mesa mark iv
TRANSCRIPT
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OOGIEBMESA
1317 Ross Street Petaluma, CA 94954
USA
The Spir i t of Art in Technology
MARK IVOwners Manual
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Hello from the Tone Farm...
YOU, the smart player and all around intuitive human, have put your trust in us tobe your amplifier company. This is something we do not take lightly. Our reward isthat weve made a classic amplifier and by choosing this amplifier, you have becomepart of the MESA family...Welcome! Our goal is to never let you down. Your rewardis that you are now the owner of an archetypical guitar amp bred of fine all tube ampheritage...benefiting from the many patented pioneering MESA/Boogie circuits thatled to the refinement of your new instrument. Feel confident, as we do, this amp willinspire many hours of musical satisfaction and lasting enjoyment. It was built withyou in mind, by players who know the value of a fine musical instrument and thecommitment it takes to make great music. The same commitment to quality, valueand support we make to you...our new friend.
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Table of ContentsMARK IV
PRECAUTIONS
OVERVIEW _____________________________ 1
FRONT PANEL:
POWER-UP ____________________________ 2
CONTROLS:
RHYTHM 1 GAIN ________________________ 3
PULL BRIGHT __________________________ 3
R 1 TREBLE ____________________________ 3
R 1 + R 2 BASS and R 1 + R 2 MID _________ 3
R 1 PRESENCE _________________________ 4
R 1 MASTER ___________________________ 3
RHYTHM 2 GAIN & FAT __________________ 4
R 1 + R 2 BASS and R1 + R 2 MID __________ 4
R 2 TREBLE ____________________________ 5
R 2 PRESENCE _________________________ 5
R 2 MASTER ___________________________ 5
SETTING THE LEAD MODE:
LEAD GAIN _________________________ 5 & 6
LEAD TREBLE __________________________ 6
LEAD BASS & LEAD MID _________________ 6
LEAD DRIVE ___________________________ 6
LEAD BRIGHT __________________________ 7
LEAD PRESENCE & LEAD MASTER ________ 7
GRAPHIC EQ ________________________ 7 & 8
OUTPUT LEVEL_________________________ 8
SILENT RECORDING (Pull Switch) _________ 8
STANDBY ______________________________ 8
POWER (Full & Tweed Power) _____________ 8
REAR PANEL:
A.C. RECEPTACLE _______________________ 9
FUSE __________________________________ 9
REVERB & REVERB FOOTSWITCH ________ 10
EQ ROCKER SWITCH ____________________ 10
SATELLITE CONTROL: EQ & SEND JACK __ 10
EFFECTS LOOP SECTION ____________ 10 & 11
RECORDING OUT _______________________ 11
SLAVE OUT (D.I.) ________________________ 11
TRIODE & PENTODE SWITCH _____________ 11
SIMUL-CLASS & CLASS A SWITCH ________ 12
HARMONICS & MID GAIN SWITCH _________ 12
POWER TUBE SUBSTITUTION ________ 12 & 13
SPEAKER JACKS _______________________ 13
MODE SELECTOR SWITCH _______________ 13
EXTERNAL SWITCHING JACK ____________ 14
GOING STEREO ________________________ 14
FACTORY SAMPLE SETTINGS ____________ 15
PERSONAL SETTINGS PAGE _____________ 16
TUBE TASK CHART _____________________ 17
TUBE NOISE & MICROPHONICS ___________ 18
DIAGNOSING PRE-AMP TUBES PROBLEMS_ 19
BIAS ADJUSTMENT ______________ 20,21 & 22
PARTS SHEET __________________________ 23
NOTE: Do to the sophistication and advancedlayout of this amplifier, we strongly urge you toread and understand the workings and how to'sof your new MARK IV...doing so will save timeand increase your enjoyment.
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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.
Do not expose amplifier to moisture, rain or water, direct sunlight orextremely 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.
Insure adequate air circulation behind amplifier.
Keep amplifier away from children.
Be sure to connect to an AC power supply that meets the power supplyspecifications listed on the rear of the unit.
If there is any danger of lightning occurring nearby, remove the powerplug from the wall socket in advance.
To avoid damaging your speakers and other playback equipment, turn offthe power of all related equipment beforemaking the connections.
Do not use excessive force in handling control buttons, switches and
controls.
Remove the power plug from the AC mains socket if the unit is to bestored for an extended period of time.
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 for this product filled out by the store atwhich it was purchased and return to MESAEngineering.
YOUR AMPLIFIER IS LOUD! EXPOSURE TO HIGH SOUND VOLUMES MAY CAUSEPERMANET 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.
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Operati ng InstructionsMARK IVMARK IV
Congratulations for choosing the MARK IV as your new musical voice. You have purchased a handbuilt instrument of the finestquality and craftsmanship. In 1984 Mesa/Boogieintroduced the worlds first Tri-Modal amplifier - the MARK lll - with separatemodes for Clean Rhythm, Crunch Rhythm and Lead Overdrive. Now the MARK IV concentrates six years of intervening designexperience into a masterful new instrument which promises years of musical enjoyment.
Every possible useful feature is included, some for the first time ever. Precise, separate adjustment of each mode is simplified by the
complete and logical array of controls...making the MARK IVeasier to use than its predecessor. No compromises were tolerated inregard to performance, reliability or component quality. Individual master-craftsmanship is evident throughout the construction andtesting of each MARK IV. And best of all, the sound quality of each mode is devastatingly accurate! We want your new MARK IVto be the last amplifier you ever need to buy.
Overview:
FRONT VIEW: MARK IV Instant Gratification Demo Settings
PU
LL
SHIFT
PU
LL
SHIFT
PULLBRIGHT
MASTERS
LEAD GAIN
RHY2 GAIN R1+R2 MID
LEAD MID
R1+R2 BASS
LEAD BASS
R1 TREBLE
LEAD TREBLE
RHY1 GAININPUT
PULL
BRIGHT
INS
TRUM
ENT
PULL
FAT
P
ULL
FAT
SILENTRECORDING
(PULL)
EQ LOOP
OUTPUT LEVEL STANDBYTWEEDPOWER
MARK IV80 240 750 2200 6600
ON FULL
POWERPRESENCE
C
ONTROLS
R2 TREBLE
LEAD DRIVE R1R2 LD
6
2
34
5789
101
0 2
3456
7
89
1010 5
2
346
789
1010
5
234
6789
1
010
5
234
6789
1010
6
234
5789
1010
5
234
6789
1010
2
34567
89
1010
5
234
679
1
010
5 234678
9
1
0
10
5 23467
89
1
0
10
5
234
6
789
10
1
0
5 234
6789
1
010
5
234
6789
1010
6
234
5789
1010
5
234
6789
1010
PULL FAT OUT
5
234
6
789
101
0
8
PULL FAT OUT PULL BRIGHT OUT
5
234
6789
1010
REAR VIEW: MARK IV
PAGE 1
3A SB
FUSE
GRAPHICEQ
REMOTE
REVERB
RECORDING
SLAVE( D
.I.)
POWERAMP
T RI OD E S IM UL -C LA SS H AR MO NI CS
PENTODE CLASS A
SPEAKERS
8 OHM 4 OHM4 OHM
MID GAIN
LEAD
VOICING
LEVEL OUT117 VOLTS60 HZ
4 AMPS
EXTERNAL SWITCHING JACKS
RHYTHM 1 RHYTHM 2 LEAD
CLASS A/ SIMUL FX LOOP EQREVERB FTSW.
SATELLITE EQ
SATELLITE SEND
SATELLITE
AUTORHY 2
AUTORHY 1
FX LOOP ONFULL TIME
FX LOOPSWITCHING
RHY 2 LEADAUTO ASSIGN SWITCHES
FX SEND
RETURN RETURN
LEFT(STEREO)
RIGHT(MONO)
SIG.
PATH
MODE SELECT
LEAD
EX SWFT SW
RHY 1
RHY 2
HANDBUILT IN PETALUMA CALIFORNIA
5
234
6789
10
10
5
234
6789
1010
ON / OFF AUTO R2
OFF
5
234
6789
1010
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First familiarize yourself with the layout of the Front Panel and plug in the FU-3 footswitch which is located on the underside of thechassis towards the middle and about mid way forward of the Rear Panel. Its not necessary to unplug the footswitch after use, simplyuse the handy fasteners on the left and right side of the cabinet and attach the unit for storage and/or transport. Make sure thefootswitch cable is connected properly. It has three pins and a key way for mating itself to the female portion of the jack. Whenconnected, the FU-3 footswitch will allow you to select the various modes,FX Loop and the EQ of the MARK IV remotely. If you dont
have the footswitch available, the MODE SELECT rotary switch located on the Rear Panel will access the modes. Before we get toospecific about each control, lets audition the 3 modes with some basic settings just to get your new MK IV up and purring.
Connect your favorite guitar to the instrument input jack. Flip the power switch to the FULL POWER position while leaving theSTANDBY switch set to STANDBY. ( It is always a good idea to practice this start up procedure as at least 30 seconds of warm-uptime lessens the shock on cold power tubes, thus prolonging their life substantially.) Using the example below as a guide, set thecontrols as illustrated and flip the STANDBY switch to the ON position. Listen to the three distinctly different modes using either thefootswitch or the MODE SELECT rotary switch as mentioned in the previous paragraph.
In the example above the Graphic E.Q. is set in the ever so popular V curve shape. Most players tend to use it more in the LEADchannel, finding the RHYTHM channel plenty sweet by itself without the use of the E.Q. ( for more information regarding the E.Q., seepage 6 .)
Viewing from the back of the amp, locate the REVERB control and set to 3. Set E.Q. switch to the center position (OFF). LEADVOICING switch should be set to HARMONICS and ignore the FX Loop for now. Set the power amp switches to SIMUL-CLASS andTRIODE.
After these initial settings have been made, plug in your guitar (STANDBY switch ON) and play! Use the three MASTER controls tobalance volumes between the modes. Use the OUTPUT LEVEL to raise or lower overall playing loudness. Dial in the PRESENCEcontrols to set brightness before adjusting TREBLE controls. RHYTHM 1 should be clean, fat, warm and round. RHYTHM 2 should benear maximum crunch, yet its capable of many other sounds as well. The LEAD mode should have searing sustain even though itsGAIN control is only around half. Now lets get into understanding the controls and the way they interact to obtain the sounds you wantto hear.
