
MO’ BASS
OWNER’S MANUAL
SWR • SCOTTSDALE, AZ • USA

Important Safety Instructions ........................................................
Introduction ...................................................................................
Mo’ Bass Features ........................................................................
Mo’ Bass Specifications ................................................................
Getting Started ..............................................................................
Front Panel Features ....................................................................
Rear Panel Features .....................................................................
Internal Features ...........................................................................
Rack Mounting Instructions ..........................................................
Frequently Asked Questions ..........................................................
Signal Path Diagram ....................................................................
Warranty Information ....................................................................
Mode Diagrams ............................................................................
Suggested Settings
SWR MO’BASS
OWNER’S MANUAL
TABLE OF CONTENTS
A
B
C
D
1
2
13
20
20
F1- F2
F2
F3
MD1-MD6
SWR
8860 E. Chaparral Rd. Suite 100, Scottsdale, AZ 85250-2618 USA
PHONE: (480) 596-9690 • FAX: (480) 367-5262
EMAIL: swrcustserve@fenderusa.com
WEB: swrsound.com
© 2001 SWR
Part #320029 • Rev. B • 05/01

IMPORTANT SAFETY INSTRUCTIONS
• CAUTION:TO REDUCE RISK OF ELECTRIC SHOCK, DO NOT REMOVE THE COVER OR BACK.
NO USER-SERVICEABLE PARTS INSIDE. PLEASE REFER TO A QUALIFIED SERVICE TECHNICIAN.
A. Read Instructions: All safety and operation instructions should be read before the product is operated.
B. Retain Instructions: The safety and operating instructions should be retained for future reference.
C. Heed Warnings: All of the warnings on this product and in the operating instructions should be adhered to.
D. Follow Instructions: All operating and use instructions should be followed.
E. Cleaning: Unplug this product from the wall outlet before cleaning. Do not use liquid cleaners or aerosol cleaners. Use a slightly
damp cloth for cleaning.
F. Water and Moisture: Do not use this product near water; for example, near a swimming pool, wet basement, and the like.
G. Accessories: Do not place this product on an unstable cart, stand, tripod, bracket or table. The product may fall, causing serious
injury to a child or adult, and serious damage to the product.
H.Ventilation: Slots and openings in the unit are provided for ventilation and to ensure reliable operation of the product, to protect it from
overheating, thus these openings must not be blocked or covered. This product should not be placed in a built-in installation such as a
bookcase or rack unless proper ventilation is provided or the manufacturer's instructions have been adhered to.
I. Grounding: This product is equipped with a three-wire grounding-type plug, a plug having a third (grounding) pin. This plug will only fit
into a grounding-type power outlet. This is a safety feature. If you are unable to insert the plug into the outlet, contact your electrician to
replace your obsolete outlet. Do not defeat the safety purpose of the grounding-type plug.
J. Power Cord Protection: Power supply cords should be routed so that they are not likely to be walked on or pinched by items placed
upon them, paying particular attention to cords at plugs and the point where they exit the product.
K. Lightning: For added protection of this product during a lightning storm or when it is left unattended and unused for long periods of
time, unplug it from the wall outlet. This will prevent damage to the product due to lightning and power-line surges.
L. Overloading: Do not overload wall outlets or extension cords as this can result in a risk of fire or electric shock.
M. Object and Liquid Entry: Never push objects of any kind into this product through the openings as they may touch dangerous voltage
points or short out par ts that could result in a fire or electric shock. Never spill liquid of any kind on the product.
N. Servicing: Do not attempt to service this product yourself as opening or removing covers may expose you to dangerous voltage or
other hazards. Refer all servicing to qualified service personnel.
O. Damage Requiring Service: Unplug this product from the wall outlet and refer servicing to qualified service personnel under the
following conditions:
1) When the power supply cord has been damaged
2) If liquid has been spilled or objects have fallen into the product
3) If the product has been exposed to rain, water, or other conductive liquids
4) If the product does not operate normally by following the operating instructions
5) If the product has been dropped or damaged in any way
6) When the product exhibits a distinct change in performance.
P. Replacement Parts: When replacement parts are required, be sure the service technician has used replacement par ts specified by the
manufacturer or have the same characteristics as the original part. Unauthorized substitutions may result in fire, electric shock, or other
hazards.
Q. Safety Check: Upon completion of any service or repairs to this product, ask the service technician to perform safety checks to
determine that the product is in proper operating condition.
R. Heat: The product should be situated away from heat sources such as radiators, heat registers, stoves or other products that produce
heat.
A

SWR MO’ BASS • INTRODUCTION
Congratulations on your purchase of the SWR Mo' Bass! You now own one of the most unique products in the history of
musical instrument amplification.
Here at SWR we share your spirit of tonal exploration and willingness to experiment in pursuit of the ultimate goal: finding
equipment that not only does the job for you as a musician, but actually enhances your overall musical experience and contributes to your creative process. The purpose of this Owner's Manual is to help guide you through the process of becoming
familiar with the many features and functions of the Mo' Bass. But before we get into turning knobs, we'd like you to know a
little bit about how the concept of the Mo' Bass came into existence.
In July of 1999, William Morris West III, an engineer/designer of custom-made audio gear for many studio musicians based
in the Nashville area, contacted SWR. He had a vision of a multi-effects unit made specifically for bass guitar, and since
SWR had a reputation in the industry as a manufacturer of top-quality bass guitar amplifiers and speaker cabinets, he saw
an opportunity for both him and the company to work together on bringing his idea to fruition. An appointment was made for
us to demo his working prototype. We wondered just how good it could be. A multi-effects unit tailored for bass?
Well, when "Mo" West showed up and did his demo, we were floored. The effects were all studio-quality ANALOG sounds.
