Mesa/Boogie Dual Rectifier Roadster 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!

Table of Contents

___________________________________________________________________________________

0

Overview

____________________________________________________________________________________

Getting Started

________________________________________________________________________________

3

________________________________________________________________________________

3-4

Ch 1 & 2 CLEAN

________________________________________________________________________________

5

Ch 1 & 2 FAT

___________________________________________________________________________________

5

Ch 1 TWEED

___________________________________________________________________________________

5

Ch 2 BRIT

_____________________________________________________________________________________

6

Ch 3 & 4 RAW

_________________________________________________________________________________

6

Ch 3 & 4 VINTAGE

______________________________________________________________________________

6

Ch 3 & 4 MODERN

______________________________________________________________________________

CONTROLS:

GAIN

_______________________________________________________________________________________

7-8

TREBLE

______________________________________________________________________________________

8

________________________________________________________________________________________

8-9

_________________________________________________________________________________________

9

____________________________________________________________________________________

9

_____________________________________________________________________________________

OUTPUT CONTROL

_________________________________________________________________________

SOLO CONTROL

______________________________________________________________________________

STANDBY SWITCH

____________________________________________________________________________

____________________________________________________________

SLAVE

_______________________________________________________________________________________

SPEAKERS

___________________________________________________________________________________

_____________________________________________________________________________________

CHANNEL STRIPS

_____________________________________________________________________________

________________________________________________________

_____________________________________________________________________

______________________________________________________________________

_______________________________________________

________________________________________________________________________

TUNER OUT

__________________________________________________________________________________

A.C. RECEPTACLE

_____________________________________________________________________________

_____________________________________________________________________

________________________________________________________________

___________________________________________________

22-26

SPEAKER HOOK-UP & IMPEDANCE MATCHING GUIDE

___________________________________________

27-32

________________________________

33-35

________________________________________________________________________________

36

FRONT PANEL:

RO A DS T E R

REAR PANEL:

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.

Overview:

on choosing the

Mesa Dual Rectifi er Roadster

as your amplifi er and welcome to the

Mesa/Boogie

Family! By

choosing this all-tube hand-built instrument you have taken a step into the future of guitar amplifi cation, for as you can see at a glance,

the

Roadster

is more than just an amp. It’s a

housed in one chassis. This arsenal of sounds is so powerful that

with them at your command, inspiration will take over and propel your playing to places you have only dreamed. Let’s take a moment

and review the features that make up this house of tone.

ally just four separate amps. If you view it as such and learn them individually and

combine and dedicate them, you will fi nd the

sounds in the

Roadster

as you go deeper. In case that was too simple sounding, here is a more expanded way of understanding the

Roadster.

Roadster

and though they may each be used for any sound, they

are grouped as two sets of lower gain Rhythm Channels (1 & 2) and two sets of high gain Lead Channels (3 & 4). The two sets are

stacked with the lower gain rhythm channels following the Input jack. Each of these channels house 3 different modes, which are

voiced differently and in certain cases have different gain structures. You’ll notice the modes are duplicated in the two types of channels

OUTPUT

SOLO

CH1 CH3

LOOP

GAIN TREBLE MID BASS PRESENCE MASTER

RAW

MODERN

VINTAGE

RAW

MODERN

VINTAGE

BOLD

SPONGY

ON

STANDBY

CLEAN

TWEED

FA

T

CLEAN

BRIT

FAT

GAIN TREBLE MID BASS PRESENCE MASTER

FRONT VIEW : COMBO

Roadster

MUTE

CH2 CH4

FOOT

CONTROLLER

CH 2

CH
1

CH 3

FT

SW

CHANNEL

POWER FUSE

120 V~
60 Hz
4 A

4 A
SLO
BLO

FUSE

HANDBUILT

IN PETALUMA

CALIFORNIA, USA

FX LOOP

CH4

CH3

EXT.

SWITCH

CH2

CH1

REVERB SOLO LOOP TUNER OUT

LOOP SYSTEM

ACTIVE

HARD BYPASS
LOOP, OUTPUT &
SOLO CONTROLS

NORMAL

SEND

LEVEL

SEND RETURN

CH 4

6L6

BIAS

EL34

REVERB

DIODE

RECTO

TRACKING

100 WATTS

50

WA

TTS

FX ON

FX
OFF

REVERB

DIODE

RECTO

TRACKING

100 WATTS

50

WATT

S

FX ON

FX

OFF

REVERB

DIODE

RECTO

TRACKING

100 WATTS

50

WATT

S

FX ON

FX

OFF

REVERB

DIODE

RECTO

TRACKING

100 WATTS

50

WATT

S

FX ON

FX

OFF

CH 3

CH 2

CH 1

SLAVE

LEVEL

OUT

REAR VIEW : COMBO

Roadster

(USE WITH TWO 8 OHM CABS)

4 OHM8 OHM

SPEAKERS

4 OHM16 OHM

This allows the

Roadster

to be many amps to many players and roam confi dently between extremely

different musical styles while retaining the ability to focus in on any one and offer a multitude of great sounds for a specifi c genre. For

example, a Blues player might dial up 1 & 2 for different clean sounds using the same mode for both chording and solo fi lls, while 3

4 provide different levels of the same lower gain solo sound. Conversely, a Rock player might confi gure 1 & 2 for semi-clean and

same modes.

This type of preamp versatility means you will never have to compromise, even when you change bands or venture into a new and

different style with your playing. You’ve chosen an amp that will grow with you.

This awesome preamp power is then sent to the

Roadster’s

Effects Loop section and we have provided a Series Loop to assure a

and out on the fl y.

