Mesa/Boogie pmn User manual

OOGIE
B
MESA
Owner's Manual
Series 2

Hello from the Tone Farm
...You, 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. By purchasing and
choosing this unit 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 now the owner of a great amp, bred of fine all tube amp heritage...benefiting
from the many pioneering and patented MESA circuits that led to the refinement of
your new instrument. Feel confident, as we do, 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.

Precautions
OVERVIEW 1/2
INSTANT GRATIFICATION
(2 DEMONSTRATION SETTINGS) 2
CHANNEL / MODE SELECT
CHANNEL 1: CLEAN & PUSHED 3
CHANNEL 2: RAW, VINTAGE & MODERN 3/4
CONTROLS
GAIN 4/5
TREBLE 5
MIDDLE 5/6
BASS 6
PRESENCE 6
REVERB (Rect-o-Verb Combo & Heads only) 6
MASTER 7
OUTPUT CONTROL 7
SOLO CONTROL 8
TOGGLE SWITCHES
STANDBY 8
POWER 8
REAR PANEL CONTROLS, SWITCHES & JACKS
SLAVE OUT 9
SPEAKERS 9
BIAS SELECT 9/10
FX LOOP: Send & Return 10
EXTERNAL SWITCHING 10
CHANNEL SELECT TOGGLE 11
FUSE 11
AC RECEPTACLE 11
FACTORY SAMPLE SETTINGS 12/13
PERSONAL SETTINGS SHEET 14/15
TUBE DESCRIPTION & TASK CHARTS 16
SPEAKER IMPEDANCE & POSSIBLE HOOK-UP SCHEMES: Amplifiers to Speaker Cabinets 17/22
DIAGNOSING POWER TUBE FAILURES & MAINTENANCE 23
DIAGNOSING PRE-AMP TUBE PROBLEMS 24
BIAS ADJUSTMENT: A feature article by Randall Smith 25/27
TRIODES, PENTODES & IRISHMEN: A feature article by Randall Smith 28/30
PART SHEET 31
TABLE OF CONTENTS
Series 2

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.

Congratulations on your choice of the
SINGLE RECTIFIER 50 Series 2
amplifi er. You have purchased a handbuilt instrument of
the fi nest quality and craftsmanship. A unique blend of yesteryears’ black magic power section design combined with our race-shop
approach to fi nely tuned, high gain pre-amp circuitry leaves the
RECT-O 50
Series 2
RECT-O 50 Series 2 RECT-O 50
standing alone...instantly a classic destined
for vintage status. With two channels housing fi ve defi nitive and distinctly different Modes, a complete array of amazing guitar sounds
can be obtained quickly and easily.
Looking to the Rear Panel assures that all your interfacing needs are covered. A Parallel Effects Loop with a MIX Control provides
tone insurance for even those questionable effects. To use the
SINGLE RECTIFIER 50
in larger rack systems, or to interface to
other power sections, the SLAVE jack and is a welcome feature. Two speaker jack combinations have been provided - two 4 Ohm and
one 8 Ohm - to ensure the proper impedance match to many types of speaker enclosures. The other features will prove to be quite
valuable to you and further along in this manual they are covered extensively.
PAGE 1
Series 2
Operating Instructions
FRONT PANEL HEAD VERSION: SOLO 50 HEAD SERIES 2
Instant Gratification Demo Settings
INPUT
CLEAN
PUSHED
MODERN
RAW
POWER
ON
ON
STANDBY
GAIN
TREBLEMIDPRESENCE BASSMASTER
SOLO OUTPUT
CH2
CH1
REAR PANEL HEAD VERSION: SOLO 50 HEAD SERIES 2
10%
FX MIX RETURN SEND
WARNING:
Unplug power
before replacing
fuse or removing
bolts mounting
F
U
S
E
F
U
S
E
POWER FUSE
2.5 A
SLO
BLO
120 V~
50-60 Hz
2.5 A
WER FUSE
FRONT PANEL COMBO VERSION: RECT-O-VERB 50 SERIES 2
INPUT
POWERSTANDBY
ON
ON
GAIN MASTER PRESENCEBASSTREBLE MID
OUTPUT
CLEAN
PUSHED
MODERN
RAW
CH2
CH1
REAR PANEL COMBO VERSION: RECT-O-VERB 50 SERIES 2
CHANNEL SOLO REVERB
WARNING:
Unplug power
before replacing
fuse or removing
bolts mounting
F
U
S
E
F
U
S
E
POWER FUSE
2.5 A
SLO
BLO
120 V~
50-60 Hz
2.5 A
WER FUSE
EXTERNAL SWITCHING
WARNING: To reduce risk of fire or
electric shock, replace fuse with
same type and rating only. Do not
CAUTION: To reduce risk of fire or electric
shock, do not remove cover. No
user-serviceable parts inside. Refer
V
I
N
T
A
G
E
V
I
N
T
A
G
E
SOLO
FUSE
CHANNEL 1
CHANNEL 2
SET TO CHANNEL 1
TO USE FOOTSWITCH
FOOTSWITCH
SOCKET
BELOW
SEND RETURN FX MIX
PARALLEL EFFECTS LOOP
10% 90%
ALL TUBE AMPLIFIER HANDMADE IN PETALUMA, CALIF USA
8 OHM 4 OHM 4 OHM
SPEAKERS
OUT
SLAVE
(USE WITH TWO 8 OHM SPKRS)
(COMBO) (TO EXT. PWR AMP)
SINGLE RECTIFIER SERIES 2 RECTOVERB
CAUTION
SWITCH MUST MATCH
TUBES IN USE
6L6
BIAS SWITCH
EL34
FUSE
CHANNEL 1
CHANNEL 2
SET TO CHANNEL 1
TO USE FOOTSWITCH
PATENTED 4,211,000 & OTHERS PENDING FOR SOLO, MUTE & LOOP CONFIGURATION
PATENTED 4,211,000 & OTHERS PENDING FOR SOLO, MUTE & LOOP CONFIGURATION
FOOT
SWITCH
SOLO CHANNEL
EXT. SWITCHING
4 OHM 4 OHM 8 OHM
SPEAKERS
WARNING:
To reduce risk of fire or
electric shock, replace fuse with
same type and rating only. Do not
CAUTION: To reduce risk of fire or electric
shock, do not remove cover. No
user-serviceable parts inside. Refer
FX LOOP
90%
CAUTION
SWITCH MUST MATCH
TUBES IN USE
EL34
BIAS SWITCH
6L6
ALL TUBE AMPLIFIER HANDMADE IN PETALUMA, CALIF USA
SINGLE RECTIFIER SERIES 2 SOLO HEAD
OUT
SLAVE
(TO EXT. PWR AMP)
REVERB
OVERVIEW:

PAGE 2
FRONT PANEL:
First familiarize yourself with the layout of the Front Panel. Next, remove the footswitch from the transport pouch located inside the
cabinet ( combo ) and connect it to the proper jack.
RECT-O-VERB Series 2
amplifi ers use a DIN jack located on the underside of
the chassis’s outer edge. Labeling which reads FOOTSWITCH SOCKET BELOW should help you locate the jack.
SOLO 50 HEAD
Series 2
amplifi ers have their DIN Jack located on the Rear Panel proper. (See illustration at the bottom of this page). If the footswitch
is not available, you may select the two channels via the manual Channel Select toggle switch located on the Rear Panel.
POWER UP:
First remove the protective covers from the tubes (plastic webbing) before connecting the A.C. cord
to a power receptacle.
Connect your favorite guitar to the instrument INPUT jack. Flip the POWER switch to the ON position while
leaving the STANDBY switch set to STANDBY.” (It is always a good idea to practice this start up procedure as at least 30 seconds
of warm-up time lessens the shock on cold power tubes, thus prolonging their life substantially.) Next, using the example below as a
guide, set the controls as illustrated and fl ip the STANDBY switch to the ON position to listen to the two distinctly different channels
using either the footswitch or the Channel Select toggle switch as mentioned in the paragraph above.
Before discussing each control, let’s audition a couple of possible ways the two channels might be confi gured for footswitchable sounds.
The fi rst example leans towards a more traditional format with a clean rhythm dialed up on CHANNEL 1( Green ) and a moderate
gain, vintage style solo sound dialed up on CHANNEL 2 ( Red ).
This second example leans in a more aggressive direction with CHANNEL 1 switched to PUSHED for a crunchy high gain rhythm
sound and CHANNEL 2 switched to MODERN for a blistering lead voice.
NOTE:
NOTE: NOTE:
CAUTION - REDUCE THE OUTPUT LEVEL CONTROL BEFORE PLAYING THESE SOUNDS AS THE ADDED GAIN IN-
CREASES VOLUME LEVELS.
Now that you’ve heard the
RECT-O 50’s
two channels, let’s move on to understanding the controls and their interactive roles in
achieving the sounds that
you
want to hear.
you want to hear.you
INSTANT GRATIFICATION: Demo Setting #2
INPUT
CLEAN
PUSHED
MODERN
RAW
POWER
ON
ON
STANDBY
GAIN
TREBLEMIDPRESENCE BASSMASTER
SOLO OUTPUT
CH2
CH1
V
I
N
T
A
G
E
WARNING:
Unplug power
before replacing
fuse or removing
bolts mounting
chassis.
F
U
S
E
F
U
S
E
POWER FUSE
2.5 A
SLO
BLO
120 V~
50-60 Hz
2.5 A
POWER FUSE
FUSE
CHANNEL 1
CHANNEL 2
SET TO CHANNEL 1
TO USE FOOTSWITCH
FOOTSWITCH
SOCKET
BELOW
PATENTED 4,211,000 & OTHERS PENDING FOR SOLO, MUTE & LOOP CONFIGURATION
RECT-O-VERB COMBO Series 2
WARNING:
Unplug power
before replacing
fuse or removing
bolts mounting
chassis.
F
U
S
E
F
U
S
E
POWER FUSE
2.5 A
SLO
BLO
120 V~
50-60 Hz
2.5 A
POWER FUSE
FUSE
CHANNEL 1
CHANNEL 2
SET TO CHANNEL 1
TO USE FOOTSWITCH
PATENTED 4,211,000 & OTHERS PENDING FOR SOLO, MUTE & LOOP CONFIGURATION
FOOT
SWITCH
SOLO 50 HEAD Series 2
INSTANT GRATIFICATION: Demo Setting #1
INPUT
CLEAN
PUSHED
MODERN
RAW
POWER
ON
ON
STANDBY
GAIN
TREBLEMIDPRESENCE BASSMASTER
SOLO OUTPUT
CH2
CH1
V
I
N
T
A
G
E

