Mesa-boogie Bass Prodigy User Manual
THE HOME OF TONE
®
Owner’s Manual
Greetings from the Home of Tone
...You, smart player and intuitive human, have put your trust in us to be your amplifier
company. This is something we do not take lightly. By choosing this instrument to be a
part of your musical voice, you have become part of the Mesa family...WELCOME!
Our goal is to never let you down. Your reward is that you are the new owner of an amp,
bred of fine all tube heritage...benefiting from the many pioneering and patented Mesa
circuits that led to the refinement of your new model. We feel confident this amp will
inspire many hours of musical satisfaction and lasting enjoyment. It was built with you in
mind by players who know the value of a fine musical instrument and the commitment it
takes to make great music. The same commitment to quality, value and support we make
to you...our new friend.
®
TABLE OF CONTENTS
Precautions
Overview _________________________________________________________________________________________ 1-3
Helpful Hints _______________________________________________________________________________________ 4
FRONT PANEL:
INSTRUMENT INPUT _________________________________________________________________________________ 5
INPUT SELECT SWITCH ______________________________________________________________________________ 5
CONTROLS:
GAIN, BASS ________________________________________________________________________________________ 6
MID _____________________________________________________________________________________________ 6-7
TREBLE ___________________________________________________________________________________________ 7
VOICE ___________________________________________________________________________________________ 7-8
MASTER ___________________________________________________________________________________________ 8
MUTE / PLAY / SILENT RECORD SWITCH ________________________________________________________________ 8
FULL / HALF POWER SWITCH _________________________________________________________________________ 9
PRE / POST: D.I. OUTPUT SELECT SWITCH ___________________________________________________________ 9-10
D.I. LIFT / GROUND, D.I. LEVEL _______________________________________________________________________ 10
SOLO CONTROL ___________________________________________________________________________________ 10
POWER SWITCH ___________________________________________________________________________________ 11
STANDBY SWITCH _________________________________________________________________________________ 11
REAR PANEL:
AC MAINS FUSE, FUSE RATING AND REPLACEMENT ____________________________________________________ 13
POWER CABLE, EXTERNAL SWITCHING _______________________________________________________________ 14
SEND / RETURN _________________________________________________________________________________ 14-15
TUNER ___________________________________________________________________________________________ 15
SLAVE ____________________________________________________________________________________________ 15
FOOTSWITCH JACK ________________________________________________________________________________ 16
SPEAKER OUTPUTS _____________________________________________________________________________ 16-17
D.I. OUTPUT _______________________________________________________________________________________ 18
FACTORY SAMPLE SETTINGS ________________________________________________________________________ 19
PERSONAL SETTINGS ______________________________________________________________________________ 20
BIASING THE KT-88 POWER TUBES ________________________________________________________________ 21-22
SPEAKER IMPEDANCE MATCHING AND HOOKUP GUIDE ______________________________________________ 23-28
TUBE NOISE AND MICROPHONICS ________________________________________________________________ 29-30
TUBE REPLACEMENT CHART ________________________________________________________________________ 32
PARTS SHEET _____________________________________________________________________________________ 33
Important Safety Instructions
Read these instructions.
Keep these instructions.
Heed all warnings.
Follow all instructions.
Do not use this apparatus near water.
Clean only with dry cloth.
Do not block any ventilation openings. Install in accordance with the manufacturer’s instructions.
Do not install near any heat sources such as radiators, heat registers, stoves, or other apparatus (including amplifiers)
that produce heat.
Do not defeat the safety purpose of the polarized or grounding-type plug. A polarized plug has two blades with one
wider than the other. A grounding type plug has two blades and a third grounding prong. The wide blade or the third
prong are provided for your safety. If the provided plug does not fit into your outlet, consult an electrician for replacement of the obsolete outlet.
Protect the power cord from being walked on or pinched, particularly at plugs, convenience receptacles, and the point
where they exit from the apparatus.
Only use attachments/accessories specified by the manufacturer.
Unplug this apparatus during lightning storms or when unused for long periods of time.
Refer all servicing to qualified service personnel. Servicing is required when the apparatus has been damaged in any
way, such as power-supply cord or plug is damaged, liquid has been spilled or objects have fallen into the apparatus, the
apparatus has been exposed to rain or moisture, does not operate normally, or has been dropped.