The

Roadster

also features Rectifi er Tracking, a feature which automatically matches the type of rectifi cation for each of the preamp

/ power sections you have confi gured. This means you can tune the power feel even further to the sound you are creating. You might

want a lower wattage clean sound with the loose, airy feel of Tube Rectifi cation and a high gain lead sound with higher power and the

tight tracking bass response of the Diode rectifi er or vice versa. Many combinations are possible and the best part is that Rectifi er

Tracking follows your choices in power settings to always mate the proper amount of rectifi cation for the number of tubes in use. For

example, if you are using either 2 x 6L6 and you choose Recto Tracking, 1 x 5U4G will be applied. If you use 4 x 6L6, 2 x 5U4G will

The

Roadster

incorporates a rich, all tube analog Reverb. Controlled per channel with the Rear Panel Reverb controls, it may be

switched in and out via the foot controller.

Our patented SOLO feature is an additional Output Level control that is wired in parallel to the Output and provides a pre-assignable,

footswitchable boost for stepping out when it’s time to solo.

A built-in Variac, our patented SPONGY/BOLD switch, is also included which enables you to reduce the A.C. line voltage for a looser

feel and increased upper harmonic spread resulting in that

sound that has the elusive sag.

And fi nally, to keep you in constant control of all the features aboard this vehicle of expression, we have supplied one of the mightiest

footswitches around. All possible Channels, Functions and Features are there for your instant access and their status is monitored

Roadster

behind us, let’s get ready to play.

Overview: (Continued)

After unpacking the amplifi er remove the plastic webbing from all of the tubes (including the preamp tubes behind the row of

2.)

Install the 5U4 Rectifi er tubes (if they are not already in place) by bending back the spring steel tube clamps just enough so that

the base of the tube will have to barely push the clamps out of the way as they go in. Be sure to line up the guide with the slot in

the socket, don’t force it…when it is lined up it will fi t in the socket easily. When the tube is lined up gently press the tube into the

socket while rocking it back and forth until it is seated.

3.)

Connect the 8 Pin DIN Footcontroller Cable to the female DIN connector located on the Rear Panel just under the Rotary Mode

4.)

Connect the A.C. Power Cable to a grounded A.C. outlet.

5.)

Flip the A.C. Mains switch to the BOLD position and wait at least 30 seconds for the power tube fi laments to warm up with the

6.)

Turn the Front Panel OUTPUT control to zero before fl ipping the STANDBY switch to the ON position. This will prevent accidental

settings that are too loud for the room and your ears. These amplifi ers are LOUD and are capable of extreme volumes and should

7.)

Flip the STANDBY to the ON position and enjoy your new instrument.

The Rear Panel CHANNEL SELECT Rotary switch must be set to FOOTSWITCH to access either Channels or features via the

footcontroller.

2.) The OUTPUT and SOLO controls work only if the Effects Loop is active.

Switch out of the LOOP BYPASS position in the

3.)

The SOLO Control is activated when the Footcontroller is connected to the FOOTSWITCH jack on the Rear Panel and the Ef-

fects Loop is taken out of LOOP BYPASS and activated. When the Footcontroller is not connected the SOLO control will have

4.)

The SOLO feature can be used to set a volume level above that of the OUTPUT control setting. It will not allow a setting below

that of the OUTPUT control.

5.)

The GAIN and TREBLE controls are the most powerful controls in all four channels. They should be used with taste and you will

fi nd that many of the best sounds are found with the controls set somewhere in their middle regions. Avoid setting the TREBLE

above 2:00 when the GAIN is maxed as the possibility of unwanted noise and squealing from microphonic tubes increases

dramatically above this setting.

6.

) You will notice a substantial volume increase when switching from either the RAW or VINTAGE modes to the MODERN mode

Getting Started:

Helpful Hints:

7.)

The PRESENCE control determines a lot about the voicing of gain sounds. Set lower it will fatten and compress single note

sounds and lend a liquid feeling to the strings in the 3 modes of Channels 3 & 4. Set higher it will add cut and brightness to the

sound and can be useful in keeping Bass response tight, especially at high GAIN settings when searching for crunch rhythm

sounds.

8.) Although Channels 3 & 4 contain duplicate modes, the PRESENCE controls are different and therefor settings and

sounds will not dial up exactly the same. CHANNEL 3 has been optimized for the RAW and VINTAGE modes

with a PRES-

showcases the more warm and fury nature of these two modes.

CHANNEL 4 houses a much more powerful PRESENCE

control that has been optimized for the MODERN mode and will go to realms of top end that are frankly ridiculous.

the difference like this

and conversely,

9.)

When switching Channels with Reverb applied or switching the Reverb itself in and out of the signal path with the Footcontroller,

Helpful Hints:

(Continued)

CHANNELS 1 & 2: CLEAN

This is the lowest gain circuit of the

Roadster’s

twelve modes and is optimized for producing bal-

anced pristine clean sounds. This mode is duplicated in CHANNEL 2 as it is extremely useful for many different

applications. For the best understanding of how to achieve a great sound in this mode, please refer back to

the GAIN control section of this manual. However, a great place to start is 12:30 or so on the GAIN control

with more sparkle available below this and more warmth apparent above...from there adjust according to your

guitars individual response.

a focused attack.