Each channel of your amplifi er contains different modes of operation that may be selected depending on your application. In this way
you may decide to use the channels for their most obvious sounds or with the fl ick of a switch - invert the channels for the opposite
sound style. The voicing of the modes is accomplished by rerouting and reconfi guring the circuit in both pre-amp and power sections
of the amplifi er. Here are the choices;
CHANNEL 1
CLEAN :
This is the lowest gain circuit of the
RECT-OS’
fi ve modes and is optimized for producing balanced
RECT-OS’ fi ve modes and is optimized for producing balanced RECT-OS’
pristine clean sounds. For the best understanding of how to achieve a great sound in this mode, please refer
back to the GAIN Control section of this manual. However, a great place to start is 12:30 or so on the GAIN
Control with more sparkle available below this and more warmth apparent above...from there adjust according
to your guitars individual response.
Because of its more traditional architecture this mode also works extremely well for vintage style drive sounds. By turning the gain
all the way up, a beautiful old school solo sound is possible...especially with neck single coil pick-ups. The TREBLE and MIDDLE
Controls can also add gain and sustain to this sound ( reduce Presence to blend highs ), but you will probably want to run the BASS
Control below 10:30 to avoid fl ubbiness and preserve a focused attack.
PUSHED:
This mode is a radical departure from the sweet shimmering blend of the CLEAN modes low gain character. Huge increases
in gain early on in the fi rst stages of the pre-amp produce one of the biggest differences between modes in the entire amplifi er and
transforms what you thought to be a tame and gentle clean channel into a raging crunch machine. This incredible amount of gain
also creates one of the most expressive solo modes in your
RECT-O
. Because there are less stages of gain for the signal to travel
through and the tone control network is tuned for the brighter nature of clean sounds, this mode responds quicker to your pick attack
and has a more urgent, snappy feel. Don’t overlook this mode for some of the
RECT-OS’
coolest overdrive solo sounds.
RECT-OS’ coolest overdrive solo sounds.RECT-OS’
NOTE:
NOTE: NOTE:
When using PUSHED with the GAIN Control maxed (5:30), do not run the TREBLE Control above (2:30). Settings above
(2:30) can create possible oscillation in certain preamp tubes in the V-1 position. This can be avoided altogether by setting the TREBLE
Control sensibly when the GAIN Control is maxed. Use the PRESENCE Control for additional brightness.
CHANNEL 2 / Modes
RAW:
This new
RECT-O
mode has the lowest gain of the three in the high gain lead channel. Its’ less saturated nature greatly en-
RECT-O mode has the lowest gain of the three in the high gain lead channel. Its’ less saturated nature greatly en-RECT-O
hances the already versatile bevy of sounds the lead channel offers. The range of gain available covers an extremely wide spectrum
and it can be set to double as a formidable alternate clean mode, a low gain purring blues sound and beyond, all the way up to a
grinding crunch or searing solo sound.
The TREBLE can be set relatively high (2:00) to add a little more gain and shred when using
RAW
for certain
crunch rhythm sounds. Don’t overlook the amazing low and medium gain soloing potential
RAW
offers, as
its more gradual GAIN response produces a wide range of voice like single note sounds that are somewhat
more dynamic due to less saturation.
VINTAGE:
This high gain mode is the famous liquid
RECT-O
voice and it can be found in its original state
RECT-O voice and it can be found in its original state RECT-O
here in CHANNEL 2. Its lush harmonic content and fat creamy feel has found its way onto so many recordings, it is now a staple for
anyone headed to the studio for an album project. Combining this super juicy, expressive preamp with the
RECT-OS’
magic 50 watt
RECT-OS’ magic 50 watt RECT-OS’
power section creates colors in gain that most players fi nd truly addictive. Single note solo work is effortless as the strings become
easy to play with
VINTAGE
modes musical and natural tube compression. Spend time learning the lower regions of the
VINTAGE
mode as the overlap between RAW and
VINTAGE
is a place where many beautiful sounds lie. These two modes are similar enough
when
VINTAGE
is set in its lower range and RAW is set in its medium to higher range and yet each possesses a character that is
unique and identifi able. You will likely fi nd your new trademark lead sound lurking somewhere in this sea of liquid gain.
PAGE 3
CHANNEL / MODE SELECT:
INPUT
HEAD VERSION
CLEAN
PUSHED
MODERN
RAW
HEAD VERSION
V
I
N
T
A
G
E
INPUT

PAGE 4
MODERN:
Aggressive. This is the word that best describes the menacing power of the
RECT-OS’
most rebellious of all modes.
RECT-OS’ most rebellious of all modes. RECT-OS’
A take no prisoners, crushing assault of top end cut and lightning fast response creates a sound of unparalleled aggression that has
set a new standard for hard core sounds. The added tightness of the low end response combined with the radically more present top
end keeps the MODERN mode tracking accurately even at extreme gain settings.
GAIN:
This control adjusts the predominant gain stage in each channels’ circuit with the function and taper being optimized for
each individual channel. Remember that your
RECT-O 50
is really two separate multi-mode amplifi ers built onto one chassis, so
RECT-O 50 is really two separate multi-mode amplifi ers built onto one chassis, so RECT-O 50
though each channel looks identical, the
GAIN
Control for each channel comes in a different place and adjusts a different point in
that channels circuit.
In most guitar amplifi ers, and especially in all-tube circuits, the
GAIN
Control is the most powerful
control in the preamp. It shapes the overall style and character of the sound and is responsible for
whether the sound is clean, overdriven or anywhere in between. In your
RECT-O 50
, the
GAIN
Control is even more powerful. It not only determines the amount of drive, but also acts as an integral
part of the tone control string as well.
To simplify the
GAIN
Controls’ role in shaping the overall tone of the sound we will look at it in two
ways -
1;
alone and
2;
in conjunction with the tone controls.
1) By itself the GAIN Control has basically three tonal regions -
Low ( 7:00 - 11:00 )
provides the cleanest, least saturated sounds and in this region the sound will be brighter and contain more
upper harmonics lending a three dimensional character to the sound.
Middle ( 11:15 - 2:00 )
enhances the saturation and replaces some of the upper harmonics with a richer, warmer quality and a fuller
bottom end response. Not yet fully saturated, this region is the easiest place to get a great sound in all three channels. This region
contains many of the
RECT-OS’
best sounds...especially for soloing due to the crucial blend of an expressive attack combined with
RECT-OS’ best sounds...especially for soloing due to the crucial blend of an expressive attack combined with RECT-OS’
ample sustain.
High ( 2:15 - 5:00 )
saturates the signal and enhances low and low mid frequencies. While this region provides the maximum satu-
ration and therefor sustain, it also compresses and softens the attack characteristics. For this reason we suggest using this higher
region of the
GAIN
Control sparingly and only when maximum sustain is needed.
NOTE:
NOTE: NOTE:
Due to the
RECT-OS’
extreme gain potential, the highest regions of the
RECT-OS’ extreme gain potential, the highest regions of the RECT-OS’
GAIN
Control may possibly push the pre-amp
tubes past what they can handle, producing microphonic squealing. While we screen and test the tubes your amplifi er was shipped
with and the tubes in your amp passed our rigourous test, we can’t predict how the tubes will respond over time exposed to extreme
gain settings. Your tubes are warranted for a period of 6 months under normal use, but you can save yourself the present and future
inconvenience of having to deal with annoying microphonic tube problems by simply using
a little common sense...Don’t turn the
Gain all the way up!
If you must for a specifi c part or at very low volumes, back down the TREBLE and PRESENCE Controls. Your
RECT-O 50
was
designed to provide amazing gain and tone at less than extreme settings removing the need for you to crank everything all the way
up. If you are not able to achieve the sound you want at sensible settings on any or all of the controls, your problem may lie elsewhere
in the signal chain, i.e. pick-ups, cabinetry, processing etc. Keep in mind you can always call on one of our product specialist Monday
through Thursday and seek some advice should you fi nd yourself struggling to get the sound you want.
CHANNEL / MODE SELECT: (Continued)
CONTROLS:
HEAD VERSION
GAIN
INPUT
CLEAN
PUSHED
MODERN
RAW
V
I
N
T
A
G
E

