Mesa-Boogie LoneStar Amplifier User Manual

OOGIE

B

M

ESA

Owner's Manual

Hello from the Tone Farm

...You, smart player and intuitive human, have put your trust in us to be your amplifi er

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!

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2-3

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3

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5

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5

THICK / NORMAL / THICKER

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5

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6

TREBLE / MID / BASS

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7-8

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8

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8-9

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9-10

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SPEAKERS & SLAVE

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TUBE MAINTENANCE & DIAGNOSIS

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TUBE DESCRIPTION & TASK CHART

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SPEAKER IMPEDANCE & POSSIBLE HOOK-UP SCHEMES - Amps to Speaker Cab

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25-30

TRIODES, PENTODES & IRISHMEN: A feature article on the workings of tubes

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31-33

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34

TABLE OF CONTENTS

FRONT PANEL CONTROLS & FEATURES

REAR PANEL CONTROLS, SWITCHES & JACKS

PRECAUTIONS & WARNINGS

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

USE COMMON SENSE AND ALWAYS OBSERVE THESE PRECAUTIONS:

READ AND FOLLOW INSTRUCTIONS OF PROPER USAGE.

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

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

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

WARNING: EU: permission from the Supply Authority is needed before connection.

WARNING: Vacuum tube amplifiers generate heat. To insure proper ventilation always make

certain there is at least four inches (100mm) of space behind the rear of the amplifier cabinet.
Keep away from curtains or any flammable objects.

WARNING: Do not block any ventilation openings on the rear or top of the amplifier. Do not

impede ventilation by placing objects on top of the amplifier which extend past the rear edge of
its cabinet.

WARNING: Do not expose the amplifier to rain, moisture, dripping or splashing water. Do not

place objects filled with liquids on or nearby the amplifier.

WARNING: Always make certain proper load is connected before operating the amplifier.

Failure to do so could pose a shock hazard and may result in damage to the amplifier.

Do not expose amplifier to direct sunlight or extremely high temperatures.

Always insure that amplifier is properly grounded. Always unplug AC power cord before changing
fuse or any tubes. When replacing fuse, use only same type and rating.

Avoid direct contact with heated tubes.

Keep amplifier away from children.

Be sure to connect to an AC power supply that meets the power supply specifications listed on
the rear of the unit. Remove the power plug from the AC mains socket if the unit is to be stored
for an extended period of time. If there is any danger of lightning occurring nearby, remove the
power plug from the wall socket in advance.

To

avoid damaging your speakers and other playback equipment, turn off the power of all related
equipment before
making the connections.

Do not use excessive force in handling control buttons, switches and controls. Do not use
solvents such as benzene or paint thinner to clean the unit. Wipe off the exterior with soft cloth.

Instruction Manual

REAR VIEW : LONE STAR

WARNING:
Unplug powe

r
before replacing
fuse or removing
bolts mounting
chassis

SLAVE

POWER FUSE

4 A
SLO
BLO

120 V~

60 Hz

4 A

FUSE

FUSE

SILICON
DIODES

TUBE
RECTIFIER
TRACKING

FA

N

ON

FA

N

OFF

First set sound with

LOOP bypassed. Then

set SEND & OUTPUT
to 50% for unity gain.
With LOOP IN, adjust

SEND to match FX.

Use OUTPUT for

RETURN level and

live volume control.

SEND

RETURN

NORMAL

MIN

SEND LEVEL

TUBE LOCATIONS

1 x 5U4 4 x 6L6

LOOP

IN

HARD BYPASS

OOGIE

B

M

ESA

LONE STAR

CH 2 REVERB CH 1

REVERB

BRIGHT

REV W

ARM

ALL - TUBE

AMPLIFIER

CHANNEL

SOLO

EXT

SW

SPEAKERS

HAND BUILT IN PETALUMA CA.

8 OHM4 OHM 4 OHM

BIAS SELECT

EL-34

WHEN

RED ON

EL-34

6L6

CAUTION: SWITCH MUST

MATCH TUBES IN USE

INPUT

FT.SW

FRONT VIEW : LONE STAR

DRIVE

CH 1

FT SW

CH 2

THICK

THICKER

CLEAN

MAL

GAIN

TREBLE

MID

BASS PRESENCE MASTER

100 W

50 W

100

W

50 W

OUTPUT

LOOP ON

SOLO

STANDBY

ON

POWER OFF

TWEED

NOR

ON

Overview:

Congratulations

on your choice of the

as your amplifi er and Welcome to the

MESA/Boogie

Family!

This hand-built instrument was crafted with the fi nest quality components and designed to provide you with years of musical inspira-

tion and toneful satisfaction.

is laid out simply and logically. Its clean, two channel layout provides a platform for ultimate

expression with a minimal learning curve. Though you have probably experienced the magic of its character already, this guide will

there easily in new musical environments.

The two channels provide the entire range of gain, from sparkling clean to totally saturated, and anywhere in between. Channel 1(top)

amps, this channel can be driven to clip and produces incredible solo possibilities for blues or roots chording styles.

Channel 2 has a split personality and can either be set to achieve a slightly gainier clone of Channel 1 or, with the fl ick of a switch

exact blend of smooth singing saturation. The bipolar nature of Channel 2 allows the

to roam effortlessly through both

vintage and modern territory with full channel switching accuracy and an emphasis on soul and simplicity. You can set up the amp for

two low gain channels, one for sparkling clean and the other driven into an old school clip or, one for low gain clean and the other for

The

takes channel switching further and allows you to choose the amount of power and type of rectifi cation you want

to combine with each preamp channel. The choices are 50 or 100 watt power ratings and Tube or Silicon Diode rectifi cation. For

accuracy, select 100 watts and the Diodes are automatically brought on line to keep things bold and authoritative. These power- se-

your footswitching needs.

Overview: (Continued)

The OUTPUT control is joined by our SOLO feature that provides an additional master output that you can trigger remotely for a

footswitchable boost when you want to feature a part. These two Front Panel controls are brought on line with the activation of the

to HARD BYPASS, all associated circuitry is removed (for you purists) from the signal path. Since the Output and SOLO controls are

wired as Loop Returns, at the end of the preamp and Loop signal path, they are defeated when the Loop is bypassed. The Power

switch is fi tted with LOW and (high/normal) ON settings to provide a built in variac so that incoming AC voltage can be reduced to

As mentioned above the Effects Loop handles outboard processing with fi nesse. The ability to HARD BYPASS the loop entirely assures

the purist in you will be satisfi ed in the studio where every nuance of tone is crucial and you don’t need the SOLO feature.

The pure, all tube Reverb is fi tted with a Bright/Warm switch that enables you to tailor the reverb sound to the style you are playing.

WARM produces a more pure, studio quality character. Individual blend controls for each channel allow you to get the mix just right

for each of the sounds you have designated to the two channels.

with larger rack or multiple amp setups. The Chan-

via external and/or midi commands with any switcher that supports grounding type logic within their programmable menus.

A Switchable BIAS SELECT feature allows you to swap tube types in the power section for different response characteristics. Use the

stock 6L6 type tubes for the greatest versatility, or swap them out for a quartet of EL34 for a brighter, looser feel and added harmonic

spread. Always use the proper setting of the BIAS SWITCH for the tube type in use!

And fi nally, a SLAVE Output and Level control round out the Rear Panel enabling you to use the

as the “dry” master

amp for a stereo setup, drive an external rack of outboard processing or, simply add additional power for larger venues. Unlike the

signal at the speaker output.

That covers the features of the

sound. First though, here are a few helpful hints to get you started.

After unpacking your new amplifi er, save the packing material and box should you move or ever want to ship you amplifi er.

2.)

Remove the plastic webbing from the power tubes before connecting the A.C. power cable!

3.)

Make sure the A.C. power cable is connected to a grounded (3 hole) socket.

4.)

Make all speaker connections with unshielded speaker cable.

5.)

Make all external processing connections to the EFFECTS LOOP with shielded cable.

HELPFUL HINTS:

6.)

When the Footswitch is not available or desired, use the Front Panel mini toggle to select the two channels.

7.)

The Front Panel OUTPUT and SOLO controls are not active until the Effects Loop is switched to the LOOP ACTIVE position. Use

the Channel MASTER controls for output volume level when the LOOP is set to HARD BYPASS.

8.)