This mode comes from our original

Mark 1 Boogie

and puts emphasis on the low mid and bottom end

and as a result the top strings of the instrument have more girth and width. This mode is duplicated in CHANNEL 2 and is very

you reset the controls for balance. We suggest running the BASS control a couple notches lower, especially

for chording.

to achieve the best results with this mode. We like to set the GAIN somewhere between 10:30 and 12:00 for

chording as this brings out the sparkle and improves the headroom.

sound with the GAIN all the way up, you will likely have to run the BASS below 9:30 to avoid fl ubbiness and

This mode appears in CHANNEL 1 only and is a gainier variation on the CLEAN that appears in both

channels. Here we have emphasized the gain in the midrange to achieve a more vintage feel that has an element of sag built in. This

Yet here in the Roadster there is just enough increased gain to take these sounds over the top and

give you that extra fi re and feel. This mode may be one of the best sounds in the Roadster and would

character and super-dynamic attack envelope. The added bounce of this feature mates perfectly with

TWEED’s preamp voicing, especially when used with the 50 watt power setting.

scheme a step further and selecting SPONGY on the A.C. POWER SELECT switch and knocking the

A.C. down for a truly soupy vibe. Whether you choose to utilize

TWEED

for these lower headroom retro

applications or, you want a sweet clipped sound with just a bit more resiliency, this mode is a wonderful

voice for any style of clean playing or soft clip soloing.

CHANNEL MODES:

CLEAN

TWEED

FAT

BRIT

FAT

CLEAN

CLEAN

TWEED

FAT

BRIT

FAT

CLEAN

CLEAN

TWEED

FA

T

BRIT

FA

T

CLEAN

CHANNELS 1 & 2: FAT

CHANNEL 1: TWEED

CHANNEL 2: BRIT

This mode appears in CHANNEL 2 only and, as the name implies, was inspired by the great sounding amps

of the 50s’ & 60s’ that were built in Great Britain. These classic amplifi ers were basically “upside down Leo circuits” but none the less had

a signature sound all their own, due largely to the fact that they were powered by the pentode available to them at the time…the Euro

style EL 34. This difference, along with minor value differences in the circuit, created a very different sound than the tweed and black

face amps born in the United States.

We have combined all the great qualities of several of these classic circuits to arrive at a sound that is pure tea bag.

With emphasis on a lower region of Treble and more punch in the low mids, this mode is truly different than the

other modes in CHANNELS 1 & 2. It works extremely well for both chording and single note soloing with its thicker,

throatier nature. It also lends itself well to clipped sounds, with its less extended top end and wider mid section,

works

very well with EL34 type power tubes so be sure to try using the Real Panel Bias switch and swapping the stock compliment of 6L6’s for

a set of EL34’s to create the ultimate pre/power match in the studio. EL34’s will most likely compromise the performance of the other

The choice is yours as to how best to use this very cool and different mode and we feel sure that, no matter how you decide to dedicate

your clean channels, you will fi nd the

mode an awesome addition to your bevy of sounds.

This new

Roadster

extremely wide spectrum and it can be set to double as a formidable alternate clean mode, a low gain

The TREBLE can be set relatively high (2:00) to add a little more gain and shred when using

for

certain crunch rhythm sounds and keep in mind CHANNEL 4 is capable of more aggressive sounds due

to its more extreme PRESENCE control taper. Don’t overlook the amazing medium gain soloing potential

offers in CHANNELS 3 & 4 where, because of the PRESENCE controls more gradual response, a

wider range of voice-like single note sounds appear that benefi t from this more compressed character.

This high gain mode is the famous liquid

Recto

voice and it can be found in its original state in CHANNELS

3 & 4. Its lush harmonic content and fat creamy feel has found its way onto so many recordings, it is now a staple for anyone headed to the

studio for an album project. Combining this super juicy, expressive preamp with the

Rectos’

black magic, tube-rectifi ed power section creates

colors in gain that most players fi nd truly addictive. Single note solo work is effortless as the strings become easy to play with

VINTAGE

VINTAGE

VINTAGE

These two modes are similar enough when

VINTAGE

is set in its lower range and RAW is set in its medium

to higher range and yet, each posses a character that is unique and identifi able. Remember that you can

swap channels to achieve different voicings of the

VINTAGE

sound and no matter which you settle upon,

you will likely fi nd your trademark lead sound lurking somewhere in this sea of liquid gain.

CHANNEL MODES:

(Continued)

BRIT

FAT

CLEAN

RAW

MODERN

VINTAGE

RAW

MODERN

VINTAGE

MASTER

RAW

MODERN

VINTAGE

RAW

MODERN

VINTAGE

MASTER

CHANNEL 3 & 4: RAW

CHANNEL 3 & 4: VINTAGE

CHANNEL 3 & 4: MODERN

Aggressive. This is the word that best describes the menacing power of the

Roadster’s

The added tightness of the low end response combined with the radically more present top end keeps

the

mode tracking accurately even at extreme gain settings. Keep in mind that when using

in CHANNEL 3 you will have to run the PRESENCE control almost all the way up to ap-

This lack of extreme top end can be a benefi t when searching for single note solo sounds in the

mode as the more compressed nature of this tamer presence range in CHANNEL 3 tends

to warm things up.

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

Roadster

is really three separate multi-mode amplifi ers built onto one chassis, so though

each channel looks identical, the

GAIN

control for each channel comes in a different place and

adjusts a different point in that channels circuit.

GAIN

control is the most powerful

control in the preamp. It shapes the overall style and character of the sound and is responsible

for whether the sound is clean, overdriven or anywhere in between. In your

Roadster

GAIN

control is even more powerful. It not only determines the amount of drive, but also acts as an

To simplify the

GAIN

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

ways -

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

contains many of the

Roadsters’

ample sustain.