2.) GAIN - In conjunction with the Tone Controls -
Basically, a simple rule applies...as the Gain is increased the Tone control string
has less and less effect on the signal until at 5:00 the signal is so saturated that you are
getting mostly Gain and very little Tone
. Again,
this is the reason we suggest using the
GAIN
Control in its middle region. Here the Tone control string is very active and provides
maximum shaping power - allowing you to dial virtually any sound you desire.
TREBLE:
As in most tube guitar amplifi ers, the
TREBLE
Control ( in both channels of your
RECT-O 50
) is the most powerful
of the rotary controls and is next in line only to the GAIN Control as a shaping tool. Because it is fi rst in the signal path of the tone
controls - and from here the Middle and Bass receive their signal - it is by far the dominant tone control. For this reason the setting of
the
TREBLE
Control is very important for equal representation of the three frequency regions to appear at their respective controls.
Like most of the controls on your
RECT-O 50,
there is an optimum region of the
TREBLE
Control where ample top end is mixed in
and yet enough signal is still passed on to the MIDDLE and BASS Controls.
Between 11:00 and 1:30 is where you’ll fi nd the sweet spot .
There are defi nitely great sounds above and
below this middle region, but the balance between the
TREBLE
Control and the other two tone controls is
compromised.
The one place you may want to throw caution to the wind and set the
TREBLE
Control above this median
zone presents itself in Channel 1 of your new
RECT-O 50
. In both modes ( Clean & Pushed ), the
TREBLE
Control can be used to dump extra gain into the mix. This is especially effective in the PUSHED mode for
crunch sounds. When doing so use the PRESENCE Control to roll off some of the more than ample top end
for a more compressed feel and fatter voice. As you might surmise, the BASS Controls’ effectiveness will be reduced, so you may
have to run a much higher setting than you are used to seeing to achieve a balance. This said, keep in mind that the
TREBLE
Control
in Channel 1 Pushed should not be set much above 2:30 to avoid unwanted microphonic tube problems.
MID:
The
MID
Control is responsible for the blend of midrange frequencies in the mix and though its effect is not as dramatic as
that of the TREBLE Control, it plays an integral part in achieving any sound in your
RECT-O 50
. It is capable of changing the feel
dramatically as it blends in a group of frequencies that tend to soften or stiffen the way a sound feels to play.
Most players tend to lean in the direction of lower
MIDDLE
Control settings ( 7:00 - 11:00 ) where a scoop in
this region produces
girth
( by letting the Bass become a little more dominant ) and a lack of punch lends a
more compressed,
even
feel to the strings and therefore less apparent resistance to the pick. As the
even feel to the strings and therefore less apparent resistance to the pick. As the even
MIDDLE
Control is increased, ( 11:30 - 1:30 ) the sound is rounded-out and fi lled-in with a focused mid attack appear-
ing rather quickly. As you would guess, the feel starts to change - becoming more resistant. Above this region
the
MIDDLE
Control could be used to compensate for either weaker pick-ups or for times when a specifi c
defi ciency is produced by either an extremely high setting of other tone controls, or a physical anomaly in the
room. While these
MIDDLE
Control settings ( 2:00 - 5:00 ) can introduce added gain and create enhanced
focus, the trade-off will be a stiffer, more forward, less compressed feel.
Channel 1 utilizes a different MIDDLE Control than that of the Channel 2
with a custom-designed taper and value. In its low range
( below 12:00 ) it functions as a normal midrange control with a taper suited to blending fi ne increments of these frequencies. Most
players lean toward a fairly radical scoop ( 7:00 - 10:30 ) for clean playing, preferring to let Treble and Bass remain dominant, thus
producing the signature sparkle and breath essential for a pristine clean sound.
PAGE 5
CONTROLS: (Continued)
HEAD VERSION
TREBLE GAIN
HEAD VERSION
MID TREBLE