As with all

MESA

amplifi ers, the

controls really work and are extremely powerful. You will fi nd most of the best

sounds will be produced by setting the controls in their middle ranges, and very rarely higher than 3:00. The balance between them is

the important part and they are most interactive when no one dominates the mix. Adhering to this scheme will avoid excessive tube

9.)

Use the LOW power setting on the A.C. POWER switch in combination with the TUBE RECTIFIER TRACKING selection on the

When connecting your processing to the Effects Loop follow these steps;

Set up your two Channels for the desired sounds

2.

3.

Connect your processor Input to the Effects Loop SEND

4.

Connect

5.

Activate Effects Loop (LOOP ACTIVE)

6.

Set processor Input Level control for unity gain (0db)

Adjust the overall Effects Loop SEND LEVEL control to fi ne tune the processors Input signal.

8.

Adjust overall playing volume with

the

Front Panel OUTPUT control.

If you are using the amplifi er with both Channels set to the 50 watt output setting, try connecting an 8 ohm load to the 4 ohm

jack. This scheme provides a brighter, snappier response and is preferable for certain styles.

When swapping from the stock quartet of 6L6 output tubes to EL34,

always check the BIAS SWITCH. Make sure it is set to

It is possible to install a quartet of 6V6 power tubes to achieve a lower overall power rating and a looser, breathier power feel.

advisable to load the amplifi er with an 8 Ohm speaker load on the 4 Ohm jack. This scheme provides the best response while at the

same time reducing stress on the tubes. Try the settings below to audition a couple of possible ways to setup the two channels.

you

want to hear.

GAIN

TREBLE

MID

BASS PRESENCE MASTER

SAMPLE #1. Sparkling Clean / Singing Lead

DRIVE

CH 1

FT SW

CH 2

THICK

THICKER

CLEAN

MAL

GAIN

TREBLE

MID

BASS PRESENCE MASTER

SAMPLE #2. Roots Clean / Old School Clip

NOR

Instant Gratification Demo Settings

STANDBY

ON

POWER OFF

ON

OUTPUT

LOOP ON

SOLO

OUTPUT

LOOP ON

SOLO

TWEED

STANDBY

ON

POWER OFF

ON

TWEED

100 W

50 W

100

W

50 W

100

W

50 W

100

W

50 W

INPUT

FT.SW

DRIVE

CH 1

FT SW

CH 2

THICK

THICKER

CLEAN

MAL

NOR

INPUT

FT.SW

HELPFUL HINTS: (Continued)

FRONT PANEL: Controls & Features

INPUT:

This is the instrument

jack. This jack feeds the preamp and since the

therefore very sensitive, always use a high quality shielded cable between the instrument and the amplifi er. This will prevent unwanted

This 1/4 inch ” stereo jack is for connection of the Channel Select Footswitch. When the

is con-

This is the pre-drive control for the high gain preamp in Channel 2. It may be switched out of the circuit, along with its

associated tube stages, to create a slightly higher gain clone of Channel 1 in (this bottom) Channel 2. When the

control is

activated (switch left, towards

), this control operates in conjunction with the GAIN control to meter the amount of preamp drive

that will be introduced into the circuit.

or 3:00 and just playing with the

to learn the regions of saturation. You will probably fi nd the

appear between 1:00 and 3:00.

will produce a warmer quality to the sound

and in most cases this is preferable. By all means experiment with setting the GAIN lower than the

character may be desirable for your application.

They are extremely powerful, as they control how your guitar feeds the preamp and also determine the signal strength that is pumped

through the tone control string. This in turn affects how the tone controls will respond. At extremely high settings you will be hearing

This is fi ne if complete saturation is the desired effect, but remember, many of the best sounds are found with more moderate settings

where the gain controls interact with the tone control string to produce a balance of frequencies.

INPUT

FT.SW

INPUT

FT.SW

INPUT

FT.SW

DRIVE

CH 1

FT SW

CH 2

THICK

THICKER

CLEAN

MAL

NOR

FOOTSWITCH:

DRIVE:

FRONT PANEL: Controls & Features

(Continued)

CHANNEL SELECT:

This 3 position mini toggle allows manual selection of the Channels when the Footswitch is not connected.

This switch is responsible for activating the

circuitry in Channel 2. Set to

active and additional tube stages are added in front of the normal “rhythm” circuitry to produce a multi-stage high gain lead channel.

CLEAN

Channel 1. Because of this additional gain in what is otherwise a “rhythm” circuit, Channel 2 is

an amazing solo channel for Roots style rhythm work or howling blues solo sounds. Cranking the

CLEAN

is a wonderful alternative to the more saturated sound of the

circuit.

You will fi nd ample gain to get notes to sound fat and singing, and still retain all of the urgent

dynamics of a clean sound that is driven to clip.

This 3 position mini toggle allows you to select between three different voicings. It selects what

frequency the Treble control will enhance. By lowering the frequency of the treble capacitor, additional gain in these frequencies is

added. This allows you to shape the sound for either sparkling clean sounds, or fatten up the Treble region and thicken the sound for

you are searching for as well as allowing you to cop the vibe of several classic amp styles.

is the best choice for clean chording and traditional blues style single note solo sounds.

three tone controls gain wise. In other words the gain of the Treble region is in line with that of

the Bass and Mid. Here the most sparkle and shimmer will appear and a beautiful blend will be

easy to achieve for all your clean work. The

selection will also let the true character

of your individual guitar shine through more than the gain enhanced character of the other two

choices. When searching for identifi able signature sounds,

would be the best choice

for traditional “black face” style clean or clipped sounds due to this lack of alteration of the classic

treble frequencies.

THICK

lowers the frequency of the Treble region while keeping the gain closer to that of the

setting. This selection fattens

the upper region and smears the line between Mid and Treble to achieve a more robust, throatier sound.

THICK

is the best choice

when searching for classic british style response for either chording or overdriven sounds. You might think of it as a “plexi” switch.

THICKER

lowers the Treble frequency even further and adds considerable gain in that region. It can enhance high gain solo work by

saturating the sound and covering up fret buzz, weak pickups or other nuances that will appear as holes in a high gain lead sound.

certain guitars or speaker choices. This setting has appeared in various clothing on virtually all

MESA

amplifi ers through the years

and is classic

Boogie.

THICKER

is the choice for the trademark singing sustain that has long been associated with our amplifi ers.

INPUT

CH 1

FT SW

CH 2

INPUT

FT.SW

DRIVE

CH 1

FT SW

CH 2

THICK

THICKER

CLEAN

MALNOR

INPUT

FT.SW

DRIVE

CH 1

FT SW

CH 2

THICK

THICKER

CLEAN

NORMAL

DRIVE / CLEAN:

THICK / NORMAL / THICKER:

FRONT PANEL: Controls & Features

(Continued)

GAIN:

This control adjusts the predominant gain stage in each channel’s circuit with the function and taper being optimized for each

GAIN

control for each channel comes in a different place and adjusts a different point in that channel’s circuit.

GAIN

control is the most

the

GAIN

control is even more powerful. It not only determines the amount

of drive, but also acts as an integral part of the tone control string as well.

To simplify the

GAIN

controls’ role in shaping the overall tone of the sound we will look at

alone and

2)

in conjunction with the tone controls.

enhances the saturation and replaces some of the upper harmonics with a richer, warmer quality and a

fuller bottom end response. Not yet fully saturated, this region is the easiest place to get a great sound in both channels. This region

contains many of the

with ample sustain.

saturates the signal and enhances low and low mid frequencies. While this region provides the maximum satu-

GAIN

control sparingly and only when maximum sustain is needed.

GAIN

gain settings. Your tubes are warranted for a period of 6 months under normal use, but you can save yourself the present and future

2.) GAIN - In conjunction with the Tone Controls -

Basically, a simple rule applies...as the Gain is increased the Tone control string

getting mostly Gain and very little Tone

this is the reason we suggest using the

GAIN

control in its middle region. Here the Tone control string is very active and provides

INPUT

FT.SW

DRIVE

CH 1

FT SW

CH 2

THICK

THICKER

CLEAN

MAL

GAIN

NOR

FRONT PANEL: Controls & Features

(Continued)

TREBLE:

As in most tube guitar amplifi ers, the

TREBLE

control ( in both channels of your

) is the most powerful

of the rotary controls and is next in line only to the GAIN control as a shaping tool. Because it is fi rst in the signal path of the tone

controls - and from here the Middle and Bass receive their signal - it is by far the dominant tone control. For this reason the setting of

the

TREBLE

control is very important for equal representation of the three frequency regions to appear at their respective controls.

there is an optimum region of

the

control where ample top end is mixed in and yet enough signal

As you might surmise, here is the

There are defi nitely great sounds

above and below this middle region ( 11:00 - 1:30 ), but the balance between

the

TREBLE

control and the other two tone controls is compromised.