The Tube Overdrive was not of this earth. The Octave Effect (he called it a "SubWave") tracked notes in registers so low it
seemed impossible. The EQ circuit was a thing of beauty, and the Chorus simply sang. By the time we heard the Synth
pumping out sounds straight off of Stevie Wonder's "Songs In The Key Of Life" album, we all knew that the project was a go.
We called it the "Mo' Bass." The name stuck.
But then another vision came to mind. What if we could combine the best of the Mo' Bass with the best of SWR? What if
we made the ultimate bass head - the famous SWR preamp with the patented Aural Enhancer circuitry, the Mo' Bass effects,
and a stereo power amp capable of delivering 400 watts per side? Marr ying the circuitr y of SWR's founder and designer the legendary Steve W. Rabe - with the circuitry of the Mo' Bass would not be an easy chore. But as SWR President/CEO
Daryl Jamison had been saying around the factory for months, "Go big or stay home!" We settled in for the long haul.
The development cycle of the Mo' Bass lasted an entire year. During that time we slaved over every detail possible. Each
individual effect was tweaked until it was as close to perfect as we could get it. Signal routing was a huge issue as we
worked to find the best ways to send clean and dir ty signals to the 1/4" outputs, the XLR outputs, the speaker outputs, the
headphone outputs, you name it. Levels were checked, matched, rechecked and rematched again. An extraordinary effort
was made for the Mo' Bass to look like nothing ever seen before, hence the design of the curved, brushed aluminum front
panel. We wanted it to look like it sounds - awesome!
We ended up with the best of both worlds. Now you own an amplifier that can be as simple or complex as you need it to be.
Run it totally clean into one speaker cabinet for classic SWR sound. Run it into two cabinets and use the chorus. Blast it
into a Megoliath 8x10 with the Overdrive on '10' (or '11' if you're Derek Smalls). Use it in the studio with everything on at
once for sounds never before recorded. Send one signal to a mixing board. Send two. Send three! Split your clean and
dirty signals using the Dual Mode feature. Combine effects. Switch back and forth. Experiment to your heart's content.
But please read the manual first, thoroughly and completely, so that you can realize the practically limitless potential of the
SWR Mo' Bass.
This way we can help you find your voice, your vision, your sound. And it's our privilege as a company to be there with you
along for the ride.
Bryan Beller
Product Development Manager
SWR Sound Corporation
Note: Please take a moment to verify that the following items were included in your SWR Mo’ Bass packaging: AC Cable,
Owner's Manual, Speakon-to-Speakon Speaker Cable, SWR Catalog.
B

MO’ BASS • FRONT PANEL FEATURES
• Dual independent input jacks compatible with both passive and active instruments
• Pre-Amp Volume Control with bi-color (green/red) LED peak clipping indicator
• Variable Limiter/Leveler Control with yellow LED indicator
• Aural Enhancer Control
• Treble Level Control
• Midrange Level Control
• Midrange Frequency Control
• Bass Level Control
• Overdrive "Drive" Control
• Overdrive Level Control
• Subwave Tone Control
• Subwave Mix Control
• Bassynth Filter Control
• Bassynth Resonance Control
• Bassynth Envelope Control
• Bassynth Mix Control
• Mo' EQ Treble Control
• Mo' EQ Midrange Control
• Mo' EQ Bass Control
• Chorus Depth Control
• Chorus Rate Control
• Push switches and unique-colored LED indicators for on/off control of all effects
• Internal Effects Bypass Switch with LED indicator
• Left and Right External Effects Blend Controls
• Dual Mode Switch with LED indicator
• Left and Right Master Volume Controls
• Illuminated Neon Power On/Off Switch
• Stereo Headphones Jack
• Screwholes for Rack Mounting (on chassis in each corner)
MO’ BASS • REAR PANEL FEATURES
• Direct Out 1/4" jack
• Tuner Out 1/4" jack
• Mo' Bass Out 1/4" jack
• Direct Out XLR jack
• Mo' Bass Out XLR jack
• Line/Direct Switch for 1/4" and XLR Direct Out Jacks
• Individual 3-position Pad Switches (0 dB, -10 dB, -20 dB) for both Direct Out and Mo' Bass Out XLR jacks
• Ground/Lift Switch for both Direct Out and Mo' Bass Out XLR jacks
• Stereo Effects Loop (Left and Right Send and Return 1/4" jacks)
• Internal Effects Bypass Footswitch jack
• Filter Sweep Pedal jack
• "Mo' Control" Footswitch jack (shown as "Ft. Sw. In")
• MIDI Out jack
• Stereo/Mono Power Amp Assign Switch
• Two 1/4" and One Speakon Left Speaker Output jacks
• Two 1/4" and One Speakon Right Speaker Output jacks
• One Speakon Bridged/Mono Output jack
• Two Speaker Fuses (3AG, 10 amp fast-blo)
• One Line Fuse (3AG, 10 amp slow-blo)
• AC Power Cord Receptacle
C

MO’ BASS SPECIFICATIONS
Note:
All measurements were taken with a line voltage of 120VAC.
All noise specifications are "unweighted."
All voltages and watts are "RMS."
All measurements taken with tone controls set flat, Aural Enhancer at minimum, all effects disengaged.
Power Ratings (minimum)
Bridge/Mono Mode
900 Watts @ 4 Ohms
650 Watts @ 8 Ohms
440 Watts @ 16 Ohms
(minimum load = 4 Ohms)
Stereo Mode (per side)
600 watts @ 2 Ohms
400 watts @ 4 Ohms
250 watts @ 8 Ohms
150 watts @ 16 Ohms
(minimum load = 2 Ohms)
Frequency Response (Power Amplifier):
-3 dB @ 10Hz to 40kHz
Sensitivity (full output under clipping, 8 ohm load, 100 Hz)
Passive Input Jack: 42 millivolts
Active Input Jack:84 millivolts
Power Amplifier (Effects Return Jack "in"): 6 volts peak-to-peak
Input Impedance
Passive/Active Input: 1 Meg Ohms
Active Input: 47K Ohms
Effects Returns: 27K Ohms
Output Impedance
Effects Sends: 220 Ohms
Tuner Output: 220 Ohms
XLR Balanced Out: 750 Ohms
Signal To Noise Ratio:
-88 dB (<10 millivolts typical)
Equivalent Input Noise:
15 nanovolts per root/hertz
Dimensions (measured from the rack ears back)
19" W x 5 " H x 13" D (the front panel flanges add 1")
Weight: 29 lbs.
