Mesa/Boogie M6 Stereo Amplifier User Manual

Mesa/Boogie M6 Stereo Amplifier User Manual

Owner’s Manual

Greetings from the Home of Tone

...You, smart player and intuitive human, have put your trust in us to be your amplifier company. This is something we do not take lightly. By choosing this instrument to be a part of your musical voice, you have become part of the Mesa family...WELCOME!

Our goal is to never let you down. Your reward is that you are the new owner of an amp, bred of fine all tube heritage...benefiting from the many pioneering and patented Mesa circuits that led to the refinement of your new model. We feel confident, this amp will inspire many hours of musical satisfaction and lasting enjoyment. It was built with you in mind, by players who know the value of a fine musical instrument and the commitment it takes to make great music. The same commitment to quality, value and support we make to you...our new friend.

Table_of_Contents

Precautions

Overview__________________________________________________________________________________________ 1-2

FRONT_PANEL:

INSTRUMENT_INPUT__________________________________________________________________________________ 3

ACTIVE_/_PASSIVE_SWITCH_ ___________________________________________________________________________ 3

CONTROLS:

GAIN_______________________________________________________________________________________________ 3

BASS_______________________________________________________________________________________________ 4

PULL_DEEP_ ________________________________________________________________________________________ 4

MID______________________________________________________________________________________________ 4-5

VOICE______________________________________________________________________________________________ 5

TREBLE_ _________________________________________________________________________________________ 5-6

DI_LEVEL_ __________________________________________________________________________________________ 6

PULL-PRE___________________________________________________________________________________________ 6

MASTER____________________________________________________________________________________________ 6

MUTE_LED_ _________________________________________________________________________________________ 7

POWER_SWITCH_____________________________________________________________________________________ 7

REAR_PANEL:

FUSE_______________________________________________________________________________________________ 8

A.C._RECEPTACLE____________________________________________________________________________________ 8

FUNCTION_SWITCHES______________________________________________________________________________ 8-9

SPEAKER_OUTPUTS__________________________________________________________________________________ 9

TUNER_ ____________________________________________________________________________________________ 9

EFFECTS_LOOP___________________________________________________________________________________ 9-10

GROUND_LIFT,_DIRECT_OUT___________________________________________________________________________ 10

FACTORY_SAMPLE_SETTINGS_________________________________________________________________________ 11

PERSONAL_SETTINGS_______________________________________________________________________________ 12

DIAGNOSING_PRE-AMP_TUBE_PROBLEMS_ _____________________________________________________________ 13

PARTS_SHEET______________________________________________________________________________________ 14

PRECAUTIONS & WARNINGS

Your MESA/Boogie Amplifier is a professional instrument. Please treat it with respect and operate it properly.

USE COMMON SENSE AND ALWAYS OBSERVE THESE PRECAUTIONS:

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.

YOUR AMPLIFIER IS LOUD! EXPOSURE TO HIGH SOUND VOLUMES MAY CAUSE PERMANENT HEARING DAMAGE !

No user serviceable parts inside. Refer service to qualified personnel. Always unplug AC power before removing chassis.

EXPORT MODELS: Always insure that unit is wired for proper voltage. Make certain grounding conforms with local standards.

READ AND FOLLOW INSTRUCTIONS OF PROPER USAGE.

Operating Instructions

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Congratulations on your choice of the M6 Carbine and welcome to the Mesa/Boogie Family!

First we would like to thank you for choosing us as your amplifier company and trusting us to help create your musical voice. This is something we never take for granted and you’ll find that we are here ready to assist you should you ever need help. Our goal is to help you sound your best at all times! We feel confident that your new amplifier will bring you many years of reliable service and rewarding inspiration and create for you a newfound freedom to express through your music.

The M6 Carbine expands the MESA Family of Bass amplifiers with an exciting new voice that’s super fast and extremely focused!

The output section relies on the same time-proven array of custom designed mosfets used in our M-Pulse, Big Block 750 and Titan models, but the preamp and driver section are all new creating a very different feel and attitude.

First a PASSIVE/ACTIVE switch determines the preamp Input sensitivity and ensures you will have the headroom you need. Up front the tube preamp utilizes a standard tone control string of Bass, Mid and Treble to shape the basic sound, but the shaping power doesn’t stop there. There is a PULL DEEP feature found on the Bass control that keeps the low end tight and articulate when pushed in or, enhances the sub-lows and adds super-top air when pulled out.