The

TREBLE

control can be used to dump extra gain into the mix. This is

especially effective in CHANNEL 1 and Channel 2 with the DRIVE bypassed. When doing so, use the PRESENCE control to roll off

some of the more than ample top end for a more compressed feel and fatter voice. As you might surmise, the BASS control’s effective-

The

control is responsible for the blend of midrange frequencies in the mix and though its effect is not as dramatic as

that of the TREBLE control, it plays an integral part in achieving any sound in your

It is capable of changing the feel

dramatically as it blends in a group of frequencies that tend to soften or stiffen the way a sound feels to play.

control settings ( 7:00 - 11:00 ) where a scoop in this region produces

girth

feel to the strings and therefore

control is increased, ( 11:30 - 1:30

) the sound is rounded-out and fi lled-in with a focused mid attack appearing rather

quickly. As you would guess, the feel starts to change - becoming more resistant.

Above this region the

control could be used to compensate for either weaker

control settings ( 2:00 - 5:00 ) can introduce added gain and create enhanced

focus, the trade-off will be a stiffer, more forward, less compressed feel.

The

control in your new

works similarly in both channels in that it determines the amount of low fre-

quencies present in a sound. However, the

it mixes in changes from channel to channel. Like the MID control, it falls in

the TREBLE control and the same scheme applies. When the TREBLE control is set high, the effectiveness of

the BASS and MID controls is reduced. If the TREBLE control is set low these two controls

try to use the TREBLE control in its middle ranges. This scenario produces nearly equal repre-

sentation of all the frequencies on the tone controls and provides a great neutral starting point

for further tweaking.

INPUT

FT.SW

DRIVE

CH 1

FT SW

CH 2

THICK

THICKER

CLEAN

MAL

GAIN TREBLE

NOR

CH 1

FT SW

CH 2

THICK

THICKER

CLEAN

MAL

GAIN MID

TREBLE

NOR

TREBLE

BASS

MID

MID:

BASS:

FRONT PANEL: Controls & Features

(Continued)

BASS: (Continued)

Note:

is very powerful and though we have taken

2 when using either the regular Channel 1 style gain circuitry cranked, or the DRIVE circuitry for higher gain lead sounds. A good

The

control is a high frequency attentuator that is placed at the end of each channels pre-amp stage

and affects frequencies higher than those of the TREBLE control. It acts independently of the other rotary tone controls and is crucial

control settings darken and, in fact compress the signal

which works well to fatten single note solo sounds, giving them girth and focus.

will fi nd the

control

This control is the master feed from the end of the pre-amp to the driver stage and the Effects Loop. As you can see each

Channel is fi tted with its own

control, enabling both channels relative volumes to be matched regardless of their extremely

different sound styles and gain signatures. The

control makes possible a wide range of sounds through its ability to use

very low Gain sounds at high volumes and conversely, high Gain sounds at low volumes and everywhere between.

Again, we suggest using the

control in its

ranges ( 9:00 - 2:00 ).

control creates the send to the Effects Loop, extreme

These channel specifi c mini toggle switches allow you to preset the output power of each

channel.

delivering maximum power and punch.

The 50 watt setting runs

only the outside (far left & far right) tubes

to achieve the bubbly elastic bounce only a

to dedicate to each of your two channels.

achieve the ultimate clean headroom and power. Meanwhile, Channel 2 could be cranked

and dedicated to a power clip solo sound by setting the power select switch to 50 watts

and bypassing the DRIVE circuitry for an awesome old school power section pushed

TREBLE

PRESENCE

MID BASS

MASTER

BASS PRESENCE

100 W

50 W

100 W

50

W

100 W

50 W

100

W

50 W

OUTPUT

LOOP ON

SOLO

MASTER

PRESENCE:

MASTER:

100W / 50W: Channel Power Select:

FRONT PANEL: Controls & Features

(Continued)

100W / 50W: Channel Power Select (Continued)

tone. This scheme would be further enhanced by selecting the TUBE RECTIFIER:

TRACKING setting on the Rear Panel RECTIFIER SELECT switch.

Or, you might want the opposite and set Channel 1 to 50 watts of sparkling, yet forgiving clean performance and go for the bold auth-

ority of 100 watt power for Channel 2 set to a soaring high gain voice using the DRIVE circuitry.

Whatever scheme you choose to use, the ability to select the power rating of each channel adds incredible expression power to the

The RECTIFIER SWITCH (Rear Panel) has a built in RECTIFIER TRACKING feature that ensures proper matching for each

power setting. In 50W, either a TUBE RECTIFIER or a silicon DIODE may be chosen as the rectifi cation element with the Tube offering

provides the reliable and powerful headroom of a 4x6L6 output section.

At some point in your experimentation with the Channel Power Select switches, try setting one or both of the Channels to

OUTPUT:

This control determines the overall output volume level of the amplifi er. After the

controls, the

OUTPUT

control allows you to change the playing level by adjusting a single

control. The

OUTPUT

control is also wired as the Effects Loop Return Level control.

amplifi er

as a power amp alone by inserting a signal

OUTPUT

control will serve as the master level control.

amplifi er

amplifi er

Connect “Dummy” plug or loose cable to SEND jack. ( This prevents any possible loading that could result in diminished RETURN

sensitivity.)

2.)

The OUTPUT Level will be the only active control on the Front Panel (the PRESENCE control of Channel 1 will be active only

when that channel is engaged - see #3 )

3.

) The SOLO control may be used to footswitch to a pre-determined amount of boost when the footswitch is connected.

as a power amp.

OUTPUT

LOOP ON

SOLO

MASTER

100 W

50

W

100 W

50

W

OUTPUT & SOLO CONTROLS:

FRONT PANEL: Controls & Features

(Continued)

OUTPUT & SOLO CONTROLS: (Continued)

SOLO: This control can only be activated if the correct Footswitch is connected

to the Footswitch DIN jack.

SOLO

is an additional fi nal output level control wired in parallel with the OUTPUT control. It is capable

of a setting above that of the OUTPUT control and can not be set below. The amount

of apparent boost also depends on that of the OUTPUT control - in that if the amplifi er

SOLO

control to work with. By

SOLO

on the fl y...giving you some control over your levels when it’s time to step out. Engineers

you with the dreaded monitor or sidefi ll version of your tone.

This sideways 3 position toggle switch determines the status of the incoming AC power. Your

incorporates a built-in VARIAC feature that enables you to reduce the line voltage to approximately 93 volts (with a

steady 117 at the wall). This

at lower overall volumes. It is especially useful in achieving old school clip sounds in Channel 1 and Channel

2 with the DRIVE bypassed.

These sounds are further enhanced when the

power feature is used in combination with the 50 watt

setting and TUBE RECTIFIER:TRACKING is selected. Another bonus is that if you were to use the

TWEED

ON

setting of the AC power switch.

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

tubes are at idle so that during power up they may warm up before being put to use. Before Power is switched on make sure the

STANDBY

switch is in the Standby position.

Wait at least 30 seconds and then fl ip the

STANDBY

switch to the ON position. This prevents tube problems

and increases their toneful life substantially.

sound

you

want, let’s move to the Rear Panel and cover the features found there.

OUTPUT

LOOP ON

SOLO

MASTER

100 W

50 W

100 W

50

W

STANDBY

ON

POWER OFF

TWEED

ON

STANDBY

ON

POWER OFF

TWEED

ON

POWER: TWEED / OFF / ON

STANDBY:

REAR PANEL:

FUSE:

This is the A.C.’s (Alternating Current) main fuse and provides protection from outside A .C. fl uctuations as well as power

tube failure damage. Should the

blow, replace it with the same rating in a Slo-Blo type package. The domestic U.S. version

FUSE

tube is going bad or is arcing you will see it! Flip the STANDBY switch to Standby immediately and replace the faulty power tube and

the

FUSE

if necessary.

just the adjacent tube or all power tubes in the “shotgun” troubleshooting tradition and save the replaced set

as spares. Spare fuses are a must for the fabled cord bag along with your spare tubes. Always carry both for

they could be worth their weight in gold someday.