D

MO’ BASS - GETTING STARTED
Connecting Your Speaker Cabinets
The Mo' Bass speaker outputs can be run in either stereo or bridged/mono modes by using the stereo/mono selector switch
on the back panel. For most situations the obvious is true: if you plan on using two speaker cabinets, run the Mo' Bass in
stereo. If you plan on using one speaker cabinet, run the Mo' Bass in mono. MAKE SURE that the stereo/mono selector
switch correlates with your desired setup. Also keep in mind that the Mo' Bass delivers 900 watts into one 4 ohm speaker
cabinet in bridge mode. Make sure that your speaker cabinet can handle the power listed in the "Power Ratings" section of
the "Mo' Bass Specifications" section of the manual.
Using One Speaker Cabinet
First, locate the "Speaker Outs" section on the rear panel of the unit. Put the stereo/mono selector switch in the "mono"
position. Connect the Speakon-to-Speakon speaker cable from the "Bridged Output" jack on the Mo' Bass to your speaker
cabinet. You will notice that both the left and right Master Volume controls on the front panel are active and will affect the
overall level even though you are in bridged/mono mode. This is normal. The impedance of your single speaker cabinet
must be no lower than 4 OHMS in bridged/mono mode.
Important: Be sure that your single 8 ohm speaker cabinet can handle at least 650 watts, and that your single 4 ohm
speaker cabinet can handle at least 900 watts. If not, it is safer to run your low-power-rated single speaker cabinet in stereo
mode off of the right speaker output.
Using Two Speaker Cabinets in Stereo Mode
Put the stereo/mono selector switch in the "stereo" position. Connect a speaker cable from either the left 1/4" or Speakon
speaker out jack to one speaker cabinet, then do the same for the right side. The Left and Right Master Volume controls
should correlate to the cabinets on each side.
If the cabinets are the same impedance, the same amount of power will be sent to each enclosure. If the cabinets are
different impedances, more power will flow to the cabinet with the lower impedance, and you should adjust the left and right
Master Volumes to achieve equal levels. Again, make sure to check the power handling capabilities and impedances of the
speaker cabinets you wish to use against the "Power Ratings" section of the "Mo' Bass Specifications" section of the
manual.
Using Two Speaker Cabinets in Bridge/Mono Mode
If you don't want separate output signals routed to different enclosures, and you are using speaker cabinets with input and
output jacks, you can "daisy chain" the enclosures together to achieve full potential of the power amps in bridged/mono
mode. Put the stereo/mono selector switch in the "mono" position. Then connect a speaker cable from the "Bridged Output"
jack on the Mo' Bass to the input jack of your first speaker cabinet. Then, to complete the "daisy chain", connect another
speaker cable from the output jack of your first cabinet to the input jack of your second cabinet. As when using one speaker
cabinet in bridged/mono mode, both Master Volume controls are active.
Important: The minimum total impedance when operating Mo' Bass in bridged/mono mode is 4 Ohms. This means that you
can use two 8 ohms enclosures safely, but when in bridged/mono mode you CANNOT use:
a) two 4 ohm enclosures (2 ohm load)
b) an 8 ohm and a 4 ohm enclosure (2.67 ohm load)
If your system falls into either of the categories above, you should run the Mo' Bass in stereo mode and connect the speaker
cabinets accordingly.
More details are available in the "Speaker Outputs" section of this manual, and we strongly recommend that you read the
entire manual. However, this should be enough information to get you started.
1

Turning On The Unit
Remove the AC cable from the accessory pack and connect it from the amplifier to a standard wall outlet. Make sure that
the Pre-Amp Volume and both Master Volume controls are set to the minimum position. Locate the power switch on the right
side of the front panel and turn the amplifier on. The power switch should then illuminate in red. Upon powering up, don't be
surprised if you hear a small pop. This is absolutely normal. (Eliminating this "power on transient" would require a component called a relay. SWR chose not to incorporate this type of component due to the fact that relays degrade signal quality
and often fail, causing the unit to have no output and requiring a tr ip to a local ser vice center.) Also, the preamp tube will
take approximately 7-10 seconds to warm up before producing signal. This too is normal.
Getting Sound Out Of The Mo' Bass
Plug your instrument into the desired input jack (please refer to "Front Panel Feature Definitions" for more detail). Turn your
instrument's volume up to at least 75% of maximum and slowly adjust the Pre-Amp Volume control.The green LED over the
Pre-Amp Volume control should illuminate every time you play. Keep playing and turning the Pre-Amp Volume control up
until you see the green LED turn red. Then back off on the Pre-Amp Volume about two numbers on the dial. Now turn up
the Master Volume controls to an equal level. You should now hear the sound of your instrument amplified through
the Mo' Bass into your speaker cabinets and the stereo headphones jack. For more detailed information, please read the
entire manual carefully, as the Mo' Bass is an extremely dynamically sensitive unit and the concept of "gain structure" is very
important and will be discussed in great detail.
FRONT PANEL FEATURES
Input Jacks
Both input jacks accept a standard 1/4" phone plug and both inputs can be used at the same time. Since the two inputs are
totally independent, no loss in volume or tone will occur by using two instruments simultaneously. However, the main
applicational use for the two separate input jacks is their difference in level, as the Passive/Active input has five times more
gain than the Active input. In other words, it's not necessarily intended as a "submixer" for two instruments, but no harm will
come from having two instruments plugged in at once. Please read below for more details.