To insure proper ventilation always make sure there is at minimum four inches (101.6mm) of space behind the rear of
the apparatus. The ventilation should not be impeded by covering the ventilation openings with items, such as newspapers, tablecloths, curtains, etc. Do not impede ventilation by placing objects on top of the apparatus which extend past
the rear edge of its cabinet.
No naked flame sources, such as lighted candles, should be placed on the apparatus.
The apparatus shall not be exposed to dripping or splashing and no objects filled with liquids, such as vases, shall be
placed on the apparatus.
READ AND FOLLOW INSTRUCTIONS OF PROPER USAGE
Important Safety Instructions
WARNING: To reduce the risk of fire or electric shock, do not expose this apparatus to rain or moisture.
The AC plug is the mains disconnect. The plug should remain accessible after installation.
WARNING: EU: permission from the Supply Authority is needed before connection.
WARNING: Always make sure 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 the amplifier is properly grounded. Always unplug AC power cord before changing fuse, tubes or removing chassis. Use only same type and rating when replacing fuse.
Avoid direct contact with heated tubes. Keep amplifier away from children.
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 when handling buttons, switches and controls. Do not use solvents such as benzene or
paint thinner to clean the unit.
Always connect to an AC power supply that meets the power supply specifications listed on the rear of the unit. Export
models: always insure unit is wired for proper voltage. Make certain grounding conforms with local standards.
Your amplifier is LOUD! Exposure to high sound volumes may cause permanent hearing damage!
When Rack Mounting this unit proper ventilation space must be maintained. Do Not cover or block Front and Rear and
allow at least 2” of open “breathing” space on both sides of the unit. Allow 2 Rack Units of open space above the unit to
allow heat to escape the upper rear vents.
NOTE: IMPORTANT – Do Not flip the STANDBY SWITCH in and out of STANDBY mode (on and off) while the amplifier is being
played or with any type of signal being amplified. The large amount of current involved in this scenario can damage the STANDBY
SWITCH.
Your Mesa/Boogie® Amplifier is a professional instrument. Please treat it with respect and operate it properly.
READ AND FOLLOW INSTRUCTIONS OF PROPER USAGE
Operating Instructions
Congratulations on your choice of the BASS PRODIGY Four:88 and welcome to the MESA/Boogie ® Family! First, we would like to
thank you for choosing us as your amplifier company and trusting us to help create your musical voice. This is something we never
take for granted and you’ll find that we are here and ready to assist you should you ever need help. Our goal is to help you sound
your best at all times! We feel confident that your new amplifier will bring you many years of reliable service, rewarding inspiration
and create for you a newfound freedom to express your music.
You have chosen an amplifier bred of a fine all-tube heritage and this model is our testament to Tube Bass Tone. Its forefathers can
be traced back to the very first MESA amplifier ever built, the MESA 450 Bass Head. In fact, the first 5 MESA amplifiers built in the
Lagunitas mountain shack were Bass amps…a piece of trivia little known and overshadowed by our overwhelming notoriety for guitar
amplification. But we’ve always loved the Bass, and have - since day one - been committed to elevating its stature through our art
form. The bloodline for MESA bass continued with the first rack-mount chassis bass amplifier in 1980, the D-180. The mid-eighties
saw the introduction of the BASS 400 and later in 1988, the BASS 400+ with its stunning Pitch, Punch and Power delivered by an
additional 6 x 6L6s to bring the total to twelve 6L6s in the mighty power section.
The 400+ went on to become a classic used by the world’s most talented Bassists for two decades. Paul McCartney, Mark King,
Stanley Clark, Jack Blades, Michael Anthony, Blasko and Bootsy Collins, are but a few of the international stars that put the 400+
center stage to anchor the band during its 20 year build cycle. Those iconic amps still bring top dollar when you can find one changing
hands on the pre-owned market. While MESA has since pioneered an entire line of tube-driven mosfet amplifiers that shored up our
place in the Bass market, the discontinuation of the 400+ left a gaping hole in the world of tube Bass amp offerings.