This two position toggle selects the type of rectifi er, Silicon Diodes or

Tube, to convert the voltage from AC to DC for the power supply. The

Dual and Triple Rectifi er SOLO

heads. It incorporates a Rectifi er Tracking™

feature that insures proper voltage is present at all times and improves reliability. This switch operates in tandem with the individual

Channel Power Select (50/100) switch located on the right side of the Front Panel.

The Rectifi er Tracking feature monitors the Channels, determines their power status and automatically selects

the proper rectifi er type - which ultimately assures the best sound. This provides optimization of the power

settings, delivering a magical tube-rectifi ed power-sag vibe for the channel set to 50 watts - and a tighter,

chooses the solid state diode rectifi ers which deliver maximum power and headroom, while tracking tighter and

TUBE RECTIFIER TRACKING

engages the 5U4 rectifi er

tube automatically (either or both channels) whenever the 50 watt selection is made on the Front Panel Channel Power Select switch.

When switching to the opposite channel, if the Channel Power Select is set to 100 watts, the Diodes are automatically engaged to

This innovative feature allows you to tune each channel for the ultimate power expression and feel. With this fl exibility you can switch

solo work with the DRIVE bypassed in Channel 2. Or conversely, set Channel 1 for a sweet low power clean sound and crank up the

your Channels, you will fi nd this power section fl exibility a remarkable step forward toward your ultimate tone.

TUBE RECTIFIER TRACKING

feature. Be

WARNING:
Unplug power
before replacing
fuse or removing
bolts mounting
chassis

POWER FUSE

4 A
SLO
BLO

120 V~

60 Hz

4 A

FUSE

FUSE

DIODES

TUBE
RECTIFIER
TRACKING

WARNING:
Unplug power
before replacing
fuse or removing
bolts mounting
chassis

POWER FUSE

4 A
SLO
BLO

120 V~

60 Hz

4 A

FUSE

FUSE

DIODES

TUBE
RECTIFIER
TRACKING

WARNING:
Unplug powe

r
before replacing
fuse or removing
bolts mounting
chassis

SLAVE

POWER FUSE

4 A
SLO
BLO

120 V~

60 Hz

4 A

FUSE

FUSE

SILICON
DIODES

TUBE
RECTIFIER
TRACKING

FA

N

ON

FA

N

OFF

First set sound with

LOOP bypassed. Then

set SEND & OUTPUT
to 50% for unity gain.
With LOOP IN, adjust

SEND to match FX.

Use OUTPUT for

RETURN level and

live volume control.

SEND

RETURN

NORMAL

MIN

SEND LEVEL

TUBE LOCATIONS

1 x 5U4 4 x 6L6

LOOP

IN

HARD BYPASS

OOGIE

B

M

ESA

LONE STAR

CH 2 REVERB CH 1

REVERB

BRIGHT

REV W

ARM

ALL - TUBE

AMPLIFIER

CHANNEL

SOLO

EXT

SW

SPEAKERS

HAND BUILT IN PETALUMA CA.

8 OHM4 OHM 4 OHM

BIAS SELECT

EL-34

WHEN

RED ON

EL-34

6L6

CAUTION: SWITCH MUST

MATCH TUBES IN USE

RECTIFIER SELECT: Diodes / Tube Rectifi er Tracking

REAR PANEL:

(Continued)

FX LOOP: Series

The

LONE STAR

and power section. This loop is wired such that the dry signal is in series with the effected (wet) signal. The circuit also incorporates

a

SEND LEVEL

control allowing you to fi ne tune the output of the preamp circuit to match the input sensitivity of your processor

circuitry

can be completely removed from the signal path with the

mini toggle. This removes all associated loop

circuitry and two tubes from the chain and ensures the purest signal

SEND

and

jacks incorporate switching

elements so that you may use the

selection and activate

the Front Panel OUTPUT and SOLO controls with nothing connected

to the Loop.

To connect your outboard processor(s) to the Effects Loop;

Connect the

SEND

jack on the

shortest possible length.

2.)

Connect the

jack of the

to your processor’s OUTPUT also using a high quality shielded cable of the short-

est possible length.

3.)

Adjust the

SEND LEVEL

control on the Rear Panel of the

to achieve an adequate match on the INPUT level indicator

of your processor. Adjust the processor Output level stage (hopefully your processor has an OUTPUT LEVEL control) to match the

volume present before connecting the device(s) to the

You can check this by simply removing both the cables from the

SEND

and

simultaneously.

4.)

Use the Front Panel OUTPUT control to raise and lower the overall volume as it is essentially an Effects Return Stage volume

control.

Normally this is minimal

processor before buying it to make sure it is compatible with the

Normally, the more professional series lines of most

NORMAL

MIN

SEND LEVEL

First set sound with

LOOP bypassed. Then

set SEND & OUTPUT
to 50% for unity gain.
With LOOP IN, adjust

SEND to match FX.

Use OUTPUT for

RETURN level and

live volume control.

SEND

RETURN

LOOP

IN

HARD BYPASS

M

LONE STAR

TUBE LOCATIONS

1 x 5U4 4 x 6L6

REAR PANEL:

(Continued)

REVERB:

The

incorporates a stunning analog Reverb circuit that is fi tted with individual Channel Mix controls and a

produces a vintage guitar amp style brighter sound fi lled with canyons of

features a smoother, warmer

character often associated with large plate studio reverbs. You will quickly see why we think

the

Enjoy!

These two 1/4” jacks provide an interface for remote control of the Channel Select

function as well as activation of the SOLO control. These jacks may be connected to an external control unit that stores a grounding

Footswitch in larger stage rigs.

The

jacks respond to any tip-to-ground latching type logic for their triggering. This

type of switching logic can be found on most midi master control switching units on the market.

This mini toggle allows for proper biasing when swapping to EL34 type power tubes for a brighter harmonic laden

whenever swapping tubes!

compliment of 6L6’s. They clip in a warmer way and during our R & D process we

found them to produce the best blend of frequencies with the least compromise

stylistically.

There are however, some wonderful clipped power sounds available for both chording and single note work with the right set of EL34’s

fi tted. Afi cionados of this sound have long recognized that nothing produces the layers of soft, lined-up harmonics like these British

style bottles and when dialed right, the

takes on a whole new personality. So when you have fi nished exploring this side

of the Atlantic for vintage magic, defi nitely take a jump across the pond and check out some of the amazing sounds that are made

feature and these opposite sounding tube types.

We recommend the 6L6 for reliability:

In our many tests and continued use of the currently available EL34 type power tubes on the

fact, along with their sonic narrowing of possible styles, is why the

ships with 6L6 power tubes.

tubes and a bag of extra fuses with you at all times when performing in the event of a tube failure. A little preparation will save you a

LOOP

IN

HARD BYPASS

OOGIE

B

M

ESA

LONE STAR

CH 2 REVERB CH

1

REVERB

BRIGHT

REV WARM

ALL - TUBE
AMPLIFIER

REVERB

BRIGHT

REV WARM

ALL - TUBE

AMPLIFIER

CHANNEL

SOLO

EXT

SW

SLAVE

SPEAKERS

HAND BUILT IN PETALUMA CA.

8 OHM 4 OHM 4 OHM

BIAS SELECT

EL-34

WHEN

RED ON

EL-34

6L6

CAUTION: SWITCH MUST

MATCH TUBES IN USE

CHANNEL & SOLO: External Switch Ports:

BIAS SELECT:

BIAS SELECT: (Continued)

switch set to 6L6 (switch down) and install four 6V6 power tubes. It

as they cannot handle the higher AC voltage and could fail and damage internal

components! When using these tubes, move the 8 ohm speaker to the 4 ohm SPEAKER OUTPUT jack. This will reduce strain on the

tubes and produce the best sonic response.