As Channel 1’s
MIDDLE
Control is swept past 1:00, it quickly starts to add gain in these midrange frequencies adding cut and punch.
As the top end of the control is reached, ( 3:00 - 5:00 ) it becomes an additional
gain control
capable of taking both CLEAN and
gain control capable of taking both CLEAN and gain control
PUSHED modes to extremes. Experiment with this cranked region in conjunction with conservative settings of the other tone controls
to balance both sound and feel. While this added fl exibility may make Channel 1’s
MIDDLE
Control a little more tricky to learn at fi rst,
it will become quite valuable as you start to realize the power of this super versatile channel.
BASS:
Last, but not least in the string of tone controls we come to the
BASS
. This control works similarly in both channels in that it
determines the amount of low frequencies present in a sound. However, the actual frequencies and
style of lows
it mixes in changes
style of lows it mixes in changes style of lows
from channel to channel. Like the MIDDLE Control, it falls in line signal-wise
after
the TREBLE Control and the same scheme applies.
after the TREBLE Control and the same scheme applies. after
When the TREBLE Control is set high, the effectiveness of the BASS and MIDDLE Controls is reduced. If
the TREBLE Control is set low these two controls become dominant.
For the most balanced sound and a balance of power between the three rotary tone controls, try to use the
TREBLE Control in its middle ranges. This scenario produces nearly equal representation of all the frequen-
cies on the tone controls and provides a great neutral starting point for further tweaking.
PRESENCE:
The
PRESENCE
Control is a high frequency attentuator that is placed at the end of each channels pre-amp stage
and affects frequencies higher than those of the TREBLE Control. It acts independently of the other rotary tone controls and is crucial
in voicing the Channel. It is a powerful global tone control. Lower
PRESENCE
Control settings darken and, in fact compress the signal
which works well to fatten single note solo sounds, giving them girth and focus. Some of the best lead sounds in your
RECT-O
will
fi nd the
PRESENCE
Control in its lower regions, where a balanced, vocal response is achieved.
Higher settings unleash the mighty roar of your
RECT-O
and this can be great for sparkling clean sounds
RECT-O and this can be great for sparkling clean sounds RECT-O
in Channel 1 and more aggressive crunch rhythm sounds in the high gain modes. Be sure to taunt the beast
that lurks in Channel 2 MODERN as the
PRESENCE
is truly amazing in this most agro mode.
REVERB: RECT-O-VERB / COMBO & HEAD
These self explanatory controls deliver the rich natural reverb sound. Although
the circuit is the same for both Channel 1 & Channel 2, the amount of
REVERB
available is not. In Channel 2 there is slightly less
REVERB
available overall because of this channels’ very nature.
The reason behind this is two fold:
1.)
that it is easier to prevent the massive amount of Gain and signal strength present in either of
Channel 2’s high gain modes from causing unwanted
REVERB
oscillations.
2.)
This channels aggressive nature lends itself more to musical styles where high settings of
REVERB
are simply not traditional. Don’t worry...there is still plenty of
REVERB
for drenched solo
work in both the RAW & MODERN Mode in Channel 2. Simply run the
REVERB
Control a little
higher than that of Channel 1.
CONTROLS: (Continued)
PAGE 6
HEAD VERSION
MID
BASS
HEAD VERSION
PRESENCE BASS
REVERB MAST
ENCE

MASTER:
This control is the master feed from the end of the pre-amp to the driver stage and the Effects Loop. As you can
see each Channel is fi tted with its own
MASTER
Control, enabling the two channels relative volumes to be matched regardless of
their extremely different sound styles and gain signatures. The
MASTER
Control makes possible a wide range of sounds through
its ability to use very low
Gain
sounds at high volumes and conversely, high
Gain
sounds at low volumes
and everywhere between.
Again, we suggest using the
MASTER
Control in its
sensible
ranges ( 9:00 - 2:00 ). Here, the channels will
sensible ranges ( 9:00 - 2:00 ). Here, the channels will sensible
be easier to match with each other and the Effects Loop will see more reasonable signal levels.
NOTE:
Because the
MASTER
Control creates the send to the Effects Loop, extreme settings will cause
a large signal to be sent to the Loop for that Channel. Not only may this cause possible overloading of the
processors Input stage, but will make balancing the two channels’ Effect Send level diffi cult.
OUTPUT:
This control determines the overall output volume level of the amplifi er. After the GAIN Controls have been set for the
desired sound style and the two channels levels have been balanced with the channel MASTER Controls, the
OUTPUT
Control
allows you to change the playing level by adjusting a single control. The
OUTPUT
Control is also wired as the Effects Loop Return
Level Control. Should you ever use your
RECT-O 50
amplifi er
as a power amp alone by inserting a signal into the RETURN jack,
the
OUTPUT
Control will serve as the master level control.
NOTE:
NOTE: NOTE:
When using the EFFECTS RETURN as an input - to use the
RECT-O
amplifi er
as a power amp
- the SOLO Control can be used to attain a footswitchable boost if the Footswitch is connected. It is wired in
parallel to the
OUTPUT
Control and therefore also controls the volume of the power section.
OUTPUT Control and therefore also controls the volume of the power section.OUTPUT
NOTE:
NOTE: NOTE:
The Effects Loop RETURN jack can serve as a power amp input so that you may use the
RECT-O
The Effects Loop RETURN jack can serve as a power amp input so that you may use the RECT-O The Effects Loop RETURN jack can serve as a power amp input so that you may use the
50
amplifi er
as a power amp for either stereo reproduction or to incorporate additional pre-amps. Here are
a few things to remember that will help you when interfacing to the
RECT-O
for use as a power amp only;
1.)
Connect “Dummy” plug or loose cable to SEND jack. ( This prevents any possible loading that could result in diminished RETURN
sensitivity.)
2.)
The OUTPUT Level will be the only active control on the Front Panel (the PRESENCE Control of Channel 1 will be active only
when that channel is engaged - see #3 )
3.
) The SOLO Control may be used to footswitch to a pre-determined amount of boost when the footswitch is connected.
4.)
Channel 2’s MODERN mode - as part of its voicing - utilizes substantially less negative feedback in the power stage creating a
scenario of greatly increased power sensitivity. This internal revoicing produces amazing results in the lead sounds and requires a
sophisticated network of elements to switch to prevent the increased power sensitivity from blowing you out of the room as Channel
2’s RAW & MODERN modes are toggled between.
Therefor, we recommend selecting Channel 1 when you wish to use the
RECT-O
as a power amp. The more conventional power
RECT-O as a power amp. The more conventional power RECT-O
sensitivity of this channel will be the most compatible with external sources. Also, using Channel 1 in a power-only application means
that the PRESENCE Control will be active which allows you to tailor the power voicing to your specifi c tastes. If you do need the extra
sensitivity that Channel 2’s MODERN mode produces for a source that is unusually weak, it is there if you need it. The PRESENCE
Control will not have any effect on the sound as it switches with the mode change to an earlier stage in the pre-amp.
5.)
The EFFECTS MIX Control must be set to 90%.
CONTROLS: (Continued)
PAGE 7
HEAD VERSION
PRESENCE
MASTER
SOLO OUTPUT
HEAD VERSION