Tone Freaks Rejoice! The BASS PRODIGY Four:88 is the next step in the MESA All-Tube Bass Amp Bloodline. Vastly improved
Tone, features, dial-ability, portability, packaging and control over the entire spectrum make the PRODIGY – and its big brother the
STRATEGY Eight:88 – an iconic step forward in Bass amplification. With an all-new tube preamp, a 5-position Rotary VOICE Selector, patented Multi-Watt 2-Way Selectable Power, Footswitchable SOLO and VOICE control, Rear Panel TUNER Output, and an all
new, high output power section utilizing four KT88s – the PRODIGY is THE tube Bass Amplifier for the new millenium.
FRONT VIEW: BASS PRODIGY ™
BRIG HT
ACTI VE
NORMAL
INPUT
PULL
BOOST
GAIN
3
2 4
BASS MID TREBLE VOICE MASTER
51
MUTE
PLAY
SIL. REC.
FULL
HALF PWR
D.I. PRE
POST
D.I. LIFT
GROUND
D.I.
LEVEL SOLO
Four:88
ON
POWER
STANDBY
ON
™
REAR VIEW: BASS PRODIGY ™
CAUTION: Unplug power before
servicing fuse or chassis
FUSE
120 V~
60 Hz
6 A
h
SLO
BLO
5 A
BASSPRODIGY 4:88
VACUUM TUBE AMPLIFIER
MUTE
LOOP
FX
HOME OF TONE
RETURN
™
SOLOVOICE 4 OHM8 OHM
SWITCHEXT
CAUTION!
SEND
®
TUNER
®
WARNING!
SLAVE
OUT
HAND BUILT IN
PETALUMA, CALIFORNIA U.S.A.
MUTE ON UNLESS SPKR IN
USE
W/ TWO
SPKRS
8Ω CABS
4 OHM
TUBE GUIDE
3 x 12AX7 4 x KT88
FT. SW.
D.I. OUT
PATENTED
6,724,897
PAGE 1
O:
The PRODIGY begins with BRIGHT, NORMAL and ACTIVE INPUT Select choices feeding an all-new tube preamp that borrows
subsections from our CARBINE hybrid architecture. This design allows increased control over a broad spectrum of frequencies
and incorporates active BASS and TREBLE controls with increased shaping power - while retaining the sweet, musical blend of
our traditional passive MID control. In addition to these we’ve included a reworked-for-tubes version of the CARBINE’s 5-position
rotary VOICE feature that allows notching or enhancement of specific midrange regions in addition to bass and treble frequency
boosting. The VOICE feature puts you instantly in iconic stylistic realms – from elastic, mid-scooped Thumbing to articulate, mid-flat
Fingerstyle, to the Classic metallic, scooped American Pick sound – with a flick of a switch. The ability to jump right to these classic
“curves” makes re-voicing on the fly in performance situations a snap, is also footswitchable, and adds immensely to the PRODIGY’s
versatility.
Your new amplifier has an update to the original feature set. The GAIN control now includes a PULL BOOST Feature that increases
the gain early in the preamp and creates a region of tube saturation toward the upper end of the control’s taper.
This boost in gain created when the GAIN control is pulled fattens up the sound, adds natural tube saturation and compresses the
attack. The higher the GAIN control is set, the more these characteristics become dominant in the mix. For maximum overdrive
levels, set the GAIN Control in the upper region of its sweep (3:00 – 5:30).
Control over the Tone would be incomplete – at least in our minds – without control over the power as well. So the PRODIGY gives
you two choices as to how to utilize the power section. As wattage ratings are often misleading and irrelevant to volume when it
comes to describing tube power, the PRODIGY offers FULL and HALF power settings on the MULTI-WATT™ switch. Each of these
choices has a distinct tonal color and persona, with FULL delivering the maximum punch, authority and headroom. HALF can deliver
some valuable and surprising mid to lower power applications for tube-driven Bass while still offering plenty of volume for a lot of live
situations. An important collection of vintage-inspired sounds await you here in HALF POWER ranging from round and warm, to
edgy, to clipped and growling – depending how you dish it out from the MASTER, all the sounds in HALF POWER beg to be recorded.
A MUTE/PLAY/SILENT RECORD switch allows convenient Front Panel muting for instrument changes, silent tuning or recording, or
any time where signal muting is needed. An AUTO-MUTE circuit is fitted to the Speaker Jacks to protect the transformer and power
tubes if no speaker is connected and is indicated by the same Front Panel LED triggered by the mini-toggle MUTE/PLAY/SILENT RECORD switch (Red LED ON = MUTE). The SILENT RECORD setting allows you to safely mute the signal at the Power Amp and use
the Prodigy preamp (including processing in the EFFECTS LOOP) to record using the D.I. OUTPUT without sound from the Speaker.