FRONT PANEL:
POWER-UP:
PULL
SHIFT
PULL
SHIFT
PULL
BRIGHT
MASTERS
LEAD GAIN
RHY2 GAIN R1+R2 MID
LEAD MID
R1+R2 BASS
LEAD BASS
R1 TREBLE
LEAD TREBLERHY1 GAIN
INPUT
PULLBRIGHT
INSTR
UMEN
T
PULL
FAT
PULL
FAT
EQ LOOP
OUTPUT LEVEL STANDBYTWEEDPOWER
MARK IV
R2 TREBLE
LEAD DRIVE
6
234
5789
1010 2
34567
89
1010 5
23
46789
1010 ON
FULLPOWER
PRESENCE
CONTROLS
80 240 750 2200 6600
SILENTRECORDING
(PULL)
R2R1 LD
5
23
4
6789
1 010
5
234
6789
1010
5 2346789
1
010
5 2346789
1
010
5
234
6789
10
10
5
234
6789
10
10
5
234
6789
1010
5
234
6789
1010
5 2346789
1
010
5
234
6789
10
10
6
234
5789
1010
5
234
6789
10
10
LEAD GAIN
Pull FAT out
RHY 1 pullBRIGHT out
RHY 2 pullFAT out
Pull Shifts forR2, Lead Out
LEAD DRIVE
Pull BRIGHT out
52
346
789
1010
5 2346789
1
010
52
346
789
1010
Pull
And now looking to the Rear Panel...
PAGE 2
3A SB
FUSE
GRAPHICEQ
REMOTE
REVERB
RECORDING
SLAVE( D
.I.)
POWERAMP
T RI OD E S IM UL -C LA SS H AR MO NI CS
PENTODE CLASS A
SPEAKERS
8 OHM 4 OHM4 OHM
MID GAIN
LEAD
VOICING
LEVEL OUT117 VOLTS60 HZ
4 AMPS
EXTERNAL SWITCHING JACKS
RHYTHM 1 RHYTHM 2 LEAD
CLASS A/ SIMUL FX LOOP EQREVERB FTSW.
SATELLITE EQ
SATELLITE SEND
SATELLITE
AUTORHY 2
AUTORHY 1
FX LOOP ONFULL TIME
FX LOOPSWITCHING
RHY 2 LEADAUTO ASSIGN SWITCHES
FX SEND
RETURN RETURN
LEFT(STEREO)
RIGHT(MONO)
SIG.
PATH
MODE SELECT
LEAD
EX SWFT SW
RHY 1
RHY 2
HANDBUILT IN PETALUMA CALIFORNIA
5
234
6789
10
10
5
234
6789
1010
ON / OFF AUTO R2
OFF
5
234
6789
1010
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PAGE 3
Setting the RHYTHM 1 mode adjusts the input sensitivity for the clean RHYTHM mode. With most guitars, this mode stays clean untilaround 8 where it begins to overdrive. Use the R1 MASTER to control loudness if you want slight overdrive at low volumes. This mode
was very carefully designed to provide great rhythm sounds, from the best of vintage, Fender-type (clean or solo)to a more modern, shimmering funk rhythm sound. Be sure to try this mode played really loud; youll love it for
blues or rock. (See the Traditional Blues setting on the Sample Settings sheet found on page 15 of this manual.)
This function adds shimmer and sparkle to your sound when activated. Note that the amount of added brightness varies with the R1GAIN setting: more brights at lower settings, less at higher. For super shimmer, run the GAIN at around 3 or 4
with the BRIGHT pulled out. For the most naturally balanced sound, run the GAIN at around 6 or 7 with theBRIGHT pulled.
This control dials in the MARK IVS predominate tonal characteristic. In the 0 to 3 range, a dark, warm jazz tone is obtainable.
Most common settings are in the 5 thru 7 range and note how the overall gain of the mode increases with higher TREBLEcontrol settings. This is because so much of the energy of the musical spectrum is channeledthrough this most powerful tone control. As this is true for all modes, the MARK IV includes threeseparate TREBLE controls.
These are the only shared tone controls aboard the MARK IV. Because of internal circuitry changes which occur when switchingmodes, you will most likely find R1s optimum setting works well for RHYTHM 2. The effect of these two tone controls is largelydetermined by the setting of the TREBLE controls. Only when the TREBLE control is set very low (or off) are the BASS and MID
controls really strong.
At normal TREBLE control settings, their effect is greatly diminished and they serve mainly to roundout and fill up the overall tone. Do note however, that setting the BASS control too high can resultin unwanted flubbiness, especially in RHYTHM 2. The recommended setting for the BASS control
is 0 to 3 and for the MID control it is 4 to 7 .
RHYTHM 1 GAIN:
RHY1 GAIN
INPUT
PULLBR
IGHT
INSTR
UMEN
T
234
78
9
1010
6 5
PULL BRIGHT:
RHY1 GAIN
PULLBRI G
HT
234
78
9
1010
6 5
CONTROLS:
RHYTHM 1 TREBLE:
RHY2 GAIN
PULL
FAT
RHY1 GAIN
PULL
BRIGHT
R1 TREBLE
23
4
78
91
010
65
234
78
9
1010
65
6
234
5789
1010
R1 + R2 BASS & R1 + R2 MID:
R1+ R2 BASS
6
234
5789
1010
R1+ R2 MIDR1TREBLE
23
4
78
91
010
65
23
4
78
91
010
65
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This control adjusts frequencies higher than those found on the TREBLE control. There are so many different sounds that RHYTHM1 can produce, you must experiment using your guitar and your ears. Try settings such as low on the TREBLE control, high on the
PRESENCE control...and the opposite...as an experiment, both with and without the BRIGHT switch.
Notice too that when playing very loud, higher settings of the PRESENCE will help you cut throughthe background wash of cymbals. Dont forget to turn RHYTHM 1 up loud and blow...Its a greatoverdrive sound as well !
This MASTER control adjusts the signal level of the RHYTHM 1 mode. It allows you to run various settings of the RHYTHM 1 GAINwhile still controlling overall RHYTHM 1 volume via the MASTER. Thats important because of the strikingtonal differences the BRIGHT switch makes at lower and higher settings of gain, and because high GAINcontrol settings are useful for producing onset of clip distortion sounds. The R1 MASTER also acts as anEffects Send Level control for RHYTHM 1.
RHYTHM 2 GAIN sets the overall characteristic of this mode, which is the most versatile of the three modes. At high settings 109and with the FAT switch pulled, RHYTHM 2 produces its maximum gain for crunch and can double as an alternate lead sound. Thismodes gain falls off quickly as the controls knob is reduced, providing a range of lower-gain onset of clip sounds and the ability to
produce an alternate voicing for clean sounds at its lowest settings.
PULL FAT has tremendous impact on both the gain and voice of RHYTHM 2. When pushed in, RHYTHM2 loses gain in the low mids and the sound reveals more of your guitars inherent personality. For cleanplaying or blues styles youll probably prefer the FAT pushed in. Work with the R2 TREBLE control andPRESENCE controls to dial in traditional blues-style solo tones from RHYTHM 2. For hard rock andmetal sounds, pull out the FAT and max the RHYTHM 2 GAIN control, using RHYTHM 2 TREBLE andPRESENCE to dial in cut and brightness.
These are the only shared tone controls on the MARK IV. You probably wont need much adjustment from their RHYTHM 1 settingbecause they are designed especially to have less dramatic effect in RHYTHM 2. Again youll noticethat the strength of these controls is influenced by how high or low the RHYTHM 2 TREBLE is set.
Excessive settings (especially of the BASS control) can cause a flubby sounding distortion if theTREBLE control is set low.
CONTROLS: (Continued)
R1 PRESENCE:
PULL
SHIFT
R2 TREBLE
PRESENCE
CONTROLS
R2 MID
62345
7
89
10106
234
5
7
2
34
7
89
1010
65
R1 MASTER:
PRES E
NCE
MAST
ERS
R1LEAD DRIVER2 TREBLE
62345
7
89
1010
62345
7
2
34
7
89
1010
65
62345
7
RHYTHM 2 GAIN & FAT:
INPUT
PULLB
RIGHT
INST
RUME
NT
PU
LLFAT6
234
5789
1010
RHY2 GAINRHY1 GAIN
6
23
457
89
1010
R1 + R2 BASS & R1 + R2 MID:
R1+ R2 BASSR1 TREBLE R1+R2 MID
6
23
457
89
1010
62
345
789
1010
62
345
789
1010
PAGE 4
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This control along with RHYTHM 2s PRESENCE control should be worked with together to produce the desired gain and brightnessof the mode. Setting the TREBLE higher, as always, increases the gain of the mode and allows increased distortion and sustain.
Lower settings allow the MID and BASS controls to become more dominant adding warmth to thesound.
RHYTHM 2s PRESENCE control also works on higher frequencies than the TREBLE, so by working with both controls, you canproduce any sound from fat and thick to searing and shredding. Dont be surprised if loud group playing requires higher PRESENCE
control settings to cut through...this is why weve provided the three modes with their separate Presencecontrols.
The RHYTHM 2 (and LEAD) PRESENCE control also has a PULL SHIFT feature. This Shift normalizesthe amount of high frequencies produced in the power section. With the PULL SHIFTS engaged, the
Presence controls will be more effective and will act on a higher frequency range. When the SHIFTS are pushed in, a punchier, moreaggressive tone is produced and the PRESENCE controls effectiveness is reduced.
This MASTER control is used to balance playing loudness in RHYTHM 2 and also determines the amount of RHYTHM 2 signal at theEffects Send jack.
This control sets up the input sensitivity for the LEAD mode. The more signal strength dialed in here, early in the preamp, the more
distortion will be available at the LEAD DRIVE control. Yet it is not necessary or recommended to turn the LEAD GAIN fully up.