The

provides one 8 ohm and two 4 ohm speaker outputs and this enables you to use many different

combinations of speaker setups. The 1x12 combo uses an 8 ohm speaker while the 2 x 12 combo uses two 16 ohm speakers wired

tion. This will not hurt the amplifi er, however mismatching in the higher direction will wear the power tubes

faster. You will fi nd sample speaker wiring diagrams later in this manual and when you get time it would

STAR

with alternate speaker combinations. We build many different types of Extension Speaker Cabinets,

all with unique characteristics, as well as a line of matching Classic cabinets to enhance both the sound

and the appearance of your

The

SLAVE

Output and its accompanying Level control provide an output for capturing the sound of both preamp and

outboard processors when using the EFFECTS LOOP is not desirable. It is not a direct recording output as it derives its signal from

the speaker jacks and is much too strong a signal to connect to the input of a console. Also there is no roll off of high frequencies or

shaping, as the speaker does this, so the sound would be less than desirable for recording applications.

designed specifi cally for this application and has the necessary circuitry to achieve this diffi cult task with

stunning results.

SLAVE

Output is powerful. Always start with the LEVEL control set to its

SLAVE

That covers the features, outputs and functions of your

expressive power. Whichever way you take it, we wish you many years of elevated inspiration and hope you fi nd lasting satisfaction

and enjoyment from this hand-crafted musical instrument.

for a Product Specialist who will be glad to help you get the answers you need.

SLAVE

SPEAKERS

HAND BUILT IN PETALUMA CA.

8 OHM 4 OHM 4 OHM

SLAVE

SPEAKERS

HAND BUILT IN PETALUMA CA.

8 OHM 4 OHM 4 OHM

REAR PANEL:

(Continued)

SPEAKERS:

SLAVE:

REAR PANEL:

(Continued)

REVERB REMOTE JACK:

The Reverb feature contains a Remote Switch jack that allows you to control the Reverb effect from

a separate footswitch. The 1/4” jack is located on the underside of the chassis just below where the SLAVE jack is located on the

extreme right side of the Back Panel.

Connecting any tip-to-ground, latching-type footswitch will allow you to toggle on and off the Reverb effect.

stores or, you can call our Customer Service department and order one for a nominal charge.

SLAVE

SPEAKERS

HAND BUILT IN PETALUMA CA.

8 OHM 4 OHM 4 OHM

REMOTE
FOOTSWITCH JACK

REST AREA

INPUT

FT.SW

DRIVE

CH 1

FT SW

CH 2

THICK

THICKER

CLEAN

MAL

GAIN

TREBLE

MID

BASS PRESENCE MASTER

100 W

50

W

100

W

50

W

OUTPUT

LOOP ON

SOLO

NOR

FACTORY SAMPLE SETTINGS

SAMPLE # 1

SAMPLE # 2

SAMPLE # 3

SAMPLE # 4

INPUT

FT.SW

GAIN

TREBLE

MID

BASS PRESENCE MASTER

OUTPUT

LOOP ON

SOLO

DRIVE

CH 1

FT SW

CH 2

THICK

THICKER

CLEAN

MAL

100 W

50

W

100

W

50

W

NOR

INPUT

FT.SW

GAIN

TREBLE

MID

BASS PRESENCE MASTER

OUTPUT

LOOP ON

SOLO

DRIVE

CH 1

FT SW

CH 2

THICK

THICKER

CLEAN

MAL

100 W

50

W

100

W

50

W

NOR

INPUT

FT.SW

OUTPUT

LOOP ON

SOLO

DRIVE

CH 1

FT SW

CH 2

THICK

THICKER

CLEAN

MAL

NOR

LONESTAR STATE

TUBE RECTIFIER TRACKING

CLEAN CLONES

DIODES

TWANG & BANGIN'

TUBE RECTIFIER TRACKING

PURR & GRIND

TUBE RECTIFIER TRACKING

GAIN

TREBLE

MID

BASS PRESENCE MASTER

100 W

50 W

100

W

50

W

ON

STANDBY

POWER OFF

ONTWEED

ON

STANDBY

POWER OFF

ONTWEED

ON

STANDBY

POWER OFF

ONTWEED

ON

STANDBY

POWER OFF

ONTWEED

ON

INPUT

FT.SW

DRIVE

CH 1

FT SW

CH 2

THICK

THICKER

CLEAN

MAL

GAIN

TREBLE

MID

BASS PRESENCE MASTER

100 W

50

W

100

W

50

W

OUTPUT

LOOP ON

SOLO

NOR

FACTORY SAMPLE SETTINGS

SAMPLE # 6

SAMPLE # 7

SAMPLE # 8

INPUT

FT.SW

GAIN

TREBLE

MID

BASS PRESENCE MASTER

OUTPUT

LOOP ON

SOLO

DRIVE

CH 1

FT SW

CH 2

THICK

THICKER

CLEAN

MAL

100 W

50

W

100

W

50

W

NOR

INPUT

FT.SW

GAIN

TREBLE

MID

BASS PRESENCE MASTER

OUTPUT

LOOP ON

SOLO

DRIVE

CH 1

FT SW

CH 2

THICK

THICKER

CLEAN

MAL

100 W

50

W

100

W

50

W

NOR

BARBEQUE

AUSTIN - TACEOUS

DIODES or TUBE TRACKING

ARMADILLO

TUBE RECTIFIER TRACKING

DIODES

SAMPLE # 5

INPUT

FT.SW

OUTPUT

LOOP ON

SOLO

DRIVE

CH 1

FT SW

CH 2

THICK

THICKER

CLEAN

MAL

100 W

50

W

100

W

50

W

NOR

PASS THE SAUCE

TUBE RECTIFIER TRACKING

GAIN

TREBLE

MID

BASS

PRESENCE MASTER

STANDBY

POWER OFF

ONTWEED

ON

STANDBY

POWER OFF

ONTWEED

ON

STANDBY

POWER OFF

ONTWEED

ON

STANDBY

POWER OFF

ONTWEED

ON

INPUT

FT.SW

GAIN

TREBLE

MID

BASS PRESENCE MASTER

OUTPUT

LOOP ON

SOLO

PERSONAL SETTINGS SHEET

SETTING # 1

SETTING # 2

SETTING # 3

SETTING # 4

SETTING # 5

INPUT

FT.SW

GAIN

TREBLE

MID

BASS PRESENCE MASTER

OUTPUT

LOOP ON

SOLO

INPUT

FT.SW

GAIN

TREBLE

MID

BASS PRESENCE MASTER

OUTPUT

LOOP ON

SOLO

INPUT

FT.SW

GAIN

TREBLE

MID

BASS PRESENCE MASTER

OUTPUT

LOOP ON

SOLO

INPUT

FT.SW

GAIN

TREBLE

MID

BASS PRESENCE MASTER

OUTPUT

LOOP ON

SOLO

DRIVE

CH 1

FT SW

CH 2

THICK

THICKER

CLEAN

MAL

100 W

50

W

100 W

50

W

NOR

DRIVE

CH 1

FT SW

CH 2

THICK

THICKER

CLEAN

MAL

100 W

50

W

100 W

50

W

NOR

DRIVE

CH 1

FT SW

CH 2

THICK

THICKER

CLEAN

MAL

100 W

50

W

100 W

50

W

NOR

DRIVE

CH 1

FT SW

CH 2

THICK

THICKER

CLEAN

MAL

100 W

50

W

100

W

50

W

NOR

DRIVE

CH 1

FT SW

CH 2

THICK

THICKER

CLEAN

MAL

100 W

50 W

100

W

50

W

NOR

STANDBY

POWER OFF

ONTWEED

ON

STANDBY

POWER OFF

ONTWEED

ON

STANDBY

POWER OFF

ONTWEED

ON

STANDBY

POWER OFF

ONTWEED

ON

STANDBY

POWER OFF

ONTWEED

ON

TUBE NOISE & MICROPHONICS:

You may occasionally experience some form of tube noise or microphonics. Certainly no cause

for alarm, this quirky behavior comes with the territory and the Tone. Much like changing a light bulb, you don’t need a technician

to cure these types of minor user serviceable annoyances and in fact, you’ll be amazed at how easy it is to cure tube problems...by

simply swapping out a pre-amp or power tube!

down. It also helps to have adequate lighting as you will need to see the tube sockets clearly to swap tubes.

sense when touching the tubes after the amplifi er has been on as they may be extremely hot!

