA

4x12 cabinets are wired 16 Ohms using four 16 Ohm speakers.

By wiring all four speakers in parallel, you can reduce the cabinet to an impedance
load of 4 Ohms (assuming the speakers are 16 Ohms each.) Further back in this manual we have included a number of possible
wiring schemes - amps to cabinets, that may be of some use to you when considering how to configure your rig.

PAGE 5