The M6 Carbine also features a new VOICE control for instant access to global character changes. Here you’ll find four iconic and distinctively different sounds and a bypass on a 5 position rotary pot that graphically shows you the EQ curve for each. To the left, positions 1 and 2 dip the midrange in two different places giving you two amazing choices for classic round, warm R & B sounds.

Turning right past the 12:00 noon FLAT position unveils two variations on the mid-bump theme. Positions 4 & 5 boost adjacent mid regions to create two powerful mid focused sounds that push articulate fingerstyle playing to the forefront of any mix or add the tight drive to Rock. Great Tone doesn’t get any simpler!

FRONT VIEW: M6 CARBINE

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(Continued)

DI LEVEL and MASTER controls make adjusting your playing volume levels quick and easy on stage. The DI LEVEL features both post and pre Tone control options, with post being the default (pushed in) setting and PULL PRE activating the pre setting that bypasses the entire preamp. A TUNER MUTE pull pot is added to the MASTER Output control for silent tuning in live or studio applications. This feature can also be triggered remotely from the Rear Panel Function Switch jack labeled MUTE.

The Rear Panel follows suit with simplicity dictating the layout of the all essential features every pro rig should include. Tucked securely between the intake/exhaust vents sit the FUNCTION SWITCH jacks and the SPEAKER OUTPUTS. The FUNCTION SWITCH

¼” jacks provide switch ports to control the Front Panel VOICE feature and the TUNER MUTE. Connecting any grounding (tip to ground) logic switch here will trigger the desired VOICE setting or the MUTE. This allows settings to be stored under programs in a master external switcher. The SPEAKER OUTPUTS utilize stage ready SPEAKON UNIVERSAL connectors which accommodate both standard ¼” phone type and Nuetrik SPEAKON locking plugs. A SPEAKER IMPEDANCE switch keeps things in the Output section properly matched and allows you to select between 8/4 Ohm loads or switch down to 2 Ohms (CRITICAL when loads of 2

Ohms are used) for full power with these low load settings.

To the right of the air intake vent are the EFFECTS LOOP and DIRECT OUTPUT sections. The DIRECT OUTPUT consists of a standard 3 pin male XLR jack and a ground lift for the circuit to chassis ground connection. Leave the switch set to GROUND (switch down - circuit grounded) unless you experience hum when connecting to a live sound board or studio recording console in which case try the LIFT position to eliminate the hum caused by the two different references to ground.

The EFFECTS LOOP is in series with the main signal and can be bypassed with the switch located above the SEND jack. The

TUNER OUT jack will feed a signal to your outboard tuner and you can use the Front Panel PULL MUTE feature located on the

MASTER control to mute the signal for silent tuning. The MUTE can also be remote triggered by connecting a grounding footswitch to the Rear Panel FUNCTION SWITCH labeled MUTE.

That wraps up our Overview of the controls and features of the M6 CARBINE and now we’re ready to look at the controls and their individual roles in creating the sounds you hear in your head. Once again, thank you for choosing Mesa and most of all Enjoy!

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FrONT PANeL CONTrOLS:

INPUT:

This jack is the instrument

INPUT which feeds the first tube in the all-tube preamp of the M6 CARBINE. It is set up with enough headroom to handle both passive and active style instruments. For active instruments you may find yourself running the

GAIN control somewhere between 10:00 and 2:00 for optimum headroom. If you do hear a soft clip creeping in at higher settings, don’t worry, this is the beauty of a tube front end. You may feel free to drive the preamp for a more furry character when hyper-clean is just too clean.

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NOTE: When driving the preamp with higher settings of the GAIN control it is wise to reduce the BASS control and any low frequencies dialed up on the ACTIVE MID control. This will protect accidental damage to speakers and help avoid tubbiness or lack of tightness in the low end.

ACTIVE_/_PASSIVE:

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This mini toggle switch controls the input headroom and impedance of the INPUT. As you might have guessed, the switch selects either the full strength PASSIVE input impedance circuit or a “padded” higher headroom ACTIVE circuit. Standard passive basses that don’t incorporate an onboard preamp should be used in the PASSIVE setting, while more modern instruments that utilize active pickups and/or an onboard preamp should be used in the ACTIVE setting.