A Word About Gain Stages
One of the most important concepts to keep in mind when using the Mo' Bass is what we mean by "gain stages." Think of
dominoes - when they're lined up in a row, the first one to fall will affect everything behind it. That's how a signal path works,
and everything added along the way contributes to the overall "gain." If the very beginning of the signal path is loaded up
with too much gain, everything behind might not behave the way you might like.
Some people like to use certain effects - especially foot pedals - in front of their amplifier. In the case of the Mo' Bass, it's
important that any pedal have an output close to unity gain in relation to its input. In other words, any pedal that might add a
lot of gain to the signal may be better off in the effects loop than in front of the amplifier.
A signal path will have several "gain stages" in the internal circuitry of the preamp and power amp alone, even before you
start adding effects. Just remember that every time you change something in the signal path, most likely a level will change.
That altered level will then feed the next part of the chain with more or less input signal, which in tur n will multiply every time
the level increases or decreases due to an effect being engaged. And so on, and so on, and so on...
Passive/Active Input Jack
This jack is designed for use with both passive and active instruments. A "passive" instrument (like a standard Jazz bass)
has no built-in preamp and does not use a battery. On the other hand, an "active" bass utilizes a battery-operated preamp
either for gain, tone controls, or both. Although labeled "passive," the Passive/Active input jack will work with all instruments
having a maximum output of less than 1 volt RMS. Some pickups such as EMG, Bar tolini, etc. employ batteries for operation
and will work perfectly using the Passive/Active input jack. Instruments from MTD, Pedulla, Sadowsky, Lakland, Ernie Ball,
Tobias, Modulus Graphite, etc.generally contain active electronics and could also be used in the Passive/Active input.
Just because you have an active bass doesn't mean that you have to use the Active input! Generally speaking, try the
Passive/Active input jack first. If you hear a small amount of distortion and the Pre-Amp Volume clip LED is not turning
red, try using the Active input jack.
2

Active Input Jack
The Active input jack should be used with instruments having a built-in (on board) preamp that will produce signals over 1
volt RMS. This jack will pad the incoming signal -14 dB. Some really "hot" pickups installed in your instrument may find the
Active input more compatible. But it's worth noting that the more complex the waveform originating from your bass guitar,
the tougher time an onboard effect will have in processing that complex signal. In other words, try not to go too crazy with
the onboard EQ of your bass preamp right off the bat. If you are using a KEYBOARD with the Mo' Bass, we have found the
best choice to be the Active input.
Note: Using the Active input with a passive instrument may result in a loss of high-end transients. Players who roll off their
high-end frequencies starting at about 2K - or who prefer a "darker" sound - may find this input more to their liking.
If you hear some distortion with your active bass and are using the Active input jack, CHECK YOUR INSTRUMENT'S
BATTERY! Also, make sure that the Pre-Amp Volume clip LED is not still turning red. Following these instructions can save
you and a service technician a lot of aggravation.
PREAMP CONTROLS
Pre-Amp V olume Control
This control adjusts the volume of the Preamp section. A bi-color (greed/red) LED indicator is located above the control. As
mentioned in the "Getting Started" section, that LED will illuminate green every time you play. If you set the level too high
the green LED will turn red, which indicates that the preamp is clipping. In order to achieve maximum signal-to-noise ratio,
set the Preamp Volume to where the green LED barely turns red upon striking your hardest note. However, this may not be
the optimal setting when using effects, so you may want to back off even further until you're done exploring the levels of all of
the effects on the Mo' Bass.
Note: Even though the Preamp Clip LED turning red indicates that at some point the preamplifier is clipping, no harm is
being done to your amplifier. However, clipping of the power amp can cause damage to your speakers and is not
recommended.
Limiter/Leveler
The Limiter/Leveler circuit is a tube limiter that helps control the dynamic range of the preamp. The Limiter/Leveler Control
sets the "threshold" for the circuit, which is the level at which limiting begins to take effect.The yellow LED above the control
will illuminate, indicating that the Limiter is active.Loss in volume caused by extreme limiting can be overcome by increasing
the levels of the Master Volume controls, as well as various controls for the onboard effects.
When processing a signal to a minor degree, the Limiter/Leveler simply puts a ceiling on the signal and gently suppresses
the peaks, creating a very smooth, even sound. As the signal is processed to a greater degree, the sound becomes more
compressed and the dynamic range of the preamp more limited. Because it uses a tube to accomplish this, the Mo' Bass
Limiter/Leveler has an extremely natural effect on the instrument's signal, much like the classic leveling amplifiers used in
professional studios around the world.
You may want dial in some of the Limiter/Leveler control even though you aren't clipping the preamp. It's a very musical
limiter and can be used in several ways. For clean sounds it can help smooth out rough edges. When used with the
Overdrive, you can achieve some very interesting sounds depending on where the "Drive" control is set. Try different
settings and see what works best for you. The yellow LED may illuminate slightly even when you have the control set at minimum. This is normal, as the Limiter/Leveler is never truly "out" of the circuit.
Note: If the Limiter/Leveler Control is set at maximum and still no limiting effect occurs, the Pre-Amp Volume Control is
probably set too low and should be increased to a desired level.
3

Aural Enhancer
SWR's Aural Enhancer Circuit was developed by SWR Founder Steve Rabe to bring out the fundamental low notes of the bass
guitar, reduce certain frequencies that help mask the fundamentals, and enhance the high end transients.The resulting frequency response should be similar to that used for recording the bass in the studio. This effect becomes more radical as
the control is turned to maximum.The result is a more "transparent" sound, and is especially noticeable when performing the
slap or thumb style technique on the bass guitar.Generally speaking, the Aural Enhancer can be described as a tone
shaping control, as it is a passive R/C network that alters the frequency response throughout the bass spectrum.This preshaping is "blended" into the original signal via the Aural Enhancer Control.Exact frequencies affected are dependent on the
characteristics of the instrument used, though we have found that most users tend to set it at '6' on the dial for optimum effect.