SOLO:
This control can only be activated if the correct Footswitch is connected
to the Footswitch DIN jack.
SOLO
is an
additional fi nal output level control wired in parallel with the OUTPUT Control. It is capable of a setting above that of the OUTPUT
Control and can not be set below. The amount of apparent boost also depends on that of the OUTPUT Control - in that if the amplifi er
is at either the extreme low or extreme high levels of the OUTPUT, its effectiveness is minimized. It has been
optimized for live performance volume levels.
If the power section is either not a part of the sound (super quiet), or producing all its rated wattage ( super
loud), there is very little signal for the
SOLO
control to work with. By using the Footswitch and selecting
SOLO
,
a pre-settable boost in overall levels is possible on the fl y...giving you some control over your levels when it’s
time to step out. Engineers may give you a bit of a frown the fi rst time you use it...but isn’t it time you heard
yourself. It might even prevent them from punishing you with the dreaded monitor or sidefi ll version of your tone.
STANDBY:
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 warm up before being put to use. Before Power is switched on make sure the
STANDBY
switch is in the Standby position.
Wait at least 30 seconds and then fl ip the
STANDBY
switch to the ON position. This prevents
tube problems and increases their toneful life substantially.
POWER:
This switch delivers the A.C. power to the
RECT-O 50.
Make sure the unit is grounded (all three terminals of the A.C.
power cord must be connected whenever possible to avoid injury to the user as well as to the unit) and that the proper voltage is
present.
Follow the cold start procedure described in the ON/ STANDBY section above when powering
up your new
RECT-O 50.
CONTROLS: (Continued)
SOLO OUTPUT
HEAD VERSION
POWER
ON ON
STANDBY
HEAD VERSION
POWER
ON
ON
STANDBY
HEAD VERSION
PAGE 8

SLAVE OUT:
This 1/4” jack provides a signal derived from the speaker jack. Perfect for using the
RECT-O 50
as a master pre-
amp, or additional power amps may be connected for more power when needed. Some players use this to derive an FX Send Signal
and go to other amps for their wet sound.
NOTE:
Once a signal is taken from the
SLAVE
, it can not be inserted back into the FX Loop Return
SLAVE, it can not be inserted back into the FX Loop Return SLAVE
jack or a feedback loop will occur. Much like holding a microphone into the PA system’s cabinets...a
loud high pitched squeal will occur.
SPEAKERS:
Sensitivity to speaker mismatching in regards to ohmage differences is low, hence no damage to the amplifi er will
occur. However, very low ohmage loads will cause the power tubes to wear faster. The
RECT-O 50
(combo only) is equipped with
a Celestion Custom 90 single 12 inch - 8 Ohm speaker, but as you can see, other speaker
confi gurations may be used.
When using two 8 Ohm speakers, connect each of them to the 4 Ohm speaker jacks that are
provided, this will equal a 4 Ohm load which is the proper impedance required when using
this particular speaker confi guration.
BIAS SELECT:
Your
RECT-O 50
amplifi er was designed with versatility in mind. So to add to the already awesome array of on
board features...we felt it essential that these new
RECT-O 50 Series 2
amplifi ers be able to adapt their power output section 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 identifi able and wonderful sounding amps created in Great Britain
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 fi nd this almost
thin at fi rst. However, afi cionados 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
PAGE 9
REAR PANEL:
REAR VIEW - HEAD VERSION
10%
FX MIX RETURN SEND
WARNING:
Unplug power
before replacing
fuse or removing
bolts mounting
chassis.
F
U
S
E
F
U
S
E
POWER FUSE
2.5 A
SLO
BLO
120 V~
50-60 Hz
2.5 A
POWER FUSE
FUSE
CHANNEL 1
CHANNEL 2
SET TO CHANNEL 1
TO USE FOOTSWITCH
PATENTED 4,211,000 & OTHERS PENDING FOR SOLO, MUTE & LOOP CONFIGURATION
FOOT
SWITCH
SOLO CHANNEL
EXT. SWITCHING
4 OHM 4 OHM 8 OHM
SPEAKERS
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.
CAUTION:
To reduce risk of fire or electric
shock, do not remove cover. No user-
serviceable parts inside. Refer
servicing to qualified personnel.
FX LOOP
90%
CAUTION
SWITCH MUST MATCH
TUBES IN USE
EL34
BIAS SWITCH
6L6
ALL TUBE AMPLIFIER HANDMADE IN PETALUMA, CALIF USA
SINGLE RECTIFIER SERIES 2 SOLO HEAD
OUT
SLAVE
(TO EXT. PWR AMP)
4 OHM 4 O
SPE
ALL TUBE AMPLIFIER HANDMADE IN PETA
SINGLE RECTIFIER SERIES 2
OUT
SLAVE
(TO EXT. PWR AMP)
HEAD VERSION
4 OHM 4 OHM 8 OHM
SPEAKERS
ALL TUBE AMPLIFIER HANDMADE IN PETALUMA, CALIF USA
SINGLE RECTIFIER SERIES 2 SOLO HEAD
OUT
SLAVE
(TO EXT. PWR AMP)
CAUTION
SWITCH MUST MATCH
TUBES IN USE
EL34
BIAS SWITCH
6L6