GAIN:

This control determines the overall character of the input sensitivity. The lower regions of the control (below 12:00) lend greater headroom and provide a scooped, brighter personality. The upper harmonics come through more prominently in this area of the control making the top end sound more transparent and sweet. This region is especially useful for funkier stuff when thumbing is in order. It keeps the rubber-band feel intact in the lows and mids while voicing the snap just high enough to avoid harshness, or the dreaded “gak” when the G string is plucked.

As the

GAIN control is increased past 12:00 a richer, more “well-rounded” voice becomes dominant and headroom starts to diminish in increments until eventually, a tube overdrive sound appears as the

12AX7 input tube is driven into saturation.

The region between 12:00 and 2:30 is where the classic, warm tube sound resides and within this narrow band you will discover a world of tone. Tiny increments here produce subtle, but important differences in the attack characteristic which in turn, feel like changes in the time domain.

By experimenting with the amount of gain, you can actually voice the amp to feel as if it bounces just ahead of the groove - or lays back a little deeper to produce a more Fatback feel. The difference in attack and sustain produces striking results as to how the bassist - and in fact the whole band - perceives things in the time domain.

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BASS:

This control is responsible for the basic mix of low frequencies in the tube pre-amp. The

BASS control is an active shelving type control as opposed to a passive style control. This means that a center Q point has been chosen and this control allows you to either boost or cut that frequency. This control differs from the low bands of the Parametric in that it has a broader Q point with a more gentle ramp as opposed to the Parametric’s’ narrow Q that is used with a separate GAIN control.

The

BASS control is actually a gain and frequency control all rolled into one with the Q center at 55Hz and harmonics in both low and high directions are affected because of its broader band nature. As the control is increased past 12:00 there is a 6db per octave rise in gain with the frequency topping out at

321Hz. With 12:00 straight-up representing “flat” (a no boost/no cut setting). As the BASS control is dialed below 12:00, 55Hz and all associated harmonics are reduced and eventually notched completely out of the signal. Conversely, there is a 6db per octave cut beginning at 55Hz going down to 20Hz where the shelving ends with a cut gain of -20db as the control approaches 7:30 (off).

This type of broad band, active rotary control makes it possible to achieve bass characteristics far beyond that of a conventional passive type control. It can increase the low end to an almost absurd level and with a flick of the wrist, dip it to near transistor radio skinniness. Needless to say, with any control this powerful a certain amount of finesse must be applied to achieve musical results. Be especially mindful of this when using the VOICE control in conjunction with the BASS control.

PULL_DEEP:

The M6 CARBINE features a pull shift for the BASS control that allows you to choose between two different regions of low end and affects how the control will react.

When the control is pushed in (normal) the bass frequencies are higher and a cut-off is employed so that below a certain point, sub-low frequencies are not part of the mix. This results in a tighter, faster feeling response that is more articulate and will stand out and be heard in a live stage environment. This also works well for recording scenarios where the Bass part needs to sync-up with a complex kick drum line or anytime you need a defined, punchy sound that won’t get lost as the layers of other parts get applied.

PULL_DEEP (control pulled out) allows the entire range of low frequencies to pass and fill in the curves creating a warm, rich sound that is foundational for smaller groups. Along with these deeper lows, a subtle enhancement of the super-high frequencies is added to create a round, breathing cushion of air the whole band can ride. Be sure to check out this setting for three-piece Rock or Blues combos and playing R & B styles where you need to ad juice to thumbing part.

MID:

This is the only passive style control in the string of rotary tone controls. This scheme was chosen for its inherently musical blend and for the way the passive style midrange control, with its wide spread and smooth taper, fills in the holes. Unlike the BASS, this control is a

boost_only, and while it can competently remove this broad spectrum of midrange from the mix, it cannot provide the extreme attenuation of an active style control.

You will find, as we did, that this control works amazingly well for shaping the midrange frequencies with a natural earthiness and character that is a perfect counterpart to its neighbors. It is hard to find bad sounds with this more forgiving control as it seems to give you just enough and no more.