If they are hot and you

don’t want to wait for them to cool off, try grasping them with a rag and also note that the glass down around the bulbous silvery tip is

considerably less hot 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

electron fl ow has overcome the control grid and excess current fl ows to the plate. You will usually hear the amp become distorted

and begin to hum slightly. If this occurs, quickly look at the power tubes as you switch the amp to STANDBY and try to identify one

as glowing 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,

the intermittent tube will visibly start to over heat before the others and thus it can be identifi ed. It should be replaced with one from

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. In the worst cases, a major arcing short occurs between the plate and the cathode with

visible lightning inside the glass and a major noise through the speaker. If this is seen to happen, IMMEDIATELY turn the amp to

Often caused by contamination within in a tube, the culprit can usually be identifi ed, and by lightly tapping on the glass,

you will probably hear the noise change. Hearing some noise through the speakers while tapping on the 12AX7’s is normal however.

And the one nearer the INPUT will always sound louder because its output is being further amplifi ed 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 probably

found the problem. To confi rm a noisy power tube, merely put the

Road King

on Standby, remove it from its socket and turn it back

on. It will cause no damage to run the

Road King

briefl y with one power tube missing. You may notice a slight background hum,

your diagnoses. You will be doing yourself and us a big favor by just following the simple guidelines previously mentioned regarding

tube replacement. You’ll probably be successful with much less effort than is required to disconnect everything and haul the unit to a

technician who will basically perform the same simple tests. If the tubes are still within their six-month warranty period, we will happily

send you a replacement. Just note the color designation on the tube label so that we can send you the appropriate match.

DIAGNOSING POWER TUBE FAILURE:

TUBE NOISE:

DIAGNOSING PRE-AMP TUBE PROBLEMS:

Because your amplifi er is an all tube design, it is quite possible that you will at some

terrupted performance. These minor pre-amp tube problems can take many forms but can generally be described in two categories:

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

came from.

The best way to approach a pre-amp tube problem is to see if it occurs only in one specifi c mode or channel. This should lead you to

the tube needing replacement. Then all that remains is to swap the suspect tube for a known good performer. If you cannot narrow

down the trouble to a specifi c mode or channel, the problem may be the small tube that drives the power tubes which is operational

show themselves in the form of crackling or hum in all modes of performance and/or weak overall output from the amplifi er. Occasion-

ally an anemic driver tube will cause the amplifi er to sound fl at and lifeless, but this is somewhat uncommon, as worn power tubes

are a more likely suspect for this type of problem.

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

they are at the start of the chain and their noise gets amplifi ed 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

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.

tube. 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 must

send back your amp, remove the chassis from the cabinet by unscrewing the four mounting bolts on the bottom top. The chassis then

slides back like a drawer and comes out from the back. Remove the big power tubes and mark them according to their location from

within the larger carton. Remove the Rectifi er tubes and wrap them also. You can leave the preamp tubes in or remove them and wrap

them separately being sure to label their location. (See Tube Task Chart.)

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

LONESTAR

6L6

6L6

REAR OF CHASSIS - viewing chassis from its bottom side

NOTE: POWER TUBES ARE HOT ! BEFORE CHANGING TUBES TURN POWER

SWITCH TO OFF AND LET COOL OR USE A RAG FOR PROTECTION.

TUBE TASK CHART

A B

A B

A B

A B

A B

RCA Jacks for Reverb

6L6

6L6

5U4

COOLING FAN

Description of Tube Functions

V3 B = FX Loop Return

V4 A = Reverb Return

V4 B = Reverb Drive

V5 A = Phase inv/driver

V5 B = Phase inv/driver

V1 A = CH2 Drive Stage

V1 B = Input Gain Stage

V2 A = 3rd Gain Stage

V2 B = 2nd Gain Stage

V3 A = FX Loop Send

V 1

V 2

V 3

V 4

V 5

BIAS ADJUSTMENT: (Part of a continuing series)

An Article written by Randall Smith that

we thought you might fi nd interesting.

“Why doesn’t

Mesa

put bias adjustments

Well, there’s 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

were either set wrong or that had wandered out of adjustment due to vibration. As any honest tech will tell you, there’s lot’s of easy

What customer is going to argue with that?

to a dead end road, it just trails off to nowhere without really completing a circuit. It’s a static voltage and regardless of what tube is

that were individually hard wired to the correct values and NEVER needed adjustment. And for 25 years, that’s how

MESA/Boogies

Time to change tubes? Just plug our tubes into any one of our amps and you’re DONE. No tech needed. NO bills and no BS about

our tolerance range. We have a very sophisticated computer - based tube testing system (nicknamed “Robotube”) that matches and

though they work perfectly during the test.

Boogies

don’t have bias adjusters are primarily in the business of selling tubes - not amps. They don’t want to throw away 30 percent

of their inventory, so they promote the idea that tubes outside our parameters can be used to “customize” amplifi ers and they criticize

MESA

tolerance tubes.

— which is quicker) what you are doing is establishing the correct amount of idle CURRENT that fl ows through the power tubes.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

( )

( )

( )

,

( , )

( )

PLATE

Structure of a 6L6 / 5881

Beam Power Pentode.

BEAM­CONFINING
ELECTRODE

SCREEN
GRID

GRID

CATHODE

BIAS ADJUSTMENT: (Continued)

control grids.

Voltage and current are NOT the same. Current is the AMOUNT of electricity, the

“quantity” — and is measured in amperes. Voltage is the degree of electric charge — like the “pressure” to use the old water analogy.

When you scrape your feet across a carpeted fl oor in dry, wintery conditions, your body can become charged with 50,000 to 100,000

volts of static electricity. And when you reach for the door knob, a spark jumps and you feel it! The voltage is super high but the cur-

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 a thing.

Yet the amount of current available can run to several hundred amperes .. enough to turn over a cold engine and get it started.

which is measured in watts.

When you set the bias of an amplifi er, you are adjusting the static VOLTAGE at the control grid of the tube in order to produce a

desired amount of idle CURRENT fl owing to the tube’s plate. A small change in grid voltage, produces a large change in the amount

of current fl owing — and that’s basically how a tube works. Say that again because it’s super important: A small change in voltage

at the grid causes a large change in current fl owing to the plate. See, that’s the essence of amplifi cation: A small change causing a

The bias conditions are what determines how much current fl ows through the big power tubes when you’re not playing. And what

drives your speakers is fl uctuations in that current fl ow when you ARE playing. If the amount of current increases and decreases

440 times per second, then you’ll hear an A note. If the fl uctuations in current fl ow are large and still at 440 per second, you’ll hear

an A that is LOUD!

circuit. But measuring VOLTAGE is easy. It is not necessary to interrupt the circuit because a voltage reading can be taken in PAR-

ALLEL 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 the

value should be. They only give the grid voltage that will produce that current. (That’s the minus 52.) But that only happens if the

tubes 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 there’s no need

for the bias voltage to be adjustable!

the bias ... but no manufacturer I know even STATES the desired current value! Be that as it may, when the original bias voltage is

altered far enough, it will compensate for the tube’s abnormal performance and the correct amount of idle current fl ow may then be

The other “advantage” of this system is that it allows some amp manufacturers to avoid matching their power tubes. The thinking

current fl ows through each one.

BIAS ADJUSTMENT: (Continued)

Again, this has some merit .. but it’s still not as good as using tubes that are matched in the fi rst

too cool, turn it down ...” are guesswork at best. Luckily, one of the great things about tube amps is that they can usually stand some

abuse without causing any real harm ... at least not immediately. But don’t these alterations imply that you are second-guessing the

amp designer and that there’s a better set of operating conditions that the designer missed but the tube sellers have discovered?

sate. But often it is the mere novelty of change that they’re really responding to and when the amp goes back to the proper original

way, we’ve seen them be far happier still!

seemingly insignifi cant 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 one

complains that these other parameters aren’t available for tinkering.

Consider our patented

circuitry where there are two different bias voltages used for separate pairs of power tubes ...

and changing one voltage also changes the other. Great care goes into getting this just right and we think we’d be asking for trouble

to have it adjustable for the world to play with ... unless you like paying to have your amp messed up. Sorry, I meant to say, “Uh, ...

your amp needed biasing.”