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

tion and therefor sustain, it also compresses and softens the attack characteristics. For this reason we suggest using this higher

GAIN

control sparingly and only when maximum sustain is needed.

CHANNEL MODES:

(Continued)

RAW

MODERN

VINTAGE

RAW

MODERN

VINTAGE

MASTER

GAIN

CLEAN

TWEED

FAT

CLEAN

BRIT

FAT

GAIN:

Roadster’s

extreme gain potential, the highest regions of the

past what they can handle, producing microphonic squealing. While we screen and test the tubes your amplifi er was shipped with

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

Roadster

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

TREBLE:

As in most tube guitar amplifi ers, the

control ( in all four channels of your

Roadster

) is the most powerful of the

- 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

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

Roadster

TREBLE

control where ample top end is mixed in and yet enough signal is still passed on to

the MIDDLE and BASS controls.

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 one place you may want to throw caution to the wind and set the

control

above this median zone presents itself in CHANNEL 1 of your new

Roadster

control can be used to dump extra

gain into the mix. This is especially effective in the TWEED mode for crunch sounds.

When doing so use the PRESENCE control to roll off some of the more than ample

top end for a more compressed feel and fatter voice. As you might surmise, the BASS controls’ effectiveness will be reduced, so you

control in Channel 1 TWEED should be used sparingly above 2:30 to avoid unwanted microphonic tube problems.

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

Roadster

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 less apparent resistance to the pick. As the

control is increased, ( 11:30 - 1:30 ) the sound is rounded-out and

GAIN

CLEAN

TWEED

FAT

CLEAN

BRIT

FAT

TREBLE

CONTROLS:

(Continued)

MID:

fi lled-in with a focused mid attack appearing rather quickly. As you would guess, the feel starts to change - becom-

control could be used to compensate for either weaker pick-ups or for times when

a specifi c defi ciency is produced by either an extremely high setting of other tone controls, or a physical anomaly in the room. While

these

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.

CHANNELS 1 & 2 utilize a different MIDDLE control than that of the CHANNELS 3 and 4

with a custom-designed taper and

value. In its low range ( below 12:00 ) it functions as a normal midrange control with a taper suited

to blending fi ne increments of these frequencies. Most players lean toward a fairly radical scoop (

7:00 - 10:30 ) for clean playing, preferring to let Treble and Bass remain dominant, thus producing the

signature sparkle and breath essential for a pristine clean sound.

As the

control in CHANNELS 1 & 2 are swept past 1:00, it quickly starts to add gain in these

gain control

capable of taking both CLEAN and TWEED modes to extremes.

to balance both sound and feel. While this added fl exibility may make CHANNEL 1 & 2

control

a little more tricky to learn at fi rst, it will become quite valuable as you start to realize the power of

this super versatile channel.

This control works similarly in all four channels in that it determines the amount of low frequencies present in a sound.

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

signal-wise

the TREBLE control and the same scheme applies. When the TREBLE control is set

these two controls become dominant.

the TREBLE control in its middle ranges. This scenario produces nearly equal representation of all the

frequencies on the tone controls and provides a great neutral starting point for further tweaking.

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

control settings darken and, in fact, compress the signal which works well to fatten single

Roadster

fi nd the

control in its lower regions, where a balanced, vocal response is achieved.

Roadster

and this can be great for sparkling clean

sounds in Channels 1 & 2 and more aggressive crunch rhythm sounds in the high gain modes. Be

sure to taunt the beast that lurks in CHANNEL 3 MODERN as the

is truly amazing in

this most agro mode.

CONTROLS:

(Continued)

TREBLE MID

MID: (Continued)

BASS:

PRESENCE:

MASTER:

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

each Channel is fi tted with its own

control, enabling the four 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 ). Here,

the channels will be easier to match with each other and the Effects Loop will see more

control creates the send to the Effects Loop, extreme

This is the overall

OUTPUT LEVEL

control for the entire amplifi er. It is located at the input to the power sec-

tion and allows you to raise adjust the playing level once you have used the individual CHANNEL MASTER controls to balance the

OUTPUT

receives its signal from the EFFECTS RETURN jack and

therefore this control is only in the signal path and active when the EFFECTS LOOP is set to LOOP

output level controls.

Roadster’s

power section as a stand alone power amp for use with external preamps, as half of a stereo

Roadster

Connect your preamp signal to the EFFECTS RETURN jack.

2.)

Select LOOP ACTIVE on the Rear Panel

3.)

Use the OUTPUT control as your power amp level control.

4.)

Adjust the PRESENCE control of the Channel you are using to taste.

5.)

Select a Channel and a power setting in that Channel.

We recommend

using the MODERN mode of CHANNELS 3 & 4 for this application as the increased power sensitivity of this

CLEAN mode and CHANNEL 3 & 4 in the RAW mode. This will provide uniform input sensitivity and the only volume difference you

will experience are those caused by the output power of the different tube settings (50 or 100 watts).

CONTROLS:

(Continued)

BASS MASTERPRESENCE

OUTPUT

SOLO

OUTPUT CONTROL:

SOLO:

This control is an additional output control wired in parallel with the main OUTPUT that you can pre-set to a higher level

and then switch to during performances. A simple idea that adds amazing potential to virtually any sound in the amplifi er. Like the

OUTPUT control,

SOLO

gets its signal from the EFFECTS RETURN jack and therefore it is only

switching scenarios. One might be a processor that you love the sound of, but steals gain from

your signal when introduced via the LOOP. However you choose to use this valuable feature,

SOLO

adds power and versatility to an already mighty package.

As mentioned above, when using the

Roadster

SOLO

control

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.