For radical and specific scooping or boosting of the midrange frequencies for modern R&B and Funk styles, there is plenty of control that is infinitely more accurate to be found in the VOICE control. Because of this, we opted for the tried and true passive style midrange control that has been working great in all of our amplifiers for decades. It’s hard to improve on a classic.

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VOICE:

This simple to use feature puts the shaping power of a parametric EQ at your fingertips without the learning curve and allows you to go right to the most iconic sounds instantly. The 5 position rotary allows you to select from four distinct and different voices aimed at all the classic Bass sounds. Most of the dramatic changes occur in the midrange where the basic character of a sound is determined right away. There are two positions that feature scooped midrange and two positions that utilize increased mids to achieve their curve. These curves are graphically pictured around the 5 positions of the rotary control and with just a quick glance you probably can tell which of these are to become your favorites. Regardless it would be wise to get familiar with them all so that you can go to a sound quickly in a performing situation. Remember that the rotary tone controls will react differently than they do when the VOICE feature is bypassed (set to position 3).

Here is a synopsis of the 5 choices found on the VOICE control;

Fairly extreme Mid cut centered at 540Hz. Excellent for dramatic thumbing/slapping styles or smooth chording.

Gentle scooping of Midrange also centered at 540Hz. Great for R & B and anytime you want to tastefully widen a sound.

Voice feature bypassed (Flat with Tone controls set at 12:00)

Midrange boost centered at 370Hz. Good choice for articulate finger style playing. Tracks your playing with articulation and enhanced definition.

Low Mid boost centered at 170Hz. Great for enhancing low mids. Works well for classic Blues or Reggae finger style work.

Keep in mind these positions use a medium Q width to avoid a notchy sound and retain an organic quality. There will be some cut or boost on the adjacent frequencies. Once you have selected a VOICE mode to use, fine tune the sound with the standard tone controls.

TREBLE:

The

TREBLE is also an active shelving style control like that found in the BASS and again, it was chosen for its ability to radically shape the upper harmonic region. Like the BASS, it also has a center Q point with harmonics above and below responding in harmony as it is dialed for either cut or boost.

As the control is increased past 12:00, it produces a 6db per octave rise in gain starting at 723Hz until

+20db is reached. From this point, gain remains constant at +20db for all frequencies above 723Hz all the way out to 20Khz. This scheme lends a sweetness of sound while retaining all the necessary cut and focus associated with a traditional passive TREBLE control. As this control is dialed below 12:00, it begins a 6db per octave cut from 3.2Khz to the shelving point at 723Hz, where it continues to attenuate all frequencies above 723Hz until - 20db is reached where cut gain remains constant until the control reaches 7:30 (off). The ability to cut these frequencies more radically makes it possible to obtain incredibly rich and warm old-school R&B and Jazz sounds that rival any recordings of the day.

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TREBLE:_(Continued)

This active shelving TREBLE control completes the rotary tone control string to create a powerful and extremely accurate network to use as your fundamental platform. It’s no wonder many first time M6 CARBINE players make the comment that just these controls combined with the GAIN create the best tone they have ever heard!

NOTE: As with the BASS control, may we remind you that a control of this type with its increased power should be used with finesse.

In the

TREBLE’S case, almost more so, because higher frequencies seem louder to the ear and are generally more painful when set

to extremes. Another reason to use care is that high frequencies tend to increase the ambient noise floor when set too high.

DI_LEVEL:

This control determines the level present at the 3 pin XLR DIRECT OUTPUT jack on the Rear Panel. The range on the control should provide an optimum level for matching the Input requirements of most any live or recording console.

PULL-PRE:

This pull pot toggles the output signal at the DIRECT OUTPUT between a POST signal (pushed in) - where the entire preamp and all the controls affect the sound – and a PRE signal (pulled out) – where the instrument signal is fed directly to the

DIRECT OUTPUT bypassing the entire preamp.

In_the_PRE_setting, the GAIN, MASTER and tone controls will not affect the signal at the DIRECT OUTPUT. You will hear the pure sound of your instrument optimized for the input impedance of a mixing console with virtually no shaping from the preamp or power section. In_the_POST setting, the GAIN, MASTER and Tone controls WILL affect the signal at the DIRECT OUTPUT. This setting will provide you with all the warmth and attack characteristics of your M6 CARBINE as it sounds when connected to a speaker enclosure. You will also have the shaping power of the GAIN, Tone controls and VOICE feature to enhance your tone.