Treble Control
The Treble Control is a shelving-type tone control that cuts or boosts high frequencies up to 10 dB in either direction.
Starting from mid-position ("flat"), turning the Treble Control counter-clockwise cuts the highs, while turning the control
clockwise boosts the highs. The shelving point for this control is about 2 KHz.
Midrange Level and Frequency Controls
These two controls work together to allow you the flexibility of choosing a par ticular midrange frequency to boost or cut.
The Midrange Level Control cuts or boosts (by up to 10 dB) the frequency set by the Midrange Frequency Control. Starting
at mid-position ("flat"), turning the Midrange Level Control counter-clockwise cuts the desired frequency. Turning the
Midrange Level Control clockwise boosts the desired frequency.When the Midrange Level Control is set at mid-position,
turning the frequency control will have no effect on the sound.
In order to find the midrange frequency you wish to boost or cut, try the following:
1. Adjust the Midrange Level Control to either the full boost or cut position.
2. Rotate the Midrange Frequency Control until the desired frequency you wish to cut or boost is found.
3. Adjust the Midrange Level Control to the desired amount of boost or cut.
Some hints from the pros: If you need to "cut through" the band a little more, try boosting 200 to 400 Hz. If you like a more
transparent sound, try cutting 800 Hz. The Midrange Level and Frequency Controls are especially useful in controlling
fretless basses and their inherent qualities.
Bass Control
The Bass Control is a shelving-type tone control that cuts or boosts the low frequencies up to 10 dB in either direction.
Starting from mid-position (flat), turning the control counter-clockwise cuts the bass response, while turning the control clockwise boosts the bass response. Shelving point for this control is about 80 Hz.
A final note on the Preamp Controls: Select each control to your taste, but remember that the more heavy EQ you have on
the front end, the more EQ you will have going into the Mo' Bass effects - sometimes a good thing, sometimes not. As
always, your own musical preferences will come into play.
Preamp T ube
Though not a "control" function of the preamp, you should be aware that the preamp in your SWR Mo' Bass is a tube preamp. The tube is a specially selected 12AX7 and should not require replacement for one to three years, depending on
usage. The tube is also used for another key function in the unit, specifically...
Overdrive
Yes, the Mo' Bass Overdrive is a Tube Overdrive. Just because there's no 50-pound tube power amp in the Mo' Bass
doesn't mean you can't get the sounds of tube-driven distortion! It works off of the very same specially selected 12AX7
preamp tube mentioned above. We've taken extra care to ensure that, unlike most bass distortion units, there is no
significant damage to the fundamental note - specifically in the low end.
Overdrive "Drive" Control
This control determines how heavily the tube overdrive circuit will distort the signal. With the control set at minimum '0',
there will be only the tiniest amount of "dirt" present in the signal path. The higher the knob is set, the dirtier the signal will
get. Fully counter-clockwise ('0') is minimum, while fully clockwise is maximum. Note that the way you attack your strings
will have an effect on the amount of drive as well. Tr y playing both harder and softer with this control set at '3', and you'll see
what we mean when we say that the controls are "dynamically sensitive."
4

Overdrive Level Control
This control determines the volume of the Overdrive circuit, and works in conjunction with the Drive control to help you keep
your levels where you want them when switching back and for th between clean and dir ty sounds. Fully counter-clockwise
('0') is minimum, while fully clockwise is maximum.Be careful when boosting this control beyond '5' on the dial - it will get
really loud when the Drive is also engaged!
Using the Overdrive
Start with the Drive and Level controls low! Now press the Overdrive switch and the red LED should illuminate. If both Drive
and Level controls are set at minimum, there will only be a slight boost in overall level. Try slowly raising the Drive to '5', and
then the Level to '3'. There should now be a noticeable difference between this and the "clean" sound. This is a good reference point to see how much boost and distortion you want out of the Overdrive.
The Drive and Level controls are designed to work together to give you a workable overall level when using the effect. If you
are using heavy amounts of Drive, you may want to reduce the Level to match your clean signal level. If you're only using a
touch of Drive, be sure to increase the Level control to bring you back to unity gain with your clean signal.You can use the
Level control to have your Overdrive effect act as a "boost" as well simply by setting the Level and Drive controls to equal a
higher level than your clean signal. Switch the effect on and off for level comparison.
Engaging the Overdrive reduces the effect of the Preamp EQ (the higher the Drive, the less Preamp EQ will affect the
signal), so you may want to use the Mo' EQ to achieve additional tone flexibility. The Mo' EQ Mid and Treble controls in
particular can greatly affect a heavily overdriven signal. Don't forget to try using the Limiter/Leveler in conjunction with
the Overdrive, especially on sounds with just a touch of dirt to them (low on the Drive and high on the Overdrive Level). And
remember, you can blend in your original "clean" signal by using the Dual Mode function and adjusting the left (clean) and
right (wet) Master Volume controls. Please see the sections marked "Mo' EQ" and "Dual Mode" later in the manual for
more details.
SubWave
The Mo' Bass SubWave is a lightning-quick sub-octave wave engine. In plain terms, it hears the note you play and
immediately generates a signal one octave below it. You may have heard the term "octave pedal" before. You may have
even used one. If so, welcome to the next generation of sub-octave signal processing.
Subwave T one Control
This control is very much like the tone control on a passive bass. It simply cuts high frequencies. When set counterclockwise to the minimum ('0'), it cuts the maximum amount of highs possible. When set clockwise to the maximum position
('10'), it leaves the subwave's high end wide open. Note that this tone control only affects the one-octave-below signal
generated by the SubWave engine. It will not affect your clean bass signal.