MESA

tubes into one of our amps and you’re ready for tone. Guar-

anteed. You’d be amazed at the number of service calls we fi eld every day that lead to a diagnosis of out-of-tolerance, non-spec tube

wrong size tires on your car, do you think changing the pressure will make them right?

doesn’t make sense to pay more of your hard earned cash for tubes that were probably made in the same Russian or Chinese fac-

tory and which have the possibility of being outside the performance window we select for your amp. And it pains us to hear the hype

and mystique built up around biasing when twenty-fi ve years of evidence affi rms our decision to make bias circuits that “never need

adjustment”. How much money and trouble that has saved

MESA/Boogie

players you couldn’t estimate.

Our rigorously tested and hand selected tubes are available at your nearest

MESA/Boogie

Pro Center or from us directly. Nobody

offers better price, quality or warranty than we do ... so why swerve?

fairly close reappear on the market. Remember, we still have some of these super rugged mondo-bottles available for older amps

Boogies

only please! Until then, Relax, Breathe and Nourish your soul!

Cheers!

MESA/Boogie Ltd.

SPEAKER IMPEDANCE MATCHING & HOOK-UP GUIDE:

Wiring up speakers to provide the most effective load and making sure that all of them are in phase will help in

creating the best sound possible. This is not too diffi cult, as long as you understand a few things about loading and how to connect

your speakers to provide an optimal resistive load.

MESA/Boogie

amplifi ers can handle 4 and 8 ohms effectively. Never run below 4 ohms in a tube amplifi er unless you are absolutely

certain that the system can handle it properly; this can cause damage to the Output transformer. A few amplifi ers can handle 2 ohms

effectively without damaging them ( for example the

MESA’S Bass 400+

). You can always have a higher resistance ( 16 ohms, for

example ) without damaging results, but too low of a resistance will likely cause problems.

When running a higher resistance ( for example: 8 ohm output into 16 ohm cabinet ), a slightly different feel and

a result of the amplifi er running a bit cooler. Sometimes when using more than one cabinet a mismatch will be the only option.

amplifi er, and you are done. In many cases, you will have a number of speakers, and then you must calculate the “load” that the ampli-

fi er will need to support. There are generally three ways to wire multiple speakers together. They are as follows:

When you wire ( hook-up ) speakers in Series, the speakers resistance ( as measured in ohms ) is additive - i.e. put-

ting two 8 ohm speakers in Series results in a 16 ohm load.

Speaker A = 8 Ohms

Speaker B = 8 Ohms

SERIES:

Connect the Negative side of Speaker A

to the Positive side of Speaker B

POSITIVE =

NEGATIVE

=

B

L

A

C

K

S

H

A

D

O

W

B

L

A

C

K

S

H

A

D

O

W

IMPEDANCE:

MIS-MATCHING:

WHAT IS MY CABINETS IMPEDANCE:

SERIES:

SPEAKER IMPEDANCE MATCHING & HOOK-UP GUIDE: (Continued)

When wiring in parallel, the resistance of the speakers decreases. Two 8 ohm speakers wired in ( hooked-up )

side of Speaker A to the Negative side of Speaker B.

This is really just two sets of Series wired speakers connected in Parallel. This is

cabinet to connect to your amplifi er. This is when you need to fi gure out the loads and how to wire them up without applying too low

of a resistance on the amplifi er.

tive side of Speaker C.

Connect the Negative side of Speaker A to the Positive

side of Speaker B. Next, connect the Negative side of

And lastly, connect the Negative side of Speaker B to the

4 Eight ( 8 ) Ohm speakers wired in Series Parallel = a

Total Load of 8 Ohms.

POSITIVE

Speaker

A

8 Ohms

Speaker

B

8 Ohms

NEGATIVE

Total Load = 4 Ohms

B

L

A

C

K

S

H

A

D

O

W

B

L

A

C

K

S

H

A

D

O

W

SPEAKER A

SPEAKER B

SPEAKER C

SPEAKER

D

NEGATIVE

All 4 Spkrs. are 8 Ohms

POSITIVE

B

L

A

C

K

S

H

A

D

O

W

B

L

A

C

K

S

H

A

D

O

W

B

L

A

C

K

S

H

A

D

O

W

B

L

A

C

K

S

H

A

D

O

W

PARALLEL:

COMBINATION OF SERIES & PARALLEL:

1

2

5

4

4 Ohm Cabinet

3

8 OHM 4 OHM 4 OHM

Partial back view of

some Mesa amp

8 Ohm Cabinet

SAFE MISMATCH

WIRING SCHEMES...Amplifier to Speaker Cabinets

4 OHM 8 OHM 16 OHM

Partial back view of amplifier

16 Ohm Cabinet

4 OHM 8 OHM 16 OHM

Partial back view of amplifier

16 Ohm Cabinet

SAFE MISMATCH

8 OHM 4 OHM 4 OHM

Partial back view of amplifier

8 OHM 4 OHM 4 OHM

Partial back view of amplifier

8 Ohm Cabinet

4 Ohm Cabinet

8 Ohm Cabinet

8 OHM 4 OHM 4 OHM

Partial back view of amplifier

8 Ohm Cabinet

8 Ohm Cabinet

6

8 Ohm Cabinet

16 Ohm Cabinet

8

4 OHM 4 OHM 8 OHM

Partial back view of amplifier

SAFE MISMATCH

8 OHM

Partial back view of amplifier

SERIES BOX

8 Ohm

4 Ohm

4 Ohm

4 Ohm Cabinet

4 Ohm Cabinet

4 OHM 4 OHM

8 OHM

Partial back view of amplifier

PARALLEL BOX

8 Ohm

16 Ohm

16 Ohm

16 Ohm Cabinet

16 Ohm Cabinet

9

4 OHM 4 OHM

7

WIRING SCHEMES...Amplifier to Speaker Cabinets

CORRECT MATCH

CORRECT

MATCH

CORRECT

MATCH

4 OHM 4 OHM 8 OHM

Partial back view of amplifier

8 Ohm Cabinet

8 Ohm Cabinet

SERIES BOX

16 Ohm

8 Ohm

8 Ohm

8 Ohm Cabinet

10

SAFE MISMATCH

12

4 OHM 4 OHM

Partial back view of amplifier

16 Ohm Cabinet

16 Ohm Cabinet

11

8 OHM

8 Ohm Cabinet

16 Ohm Cabinet

16 Ohm Cabinet

4 OHM4 OHM8 OHM

Partial back view of amp

PARALLEL BOX

8 Ohm

16 Ohm

16 Ohm

WIRING SCHEMES...Amplifier to Speaker Cabinets

CORRECT MATCH

SAFE MISMATCH

4 OHM 4 OHM 8 OHM

Partial back view of amplifier

8 Ohm Cabinet

8 Ohm Cabinet

SERIES BOX

16 Ohm

8 Ohm

8 Ohm

16 Ohm Cabinet

13

SAFE MISMATCH

WIRING SCHEMES...Amplifier to Speaker Cabinets

4 OHM4 OHM8 OHM

Partial back view of amplifier

16 Ohm Cabinet

16 Ohm Cabinet

PARALLEL BOX

8 Ohm

16 Ohm

16 Ohm

16 Ohm Cabinet

SAFE MISMATCH

14

ON TRIODES, PENTODES & IRISHMEN:

With apologies to Friends and Relatives from the Emerald Isle - who will make their appearance soon enough - the humor which

follows is dedicated to the memories of Spec McAuliff and Fae (Rafael) McNally, two of the True Greats.

As their numerical references suggest, the terms Diode, Triode and Pentode indicate the number of elements within the vacuum

tube i.e. two, three or fi ve. All tubes also require a fi lament or heater which is not included in the count. Its purpose is to excite elec-

trons from the cathode coating by raising the temperature such that they are able to boil out of the electron-rich coating material

and form a cloud of free electrons in the vacuum space surrounding the cathode.

Although the term fi lament and heater are often used interchangeably, there are specifi c differences: A fi lament is a directly heated

cathode where cathode coating is applied directly to the heating element. Examples are 5U4 twin diode rectifi er and 300B triode

amplifi er tubes. A heater, on the other hand, is a heating element which is separate from the cathode and is usually inserted within

the tubular cathode sleeve. Examples are 12AX7 twin triode amplifi er and 6V6 or EL84 beam power pentode tubes. In all cases this

fundamental aspect of each tube’s construction is clearly visible, especially when the heating element is glowing red hot.