Best results will occur with settings in the 8 range. As you approach a Gain of 7 the Lead sound willbecome extremely focused, rich and smooth; above 8 , total saturation occurs, reducing the effectivenessof the tone controls and causing increased microphonics and noise in the preamp tubes. Youll noticesubtle shifts in distortion tonality by trying different mixes of LEAD GAIN and LEAD DRIVE. The LEADGAIN control incorporates a PULL FAT for thickening the sound and saturating the signal further. This pullshift lowers the frequency of the Treble, adding a boost in the lower midrange. Try this shift for beefing upthe sound of weaker, stock pick-ups or simply for adding focus at virtually any setting of the GAIN control.
CONTROLS: (Continued)
RHYTHM 2 TREBLE:
R2 TREBLER1 +R2 BASS R1 +R2 MID
62
345
7
891
010
6
23
457
8
91010
6
23
457
8
9
1010
R2 PRESENCE:
R2 MASTER:
PAGE 5
SETTING THE LEAD MODE:
LEAD GAIN:
PU
LL
SHIFT
TREBLE
PR
ESENCE
CO
NTROLS
R 1
62
345
7
89
1
010
6
23
457
8
9
1010
6
23
45
10
R 2
239
1010
PULLBRIGHT
MASTERS
LEAD DRIVER2 TREBLE
P
ULL
R 2R 1
52
346
7
8
91
010
6
23
457
89
1010
6
23
457
89
1010
PRES
CONT
239
1010 2
39
1010
INPUT
PULL
BRIGH
T
INST
RUME
NT
RHY2 GAINRHY1 GAIN
PU
LLFA
T
PU
LLFA
T
LEAD GAIN
5
234
6789
1010
6
23
457
89
1010
6
23
457
89
1010
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There are also some great singing, slightly distorted sounds that come from low settings of Gain and Drive with FAT pushed in. Onsetof Clip and threshold of distortion are phrases often used to describe these sounds, which reveal the true blue beauty of the MARKIVs all-tube lineage (see the traditional blues setting on the Sample Settings sheet further back in this manual).
This control along with RHYTHM 2s PRESENCE control should be worked with together to produce the desired gain and brightnessof the mode. Setting the TREBLE higher, as always, increases the gain of the mode and allows increased distortion and sustain.
Lower settings allow the MID and BASS controls to become more dominant adding warmth to thesound.
Both of these controls add body and warmth without really affecting the strength of the signal. Merely dial in to your liking but noteagain that too much Bass combined with too high of a LEAD GAIN setting willtake away from the tight, highly focused lead sound that this mode offers.
This control works in conjunction with LEAD GAIN to determine the amount of sustain and overdrive. It is not necessary or evenrecommended to run the LEAD DRIVE way up in order to generate a sound that is fully saturated, so try settings in the 5 to 7region. Higher settings tend to increase noise and squealing without really embellishing the sound or feel.
Notice that this control comes on very rapidly at low settings, then changes onlygradually throughout the rest of its rotation. Familiarize yourself with the point
which represents the beginning or threshold of overdrive; it creates an ex-pressive distortion which is touch-sensitive to picking dynamics, providing har-monics that stay glued to the fundamental note. Youll find lots of great soundsin this 2 to 4 region!
PAGE 6
LEAD GAIN: (Continued)
CONTROLS: (Continued)
LEAD TREBLE:
LEAD BASS & LEAD MID:
INPUT
PULLBRIGHT
I NST
RU
MEN
T
RHY2 GAINRHY1 GAIN
PULLF
AT
P U
LLF
AT
LEAD GAIN
R1 TREBLELEAD TREBLE
52
346
7
8
9
1
010
6
2
34
578
9
101
0
6
23
457
89
1010
6
23
457
89
1010
6
23
457
89
1010
INSTR
UMEN
T
PULL
FAT 5 5
INPUT
PULLBRI G
HT
RHY2 GAINRHY1 GAIN
PULL
FAT
LEAD GAINR1 TREBLE
LEAD TREBLER1+R2 BASSLEAD BASS
R1+R2 BASSLEAD MID
23
467
8
91
010
23
467
8
91
010
6
23
457
89
1010
6
23
457
89
1010
6
23
457
89
1010
6
23
457
89
1010
6
23
457
89
1010
6
23
457
89
1010
6
23
457
89
1010
LEAD DRIVE:
INSTR
UMEN
T
PULL
FAT 5 5
INPUT
PULLBRI G
HT
RHY2 GAINRHY1 GAIN
PULL
FAT
LEAD GAINR1 TREBLE
LEAD TREBLER1+R2 BASSLEAD BASS
R1+R2 BASSLEAD MID
23
467
8
91
010
23
467
8
91
010
6
23
457
89
1010
6
23
457
89
1010
6
23
457
89
1010
6
23
457
89
1010
6
23
457
89
1010
6
23
457
89
1010
6
23
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89
1010
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PAGE 7
The importance of this switch is a must to understand. At low to medium playing volumes, the LEAD BRIGHT adds desirable sizzle,and gain in the highs to the overdrive sound and contributes to a big easy feeling as well. At high volumes the LEAD BRIGHT can
cause real problems, such as excess squealing and noise. At high volumes it is often not necessary to supple-ment the LEAD modes natural gain because the power amplifier will also be going into overdrive. So please
keep in mind how your Boogies cascading gain works: there are several amplifier stages in a row with gaincontrols at all the crucial points in between, so you can produce enormous amounts of amplifier gain at lowvolumes. Your MARK IV is capable of playing very loud as well, but it is not feasible to play with high gainand high volume simultaneously without causing squealing, feedback and excess noise. A Ferrari is a greatcar in tight corners and it is wickedly fast on the straightaway, but at some combination of speed and corneringit will spin-out. So will your MARK IV !
So remember to balance gain with volume. In the LEAD mode, a general guideline might be push in the BRIGHT for loud playingand pull out the BRIGHT at lower volumes. Your 12AX7 tubes will be much happier...and so will your soundman! (Another switchsimilarly dangerous at high gain/high volume settings is the Rear Panel LEAD VOICING switch, described later in this manual.)
These two controls work similarly to the ones previously discussed. Note that adding lots of PRESENCE (which is extra gain in thehighest frequency range) to high gain and high volume settings may aggravate the spin-out of squealing and excess noise. The LEAD
PRESENCE control has a PULL SHIFT which operates just like the R2 PRESENCE PULL SHIFT - it reducesthe amount of low frequencies and shifts the range of the Presence effect.
You may find that pulling out the PRESENCE control gives you a better balance when playing with a band,while pushing in the PRESENCE control provides a bigger and fatter sound for miced up recording. Whenthe shift is pushed in and the graphic EQ is set to the Classic V setting (see below), unholy amounts of tight,chunking bottom end are available. Give this setting a try for metal rhythm grooves.
This feature can be switched IN or OUT via the footswitch or the mini-rocker switch located on the Rear Panel. The rear rocker switchhas three positions: left is EQ IN (all modes), center position is EQ OUT (all modes) and right position is EQ AUTO RHY 2, which
means the EQ comes on automatically whenever RHYTHM 2 is selected.
Note that once the EQ is switched IN via the rocker switch, the footswitch will not be able totake it back out. Indicator LEDs on both the footswitch and the amplifiers Front Panel indicateEQ status. Setting up the EQ is strictly a matter of personal taste and enjoyment, so prepare to
have some fun dialing in fine nuances of tonal shading - or going for the outer extremes ofweirdness! The one setting we recommend you use as a departure point is one we call theclassic V. It involves boosting the lowest and highest frequency sliders the most, boosting the240 and 2200 sliders somewhat less and cutting the 750 center band.
You can be as subtle or extreme as you want with this pattern; and when youre going for extremes, youll notice that the 750 s lider isthe one thats by far the most crucial. Once youve boosted the other four bands, youll find that by adjusting only the 750, you candetermine the strength of the entire EQ effect. Youll also notice that there is a certain point where the sound goes from maximumthrash to thin and buzzy. Youll find that your ears quickly become adjusted (addicted?) to this hyper-tone and when you switch the
CONTROLS: (Continued)
LEAD BRIGHT:
PULLBRI G
HT
MASTERS5
23
46789
1010
R1LEAD DRIVE
R2 TREBLE
6
23
457
89
1010
6
23
457
8
9
1010
6
23
457
89
1010
PRESE
NCE
CONTR
OLS
LEAD PRESENCE & LEAD MASTER:
PULLBRI G
HT
MASTERS
R1LEAD DRIVE
R2 TREBLE
52
346
7
8
91
010
PRESENCE
CO
NTROLS 5
23
467
8
91
010
6
23
457
89
1010
6
23
457
89
1010
GRAPHIC EQ:
SILENTRECORDING
(PULL)
OUTPUT LEVEL80 240 750 2200 6600
6
23
457
89
1010
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8/12/2019 Mesa Mark IV
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EQ back out of the circuit, the straight tone sounds to flat. Dont worry! Its just hearing hangover. All the MARK IVsmodes weredeveloped without using the EQ so that it could be an accessory - not a necessity.
This control adjusts the playing loudness of all three modes equally. Once youve got the sounds set up as you would like them, usingthis one control will allow you to work louder or softer venues. Notice that the OUTPUT LEVELcontrol also functions as an Effects Return control, owing to its location in the signal chain.
This push/pull switch turns off the signal at the output stage therefore muting the speaker. This enables you to record silently (usingthe RECORDING out jack, not the SLAVE D.I.) without the need to disconnect the speaker.Signal strength to the recording circuit is still regulated by the OUTPUT LEVEL control, eventhough the speaker cannot be heard.
NOTE: Remember...a load must be maintained on the amplifier to avoid damage to thetransformer. A soak resistor (8 ohms) can be purchased for just such purposes. See yourlocal dealer or give us a call and well assist you if need be.
The STANDBY switch turns off the high voltages inside the amplifier while allowing the tube filaments to stay warm and ready forimmediate use. Its a good practice to turn on the A.C. power with this switch in theSTANDBY position, allowing the tubes 30 seconds or so to warm up. This procedureprevents tube problems and increases their toneful life substantially.
The STANDBY switch is also the perfect feature for set breaks as well.
NOTE: Remember...remove the protective plastic coating from the tubes before youconnect the MARK IV to an A.C. outlet.