The PRE setting is useful for large venues when the sound you have dialed up for your optimum stage tone might have to much low end for the front of house engineer to balance through a large PA where there are subs employed. POST is great for Direct feeds in smaller venues where some extra bottom end is preferred or for recording where you need to be able to craft your sound for specific tracks using the on-board controls.

NOTE: Always start by turning the DI LEVEL all the way down before connecting the M6 CARBINE to the console. After connect-

ing the DI OUTPUT to the console, slowly increase the signal until you reach the desired level. This procedure will prevent damage to equipment and ears should someone play a note before the levels have been set to optimum levels.

MASTER:

The

MASTER control is the feed to the Simul State power section and determines the overall playing volume of the

M6 CARBINE An optimum setting will be determined by the setting of the GAIN control as well as the entire tone control network.

All these controls affect the signal strength at the end of the preamp and can make the MASTER control very sensitive.

NOTE: Remember to use with caution as the MASTER is the gas pedal for the massive power avail-

able. We suggest a zero setting at each power up to avoid damage to speakers and ears.

PULL-MUTE

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MUTE_LED:

This LED indicates that the Tuning MUTE function has been triggered either by pulling out the Front Panel MAS-

TER PULL MUTE, or by the Rear Panel Function Switch jack. When this LED is illuminated there will be no signal present at the

SPEAKER OUTPUT jacks.

PULL-MUTE

POWER_SWITCH:

This switch delivers the A.C. power to the M6 CARBINE. 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 amplifier). Also, make sure that the proper voltage requirements are present at the A.C. wall socket receptacle.

NOTE:_As a reminder, never alter the A.C. power cord in any way for possible damage to the

amplifier may occur not to mention the possibility of a fire outbreak.

Now that we have reviewed the features and controls on the Front Panel, let’s take a spin around back and review the interfacing connections.

Now that we’ve gone through the Front Panel of your M6 CARBINE, let’s go around back and take a look at the features of the

Rear Panel.

REST AREA

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FUSE

F USE reAr PANeL CONTrOLS:

REAR_VIEW:_M6_CARBINE

FUSE

F USE

FUSE:

This is the A.C. Mains Fuse for the M6 CARBINE. REPLACE ONLY WITH A SLO-BLO TYPE FUSE OF THE PROPER

RATING. THIS IS EXTREMELY IMPORTANT, AS THE M6 CARBINE DRAWS A SUBSTANTIAL AMOUNT OF CURRENT AT HIGH

OUTPUT LEVEL SETTINGS.

FUSE

F USE

FUSE rating for USA - 10A S.B. / 120 Volts.

A.C._RECEPTACLE:

FUSE

F USE

The removable “Euro” Style” A.C. cord that is supplied with the M6 CARBINE makes set-ups and teardowns after the gig a snap. It also makes de-racking much easier when you wish to remove the unit from a hardwired rack system where all the A.C. cords have been cable-tied in. Additional heavy duty cords are available should you ever need one...simply call us and we can ship one directly to you for a nominal charge, plus shipping cost. Make sure the A.C. cord is firmly in its socket (receptacle) before powering up the amplifier.

NOTE: NEVER ALTER THE THREE PRONG POWER CORD IN ANY WAY.

FUNCTION_SWITCHES:

These five ¼” jacks are provided to allow control of the Front Panel VOICE feature and Tuner MUTE from a master switching device. In this scenario, all sounds and features are controlled from one source and usually these commands are stored in the master switcher under programs (usually midi) that can be recalled with one footswitch keystroke.

The M6 CARBINE Function jacks respond to simple grounding type (tip-to-ground) latching (not momentary) logic and most switchers on the market offer several jacks that can be dedicated to this type of logic.

To_trigger_a_VOICE_mode_remotely_using_the_Function_Switches: Select VOICE position 3/ EXT SWITCH (straight up). Connect a standard ¼” unshielded (speaker type) cable to the VOICE jack(s) of your choice and “ground the tip to the ring” of the opposing end of the cable. The corresponding VOICE mode will be engaged and you will hear the sound change. In most master switchers this will be as easy as connecting the cable, choosing an available program number, hitting a key to ground that jack, and then pressing the Store or Enter key. If you find you only need to footswitch one of the voicings, you can use a simple one-button footswitch, which are readily available at most music stores. If you can’t locate one, call us and ask to speak to a Product Specialist and we can make you one for a nominal charge.