Subwave Mix Control
This control allows you to blend your original bass signal with the SubWave signal to suit your musical taste. The midposition of this control is a 50/50 split between clean and sub-octave signals. When set counter-clockwise to the "bass" position, you will hear 100% original bass signal and no SubWave. When set clockwise to the "sub" position, you will hear 100%
SubWave and no original bass signal.
Using The SubWave
For most applications, set the SubWave Tone Control at minimum ('0') and the SubWave Mix Control at the mid-point. Now
press the SubWave switch and the blue LED should illuminate. These settings will give you the most basic "sub-octave"
sound. Now try slowly increasing the SubWave tone control up to '5' on the dial. You will notice that the overall sound is now
more synth-like. This is normal. You can now adjust the Subwave Tone Control to taste.
Note: If you want to hear what the pure SubWave sounds like, try setting the SubWave Tone Control at '10' and the
SubWave Mix Control all the way at "sub." Pretty cool, huh?
Be sure to remember to set the Subwave Mix control back at '0' before disengaging the effect during your experimentation.
Why? Because as we mentioned, when the Mix control is all the way at "sub" there is no "original bass signal" present in
the signal path. The level of the pure SubWave is much lower than the bass guitar signal. So if you switch the SubWave
effect off when the Subwave Mix control is all the way at the Sub position, and your original bass signal has a lot of EQ on
it - and especially if the Overdrive is engaged - you may get a boost in your signal level you weren't expecting!
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Bassynth
Based on the design of a classic analog synthesizer, this effect generates a sawtooth waveform that can be altered by the
Filter, Resonance or Envelope controls. It then can be blended with the original bass signal using the Mix control. This is the
most dynamically sensitive and complex of all the effects on the Mo' Bass. We strongly recommend that you read the entire
Bassynth section carefully - both the control knob definitions and the guide to using them - so you can get the most out of
this incredibly musical effect.
Bassynth Filter Control
This control allows the user to take away certain overtones that are present in the raw waveform (otherwise known as
"Subtractive Synthesis"). In simple ter ms, it acts like an equalizer for the waveform - taking away treble but not adding bass.
When set counter-clockwise to the minimum position ('0'), the filter is "fully closed" and will subtract as many overtones as
possible.
When set clockwise to the maximum ('10'), the filter is "wide open" and subtracts nothing. In addition to the control knob,
input gain and how you attack your strings are just two of the many things that can affect when the filter opens and closes.
Please refer to the "Using The Bassynth" section for more details.
Bassynth Resonance Control
This function allows a narrow band of frequencies (the resonant peak) on the filter to become relatively more prominent.
Filter resonance is also known as "emphasis" and "Q". It is also referred to in some older instruments as regeneration or
feedback, because feedback was used in the circuit to produce a resonant peak. It produces a very distinctive sound in the
analog filter process, and is an important part of the overall sound produced by the Basssynth.
When set clockwise to the minimum position ('0'), there is no resonant peak present and the frequencies are sent evenly
across the spectrum through the filter. As you increase the knob, the prominent band of frequencies sent through the filter
will narrow and the effect will become more dramatic.Please refer to the "Using The Bassynth" section for more details.
Bassynth Envelope Control
The Envelope Control is a signal-processing device in the Bassynth that controls amplitude over a certain time frame. In notso-technical terms, it gives the sound its shape. The Envelope Control tells when the Bassynth should go up and down in
volume, and the time it should take to go up and down. In addition to the control you have on the knob itself, these
parameters are also in the hands of the player as they can be controlled by the dynamic articulation of the musician through
string attack. This control creates the "wah-wah" type effect.
When set clockwise to the minimum position ('0'), the Envelope will affect the signal as quickly as possible, so quick that it
will have practically no affect at all. As you increase the knob, the Envelope effect will slow down, allowing you to hear the
shift in amplitude. Please refer to the "Using The Bassynth" section for more details.
Bassynth Mix Control
This control allows you to blend your original bass signal with the Bassynth signal to suit your musical taste. The midposition of this control is a 50/50 split between clean and Bassynth signals. When set counter-clockwise to the "bass"
position, you will hear 100% original bass signal and no Bassynth. When set clockwise to the "synth" position, you will hear
100% Bassynth and no original bass signal.
Using The Bassynth
The Mo' Bass Bassynth will react differently to every single user. Factors such as the kind of bass, the EQ of the bass, the
pickup selection on the bass, the technique of the player, the Pre-Amp volume of the Mo' Bass, the control settings of the
Basssynth itself, and the Bassynth Mix control will all come into play. Spend some time with it and become comfortable you'll probably stumble across a sound that we haven't even heard yet. Here at the factory, it happens to us all the time!
The following is a "road map" for getting acquainted with the Mo' Bass Bassynth. For simplicity's sake, we used a Jazz bass
for the following examples.
Start by setting the Pre-Amp Volume on the Mo' Bass to '4'. Set the Filter, Resonance and Envelope Controls to minimum
('0'). Now set the Bassynth Mix Control all the way to "Synth." Press the Bassynth switch and the amber LED should illuminate. Start playing your bass. You should hear practically nothing. Don't panic - this is normal. (continued next page)
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Using The Bassynth (continued)
Now bring the Filter Control up to '3' on the dial, and play again. You should now star t to hear some sound. Turn the Filter
control further up to '7', and a very obvious "synth" sound should be present. Tr y attacking the strings both harder and
softer. When you play harder, more high frequency should be present. A softer attack will result in a "darker" sound. This
is what we mean when we say that the Bassynth is a highly dynamic effect.
Now let's try the resonance control by setting it to '6' on the dial. When you increase the resonance, the signal will decrease
slightly in overall level because you are taking away certain frequencies upon the initial attack. This is normal. The sound
should now resemble that of a classic synth even more. Tr y experimenting with your string attack again - things about the tone
will change. Try both the Filter and the Resonance controls in various positions...and try not to let time get away from you!