This switch has three positions: FULL POWER, OFF and TWEED POWER. The OFF position is in the center and is unlabeled. UseFULL POWER for maximum volume and clean headroom. TWEED POWER works like a built-in variac, reducing all the internal
voltages for a spongy, vintage feeling and an extraordinary brown sound.
POWER is reduced somewhat too, making it easier to achieve a big overdriven power sound, espe-cially when TWEED POWER is used in conjunction with Class A power (this will be explained later inthis manual). Another virtue of TWEED POWER is that the lowered voltages will greatly extend tubelife and overall reliability, while still producing enough power to work many of your gigs...and all of yourrecording sessions!
CONTROLS: (Continued)
GRAPHIC EQ: (Continued)
OUTPUT LEVEL:
SILENT RECORDING: (Pull Switch)
STANDBY:
OUTPUT LEVEL
80 240 750 2200 6600
2
34
5 678
9
1 0 10
SILENTRECORDING
(PULL)
EQ
STANDBY
MARK IV
ON
PAGE 8
80 240 OUTPUT LEVEL750 2200 6600
24
5
67
8 9
1
0
10
SILENTRECORDING
(PULL)
3
80 240 750 2200 OUTPUT LEVEL6600
SILENTRECORDING
(PULL)
2
345
67
8
91
010
POWER: (Full & Tweed Power)
OUTPUT LEVEL
SILENTRECORDING
(PULL)
EQ
STANDBY
MARK IV
ON
LOOP
TWEEDPOWER
FULLPOWER
2
34
5 678
9
1 0 10
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PAGE 9
The MARK IV uses a removable I.E.C. type power cord to supply the A.C. power. The power cord supplied with your unit shouldbe used whenever possible as we chose it for its snug fit. Because this type of RECEPTACLE is somewhat universal and used in
many products both in and out of electronic musical instrument domain, you may use other cords of thistype when the one supplied is not available. Should this become necessary, check that the cord is seated allthe way into the RECEPTACLE to insure an uninterrupted performance. In the U.S., the proper voltage is
117 volts A.C. (110-120). Always be sure to connect the MARK IV to its rated voltage to avoid damaginginternal circuitry.
The FUSE should be a 3 amp Slo-Blo for use with 100 or 117 volt A.C. Mains. Should the FUSE blow, replace it with a similar type andrating, then watch the power tubes as you start the amp back up again.
Warm up the tubes first with the amplifier in STANDBY mode, then, watching them carefully, flip the STANDBY
switch to ON. If you see a tube arc or spark inside, that is definitely the problem and can be remedied by aneasy power tube replacement. In many cases though, the bad tube will only fail intermittently. Watch for a
while and if any tubes start to run red-hot, this is the cause of your original problem.
If everything appears OK, tap on each power tube to reveal the faulty one, because a blown fuse is nearlyalways caused by a bad power tube (s). Running the amp in TWEED power will very likely offer a temporaryremedy and let you get through the gig. If the FUSE blows immediately when switching on the A.C. power (in
the STANDBY mode), then some other problem is the cause, most likely a failed rectifier diode. (See the section on tube maintenancefurther back in this manual for more assistance and helpful hints on how to maintain the life of the power tubes).
REAR PANEL MKIV
A.C. RECEPTACLE:
FUSE:
3A SB
FUSE
117 VOLTS60 HZ
4 AMPS
3A SB
FUSE
RECORDING
SLAVE( D
.I.)
POWERAMP
T RI OD E S IM UL -C LA SS H AR MO NI CS
PENTODE CLASS A
SPEAKER
S
8 OHM 4 OHM4 OHM
MID GAIN
LEAD
VOICING
LEVEL OUT
117 VOLTS60 HZ
4 AMPS
EXTERNAL SWITCHING JACKS
RHYTHM 1 RHYTHM 2 LEAD
CLASS A/ SIMUL FX LOOP EQREV FTSW.
SATELLITE EQ
SATELLITE SEND
SAT
ELLITE
AUTORHY 2
AUTORHY 1
FX LOOP ONFULL TIME
FX LOOPSWITCHING
RHY 2 LEADAUTO ASSIGN SWITCHES
FX SEND
RETURN RETURN
LEFT(STEREO)
RIGHT(MONO)
SIG.
PATH
MODE SELECT
LEAD
EX SWFT SW
RHY 1
RHY 2
HANDBUILT IN PETALUMA CALIFORNIA
234
56789
1 010
GRAPH
ICEQ
ON OFFAUTO R2
REMOTE
REVERB
234
56789
10 10
23456
789
10 10
REST AREA
3A SB
FUSE
117 VOLTS60 HZ
4 AMPS
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PAGE 10
REVERB is a simple depth control which activates the rich all-tube, three-spring analog circuitry. Even though many players havemore modern digital reverbs and delays, there is still something quite pleasant about this natural-sounding,traditional Reverb system that we think youll enjoy. The REVERB effect may seem more intense in somemodes (such as RHYTHM 1) than in other modes, because each mode has a slightly different EQ character-
istic and attack dynamic. This represents normal REVERB operation and is no cause for concern.
The 1/4" jack on the Rear Panel labeled REV FTSW. (as shown in the illustration) allows you control of theREVERB remotely when the (optional)Mesa/BoogieREVERB footswitch is connected. See your nearestBoogiePro Center for this item or call us directly well be happy to assist you.
This feature was explained earlier in the Graphic EQ section of this manual. Refer back to it if you need help understanding what thefunction of this switch is.
Mesa/Boogie offers two different Satellite companion amplifers that enable you to either reinforce your already amazing tone, or splitand process the signal using the Effects Loop. A simple 60 watt version called the Satellite Sixty, as well as a 75 watt Simul-Class with
Graphic EQ make up this supportive duo with the Simul-Satellite being the obvious
choice for most MARK IV owners. In the popular stereo scheme, a processors Out-puts feed the two Returns ( Left and Right ) on the MARK IVS Rear Panel and theLeft Return is then sent on to the matching Satellites Input via the Satellite Send jack.This buffered line may then travel across the stage with little or no tonal degradationdue to cable length or impedance mismatching.
The MARK IV has the ability to control the Simul-Satellites Five Band EQ remotelyand automatically - tracking the auto assign function and the Footcontroller choices as
they are used aboard the MARK IV. In this way every nuance and setting of the master amp is relayed to the slave amp creating atruly awesome spread tonally and dynamically.
This section of the MARK IV is quite sophisticated, offering two LOOPS and a selector switch. The LOOP labled NORMAL stays onall the time. The other LOOP is switched IN or OUT of the circuit by either the footswitch, the programming rocker switches or the
external jacks (when the MARK IV is being controlled by a MIDI switcher). Notice that if the switchableLOOP is turned on by the rockers or the external jack, the footswitch cannot turn it back off. Two rockerswitches are provided so you can pre-set the LOOP to come on in conjunction with any one or two modes.(If an effect is desired on all three modes, use the NORMAL LOOP.) The LOOPS were designed in this wayso you can automatically have your effects in when selecting, say, RHYTHM 1 and/or RHYTHM 2, yet still
REAR VIEW MKIV (Continued)
REVERB & REVERB FOOTSWITCH:
EFFECTS LOOP SECTION:
SIG.
PATH
AUTORHY 2
AUTORHY 1
FX LOOP ONFULL TIME
FX LOOPSWITCHING
RHY 2 LEADAUTO ASSIGN SWITCHES
FX SEND
RETURN RETURN
LEFT(STEREO)
RIGHT(MONO)
SATELLITE CONTROL: EQ & Send Jack
GRAPHICEQ
ON OFF AUTO R2
REMOTE
R
EVERB
REV FTSW.
SATELLITE EQ
SATELLITE SEND
SATELLITE
SIG.
PATH
2345
67
89
1
0
10
FUSE
3A SB
GRAPHICEQ
ON OFF AUTO R2
REMOTE
REVERB 2
3456
789
1
010
REV FTSW.
SATELLITE EQ
SATELLITE SEND
SATELLITE
SIG.
PATH
117 VOLTS60 HZ
4 AMPS
EQ ROCKER SWITCH:
FUSE
3A SB
GRAPHICEQ
ON OFF AUTO R2
REMOTE
REVERB 2
34567
89
1
010
REV FTSW.
SATELLITE EQ
SATELLITE SEND
SATELLITE
SIG.
PATH
117 VOLTS50-60 HZ4 AMPS
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8/12/2019 Mesa Mark IV
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PAGE 11
be able to footswitch in the effects mid-way through a LEAD mode solo, for example. Remember that the MASTERS double as effectssend controls and the OUTPUT LEVEL also works as an Effects Return control.
Following the enormous success of this feature in the Quad and Studio Preamps, where theyve been used on numerous professional- and countless home recordings, this proven recording circuitry has been included into your new MARK IV. This recording circuit
can be used while performing live or silently at all hours of the night. Do not unplug thespeaker when you wish to record silently - merely use the SILENT RECORDING pull switch(located on the amplifiers Front Panel).
Even though the RECORDING OUT has its own LEVEL control, the amount of signal availableis determined by the MASTERS and the OUTPUT LEVEL control. Youll find that the RE-CORDING OUT does a pretty remarkable job of simulating the complex functions of poweramp, speakers and microphone while at the same time in very little need of any EQing.
Notice also that the presence controls are inactive in the recording process, as they are part of the power amp section. The built-in EQworks well for adjusting tonal nuances when recording and your mixing boards EQ may also be helpful, though not much of either isneeded. Finally, you may use the RECORDING OUT for driving the p.a. directly. For stereo recording, connect the RECORDING OUTto your stereo effect, then connect the left and right outputs of the effect into separate channels of the recording mixer.
This is a traditional Boogie feature that offers an adjustable-level signal for driving external slave power amplifiers. Here the signal isderived from the speaker terminal, so a speaker (or load resistor) must be connected at all times! The D.I. can also be used as a
feed to a p.a. but quite a lot of EQing will be needed at the board. For much better results, usethe RECORDING OUT when feeding a p.a. board.