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FUNCTION_SWITCHES:_(Continued)

The live performance power of the M6 CARBINE is greatly expanded by the inclusion of the Function Switch jacks as you gain access to alternate sounds without having to walk back to the amplifier or stop playing to adjust knobs.

NOTE: If the Front Panel VOICE select switch is set to any position other than 3/EXT SWITCH and you use a function switch jack to trigger another different VOICE mode, you will activate two VOICE modes at once. This will not hurt the amplifier and depending on the combination, you may actually create a sound that is desirable. For example, you might like the mid scoop of position 2 blended with the mid bump of either position 4 or 5. Feel free to experiment as you might create a unique sound that is all yours.

If you are in a VOICE mode and try to trigger that same mode with the Function Switches you will hear no change as the mode is already selected.

To_trigger_the_Tuner_MUTE_feature: simply connect an unshielded ¼” cable to the MUTE Function Switch jack and ground the tip to the ring of the opposing end of the cable with either a master switcher or a latching type (not momentary) grounding footswitch.

NOTE: The Front Panel PULL MUTE feature overrides the Function Switch jack. Once MUTE is engaged on the Front Panel by pulling the MASTER control out, MUTE can not be defeated via the Rear Panel Switch jacks.

SPEAKER_OUTPUTS:

These are the Speaker Outputs for the M6 CARBINE. These jacks accept Nuetrik locking SPEAKON type connectors or standard ¼” phono type plugs. This is the suggested configuration. With an 8 ohm speaker load and the impedance switch set to 8/4, your M6 CARBINE will produce approximately 300 watts of clean power.

A 4 ohm speaker load and the impedance switch set to 8/4, your M6 CARBINE will produce approximately 600 watts of clean power. Due to a limiter circuit added to protect the amplifier, a 2 ohm speaker load with the impedance switch set to 2 OHM will still produce approximately 600 watts of clean power.

When using a 2 ohm speaker load, make sure the SPEAKER IMPEDANCE switch is set to the 2 OHM

(switch down) setting. This is critical for reliability.

NOTE: Always match the SPEAKER IMPEDANCE switch setting to the speaker load in use. Playing at high volumes with a 2 ohm

load connected while the SPEAKER IMPEDANCE switch is set to the 8/4 OHM setting will cause the short circuit protection circuit to trigger a mute at the SPEAKER OUTPUT. This will interrupt your performance and is necessary to prevent the mosfet power devices from getting too hot and being damaged.

TUNER:

This Rear Panel auxiliary TUNER output provides for Rear Panel interfacing of rack mount tuners, where it is preferable to have all wiring stay in the rear of a rack system.

EFFECTS_LOOP:

The M6 CARBINE incorporates an internal EFFECTS LOOP to handle the interfacing of outboard processing. This circuit is a patch point between the preamp and the power section and it is wired in series with the dry (un-affected) signal. Since this loop is a series-type loop (as opposed to parallel) it is important that you use good quality processors “in the middle” of your amp. While the loop is compatible with most processor Input/Output impedance demands, there can be a lot of room for sonic compromise in some of the less expensive units. Remember that every part in your signal path is a tone part.

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EFFECTS_LOOP:_(Continued)

NOTE: Always use good quality shielded cable of the shortest possible length when patching your effects. One foot lengths are preferable - with lengths of more than 3 feet (each cable) starting to roll off top end and reduce midrange punch and clarity.

The LOOP is fitted with a “Hard Bypass” switch that allows you to completely remove all associated LOOP circuitry from the signal path when you are in the studio or when the LOOP is not to be used. While many won’t be able to hear any discernible difference with the LOOP bypassed, for you purists, it will give you peace of mind that your signal is as direct as possible.

To use the EFFECTS LOOP:

1) Connect the SEND jack to your processor’s Input

2) Connect the RETURN jack to your processor’s Output

3) Switch the EFFECTS LOOP BYPASS switch to the ON position.

4) Adjust the processor’s Input/Output Level attenuator to achieve unity gain by toggling the LOOP switch in and out of BYPASS while making fine adjustments at the processor until you hear no level difference. Keep in mind you might have to adjust the M6

CARBINE OUTPUT control also if the processor indicating lights read unity gain (look good and are not clipping).