This three position toggle switch determines the status of the incoming AC power. “SPONGY”

works like a built in Variac, reducing all the internal voltages for a true vintage feeling and that extraordinary “brown sound.” Power is

set to the TUBE RECTIFIER position.

Roadster

in the SPONGY power setting will also extend tube life and overall reliability,

while still producing enough power to work many of your gigs...and all of your recording needs! For

whenever possible to avoid injury to the user as well as to the unit) and that the proper voltage is

Roadster

CONTROLS:

(Continued)

OUTPUT

SOLO

BOLD

SPONGY

ON

STANDBY

BOLD

SPONGY

O

ON

STANDBY

STANDBY:

POWER: BOLD / OFF / SPONGY

This 1/4” jack and control provide a signal derived from the speaker jack. Perfect for using either the

Roadster

head version

or combo as a master pre-amp and additional power amps for more power when needed. Some players use the

SLAVE

to derive an

Two 4 Ohm, one 8 Ohm and one 16 Ohm jack are provided for speaker interfacing. The

Roadster

is not very sensi-

tive to speaker mismatches and will not be damaged by them, except that very low ohmage loads will cause the power tubes to wear

faster. A single twelve-inch 8 Ohm speaker should generally be connected to the 8 Ohm output. When using two 8 Ohm speakers,

connect them both to the 4 Ohm outputs provided (because the total load is 4 Ohms in that case.) Check out the information further

4x12 cabinets may be 4, 8 or 16 Ohms. If you are not sure of the impedance of your cabinet, you may

speakers.

MESA

4x12 and 4x10 cabinets come standard wired to 8 Ohms, and are wired in series-

MESA

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

all four speakers in parallel, you can reduce the cabinet to an impedance load of 4 Ohms (assuming

the speakers are 16 Ohms each.) No matter how unusual your speaker setup, it is always possible to

get good performance.

These 4 rotary controls determine the dry/wet mix ratio for the rich analog

and are wired to the Reverb return

circuit. Each of the 4 Channels have a dedicated control so that a different Reverb mix can be attained for each individual sound.

The controls sweep from a subtle background effect at their low range to a drenched, swimming effect at

the top of the control. Several factors affect the

tone and drive including the different Modes’ gain

structures, preamp gain settings and CHANNEL MASTER and OUTPUT control settings. Generally speaking,

smeared, washy Reverb sounds. This difference can be useful, desirable and is a normal characteristic of

The

may be switched in and out of the circuit via the

button on the Footcontroller.

is mixed with the dry signal after switching

signal, and the prior Channels sound coming through the

in the current

FOOT

CONTROLLER

CH 2

CH
1

CH 3

FT

SW

CHANNEL

POWER FUSE

120 V~
60 Hz
4 A

4 A
SLO
BLO

FUSE

HANDBUILT

IN PETALUMA

CALIFORNIA, USA

FX LOOP

CH4

CH3

EXT.

SWITCH

CH2

CH1

REVERB SOLO LOOP TUNER OUT

LOOP SYSTEM

ACTIVE

HARD BYPASS
LOOP, OUTPUT &
SOLO CONTROLS

NORMAL

SEND

LEVEL

SEND RETURN

CH 4

6L6

BIAS

EL34

REVERB

DIODE

RECTO

TRACKING

100 WATTS

50

WA

TTS

FX ON

FX

OFF

REVERB

DIODE

RECTO

TRACKING

100 WATTS

50

WATT

S

FX ON

FX

OFF

REVERB

DIODE

RECTO

TRACKING

100 WATTS

50

WATT

S

FX ON

FX

OFF

REVERB

DIODE

RECTO

TRACKING

100 WATTS

50

WATT

S

FX ON

FX

OFF

CH 3

CH 2

CH 1

SLAVE

LEVEL

OUT

REAR VIEW : COMBO

Roadster

(USE WITH TWO 8 OHM CABS)

4 OHM8 OHM

SPEAKERS

4 OHM16 OHM

REAR VIEW: Roadster Combo

SLAVE

LEVEL

OUT

(USE WITH TWO 8 OHM CABS)

4 OHM

KERS

4 OHM

(USE WITH TWO 8 OHM CABS)

4 OHM8 OHM

SPEAKERS

4 OHM16 OHM

REAR PANEL CONTROLS & FEATURES

CH 4

REVERB

DIODE

RECTO

TRACKING

100 WATTS

50

WA

TTS

FX ON

FX

OFF

SLAVE:

SPEAKERS:

REVERB:

CHANNEL STRIPS:

These 4 clusters of switches and controls house the specifi c features that can be pre-assigned per individual

channel. Once you have deciphered one, you have learned the

Roadster’s

secret and are ready to roll, for they are simply repeated

for the 4 channels.

This section is where you choose the status of the LOOP, your power setting (50/100 watts), the

type of Rectifi er you wish to use and your Reverb Mix Level. Each preamp channel has a corre-

sponding

CHANNEL STRIP

to give you voicing and feel control over each of the four footswitchable

sounds for the ultimate fl exibility and maximum tone.

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

converts the voltage from AC to DC for the power supply. The

Roadster

incorporates a further improved version of our patented

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

Calls up the silicon diode rectifi er, which offers more punch, a tighter attack with more brightness and substantially more

application where maximum headroom is needed or tight bass response is called for. Situations that usually require this are clean

the tight, bold authority of the Silicon Diodes. Selecting RECTO TRACKING brings on-line one 5U4 when in 50 watts and two 5U4s

when 100 watts is selected.