A final use for the SLAVE is to drive a string of effects. This is a complex set-up requiringanother power amp (stereo) and two, or better yet three speaker cabs. In this hook-up theentire MARK IV functions as a tone-generating preamp, with the output taken from theSLAVE D.I. and fed into the effects string. The output of the last effect is then used to drive astereo power amp - such as our 50/50 Stereoor Stereo Simul-Class Two Ninetypoweramps - which in turn would power a pair of speakers.
Remember, the speaker jack of the MARK IV must be loaded by either a power-soak type resistor (which alters the tone badly)or an actual speaker. This middle speaker will provide a dry or un-effected sound and is sometimes just a single 12 hidden under thestage.
NOTE: Once signal is taken from the SLAVE D.I. Output, it cannot be inserted back into the MARK IV as a feedback loop will becreated resulting in a terrible squeal. Think of the SLAVE as a one way send.
This switch reconfigures the circuitry for the two outer-end power tubes. PENTODE increases power and punch, and results in aharder clip. Use this setting for loud, live applications such as un-miced blues or country gigs.
TRIODE lowers the power and softens and smooths the onset of clip. This makes it easier to get a richsinging sound full of sustain and harmonics, but some headroom is sacrificed for this sweeter response.
REAR VIEW MKIV (Continued)
EFFECTS LOOP SECTION: (Continued)
RECORDING OUT:
RECORDING
SLA
VE(D.I
.)
LEVEL OUT
23456
789
10 10
AUTORHY 2
AUTORHY 1
FX LOOP ONFULL TIME
FX LOOPSWITCHING
RHY 2 LEADAUTO ASSIGN SWITCHES
FX SEND
RETURN RETURN
LEFT(STEREO)
RIGHT(MONO)
2345
67
89
1
010
SLAVE OUT(D.I.):
RECO
RDING
SLAV
E(D. I
.)
LEVEL OUT
2
34567
89
1
010
AUTORHY 2
AUTORHY 1
FX LOOP ONFULL TIME
FX LOOPSWITCHING
RHY 2 LEADAUTO ASSIGN SWITCHES
FX SEND
RETURN RETURN
LEFT(STEREO)
RIGHT(MONO)
2345
6
789
1
010
TRIODE / PENTODE SWITCH:
POWERAMPTRIODE SIMUL-CLASS HARMONICS
PENTODE CLASS A MID GAINLEAD
VOICING
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8/12/2019 Mesa Mark IV
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This switch selects between two-tube and four-tube operation in the power section. In the CLASS A position, only the two end powertubes are active, producing around 30 watts before clipping when operating TRIODE, or 50 watts when in PENTODE. For the nastiest
shredding tone and the greatest amount of power amp distortion, use CLASS A with TWEEDPOWER and TRIODE.
In the SIMUL-CLASS position, the middle two 6L6s switch on in parallel with the end tubes andthe total output is combined through our unique output transformer. Youll find an increase inlow-end punch as well as overall volume as the power kicks up to around 85 watts PENTODEor 70 watts TRIODE (power ratings based on standard U.S. music amp specs which call for 120volt A.C. Mains and allow 5% distortion).
When you deliberately push the power section into clip, the wattage continues to rise, peaking out at about double. The MARK IVprovides an external jack for the power switching function so this feature can be programmed to operate in sync with, say, RHYTHM2 via a MIDI switcher such as our MIDI Matrix.
NOTE: For the external jack to function properly, the mini-rocker switch must remain in the CLASS A position.
This switch affects the LEAD mode only. Most noticeable is the big increase in gain and sustain when MID GAIN is selected. Thisadded gain is focused in the mid-range punch region and is most noticeable when the LEAD DRIVE control is set very low - at t he
threshold of distortion point discussed earlier. Using this low setting with the MID GAIN on(switch in the down position) produces a punchier, fatter blues sound, especially when used
with Pentode and Simul-Class.
As the setting of the LEAD DRIVE control is increased, the MID GAIN continues to add hugeamounts of extra boost, which at some point will become overwhelming and will cause unnec-
essary noise, squealing and feedback when used in conjunction with the LEAD BRIGHT andLEAD FAT switches. For loud high-gain lead playing most seasoned veterans will prefer theswitch in its HARMONICS position (so named because it produces a carefully balanced har-
monic spectrum rather than the blatant mid-boost sound). To duplicate the sounds of our fabled MARK II-C, switches should be setfor HARMONICS and TRIODE, with the PRESENCE controls pulled out. This produces a great balance between punch, smoothnessand rich overtones to deliver a guitar voice thats truly classic! Notice that hiss, noise and feedback levels are extremely low for anamplifier with this much gain.
This procedure is in keeping with Mesa/Boogies quest for ultimate versatility. As you know, different tubes offer different sounds andplaying characteristics and your new MARK IV offers four choices: FIRST: the standard four 6L6s which produce by far the best all-
around performance. They deliver the most powerful clean sounds along with the richest distortion. SECOND: Type 5881 is similar tothe 6L6, but these tubes are just slightly less powerful. Although they will produce a somewhat rounder, more vintage tone. THIRD:For those seeking the traditional British edge to their overdrive sounds, EL-34s can replace the 6L6s in the end two sockets (outer-left and outer-right). When running the amp in class A, only the two EL-34s will be operating. In Simul-Class, a combination of two6L6s plus the EL-34s produce a louder, fatter sound while retaining the British edge. (Expect the clean sound to suffer a bit wheneverEL-34s are used.) All combinations of Triode, Pentode, Tweed and Normal power can be used with this EL-34/6L6 combination.
FOURTH: Those of you who recall the great sounds of old Fender Deluxes will be delighted to know that four 6V6s can also be usedin the MARK IV...but, ONLY when TWEED and SIMUL-CLASS are selected. Also, to reduce tube wear when using 6V6s, the 8
REAR VIEW MKIV (Continued)
SIMUL-CLASS / CLASS A SWITCH:
LEVEL OUT
POWERAMPTRIODE SIMUL-CLASS HARMONICS
PENTODE CLASS A
SPEAKERS
8 OHM 4 OHM4 OHM
MID GAINLEAD
VOICIN
G
234567
89
1
010
2345
67
89
1
010
PAGE 12
HARMONICS / MID GAIN SWITCH:
LEVEL OUT
POWERAMPTRIODE SIMUL-CLASS HARMONICS
PENTODE CLASS A
SPEAKERS
8 OHM 4 OHM4 OHM
MID GAINLEAD
VOICING
2345
67
89
1
010
2345
67
89
10
10
POWER TUBE SUBSTITUTION:
-
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PAGE 13
ohm speaker should be plugged into the 4 ohm jack. However, please note that Mesa/Boogie cannot accept responsibility forany blown 6V6s incurred during such usage! Proper operation depends totally on the correct setting of the aforementioned switchesand this will be impossible to verify for warranty tube coverage. So please exercise caution when using 6V6s! Incorrect setting of theswitches wont usually cause immediate tube failure, but the strain caused is far in excess of recommended ratings.
These two outer tubes can be substituted with EL-34s.CAUTION: Place amp in STANDBY mode when changingtubes.
CAUTION: Tubes can become very HOT...they can causeinjury. Use care in removing tubes that are warm/hot andnever remove a tube by pulling on the glass. Instead, grabthe tubes socket or base and rock the tube from side toside while pulling gently downward.
Speaker jacks for both 8 ohm and 4 ohm loads are provided. CAUTION: A speaker (or load resistor) must remain connected toa speaker output on your MARK IV to prevent damage to the power tubes and transformer! (For silent recording, merely pullthe designated switch on the OUTPUT LEVEL control located on the Front Panel and do not disconnect the speaker.)
Two 4 ohm jacks are provided and should be used when you wish to run two 8 ohm speakersor cabinets. (This is because two 8 ohm loads connected in parallel present a combined loadto the amplifier of 4 ohms.) Speaker mis-matching is not a cause for great concern - unless thecombined load is considerably less than the rated impedance. If, for example, you run two 4ohm cabinets - each plugged into a 4 ohm jack - the amplifier would see 2 ohms as the totalload. And while this will not cause immediate damage, it will result in shortened power tubelife. Mis-matching on the high side is always preferable, if you have no choice.
This switch determines the method of control over your MARK IVS switching functions. The first position activates the footswitch.The next three positions select the individual modes manually.
The last position enables the use of the EXTERNAL SWITCHING jacks. If ever the switchingfunctions seem to operate incorrectly, always check that the MODE SELECTOR switch is setto the proper position.
REAR VIEW MKIV (Continued)
POWER TUBE SUBSTITUTION: (Continued)
POWERAMP
T RI OD E S IM UL- CL AS S H AR MON ICS
PENTODE CLASS A
SPEAKERS
8 OHM 4 OHM4 OHM
MID GAIN
LEAD
VOICING
EXTERNAL SWITCHING JACKS
RHYTHM 1 RHYTHM 2 LEAD
CLASS A/ SIMUL FX LOOP EQ
MODE SELECT
LEAD
EX SWFT SW
RHY 1
RHY 2
HANDBUILT IN PETALUMA CALIFORNIA
OUT
44NGWHT
6L6GC
STR454
44NGWHT
6L6GC
STR454
44NGWHT
6L6GC
STR454
44NGWHT
6L6GC
STR454
NOTE:
SPEAKER JACKS:
LEVEL OUT
POWERAMPTRIODE SIMUL-CLASS HARMONICS
PENTODE CLASS A
SPEAKERS
8 OHM 4 OHM4 OHM
MID GAINLEAD
VOICING
2345
67
89
1
010
2345
67
89
1
010
MODE SELECTOR SWITCH:
SIMUL-CLASS HARMONICS
CLASS A
4 OHM4 OHM
MID GAINLEAD
VOICING
MODE SELECT
LEAD
EX SWFT SW
RHY 1
RHY 2
HANDBUILT IN PETALUMA CALIFORNIA
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PAGE 14
REAR VIEW MKIV (Continued)
EXTERNAL SWITCHING JACKS:
POWERAMPTRIODE SIMUL-CLASS HARMONICS
PENTODE CLASS A
SPEAKERS
8 OHM 4 OHM4 OHM
MID GAINLEAD
VOIC
ING
MODE SELECT
LEAD
EX SWFT SW
RHY 1
RHY 2
HANDBUILT IN PETALUMA CALIFORNIA
EXTERNAL SWITCHING JACKS
RHYTHM 1 RHYTHM 2 LEAD
CLASS A/ SIMUL FX LOOP EQ
These jacks allow remote (usually MIDI-programmed) operation of your amplifiers functions from an external switching source, suchas the Mesa/BoogieMIDI Matrix. In each case, the switching is accomplished by connecting (shorting) the jacks tip to its ring.