NOTE: The EFFECTS LOOP IS optimized for professional quality rack mount processors. Most pedal type effects work better in the

“front-end” between your instrument and the INPUT. You will experience some tonal changes because of the additional cable and the fact that your instrument will no longer be going straight into the grid of the first tube. It’s up to you to decide if the trade off is acceptable.

GROUND_LIFT,_DIRECT_OUT:

This section captures the entire pre-amp signal including the Effects Loop and allows you to send a Balanced signal to either a House Main Board or a Recording console. There are two elements to this circuit which are;

_(1) a male

XLR jack and

(2) a GROUND LIFT switch.

GROUND_LIFT:_This switch removes the circuit-to-chassis ground connection from the XLR jack. Leave it in the grounded position (switch down) normally unless you experience a hum when connecting to a console. If you do experience a hum when connecting the XLR Output to a console, try lifting the ground (switch up) on the circuit. This will usually (but not always) remedy most ground loop type noise from the signal path.

Sometimes it may also be necessary to lift the A.C. Cable Ground also by using a 3-2 ground adapter to achieve a quiet signal path.

NOTE: Ground loops can occur in many places in a complex signal path. The DIRECT OUTPUT GROUND LIFT switch is not a cureall and therefore should not be expected to remedy every type of ground related problem.

Now that we have the Rear Panel sussed-out, you are ready to enjoy the musicality and shear power of the M6 CARBINE. We hope this instrument brings you many years of inspiration and musical discovery. From all of us here at MESA…Enjoy!

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SAMPLE_#1:__STRAIGHT_UP_GREAT

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SAMPLE_#2:__BIG_&_WIDE

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SAMPLE_#3:__TIGHT_TRACKING

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SAMPLE_#4:__SLAP_HAPPY

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DIAGNOSING_PRE-AMP_TUBE_PROBLEMS:

At some point it is quite possible that you will experience some kind of minor preamp tube noise. Rest assured - this is no cause for alarm and you can take care of the problem yourself in a matter of minutes by simply swapping tubes. It is always a good idea to keep at least a couple of spare pre-amp tubes on hand at all times to insure uninterrupted performance. These minor pre-amp tube problems can take many forms but can generally be described in two categories:

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 more noticeable in the higher gain “HI” modes. Microphonic problems are easily identified because the problem is still present even with the instruments’ volume off or unplugged altogether - unlike pick-up feedback which ceases as the instrument is turned down. Microphonic noise is caused by mechanical vibration and shock: think of banging a microphone around and you’ll 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. This should lead you to the tube needing replacement. If you cannot narrow down the trouble to a specific mode or channel, the problem may be the small tube that drives the power tubes which is operational in all modes and channels. Though rare, a problem with the driver tube would show up in all aspects of performance - so if you can’t 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 output from the amplifier.

Sometimes making the diagnosis is more trouble than it’s worth and it’s faster and easier to merely replace the small pre-amp tubes

ONE AT A TIME with a replacement known to be good. But MAKE SURE you keep returning the tubes to their original socket until you hit the one that cures the problem. You’ll notice that tubes located nearer to the INPUT jack always sound noisier...but this is because they 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

“input socket” (usually labeled V1) needs to be the least noisy of the bunch. The tube that goes at the end of the preamp chain - just ahead of 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.

ALWAYS return a perfectly good tube to its original socket. Also it’s a good idea to put the amp on STANDBY when swapping tubes to reduce the heat build up in the tubes themselves and to prevent explosive noises (which can still occur even if you are pulling the tubes away from their sockets gently) from coming through the speaker.

To wrap the chassis, use plenty of tightly wadded up newspaper so there is at least six inches of “crush space” between the chassis and the cardboard box. Bubble wrap also works well, but please DON’T use styrene peanuts - they will shift during transit and get lodged inside your electronics as well as allowing your amp to end up at the bottom of the box unprotected and possibly damaged.

Pre-amp tubes don’t normally wear out as a rule. Therefore, it is not a good idea to change them just for the sake of changing them.

If there isn’t a problem - don’t 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 troubleshooting 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 into oscillation or start crackling or any other form of bizarre noise, it is considered normal and functional.

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