Let's move on to the Envelope Control. First set the Filter control at '2' and the Resonance control at '7'. Now strike an open
note and slowly turn the Envelope Control until you hear a "wah" sound. The harder you play, the more present the "wah"
will become (think "Chameleon" by Herbie Hancock).At this point, all three Bassynth controls are working in harmony and all
will affect each other. For instance, if you open up the Filter too much, the "wah" from the Envelope may go away. If you
close the Filter too much, the Envelope won't have a chance to "wah" anything. How you attack the strings can make all the
difference in the world.
With an active bass, the overall gain structure will be slightly different.You may find you want to back off on the Pre-Amp
Volume of the Mo' Bass preamp to keep the Bassynth from seeing too hot a signal. Also, the tone controls on your active
bass will greatly affect the Bassynth. One particular example: your midrange control may directly affect the sensitivity of the
Envelope control.
You've now got three onboard controls, your bass and your fingers to find new sounds within the Bassynth. Mix and match
at will!
Once you've fully explored the possibilities, try adding the Subwave to the Basssynth. Now both the Subwave and the
Bassynth signals will be affected by the Filter, Resonance and Envelope controls. (It should be noted that when the
SubWave effect is activated, the raw sub waveform is routed to the Bassynth, regardless of where the SubWave Mix and
SubWave Tone Controls are set.)
Want more? Add in the Mo' EQ. Try experimenting with each of the tone controls individually - they'll all do something
unique to the sound of the Bassynth.
Not satisfied yet? Throw the Chorus into the mix. Now try some experimenting.
Once you're feeling comfor table with the Bassynth itself, try blending in the "clean" signal by bringing the Bassynth Mix knob
slowly back towards mid-position. At exactly '3' on the "Synth" side (3:00 PM), the effect will be completely out of phase with
the input and the level will drop dramatically. This is normal and can be used for some really strange sounds. As you move
past the '3' point, level will return to normal and the phasing will stop.
Also try using the Dual Mode function. You may find that you want the Mix control completely on "Synth" and run the unit in
Dual Mode to blend the original signal back in with your stereo Master Volume controls. (Please refer to the "Dual Mode"
section for more details.) There are plenty of creative choices to make, and we encourage you to make them.
Hidden Feature 1: Envelope Follower
For those who want to use the Bassynth as more of a traditional envelope follower - or put more plainly, if you want to slap
and pop through the Bassynth Filter - we've designed a "hidden feature." If you engage the Overdrive while the Bassynth is
on, the filter will see the original bass signal as opposed to the sawtooth wave. Confused? Try this - set the Overdrive
"Drive" Control at minimum and the Overdrive Level Control at around '2'. Then engage the Overdrive and the Bassynth
simultaneously. You should now hear the clean bass signal going through the filter. You may need to readjust your Filter,
Resonance and Envelope levels to achieve maximum effect. Again, how hard you play will have a major affect on the
sound itself.
Hidden Feature 2: Phase-O-Matic
Also, there's no law that says you have to keep the Overdrive "Drive" Control at minimum. Try slowly turning the Drive
Control up while the Basssynth is engaged. It should start sounding pretty nasty! If you set the Bassynth Mix Control at '3'
on the "synth" side of the control while the Overdrive is engaged and roaring, the 180-degree phasing will occur
in ways you never thought possible.
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Filter Sweep Pedal
Want to get even crazier? We've provided the ability to control the opening and closing of the Bassynth's filter with an
"expression" foot pedal, like the type of pedals commonly used with keyboards. Simply plug the pedal’s STEREO cable into
the "Filter Sweep Pedal" jack on the rear of the Mo' Bass. Set the Filter control to the minimum ('0'). Then str ike a note and
slowly move the pedal back and forth. From one end of the pedal to the other, you should hear the entire range of the filter.
The Filter Sweep Pedal will start at whatever point you preset on the Mo' Bass Filter control (be it '0', '3', '6', etc.) and open
up the filter from that point up to '10'. Remember, just because you have the pedal in the circuit doesn't mean that the
Basssynth won't react to the dynamic sensitivity of your attack - it's still touch-sensitive.
Important: You can use a standard volume pedal for this function, but you will need a special cable called an "insert cable."
Plug the two "mono" ends into your volume pedal's in/out jacks and plug the "stereo" end into the Mo' Bass "Filter Sweep
Pedal" jack.)
There are so many potential combinations of sounds when using the Bassynth in conjunction with the other effects in the
Mo' Bass that even we couldn't pretend to know them all. And even if we did, it's probably best that you discover them for
yourself. Take your time, turn the knobs slowly, and have at it.
Mo' EQ
This EQ is a fundamentally different type of EQ than the one found in the preamp stage of the Mo'Bass. Technically
speaking, the Mo'EQ is a Band Pass-type of EQ, while the Mo' Bass preamp contains semi-parametric and shelving types of
EQ. A Band Pass Filter EQ has a fixed bandwidth, with the cut or boost affecting only the frequencies within the bandwidth
parameter.The bandwidth at the frequencies specified for each tone control is 1 octave.
Mo' EQ Treble Control
The band pass filter on this EQ control is set at 10 kHz. That's pretty high for the typical bass amp. Starting from mid-position ("flat"), turning the Mo' EQ Treble Control counter-clockwise cuts the highs at 10 kHz, while turning the control clockwise
boosts the highs at 10 kHz. Boosting 10kHz will add a subtle, yet sweet "glassy" overtone to the signal.
Mo' EQ Midrange Control
The band pass filter on this EQ control is set at 1.5 kHz. Starting from mid-position ("flat"), turning the Mo' EQ Midrange
Control counter-clockwise cuts the upper mids at 1.5 kHz, while turning the control clockwise boosts the mids at 1.5 kHz.