Your new MARK IVsstereo capabilities can only increase your musical sound and enjoyment. Mesa/Boogiessatellite poweredspeakers - the Satellite 60 and the Simul-Satellite - which are specially designed to provide a second channel of amplification for yourBoogiecombo amp and your stereo effects. The drawings below illustrate a simple hook-up procedure for going stereo. Check with
your Mesa/Boogie Pro Center or call us direct for more information if you need it, were always more than happy to assist you, ournew family member. Thanks !
GOING STEREO:
REV FTSW.
SATELLITE EQ
SATELLITE SEND
SATELLITE
AUTORHY 2
AUTORHY 1
FX LOOP ONFULL TIME
FX LOOPSWITCHING
RHY 2 LEADAUTO ASSIGN SWITCHES
RETURN
LEFT(STEREO)
RIGHT(MONO)
SIG.
PATH
FX SEND
RETURN
MARK IV (rear panel) Stereo Effects Unit (rear panel)
LEFT & RIGHTOUTPUTS
LEFT & RIGHT(mono)
SEND
RETURN
EFFECTS
2345
67
89
1
010
EFFECTSLEVEL
HANDBUILT IN PETALUMA CALIFORNIA
GROUNDA OFF B
2.5ASB
FUSE
1.5A
Satellite (rear panel)INPUTS
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PAGE 15
PULL
SHIFT
PULL
SHIFT
PULLBRIGHT
MASTERS
LEAD GAIN
RHY2 GAIN R1+R2 MID
LEAD MID
R1+R2 BASS
LEAD BASS
R1 TREBLE
LEAD TREBLE
RHY1 GAIN
INPUT
PULL
BRIGHT
INSTRU
MENT
PULL
FAT
PULL
FAT
SILENTRECORDING
(PULL)
EQ LOOP
OUTPUT LEVEL STANDBYTWEEDPOWER
MARK IV
R1 R2
ON FULLPOWERP
RESENCE
CONTROLS
R2 TREBLE
LEAD DRIVE
LD
78
3 2
PULL
SHIFT
PULL
SHIFT
PULL
BRIGHT
MAS
TERS
LEAD GAIN
RHY2 GAIN R1+R2 MID
LEAD MID
R1+R2 BASS
LEAD BASS
R1 TREBLE
LEAD TREBLE
RHY1 GAININPUT
PULL
BRIGHT
INST
RUME
NT
PULL
FAT
PULL
FAT
SILENTRECORDING
(PULL)
EQ LOOP
OUTPUT LEVEL STANDBYTWEEDPOWER
MARK IV
R1 R2
ON FULLPOWERP
RESENCE
CONTROLS
R2 TREBLE
LEAD DRIVELD
3
PULL
SHIFT
PULL
SHIFT
PULLBRIGHT
MASTERS
LEAD GAIN
RHY2 GAIN R1+R2 MID
LEAD MID
R1+R2 BASS
LEAD BASS
R1 TREBLE
LEAD TREBLE
RHY1 GAININPUT
PUL
LBRIGHT
INST
RUM
ENT
PULL
FAT
PULL
FAT
SILENTRECORDING
(PULL)
EQ LOOP
OUTPUT LEVEL STANDBYTWEEDPOWER
MARK IV
R1 R2
ON FULLPOWERP
RESENCE
CONTROLS
R2 TREBLE
LEAD DRIVE
23
10
LD
PULL
SHIFT
PULL
SHIFT
PULLBRIGHT
MASTERS
LEAD GAIN
RHY2 GAIN R1+R2 MID
LEAD MID
R1+R2 BASS
LEAD BASS
R1 TREBLE
LEAD TREBLE
RHY1 GAININPUT
PULL
BRIGHT
INS
TRUM
ENT
PULL
FAT
PULL
FAT
SILENTRECORDING
(PULL)
EQ LOOP
OUTPUT LEVEL STANDBYTWEEDPOWER
MARK IV
R1 R2
ON FULLPOWERP
RESENCE
CONTROLS
R2 TREBLE
LEAD DRIVELD
PULL
SHIFT
PULL
SHIFT
PULLBRIGHT
MASTERS
LEAD GAIN
RHY2 GAIN R1+R2 MID
LEAD MID
R1+R2 BASS
LEAD BASS
R1 TREBLE
LEAD TREBLE
RHY1 GAININPUT
PU
LL
BRIGHT
INS
TRUM
ENT
PULL
FAT
PULL
FAT
SILENTRECORDING
(PULL)
EQ LOOP
OUTPUT LEVEL STANDBYTWEEDPOWER
MARK IV
R1 R2
ON FULLPOWERP
RESENCE
CONTROLS
R2 TREBLE
LEAD DRIVELD
80 240 750 2200 6600
80 240 750 2200 6600
6 10 5 5
5 4 5
3 7
6
3 2
5 3 3
PULL PULL
PULLPULL
PULL PULL
(NO EQ)PULL
67
4
5 4 2
5 7 0
4
78 9 56 0 0
PULL PULL
3 343 2
PULL PULL
3 2
3
3
PULL PULL PULL
PULLPULL
10 10 67 3 8 2 5 023
8 67 3 7 3 43 2 1
80 240 750 2200 6600
8 34
3
1 0 0
567
67
4 5
3
45
PULL
PULL
PULLPULL
80 240 750 2200 6600
45 5 5 67
5
80 240 750 2200 6600
0 0744
PULL
10 10
8
PULL PULL
0 4 3 4 8 2
2
2
Factory Sample SettingsMARK IVClean / Crunch / Lead
Vintage Clean / Clip / Howl
Blues / Grind / Sear
Twang / Purr / Sing
All Out Agro
(RHY 2 OPTIONAL)
(EQ OPTIONAL)
(OPTIONAL)
(EQ OPTIONAL)
(OPTIONAL)
(EQ OPTIONAL)
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PAGE 16
PULL
SHIFT
PULL
SHIFT
PULLBRIGHT
MASTERS
LEAD GAIN
RHY2 GAIN R1+R2 MID
LEAD MID
R1+R2 BASS
LEAD BASS
R1 TREBLE
LEAD TREBLE
RHY1 GAININPUT
PULLBRIG
HT
I NSTR
UMEN
T
PULL
FAT
PULL
FAT
SILENTRECORDING
(PULL)
EQ LOOP
OUTPUT LEVEL STANDBYTWEEDPOWER
MARK IV
R1 R2
80 240 750 2200 6600
ON FULLPOWERP
RESENCE
CONTROLS
R2 TREBLE
LEAD DRIVELD
PULL
SHIFT
PULL
SHIFT
PULLBRIGHT
MASTERS
LEAD GAIN
RHY2 GAIN R1+R2 MID
LEAD MID
R1+R2 BASS
LEAD BASS
R1 TREBLE
LEAD TREBLE
RHY1 GAININPUT
PULLBRIGHT
INS
TRUM
ENT
PULL
FAT
PULL
FAT
SILENTRECORDING
(PULL)
EQ LOOP
OUTPUT LEVEL STANDBYTWEEDPOWER
MARK IV
R1 R2
80 240 750 2200 6600
ON FULLPOWERP
RESENCE
CONTROLS
R2 TREBLE
LEAD DRIVELD
PULL
SHIFT
PULL
SHIFT
PULLBRIGHT
MASTERS
LEAD GAIN
RHY2 GAIN R1+R2 MID
LEAD MID
R1+R2 BASS
LEAD BASS
R1 TREBLE
LEAD TREBLE
RHY1 GAININPUT
PULLBRIG
HT
I NSTR
UMEN
T
PULL
FAT
PULL
FAT
SILENTRECORDING
(PULL)
EQ LOOP
OUTPUT LEVEL STANDBYTWEEDPOWER
MARK IV
R1 R2
80 240 750 2200 6600
ON FULLPOWERP
RESENCE
CONTROLS
R2 TREBLE
LEAD DRIVELD
PULL
SHIFT
PULL
SHIFT
PULLBRIGHT
MAST
ERS
LEAD GAIN
RHY2 GAIN R1+R2 MID
LEAD MID
R1+R2 BASS
LEAD BASS
R1 TREBLE
LEAD TREBLE
RHY1 GAININPUT
PULLBRIG
HT
I NSTR
UMEN
T
PULL
FAT
PULL
FAT
SILENTRECORDING
(PULL)
EQ LOOP
OUTPUT LEVEL STANDBY
TWEED
POWER
MARK IV
R1 R2
80 240 750 2200 6600
ON FULLPOWERP
RESENCE
CONTROLS
R2 TREBLE
LEAD DRIVELD
PULL
SHIFT
PULL
SHIFT
PULLBRIGHT
MASTERS
LEAD GAIN
RHY2 GAIN R1+R2 MID
LEAD MID
R1+R2 BASS
LEAD BASS
R1 TREBLE
LEAD TREBLE
RHY1 GAIN
INPUT
PULLBRIG
HT
I NSTR
UMEN
T
PULL
FAT
PULL
FAT
SILENTRECORDING
(PULL)
EQ LOOP
OUTPUT LEVEL STANDBYTWEEDPOWER
MARK IV
R1 R2
80 240 750 2200 6600
ON FULLPOWERP
RESENCE
CONTROLS
R2 TREBLE
LEAD DRIVE
LD
Personal Sett ingsMARK IV
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Description of Tube Functi
V1A= Input Stage
V1B= Tone Recovery Stage
(post tone controls)
V2A= Third Gain Stage (Rhythm Modes)and Fifth Lead Gain Stage
V2B= FX Return Stage
V3A= Fir
V3B= Re
V4A= Se Hig
V4B= Re
V5= Ph
Power Tube Substitution:
6V6's in Tweed & Simul-Class
in all 4 sockets.
5881's in all 4 or Class A Sockets.