The tube rectifi er sound

takes a power section walk down memory lane, paying tribute to those vintage gems of yesteryear. In those

early days of amplifi cation the only rectifi ers available

tubes. Unbeknownst to their creators, these sweet sounding amplifi ers

would someday become relics as the demand for higher volumes and more power per package led to the abandonment of the tube

as a rectifi er, in favor of the fi ve cent silicon diode’s greater effi ciency. With this decision went much of the sweetness and soul and by

the late ‘60’s most amps were bold, loud and effi cient…but unfortunately sometimes lacking that earlier soul. We sought to bring that

Dual Rectifi er

Don’t forget the Front Panel AC switch incorporates the reduced voltage SPONGY setting. This adds yet another dimension

to the power expression scenario and can produce amazing results when combined with the RECTO TUBE-TRACKING feature. Be

sure to experiment with these two features in combination with each other.

CH 4

REVERB

DIODE

RECTO

TRACKING

100 WATTS

50

WA

TTS

FX ON

FX

OFF

REAR PANEL CONTROLS & FEATURES

(Continued)

RECTIFIER SELECT with TUBE-TRACKING:

DIODE:

RECTO TUBE-TRACKING:

FX ON / FX OFF SWITCH:

This mini toggle switch in each Channel Strip assigns the Series EFFECTS LOOP and determines

Your

Roadster

is fi tted with a Series Effects Loop for interfacing outboard processing. The Loop is placed at

the junction between the preamp and the power amp and is optimized for levels that will match up with most good quality processing

devices. A SEND LEVEL Control is provided to fi ne tune the signal strength coming from the preamp and allows for some compensa-

tion for extreme Channel MASTER settings.

This mini toggle controls the status of the Effects Loop in each Channel once the LOOP has been

engaged via the master LOOP SYSTEM IN/LOOP BYPASS switch that is located adjacent to the

automatically when that Channel is selected with either the Footcontroller or the Channel Select

circuit.

The Loop may be switched out of the signal path completely using the LOOP SYSTEM IN/HARD BYPASS switch located adjacent

to the loop. This switch engages the Loop SEND and RETURN jacks, SEND LEVEL Control, OUTPUT and SOLO Control and all

associated circuitry. When LOOP BYPASS is selected (switch up) the entire Loop is removed from the signal path and the individual

Channel MASTER Controls become your fi nal output level controls. This HARD BYPASS feature allows you to use your

Roadster

all its raw glory in the studio where processing will be added later on a separate channel and you need every ounce of pure, unfi ltered,

Tone for a magical performance.

Connect the SEND to your processor’s INPUT.

2.)

Connect the RETURN to your processor’s OUTPUT.

3.)

Set the Four Channels to you dedicated sounds and levels using the Channel MASTER Controls.

4.)

5.)

Select LOOP SYSTEM IN on the LOOP Select switch.

6.)

Set your processor’s INPUT Level control for unity gain.

7.)

After playing in each channel, Adjust the Rear Panel SEND LEVEL to achieve a good unity gain peak level (remember that clean

sounds will peak a bit higher because of their more dynamic, less compressed nature).

8.)

Adjust the Front Panel OUTPUT Control to the desired playing volume.

9.)

Connect the Footswitch (to the Rear Panel FOOT CONTROLLER jack, select SOLO and adjust the SOLO Control for the desired

amount of volume boost.

REAR PANEL CONTROLS & FEATURES

(Continued)

DIODE

RECTO

TRACKING

100 WATTS

50

WA

TTS

FX ON

FX

OFF

FX LOOP

LOOP SYSTEM

ACTIVE

HARD BYPASS
LOOP, OUTPUT &
SOLO CONTROLS

NORMAL

SEND

LEVEL

SEND RETURN

EFFECTS LOOP:

PATCHING EFFECTS:

PATCHING EFFECTS: (Continued)

You will fi nd the

a welcome feature for all rack type processing and when good quality

cables are used and kept to a length of 3 feet or less, you will notice very little if any degradation in the sound of your

Roadster

professional grade quality from reputable manufacturers. In a series confi guration, your amplifi ers sound will depend on the integrity of the

processor’s input and output stages, because you have inserted something into the heart of the most sensitive place in your amplifi er.

You may, at times, wish to use the

Roadster

as a stand alone power amp

for amplifi cation of processing or as half of a larger stereo rig. Because of the channel and mode specifi c changes that take place

The FX LOOP SELECT switch must be set to LOOP SYSTEM IN (Loop engaged).

2.)

The FX LOOP RETURN jack is the INPUT to the power section. This jack bypasses the entire preamp including the GAIN and

all the Tone Controls.

3.)

The OUTPUT is your level control.

4.)

You may use the SOLO Control for a footswitchable volume boost (Footswitch must be connected).

5.)

You may use the Channel Strip POWER SELECT switches to select a power rating that is appropriate for the venue or applica-

tion.

6.)

The choice of rectifi ers is still available when using the

Roadster

amplifi ers, but for guitar applications it is nice to have the choice of the saggy response of tube rectifi cation.

Roadster’s

Why can’t there be more separation at this point in the circuit? There could be if we -and you - didn’t care about TONE. This is

REAR PANEL CONTROLS & FEATURES

(Continued)

USING THE FX RETURN AS A POWER AMP INPUT:

USING THE FX RETURN AS A POWER AMP INPUT: (Continued)

Roadster’s

Roadster

These seven jacks are provided so that you may control the 4 Channels, the EFFECTS LOOP, The

Roadster

as part of a Midi rig

where all sounds are called up via a Midi Footcontroller and both amplifi er and effects settings are stored under a midi program

The

jacks override the

Roadster’s

Footcontroller. Once a Chan-

turned “Off” until the logic at the Switch Port is reversed.