Cutting 1.5 kHz can help you "scoop" the EQ for a more transparent sound, while boosting it will help accentuate the upper
mids of your tone.
Mo' EQ Bass Control
The band pass filter on this EQ control is set at 40 Hz. That's very low for the typical bass amp. Starting from mid-position
("flat"), turning the Mo' EQ Bass Control counter-clockwise cuts the lows at 40 Hz, while turning the control clockwise boosts
the lows at 40 Hz. Boosting 40 Hz is something you may feel rather than hear...but boy, you'll feel it. We recommend using
some caution when operating this control. It could cause the wrong speaker cabinet to wince in pain and cry for mercy. Turn
the knob slowly, OK?
Using Mo' EQ
Like we've been saying all along, it's better to have certain kinds of EQ post-effects rather than pre-effects. The Mo' EQ was
designed primarily to enhance the characteristics of the onboard effects. To engage the effect, press the Mo' EQ switch and
the green LED should illuminate.
When used in conjunction with the Overdrive, the Mo' EQ Bass Control can help boost low-end along with a boost in gain and
overall level. The Mo' EQ Midrange and Treble Controls can help define and bring to prominence just the right "edge" on your
overdriven signal. It can also produce feedback, which could be a good or bad thing depending on how you feel about it.
The SubWave generates enough extra low-end all by itself for most people, but maybe you really want to shake the house.
Boost the Mo' EQ Bass control while engaging the SubWave and watch the walls rattle. Or, if the bass becomes
overbearing, maybe you actually want to cut a little bit at 40 Hz.
In our opinion, the Mo' EQ is most dramatic when it's when used in conjunction with the Bassynth. Notice how the Bassynth
Resonance Control becomes more dramatic with a liberal dose of the Mo' EQ Treble Control. And how the Bassynth
Envelope and Filter Controls appreciate the presence of a boosted Mo' EQ Midrange Control. As for the way the Bassynth is
affected by the Mo' EQ Bass control, all we can say is stand back, be careful, and turn the knob slowly when boosting. (Your
speaker cabinet will thank you in the morning.) (continued)
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Using Mo' EQ (continued)
Please note that when the Bassynth Filter and Envelope Controls are "open" and the Resonance Control is at the minimum
position, the level of the Bassynth will be higher than the level of the original bass signal, which is normal. However, when
boosting the Mo' EQ Bass Control while the Bassynth is engaged and in that position, that boost will become very dramatic.
Please exercise caution.
Though designed to be a post-effects EQ, there is no reason why you can't use the Mo' EQ as an additional EQ for clean
sounds. In addition to being a different type of EQ (Band Pass vs. shelving/semi-parametric), the Mo' EQ is centered at
much different frequencies (40 hz, 1.5 kHz, 10kHz) than the preamp EQ (80 Hz, variable 200-800 Hz, 2 kHz). The effect is
more subtle, but it can also be the difference between almost what you want and exactly what you want. Try combining both
and see what's best for you.
Chorus
The Mo' Bass Chorus is a warm, analog, very traditional effect. What most people refer to as a "chorus" is, in truth, a
modulated delay.
Chorus Depth Control
This control determines the amount of chorus applied to the original bass signal. When set at minimum ('0'), the delay is
very short, resulting in a very subtle "phasing" effect. As you increase the knob clockwise, the delay time becomes longer
and causes more of a "doubling" sound, making the effect more dramatic.
Chorus Rate Control
This control determines the speed at which the delay time is modulated.When set at minimum ('0'), the Chorus waveform
grows in amplitude and will take over one whole second to complete. As you increase the knob clockwise, the rate of the
Chorus effect will increase. This control also affects the rate at which the yellow LED indicator "glows."
Using The Chorus
To engage the effect, press the chorus switch and the yellow LED should illuminate and "glow" as mentioned above. For a
simple, warm chorus, try setting the Chorus Depth control at '3' and the Chorus Rate control at '2'. To achieve more of a
tremolo effect, set the Rate very high and the Depth very low. You can get a "fattening" effect without sounding like a chorus
if you set the Depth at '10' and the Rate at '0'. For something really weird, tur n both controls all the way up and look to see if
the aliens have landed yet.
Using the chorus can greatly enhance the use of harmonics, allowing them to "ring out" better and longer. Clean sounds
can become crystal-clear when both the Mo' EQ and the Chorus are engaged. It enhances the Overdrive and the SubWave
in obvious ways. It also simulate a "third oscillator" when used in conjunction with the Bassynth and the SubWave
simultaneously. As with all of the effects on the Mo' Bass, experimentation is encouraged.
A Final Word On The Mo' Bass Preamp And Effects
It's easy to forget that, with all of the bells and whistles on the front panel, you can still easily achieve a great clean bass
tone. You can also get just about any affected sound you want through various combinations of effects, blends and levels.
But it's important to remember that one thing in the signal path can affect something after it, and that gain levels can
have wide-ranging implications for effects as dynamically sensitive as the effects on the Mo' Bass. Do yourself a favor and
take the time to see what happens to your signal level when you engage and disengage effects BEFORE you get to the gig,
or even the rehearsal.
DUAL MODE
Up until this point, you've operated the Mo' Bass in what we call "Single Channel Mode." In Single Channel Mode the
"single" signal starts at the preamp and goes through all of the Mo' Bass effects. The wet-to-dry ratio of those inter nal
effects is determined by the position of the two Mix controls (SubWave Mix and Bassynth Mix) in the signal path of the unit.
After the Chorus section (the last Mo' Bass effect in the chain), the signal then is routed to the power amps. At that point,
the power amps can be run in stereo mode or bridged into a mono-block configuration. In Single Channel Mode, both left
and right power amps - whether bridged mono or not - and their respective speaker outputs will see the same signal. Turn
on an effect and it will come out of both sides (if it's mixed in, of course).Turn the effect off and clean bass will come out
both sides. (continued)
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