The cathode, then, would be considered the fi rst numbered element because it is the source of the electrons. The word itself is

from the Greek literally meaning completely down, which implies a sense of central origin - like the center of the earth where

Tone begins. It might be said that an ecstatic audiophile experiences a positive catharsis, his soul being purifi ed when his system

transports him to Audio Nirvana. The only trouble with taking this positive imagery too far is that the cathode is, unfortunately,

experienced the more common negative catharsis when they emerge from the emotional rebirth kicking and screaming in rage and

frustration.

Once heated, the intrinsically negative electrons are energetic little fellows of almost no mass. Thus they may be accelerated al-

one another and thus within the electron cloud surrounding the cathode, there is much jostling and elbowing as each one tries to

Visualize, if you will, a group of sub-atomic Irishmen milling about and in a repellent, negative state of mind. All are scowling and

orderly, if rapid movement of the lot in a single direction. This is what happens when a positively charged element called the anode

or plate is introduced into the vacuum.

The plate is the large metal element most prominently visible through the glass of an electron tube. It is the outermost element of

a tube’s structure and it surrounds all the others. The cathode is at the center radiating electrons outwards. As higher and higher

of the hot, electron-rich cathode as you can easily imagine other Irishmen impatiently taking up the places of those who’ve gone

a cathoding surface. Thousands of tiny bubbles suddenly appeared - and continued to fl ow from the raisin. Of course the bubbles

were made up of gas dissolved in the beverage, but the analogy makes it easy to visualize the loosely bound electrons dissolved

strongly repelled by a negatively charged plate and they are. Thus, if an alternating current - such as comes from a transformer - is

applied to the plate, electrons will fl ow only during the times when the plate is positively charged. During periods of negative plate

charge, electron fl ow is stopped and the space charge of electrons remains compressed in the area around the cathode.

ON TRIODES, PENTODES & IRISHMEN: (Continued)

Thus a diode tube - one with a cathode and an anode - is mostly used to

time is strictly enforced at Irish pubs: During normal operation, the traffi c fl ow is similarly unimpeded and uni-directional toward the

the bar remains positively charged.

This section is a continuing technical treatise on the workings of Irish Pubs but to make it easier for the layman to

some control over the fl ow can be a necessary and useful advantage. This led to the invention of those swinging louvered saloon

doors which are open at the top and bottom. They are patterned after the control grid of the vacuum tube, which is a loosely wound

coil of thin wire located between the cathode and the plate.

tive electrons can still FEEL the strong attraction - just as the Irishmen can see in through the louvers of the bar doors. They know

what pleasures lie beyond, but to get there requires overcoming the negative infl uences controlling the access. This negative infl u-

ence is typically called a Bias. In electronic terms that means the grid is supplied with a voltage which is slightly MORE NEGATIVE

than the already negative electrons. The more negative the Bias, the more it tends to neutralize the attraction of the plate and repel

the electrons back toward the cathode.

The Irish can be similarly charged with Bias, but unless you are Irish yourself, this type of Biasing may be more diffi cult to under-

stand. The effect is similar though: The more negative the Bias, the more it impedes forward progress. Generally speaking though,

the electronic Bias of the grid is easiest to overcome, and for two main reasons: First, the Bias is set - like the bar doors - to allow

some passage. Second, the grid is mostly NOT THERE, like the louvered doors which are mostly open spaces. Unlike the plate

which is solid, the grid is like a coiled bed spring. It can create a repelling fi eld but mostly it’s empty space in between widely sepa-

only slightly will have an enormous effect on how much current fl ows through... and that’s what AMPLIFICATION is: a small change

The purpose of the louvered bar doors is similar to that of the grid, namely, to give momentary pause while still revealing the

to come back later. Most just pause slightly then go on through. That is the purpose of the bar doors: to prevent everyone from

crowding in all at once - and as the door is made less of a barrier, wider spaces between the louvers, more of the bar’s attractive

Occasionally though, bar doors - even the louvered type - were found to be too effective, and too many customers

turned away. Something further was needed to increase the attraction of the bar and overcome the

Thus the cocktail waitress was invented.

Once again the idea was inspired by the vacuum tube. It had been discovered in some tubes, often large power types, that the

distance to the plate was too great to attract enough electrons past the negative infl uence of the control grid. So another grid coil of

fi ne wire was inserted between the fi rst grid and the plate. This was called the screen grid and carrying a highly positive charge, it

functioned as a “bait” for the plate.

shadow of the control grid. This way the electrons responding to the pull of the screen grid are lined up in sheets as they pass be-

tween windings of the inner control grid... only to fi nd that they have been fooled! Once past the control grid and drawn toward the

screen grid, they discover...there’s almost nothing there. The path they’re on has them aligned to zing straight through the spaces

far, there’s no stopping them. The infl uence of the plate takes over and - being solid metal and of the highest positive attraction - it

TRIODES:

PENTODES:

PENTODES: (Continued)

Thus the proper cocktail waitress - visible through the louvers - is scantily clad so as to be all the more

effective at reinforcing the attractive infl uence of her bar and by being located in between the door and the bar, she serves as bait

to lure customers past the door’s negative infl uence. Once through the door however, it is the rare Irishman who actually comes in

Once at the bar though, the circuit is complete and the process of soul-nourishing works its ritual magic. Biases having been over-

come, illusory nightingales having vanished, the spirits truly soar and the once surly Irishmen now are fi lled with warmth, wit and

With appreciative thanks to the inhabitants of the Land of the Leprechaun, we have now concluded our little diversion into the

A feature article by Randall Smith

REAR VIEW : LONE STAR

WARNING:

Unplug powe

r

before replacing

fuse or removing

bolts mounting

chassis

SLAVE

POWER FUSE

4 A

SLO

BLO

120 V~

60 Hz

4 A

WER FUSE

FUSE

FUSE

SEND

RETURN

NORMAL

MIN

SEND LEVEL

TUBE LOCATIONS

1 x 5U4 4 x 6L6

1 x 5U4 4 x 6L6

LOOP

IN

HARD BYPASS

OOGIE

B

M

ESA

LONE STAR

CH 2 REVERB CH

1

REVERB

BRIGHT

REV WARM

ALL - TUBE

AMPLIFIER

CHANNEL

SOLO

EXT

SW

SPEAKERS

4 OHM 4 OHM8 OHM

BIAS SELECT

EL-34

WHEN

RED ON

EL-34

6L6

CAUTION: SWITCH MUST

MATCH TUBES IN USE

INPUT

FT.S

W

FRONT VIEW : LONE STAR

DRIVE

CH 1

FT SW

CH 2

THICK

THICKER

CLEAN

MAL

GAIN

TREBLE

MID

BASS PRESENCE MASTER

100 W

50 W

100

W

50 W

OUTPUT

LOOP ON

SOLO

STANDBY

ON

POWER OFF

TWEED

SWITCH pt#

JACK pt#

SWITCH pt#

ALL KNOBS 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#

SWITCH pt#

SWITCH pt#

SWITCH pt#

SWITCH pt#

SWITCH pt#

JACK pt#

610120

610123

591047

703300

LED LENS

pt#

607303

591739

593794

591048

591278

591278

591048 593794

591047

591047

591047

591047

581739

607303

607111

408015

607111

607111

591047591047

600639

600631

ON

SILICON

DIODES

TUBE

RECTIFIER

TRACKING

FA
N

ON

FA
N

OFF

First set sound with

LOOP bypassed. Then

set SEND & OUTPUT

to 50% for unity gain.

With LOOP IN, adjust

SEND to match FX.

Use OUTPUT fo

r

RETURN level and

live volume control.

SWITCH pt#

FUSE pt# 790347 DOMESTIC

JACK pt#

JACK pt#

SWITCH pt#

JACK pt#

JACK pt#

SWITCH

pt#

LED pt#

P.C. MOUNTED

SWITCH pt#

SPEAKER JACKS

pt#

618112

618112

607201

618112

618356

AC RECEPTACLE

pt# 613713

593736

607111

FUSE pt# 790346 EXPORT

607200

607200

618112

618112

703300

JACK pt#

593740

593738 593738

The Spirit of Art in Technology

OOGIE

B

M

ESA

Thank you

for trusting MESA/Boogie to be your amplifier
company and we wish you many years of toneful enjoyment from
this handbuilt all tube instrument.

The Spirit of Art in Technology

1317 Ross Street Petaluma, CA 94954

USA

[phone] FAX NO. [phone]