This jack located in the stack of EXTERNAL SWITCH ports

is a Tuner Output and allows for silent tuning

jack, tap TUNER MUTE on the Footcontroller and the signal to the speakers will be muted. The signal will remain muted until you tap

TUNER MUTE again to bring the signal back.

The removable “Euro” Style” A.C. cord that is supplied with your new

Roadster

downs after the gig a snap. It also makes de-racking much easier when you wish to remove the unit from a hard wired rack system

where all the A.C. cords have been cable-tied in. Additional heavy duty cords are available should you ever

A.C.

found on the tube side of the chassis before

REAR PANEL CONTROLS & FEATURES

(Continued)

FOOT

CONTROLLER

CH 2

CH
1

CH 3

FT

SW

CHANNEL

CH4

CH3

EXT.

SWITCH

CH2

CH1

REVERB SOLO LOOP TUNER OUT

FOOT

CONTROLLER

CH 2

CH
1

CH 3

FT

SW

CHANNEL

POWER FUSE

120 V~
60 Hz
4 A

4 A
SLO
BLO

FUSE

A.C. Receptacle

EXTERNAL SWITCHING:

TUNER OUT:

A.C. RECEPTACLE:

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

tioned in the STANDBY switch section and watch the power tubes as you fl ip the STANDBY to the ON position.

the faulty power tube and the

if necessary.

and blew the

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

worth their weight in gold someday.

The Serial Number of your amplifi er is printed on a small metal tag attached to the tube side of the chassis

for warranty.

That covers the features and functions on the Rear Panel and by now you should be ready to start crafting your dream Tone. If you

would like some examples of ways to set the modes in your

Roadster

for different applications, you may fi nd the following SAMPLE

We wish you a lifetime of amazing and inspirational Tone from your new musical instrument and our hope is that it takes you to new

and exciting places on your musical journey.

REAR PANEL CONTROLS & FEATURES

(Continued)

FOOT

CONTROLLER

CH 2

CH
1

CH 3

FT

SW

CHANNEL

POWER FUSE

120 V~
60 Hz
4 A

4 A
SLO
BLO

FUSE

REST AREA

SERIAL NUMBER:

FACTORY SAMPLE SETTINGS:

CLEAN

TWEED

FA

T

CLEAN

BRIT

FA

T

GAIN TREBLE MID BASS PRESENCE MASTER

CHANNEL 1 SETTING #1 Versa Clean

CLEAN

TWEED

FA

T

CLEAN

BRIT

FA

T

GAIN TREBLE MID BASS PRESENCE MASTER

CHANNEL 1 SETTING #2 Spank

CLEAN

TWEED

FA

T

CLEAN

BRI

T

FA

T

GAIN TREBLE MID BASS PRESENCE MASTER

CHANNEL 1 SETTING #3 Tweed Howl

CLEAN

TWEED

FA

T

CLEAN

BRIT

FA

T

GAIN TREBLE MID BASS PRESENCE MASTER

CHANNEL 1 SETTING #4 Fat Solo

DIODE

RECTO

TRACKIN

G

100 WATTS

50

WA

TTS

FX ON

FX

OFF

DIODE

RECTO

TRACKIN

G

100 WATTS

50

WA

TTS

FX ON

FX

OFF

DIODE

RECTO

TRACKIN

G

100 WATTS

50

WA

TTS

FX ON

FX

OFF

DIODE

RECTO

TRACKIN

G

100 WATTS

50

WA

TTS

FX ON

FX

OFF

FACTORY SAMPLE SETTINGS:

CLEAN

TWEED

FA

T

CLEAN

BRIT

FAT

GAIN TREBLE MID BASS PRESENCE MASTER

CHANNEL 2 SETTING #1 Skinny Skank

CLEAN

TWEED

FA

T

CLEAN

BRIT

FA

T

GAIN TREBLE MID BASS PRESENCE MASTER

CHANNEL 2 SETTING #2 Rhythm Mix

CLEAN

TWEED

FAT

CLEAN

BRIT

FA

T

GAIN TREBLE MID BASS PRESENCE MASTER

CHANNEL 2 SETTING #3 Power Rhythm

CLEAN

TWEED

FAT

CLEAN

BRIT

FA

T

GAIN TREBLE MID BASS PRESENCE MASTER

CHANNEL 2 SETTING #4 Brit Grind

DIODE

RECTO

TRACKING

100 WATTS

50

WA

TTS

FX ON

FX

OFF

DIODE

RECTO

TRACKING

100 WATTS

50

WATTS

FX ON

FX

OFF

DIODE

RECTO

TRACKING

100 WATTS

50

WA

TTS

FX ON

FX

OFF

DIODE

RECTO

TRACKIN

G

100 WATTS

50

WA

TTS

FX ON

FX

OFF

FACTORY SAMPLE SETTINGS:

RAW

MODERN

VINTAG

E

RAW

MODERN

VINTAG

E

GAIN TREBLE MID BASS PRESENCE MASTER

CHANNEL 3 SETTING #1 Purring Blues

RAW

MODERN

VINTAG

E

RAW

MODERN

VINTAG

E

GAIN TREBLE MID BASS PRESENCE MASTER

RAW

MODERN

VINTAGE

RAW

MODERN

VINTAGE

GAIN TREBLE MID BASS PRESENCE MASTER

CHANNEL 3 SETTING #2 Smooth Grind

CHANNEL 3 SETTING #3 Liquid Solo (Recto Vintage)