PAGE 10
BIAS SELECT: (Continued)
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 new
RECT-O 50
amplifi ers. If you need a variety
of sounds and rely on a clean chording sound much of the time, you will likely prefer the stock compliment of 6L6’s that both of these
two versions are fi tted 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.
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 available 6L6. This is another reason
why your new
RECT-O 50
amplifi er 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.
Make sure that the BIAS Switch is set correctly to match the tube type that you are using.
Failure to
do this will result in tube failure that could possibly burn resistors in the Bias supply. Although this is a fairly simple repair
for an authorized technician, it is easily avoidable.
ALWAYS CHECK THE BIAS SWITCH setting if you experiment with alternate tube types and you will enjoy uninterrupted
performances from your amplifi er.
EFFECTS LOOP: SEND, RETURN & MIX
These two 1/4” jacks are the patch point for external signal processing effects. The
EFFECTS LOOP
in the
RECT-O 50
is wired in parallel with the unaffected or dry signal which enables you to preserve the integrity
of the all tube tone and feel that the
RECT-O 50
is capable of delivering. To use the
EFFECTS
LOOP
for your processors, simply connect the Effects Loop
SEND
jack to your fi rst effects’ Input
jack. Connect your last effects Output jack to the Effects Loop
RETURN
jack.
Use the rotary
MIX
Control to blend in the desired amount of the processed signal with the original
dry signal. The least degradation of signal is usually found by setting the processor’s mix at 100%
and the
EFFECTS LOOP MIX
Control at the lower end of the control. In this manner the least
amount of your pure tone will be processed and you will be dialing in a “very small amount” of a
“very wet” signal to be mixed with the original. This method seems to produce the best results for
tone and signal to noise ratio. The
EFFECTS LOOP
interrupts the signal between the pre-amp
and power section. Therefore, the
RETURN
jack can double as a power amp input jack. You will also want to run the
MIX
Control at
90% to use the
EFFECTS LOOP
as a Power In patch point. Connect your last effects’ Output jack to the Effects
RETURN
jack. We
suggest that when using the
RECT-O 50’s
power section only, that you have the amp switched to Channel 1’s CLEAN mode or
Channel 2’s MODERN mode. This assures a more neutral power sensitivity thus making the
RECT-O 50
more friendly to use as a
power amp. See PRESENCE Control section of this manual for more information.
EXTERNAL SWITCHING:
These jacks allow ( usually MIDI-programmed ) operation of your amplifi er’s functions from an external
switching source. The switching is accomplished by connecting ( “shorting” ) the jack’s “Tip” to its “Ring” (or ground.)
10%
FX MIX RETURN SEND
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.
FX LOOP
90%
SOLO CHANNEL
EXT. SWITCHING
CAUTION: To reduce risk of fire or electric
shock, do not remove cover. No user-
serviceable parts inside. Refer
servicing to qualified personnel.
REAR PANEL: (Continued)

CHANNEL SELECT:
This switch simply allows you to switch between the two channels (CHANNEL 1 and CHANNEL 2) without
using the Channel Select Footswitch or, when one is not available.
To use the footswitch however, the Channel Select switch must be in the (up) position.
FUSE:
This is the A.C.’s (Alternating Current) main fuse and provides protection from outside A .C. fl uctuations as well as power
tube failure damage. Should the
FUSE
blow, replace it with the same rating in a Slo-Blo type package. The domestic U.S. version
requires a 2.5 amp Slo-Blo fuse. A power tube short or failure is often the cause of a blown fuse...Follow the cold start procedure
mentioned in the ON/STANDBY switch section and watch the power tubes as you fl ip the
STANDBY switch to the ON position.
If a power tube is going bad or is arcing you will see it! Flip the STANDBY switch to Standby
immediately and replace the faulty power tube and the fuse if necessary. If you see nothing
abnormal as you lift the STANDBY switch it is possible that a power tube shorted temporarily
and blew the
FUSE
. If this is the case it may work again normally. To be extra safe, you might
want to replace just the adjacent tube or all power tubes in the “shotgun” troubleshooting
tradition and save the replaced set as spares. Spare fuses are a must for the fabled cord
bag along with your spare tubes. Always carry both for they could be worth their weight in
gold someday.
A.C. RECEPTACLE:
The total power consumption for the
RECT-O 50
is 2.5Amps @ 120 Volts. Thus, a 15 Amp circuit (which is
what most house circuitry is wired with) is adequate. Make sure the Euro style A.C. power cord is fi rmly seated in the power receptacle
before powering up the unit. Always connect the A.C. cord to a 3 terminal grounded socket. If none are available, connect the A.C.
power cord to a ground lift adaptor and then connect to a 2 terminal outlet. This may also be
necessary from time to time for noise problems.
This style of power cord will make tear-downs and cable routing a lot easier and save you time
as well. If you should ever need a replacement, just call and we’ll be happy to send you another
one for a nominal charge or visit your nearest
MESA/Boogie
Pro Center.
MESA/Boogie Pro Center.MESA/Boogie
CHANNEL 1
CHANNEL 2
SET TO CHANNEL 1
TO USE FOOTSWITCH
HEAD VERSION
WARNING:
Unplug power
before replacing
fuse or removing
bolts mounting
chassis.
F
U
S
E
F
U
S
E
POWER FUSE
2.5 A
SLO
BLO
120 V~
50-60 Hz
2.5 A
POWER FUSE
FUSE
PATENTED 4,211,000 & OTHERS PENDING FOR SOLO, MUTE & LOOP CONFIGURATION
WARNING:
Unplug power
before replacing
fuse or removing
bolts mounting
chassis.
POWER FUSE
2.5 A
SLO
BLO
120 V~
50-60 Hz
2.5 A
POWER FUSE
HEAD VERSION
PAGE 11
REAR PANEL: (Continued)