EL-34's in Class A sockets only.
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PAGE 18
You may occasionally experience some form of tube noise or microphonics. Certainly no cause for alarm, this quirky behavior comeswith the territory and the Tone. Much like changing a light bulb, you dont need a technician to cure these types of minor userserviceable annoyances and in fact, youll be amazed at how easy it is to cure tube problems...by simply swapping out a pre-amp orpower tube!
First may we suggest that you set the amplifier up on something so that you can get to the tubes comfortably without having to bend
down. It also helps to have adequate lighting as you will need to see the tube sockets clearly to swap tubes. Use caution and commonsense when touching the tubes after the amplifier has been on as they may be extremely hot! If they are hot and you dont want to waitfor them to cool off, try grasping them with a rag and also note that the glass down around the bulbous silvery tip is considerably lesshot which makes it easier to handle. Gently rock the tube back and forth as you pull it away from its socket.
There are two main types of tube faults: shorts and noise. Both large and small tubes may fall prey to either of these problems butdiagnosis and remedy is usually simple.
If a fuse blows, the problem is most likely a shorted power tube and shorts can either be mild or severe. In a mildly shorted tube the
electron flow has overcome the control grid and excess current flows to the plate. You will usually hear the amp become distorted andbegin to hum slightly. If this occurs, quickly look at the power tubes as you switch the amp to STANDBY and try to identify one asglowing red hot. It is likely that two of a pair will be glowing since the shorted tube will pull down the bias for its adjacent mates, butone tube may be glowing hotter and that one is the culprit. The other two are often fine unless theyve been glowing bright redfor several minutes.
Because there is no physical short inside the tube (just electrons rioting out of control) merely switching to STANDBY for a fewmoments then back to ON will usually cure the problem...at least temporarily. Watch the tubes carefully now. Should the problemrecur, the intermittent tube will visibly start to over heat before the others and thus it can be identified. It should be replaced with onefrom the same color batch, shown on its label. Call us and we will send one out to you. The severe short is not nearly so benign. Inthe worst cases, a major arcing short occurs between the plate and the cathode with visible lightning inside the glass and a majornoise through the speaker. If this is seen to happen, IMMEDIATELY turn the amp to STANDBY. By this time the fuse probably will haveblown. Such a short is usually caused by a physical breakdown inside the tube including contaminate coming loose or physicalcontact (or near contact) between the elements. Replace it and the fuse with the proper slo-blo type and power up the amp using thepower up procedure as we described earlier in this manual.
Often caused by contamination within in a tube, the culprit can usually be identified, and by lightly tapping on the glass, you willprobably hear the noise change. Hearing some noise through the speakers while tapping on the 12AX7s is normal however. And theone nearer the INPUT will always sound louder because its output is being further amplified by the second 12AX7.
The power tubes should be all but quiet when they are tapped. If crackling or hissing changes with the tapping, you have probablyfound the problem. To confirm a noisy power tube, merely put the MARK IV on Standby, remove it from its socket and turn it backon. It will cause no damage to run the MARK IV briefly with one power tube missing. You may notice a slight background hum,however, as the push-pull becomes unbalanced. Whenever you are trying to diagnose a suspect tube, keep your other hand on thePOWER and STANDBY switches ready to shut them off instantly in the unlikely case you provoke a major short. If you think youvelocated a problem tube but arent sure, we recommend substituting the suspect with a new one just to be sure of your diagnoses. You
will be doing yourself and us a big favor by just following the simple guidelines previously mentioned regarding tube replacement.Youll probably be successful with much less effort than is required to disconnect everything and haul the unit to a technician who willbasically perform the same simple tests. If the tubes are still within their six-month warranty period, we will happily send you areplacement. Just note the color designation on the tube label so that we can send you the appropriate match.
DIAGNOSING POWER TUBE FAILURES:
TUBE NOISE & MICROPHONICS
TUBE NOISE:
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PAGE 19
Because your amplifier is an all tube design, it is quite possible that you will at some point experience minor pre-amp tube noise. Restassured - this is no cause for alarm and you can take care of the problem yourself in a matter of minutes by simply swapping tubes.
Let us begin by saying; It is a very good idea to keep at least a couple of spare pre-amp tubes on hand at all times to insureuninterrupted performance. These minor pre-amp tube problems can take many forms but can generally be described in two catego-ries: Noise and Microphonics. Noise can be in the form of crackling, sputtering, white noise/hiss and/or hum. Microphonic problems
usually appear in the form of a ringing or high pitched squealing that gets worse as the gain or volume is increased thus are morenoticeable in the higher gain HI modes. Microphonic problems are easily identified because the problem is still present even with theinstruments volume off or unplugged altogether - unlike pick-up feedback which ceases as the instrument is turned down. Micro-phonic noise is caused by mechanical vibration and shock: think of banging a microphone around and youll understand where the
word came from.
The best way to approach a pre-amp tube problem is to see if it occurs only in one specific mode or channel. Then refer to the TUBETASK CHART found on page 17 and it should lead you to the tube needing replacement. Then all that remains is to swap the suspecttube for a known good performer.
If you cannot narrow down the trouble to a specific mode or channel, the problem may be the small tube that drives the power tubeswhich is operational in all modes and channels. Though rare, a problem with the driver tube would show up in all aspects of perfor-mance - so if you cant narrow the problem down to being mode or channel specific, you may want to try replacing the driver tube.Driver problems generally show themselves in the form of crackling or hum in all modes of performance and/or weak overall outputfrom the amplifier. Occasionally an anemic driver tube will cause the amplifier to sound flat and lifeless, but this is somewhat uncom-mon, as worn power tubes are a more likely suspect for this type of problem.
Sometimes making the diagnosis is more trouble than its worth and its faster and easier to merely replace the small pre-amp tubesONE AT A TIME with a replacement known to be good. But MAKE SURE you keep returning the tubes to their original socket until youhit the one that cures the problem. Youll notice that tubes located nearer to the INPUT jack always sound noisier...but this is becausethey are at the start of the chain and their noise gets amplified over and over by the tubes that follow. The tube that goes into this inputsocket (usually labeled V1) needs to be the least noisy of the bunch. The tube that goes at the end of the preamp chain - just aheadof the power tubes - can be quite noisy without causing any problem at all. The tubes in your amp have already been located in the
most appropriate sockets and this is why you should NEVER pull them all out at once and ALWAYS swap them one at a time. ALWAYSreturn a perfectly good tube to its original socket. Also its a good idea to put the amp on STANDBY when swapping tubes to reducethe heat build up in the tubes themselves and to prevent explosive noises (which can still occur even if you are pulling the tubes awayfrom their sockets gently) from coming through the speaker.
Remember, take your time, be patient and chances are real good that you can fix your amp yourself by finding and replacing the badtube. It kills us to see someone who has shipped their amp back to us...and all it needed was a simple tube replacement! If you mustsend back your amp, unplug the power cord, speaker and reverb cables then remove the chassis from the cabinet by unscrewing thefour mounting bolts on top. The chassis then slides back like a drawer and comes out. Remove the big power tubes and mark themaccording to their location from left to right 1, 2 etc. They need to be wrapped separately with plenty of wadded up newspaper aroundthem and put in a smaller box within the larger carton. To wrap the chassis, use plenty of tightly wadded up newspaper so there is atleast six inches of crush space between the chassis and the cardboard box. Bubble wrap also works well, but please DONT use
styrene peanuts - they will shift during transit and get lodged inside your electronics as well as allowing your amp to end up at thebottom of the box unprotected and possibly damaged. Pre-amp tubes dont normally wear out as a rule. Therefore, it is not a goodidea to change them just for the sake of changing them. If there isnt a problem - dont fix it. If there is no result from your substitutions,it may be possible that you have more than one problematic tube. Though rare, this does happen and though it makes the trouble-shooting process a little more intimidating, it is still possible to cure the problem yourself.
NOTE: It is normal to hear a slight metallic ringing sound when tapping on the preamp tubes. As long as the tube does not break intooscillation or start crackling or any other form of bizzare noise, it is considered normal and functional.
DIAGNOSING PRE-AMP TUBE PROBLEMS:
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PAGE 20
NOTE: An article written by Randall Smith that we thought you might find interesting.
Heres a question we often hear:
Why doesnt Mesa put bias adjustmentsin their amplifiers?
Well, theres a short answer and a long answer to this question.
The short answer is that during my 12 years of repairing Fenders, one of the most frequent problems I saw was bias controls that wereeither set wrong or that had wandered out of adjustment due to vibration. As any honest tech will tell you, theres lots of easy moneyto be made by sprinkling holy water on amplifiers ... uh, what I meant to say is Your amp needed biasing. See what I mean? What
customer is going to argue with that?
It only takes a moment and a volt meter: The Fender diagram shows how: Adjust this trim pot for - 52 volts. Thats it. Nothing more.
Now dont be fooled into thinking that tubes draw more or less bias, they dont. The way a bias supply is connected to a tube is akinto a dead end road, it just trails off to nowhere without really completing a circuit. Its a static voltage and regardless of what tube is inthe socket or even if the tubes arent plugged in at all, it doesnt change the bias voltage a bit.
So the end of the short answer is this: Since a bias supply needs to put out the right voltage and never vary, I wanted to buildamplifiers that were individually hard wired to the correct values and NEVER needed adjustment. And for 25 years, thats how Mesa/Boogieshave been built.
Time to change tubes? Just plug our tubes into any one of our amps and youre DONE. No tech needed. NO bills and no BS aboutbiasing. And most important: The bias is RIGHT because it cant change!
Now, you want the long answer? Heres more information on how our hard-wired bias avoids trouble. Please read on.
But first, lets make an important distinction. Our business is designing and building high performance amplifiers. And for this we needtubes whose variance is within a narrow range. Our warehouse is full of rejects ...oh, they work they just dont perform within ourtolerance range. We have a very sophisticated computer - based tube testing system (nicknamed Robotube) that matches andmeasures tubes over seven important parameters. It can even predict which tubes are likely to have a shortened lifetime eventhough they work perfectly during the test.