CHANNEL 3 SETTING #4 Giant Fur

RAW

MODERN

VINTAG

E

RAW

MODERN

VINTAG

E

GAIN TREBLE MID BASS PRESENCE MASTER

DIODE

RECTO

TRACKIN

G

100 WATTS

50

WA

TTS

FX ON

FX

OFF

DIODE

RECTO

TRACKIN

G

100 WATTS

50

WA

TTS

FX ON

FX

OFF

DIODE

RECTO

TRACKIN

G

100 WATTS

50

WATTS

FX ON

FX

OFF

DIODE

RECTO

TRACKIN

G

100 WATTS

50

WA

TTS

FX ON

FX

OFF

FACTORY SAMPLE SETTINGS:

RAW

MODER

N

VINTAGE

RAW

MODER

N

VINTAGE

GAIN TREBLE MID BASS PRESENCE MASTER

RAW

MODERN

VINTAGE

RAW

MODER

N

VINTAG

E

GAIN TREBLE MID BASS PRESENCE MASTER

RAW

MODER

N

VINTAGE

RAW

MODERN

VINTAGE

GAIN TREBLE MID BASS PRESENCE MASTER

RAW

MODER

N

VINTAGE

RAW

MODERN

VINTAGE

GAIN TREBLE MID BASS PRESENCE MASTER

CHANNEL 4 SETTING #1 Atlantic Blues

CHANNEL 4 SETTING #2 Stripped Grind

CHANNEL 4 SETTING #3 Hot Liquid Solo

CHANNEL 4 SETTING #4 Recto Modern

DIODE

RECTO

TRACKIN

G

100 WATTS

50

WA

TTS

FX ON

FX

OFF

DIODE

RECTO

TRACKIN

G

100 WATTS

50

WA

TTS

FX ON

FX

OFF

DIODE

RECTO

TRACKIN

G

100 WATTS

50

WA

TTS

FX ON

FX

OFF

DIODE

RECTO

TRACKIN

G

100 WATTS

50

WA

TTS

FX ON

FX

OFF

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

Roadster

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

Roadster

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

as the push-pull becomes unbalanced. Whenever you are trying to diagnose a suspect tube, keep your other hand on the POWER

and STANDBY switches ready to shut them off instantly in the unlikely case you provoke a major short.

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

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 Positive side of Speaker D 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

KNOB

pt#408110

ROTARY POT

pt# 608100

HOLDER pt# 790347

FUSE(4A) pt# 790403

POT pt#

KNOB pt#

408116

590378

JACK pt#

618356

KNOB

#

LENS

# 703300

408113

REAR PANEL: ROADSTER

FRONT PANEL: ROADSTER

OUTPUT

SOLO

CLEAN

PUSHED

FA
T

CLEAN

PUSHED

FA
T

GAIN TREBLE MID BASS PRESENCE MASTER

CH1

CH2 CH4

CH3

LOOP

MUTE

GAIN TREBLE MID BASS PRESENCE MASTER

RAW

MODERN

VINTAGE

RAW

MODERN

VINTAGE

BOLD

SPONGY

ON

O

STANDBY

INSTRUMENT INPUT

JACK pt# 610120

SWITCH

pt# 607313

(6) LENS

pt# 703300

SWITCH

pt#

ALL KNOBS ON FRONT PANEL CHR

OME / KNURLED pt# 408110

SWITCH

pt# 607313

SWITCH pt#

pt# 600631

pt# 600639

BULB pt# 703047

HOLDER pt# 703850

LENS pt# 703782

NOTE

607313

607313

619112

SWITCH pt# 607200

590792 590792 590792 590792

ROTARY POT

#

590736

(12) CHANNEL STRIP

TOGGLE SWITCHES

pt# 607200

(4) REVERB CONTROL KNOBS

pt# 408116

590739 590148 590378

590150 590792 590792 590794 590738 590737 590739 590740

590792

590792

590792

590792

590150590739

590737

590738

590794

590792590792590150

590378

590148

590739

R O A D S T E R

FOOT

CONTROLLER

CH 2

CH

1

CH 3

FT

SW

CHANNEL

POWER FUSE

120 V~

60 Hz

4
A

4
A

SL
O

BLO

WER FUSE

FUSE

HANDBUILT

IN PETALUMA

CALIFORNIA,

USA

FX LOOP

CH4

CH3

EXT.

SWITCH

CH2

CH1

REVERB SOLO LOOP TUNER OUT

LOOP SYSTEM

ACTIVE

HARD BYPASS

LOOP, OUTPUT &

SOLO CONTROLS

NORMAL

SEND

LEVEL

SEND RETURN

CH 4

6L6

BIAS

EL34

REVERB

DIODE

RECTO

TRACKING

100 WATT

S

50

WATT

S

FX ON

FX

OFF

REVERB

DIODE

RECTO

TRAC

KING

100 WATTS

50

WATT

S

FX ON

FX

OFF

REVER

B

DIODE

RECTO

TRAC

KING

100 WATTS

50

WATT

S

FX ON

FX

OFF

REVERB

DIODE

RECTO

TRACKING

100 WATTS

50

WATT

S

FX ON

FX

OFF

CH 3

CH 2

CH 1

SLAVE

LEVEL

OUT

(USE WITH TWO 8 OHM CABS)

4 OHM8 OHM

SPEAKERS

4 OHM16 OHM

SWITCH

pt# 607200

4 DOUBLE JACKS

pt# 619357

JACKS

pt#

(4) SPEAKER

JACKS

pt# 619112

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]