PAGE 12
FACTORY SAMPLE SETTINGS
HEAD VERSION SHOWN
MASTER GAIN TREBLEMIDPRESENCE BASS
SOLO OUTPUT
MASTER GAIN
TREBLE
MIDPRESENCE BASS
SOLO OUTPUT
MASTER GAIN TREBLEMIDPRESENCE BASS
SOLO OUTPUT
GAIN
TREBLEMIDPRESENCE BASS
SOLO OUTPUT
MASTER
CH2
CH1
CH2
CH1
CH2
CH1
CH2
CH1
SAMPLE 1 Sparkling Clean
SAMPLE 2 Pushed Bluesy Rhythm / Solo: Both Channels
SAMPLE 3 Blues Lead: Both Channels
SAMPLE 4 High Gain Lead / Crunch: Both Channels
INPUT
CLEAN
PUSHED
MODERN
RAW
V
I
N
T
A
G
E
INPUT
CLEAN
PUSHED
MODERN
RAW
V
I
N
T
A
G
E
INPUT
CLEAN
PUSHED
MODERN
RAW
V
I
N
T
A
G
E
INPUT
CLEAN
PUSHED
MODERN
RAW
V
I
N
T
A
G
E
FACTORY SAMPLE SETTINGS
HEAD VERSION SHOWN

PAGE 13
MASTER
GAIN TREBLE MID PRESENCE
BASS
OUTPUT
MASTER
GAIN TREBLE MID PRESENCE
BASS
OUTPUT
PRESENCEBASS
MID
TREBLE
GAIN MASTER
CH2
CH1
CH2
CH1
BASS
GAIN MASTER
PRESENCE
TREBLE
OUTPUT
CH2
CH1
MID
OUTPUT
CH2
CH1
FACTORY SAMPLE SETTINGS
COMBO VERSION SHOWN
SAMPLE 1 Sparkling Clean
SAMPLE 2 Pushed Bluesy Rhythm / Solo: Both Channels
SAMPLE 3 Blues Lead: Both Channels
SAMPLE 4 High Gain Lead / Crunch: Both Channels
INPUT
CLEAN
PUSHED
MODERN
RAW V
I
N
T
A
G
E
INPUT
CLEAN
PUSHED
MODERN
RAW V
I
N
T
A
G
E
INPUT
CLEAN
PUSHED
MODERN
RAW V
I
N
T
A
G
E
INPUT
CLEAN
PUSHED
MODERN
RAW V
I
N
T
A
G
E

PAGE 14
SOUND 1
SOUND 2
SOUND 3
SOUND 4
PERSONAL SETTINGS PAGE
HEAD VERSION SHOWN
MASTER GAIN
TREBLEMIDPRESENCE BASS
INPUT
CLEAN
PUSHED
MODERN
RAW
SOLO OUTPUT
CH2
CH1
V
I
N
T
A
G
E
MASTER GAIN
TREBLE
MIDPRESENCE BASS
INPUT
CLEAN
PUSHED
MODERN
RAW
SOLO OUTPUT
CH2
CH1
V
I
N
T
A
G
E
MASTER GAIN
TREBLE
MIDPRESENCE BASS
INPUT
CLEAN
PUSHED
MODERN
RAW
SOLO OUTPUT
CH2
CH1
V
I
N
T
A
G
E
MASTER GAIN
TREBLE
MIDPRESENCE BASS
INPUT
CLEAN
PUSHED
MODERN
RAW
SOLO OUTPUT
CH2
CH1
V
I
N
T
A
G
E

PAGE 15
SOUND 1
SOUND 2
SOUND 3
SOUND 4
PERSONAL SETTINGS PAGE
COMBO VERSION SHOWN
GAIN MASTER PRESENCEBASSTREBLE MID
CH2
CH1
INPUT
CLEAN
PUSHED
MODERN
RAW
OUTPUT
V
I
N
T
A
G
E
SOLO
GAIN MASTER PRESENCEBASSTREBLE MID
CH2
CH1
INPUT
CLEAN
PUSHED
MODERN
RAW
OUTPUT
V
I
N
T
A
G
E
SOLO
GAIN MASTER PRESENCEBASSTREBLE MID
CH2
CH1
INPUT
CLEAN
PUSHED
MODERN
RAW
OUTPUT
V
I
N
T
A
G
E
SOLO
GAIN MASTER PRESENCEBASSTREBLE MID
CH2
CH1
INPUT
CLEAN
PUSHED
MODERN
RAW
OUTPUT
V
I
N
T
A
G
E
SOLO

PAGE 16
RECT-O-VERB / SOLO 50
6L6 6L6
PARTIAL VIEW OF LARGE TRANSFORMER
12AX7
REAR OF CHASSIS
(HEAD VERSION)
NOTE: POWER TUBES ARE HOT ! BEFORE CHANGING TUBES TURN POWER SWITCH TO OFF AND LET COOL OR USE A RAG FOR PROTECTION.
TUBE TASK CHART
Description of Tube Functions
V1A= Input Stage V1B= 2nd Stage (Rhythm & Lead) V2A=3rdStage Rhythm V2B= 3rd Stage Lead V3A= 4th Stage Lead V3B= 5th Stage Lead
V5
V4
V3
V2
V1
A B A B A B A BA B
V4A= FX Send V4B=FX Return V5=A V5=B Phase Inverter