Because our business is building quality amps, we can afford to reject a lot of wayward tubes. The guys you hear complaining
because Boogies dont have bias adjusters are primarily in the business of selling tubes - not amps. They dont want to throw away30 percent of their inventory, so they promote the idea that tubes outside our parameters can be used to customize amplifiers andthey criticize us because our amps cant be adjusted to accommodate their out-of-Mesatolerance tubes.
Now you might be thinking, But I thought you just said that tubes dont draw bias, therefore they dont effect the bias supply and thusit doesnt need to be adjustable.
BIAS ADJUSTMENT: (Part of a continuous series)
..
.
.
.
...........
.......
..............
.......
( )
( )( ),
( , )
( )
PLATE
Structure of a 6L6 / 5881
Beam Power Pentode.
BEAM-
CONFININGELECTRODE
SCREENGRID
GRIDCATHODE
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PAGE 21
And thats right. Tubes dont effect the bias setting, but the bias setting does effect how the tubes work. But how it effects the tubes isdifficult to measure.
When you set the bias (whether its by selecting the right resistors, as we do, or adjusting a trimmer which is quicker) what you aredoing is establishing the correct amount of idle CURRENT that flows through the power tubes. But you cant adjust the currentdirectly, you can only change it by adjusting the amount of bias VOLTAGE that goes onto the tubes control grids.
Voltage and current are NOT the same. Current is the AMOUNT of electricity, the quantity and is measured in amperes. Voltageis the degree of electric charge like the pressure to use the old water analogy. Let me illustrate how different voltage and currentare:
When you scrape your feet across a carpetted floor in dry, wintery conditions, your body can become charged with 50,000 to 100,000volts of static electricity. And when you reach for the door knob, a spark jumps and you feel it! The voltage is super high but thecurrent (measured in micro-amps) is tiny - otherwise you would die from electrocution.
Contrast this with your car battery, which puts out a mere 12 volts. You can lay your hands right across the terminals and not feel athing. Yet the amount of current available can run to several hundred amperes .. enough to turn over a cold engine and get it started.
So current and voltage are two totally separate electrical parameters though when you multiply them together, you get POWER,which is measured in watts.
When you set the bias of an amplifier, you are adjusting the static VOLTAGE at the control grid of the tube in order to produce adesired amount of idle CURRENT flowing to the tubes plate. A small change in grid voltage, produces a large change in the amountof current flowing and thats basically how a tube works. Say that again because its super important: A small change in voltage atthe grid causes a large change in current flowing to the plate. See, thats the essence of amplification: A small change causing a largechange. And here its a small voltage change causing a large current change.
The bias conditions are what determines how much current flows through the big power tubes when youre not playing. And whatdrives your speakers is flucuations in that current flow when are ARE playing. If the amount of current increases and decreases 440times per second, then youll hear an A note. If the fluctions in current flow are large and still at 440 per second, youll hear an A thatis LOUD!
But for purposes of biasing, its the amount of plate current flowing with no signal applied thats important. Unfortunately current ishard to measure because the circuit must be interuppted as in cut the wire and the meter spliced in series with the brokencircuit. But measuring VOLTAGE is easy. It is not necessary to interrupt the circuit because a voltage reading can be taken inPARALLEL with the circuit intact.
Thus, as a matter of convenience, most bias settings are given in volts at the grid ... even though current through the plate is theimportant factor. In fact plate current is so inconvenient (and dangerous) to measure that Fender doesnt even state what the correctvalue should be. They only give the grid voltage that will produce that current. (Thats the minus 52.) But that only happens if thetubes being used are in spec.
As long as the tubes ARE in spec, the right bias voltage will always give the correct plate CURRENT but then theres no needfor the bias voltage to be adjustable!
If the tubes are NOT in spec, then the only proper way to re-set the bias is to cut the circuit and measure the current while adjustingthe bias ... but no manufacturer I know even STATES the desired current value! Be that as it may, when the original bias voltage isaltered far enough, it will compensate for the tubes abnormal performance and the correct amount of idle current flow may then berestored. Clearly this is something most repair techs should not attempt.
BIAS ADJUSTMENT (Continued)
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Some newer amps have LED indicators connected to the circuit which will turn on when the right threshold of current flow has beenreached. This is an improvement, and almost worthy if youre willing to except resistors and lights added into your amplifiers audiopath which we arent. The other advantage of this system is that it allows some amp manufacturers to avoid matching their powertubes. The thinking is that adjusting the bias to each tube separately eradicates the inherent differences between the tubes by insuringthat the same current flows through each one.
Again, this has some merit .. but its still not as good as using tubes that are matched in the first place because compensating for themis-match causes the push-pull circuit itself to become unbalanced. Two wrongs dont really make a right.
Some of the other recommended biasing, methods such as -.. tubes running red hot, increase the bias .. sounds harsh and runstoo cool, turn it down ... are guesswork at best. Luckily, one of the great things about tube amps is that they can usually stand someabuse without causing any real harm ... at least not immediately.
But dont these alterations imply that you are second-guessing the amp designer and that theres a better set of operating conditionsthat the designer missed but the tube sellers have discovered? Now some players may like the sound of their amp altered by tubes
with extreme characteristics and with the bias set to help compensate. But often it is the mere novelty of change that theyre reallyresponding to and when the amp goes back to the proper original way, weve seen them be far happier still!
Because every part in every one of our designs has been meticulously evaluated, compared and stressed over no matter howseemingly insignificant it might be. And with every design we look for a sweet spot where all the parameters including the bias come together to give the best sonic performance, consistently and reliably. Every part and voltage is important yet no onecomplains that these other parameters arent available for tinkering.
Consider our patented Simul-Classcircuitry where there are two different bias voltages used for separate pairs of power tubes ... andchanging one voltage also changes the other. Great care goes into getting this just right and we think wed be asking for trouble tohave it adjustable for the world to play with ... unless you like paying to have your amp messed up. Sorry, I meant to say, Uh, ... youramp needed biasing. If that doesnt appeal to you, then merely plug a matched set of Mesatubes into one of our amps and youreready for tone. Guaranteed. Youd be amazed at the number of service calls we field every day that lead to a diagnosis of out-of-tolerance, non-spec tube problems. To think these would be prevented by including a bias adjustment is something of an insult to you
and us. If you put the wrong size tires on your car, do you think changing the pressure will make them right?
Please, dont think this is a blanket indictment of the other guys selling tubes it isnt. And their tubes arent all bad either. It justdoesnt make sense to pay more of your hard earned cash for tubes that were probably made in the same Russian or Chinese factoryand which have the possibility of being outside the performance window we select for your amp. And it pains us to hear the hype andmystique built up around biasing when twenty-five years of evidence affirms our decision to make bias circuits that never needadjustment. How much money and trouble that has saved Mesa/Boogieplayers you couldnt estimate.
Our rigorously tested and hand selected tubes are available at your nearest Mesa/BoogiePro Center or from us directly. Nobodyoffers better price, quality or warranty than we do ... so why swerve?
Next time well talk about our part in developing the great Sylvania STR 415 type 6 6 and how were on the verge of seeing some thing
fairly close reappear on the market. Remember, we still have some of these super rugged mondo-bottles available for older amps Boogiesonly please! Until then, Relax, Breathe and Nourish your soul!
Cheers!Mesa/Boogie Ltd.
Randall SmithDesigner & President
BIAS ADJUSTMENT (Continued)
PAGE 22
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REAR VIEW: MARK I V
P
ULL
SHIFT
P
ULL
SHIFT
PULLBRIGHT
MASTERS
LEAD GAIN
RHY2 GAIN R1+R2 MID
LEAD MID
R1+R2 BASS
LEAD BASS
R1 TREBLE
LEAD TREBLE
RHY1 GAIN
INPUT
PU
LL
BR
IGHT
INS
TRU
MEN
T
PULL
FAT
PULL
FAT
80 240 750 2200
P
RESENCE
C
ONTROLS
R2 TREBLE
LEAD DRIVER1 R2 LD
3A SB
FUSE
A OFF B
GROUND
GR
APHICEQ
REMOTE
REVERB
RECORDING
SLA
VE( D
.I.)
POWERAMP
TRI ODE S IM UL-CLASS HARMONI CS
PENTODE CLASS A
SPEA
KERS
8 OHM 4 OHM4 OHM
MID GAIN
LEAD
VOICING
LEVEL OUT
117 VOLTS
50-60 HZ
200 WATTS MAX.
REVERB FTSW.
SATELLITE EQ
SATELLITE SEND
SATELLITE
AUTORHY 2
AUTORHY 1
FX LOOP ONFULL TIME
FX LOOPSWITCHING
RHY 2 LEADAUTO ASSIGN SWITCHES
FX SEND
RETURN RETURN
LEFT(STEREO)
RIGHT(MONO)
SIG.PATH
MODE SELECT
LE
EFT SW
RHY 1
RHY 2
HANDBUILT IN PETALUMA CALIFON / OFF AUTO R2
POT pt# POT pt# POT pt# POT pt#
POT pt# POT pt#
POT pt# POT pt#
POT pt# POT pt# POT pt# POT pt# POT pt# POT pt#
POT pt# POT pt# POT pt#
KNOBS
pt#
EQ pt# 588535
KNOB
pt# 408538
KNOBpt#
INPUT JACK
JACK pt# 610110
KNOBS
pt#
LED
pt#LED
pt#
LED
pt#
SPK. JACKSALL 3 pt#
POT pt#
SWITCHESALL 3 pt#
JACK pt#
POT pt#
JACKpt#
SWITCHESALL 3 pt#
KNOBpt#
POT pt#
JACKpt#
JACKpt#
JACKpt#SWITCH
pt#
SWITCHpt#
JACK pt#
JACK pt#
KNOBpt#
KNOBpt#
POT pt#
JACKpt#FUSE HOLDER
pt#
FRONT VIEW:MARK I V
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The Spir i t of Ar t in Technology
OOGIEBMESA
Thank youfor trusting MESA/Boogie to be your amplifiercompany and we wish you many years of toneful enjoyment from thishandbuilt all tube instrument.
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The Spir i t of Art in Technology
1317 Ross Street Petaluma, CA 94954
USA
(707) 778-6565 FAX NO. (707) 765-1503