The Rear Panel D.I. OUTPUT signal can be derived from either PRE (your instrument) or POST (the entire preamp) with the Front
Panel D.I. Switch. The D.I. OUTPUT signal strength is controlled by the Front Panel D.I. LEVEL located at the far right side of the
Chassis next to the SOLO™ Control. And a valuable D.I. LIFT switch can float the Circuit Ground from Chassis Ground to reduce
noise into the Console when the Ground references are different.
The PRODIGY incorporates our SOLO™ feature that has become so popular on our guitar amplifiers, which gives you a pre-settable
and footswitchable boost for any time you want to feature a specific part or section in a song. The SOLO control can also be used to
compensate for an instrument with a lower output due to weaker pickups.
Jumping to the Rear Panel you are greeted with the EXTERNAL SWITCH jacks which make the PRODIGY compatible with virtually
any switching system’s architecture. These provide for external control of the MUTE, VOICE and SOLO™ features with a master
(usually midi) switcher or with any separate “tip to ground” latching-type switch logic.
From there we find the buffered Series EFFECTS LOOP that allows seamless interfacing of your high quality outboard processing.
Remember that this sensitive point between preamp and power section is an important Tone stage. Try to use outboard processing
of the same caliber as your amplifier. Ignoring this advice will likely result in compromised sound. The Loop is a critical junction/
impedance crossroads point between preamp and power and to put inferior foreign objects in the signal path here will produce Tone
of the lowest common denominator.
PAGE 2
O: (Continued)
Next you’ll find a pair of jacks for the TUNER Output and the SLAVE Level. The TUNER output captures your instrument and preps
it for the long journey to the front of the stage or just upstairs to the top of your amp. The SLAVE provides an output for capturing the
sound of both preamp and power section for use in connecting your preamp and power section tonality to additional power sections
and cabinets for truly coliseum grade rigs.
To handle virtually any speaker cabinet scenario, the PRODIGY is fitted with 3 SPEAKER OUTPUTS capable of handling a variety
of impedance/cabinet loads. One 8 OHM and two 4 OHM Outputs ensure that you can always find an impedance-correct match
regardless of your cabinet choices.
The PRODIGY Footswitch DIN Input resides just to the right of the SPEAKER OUTPUTS and here is where the optional Footswitch
& Cable is connected to your amplifier.
Finally, a MESA first – a 2 position BIAS SET switch and trim pot resides on the rear Tube Deck labeled Operate and Set Bias. This
SET-BIAS position allows you to check and set your bias quickly and easily for maintenance or when replacing power tubes to set
BIAS on the big KT88s. There’s no need to take the amp to a technician when it’s time to change tubes as this bias method is completely user-serviceable and easy to dial in your bias just right.
INSTANT GRATIFICATION
The PRODIGY is about the easiest amp on the planet to get a great sound from quickly – and with the VOICE Control – several great
sounds.. Just set most of the controls at noon…and enjoy! From those settings, may we recommend you sweep the VOICE Control
from position 1 to 5 and experience what a difference the various MID voicings combined with bass and treble enhancements can
provide.
NOTE: COLD START PROCEDURE: When powering up your PRODIGY from cold, ALWAYS follow this Start Up Procedure: We
have found the currently available KT88s require substantially more time than 6L6s or EL34s to warm up to full operating temperature.
If you hit them with high voltage with the STANDBY sooner than three minutes, you may hear some crackling as well as a slow volume
increase as they get up to full temperature. This subsides once they are fully warm, and while it might not hurt the tubes per se, it is
better to warm them up for at least three minutes (or longer) whenever you can.
NOTE: IMPORTANT! – Do Not flip the STANDBY SWITCH in and out of STANDBY mode (on and off) while the amplifier is being
played or with any type of signal being amplified. The large amount of current involved in this scenario can damage the STANDBY
SWITCH.
1. Begin with STANDBY in the STANDBY Position.
2. Switch POWER to ON and WAIT at least three minutes or longer for the tubes to “warm up”. (With STANDBY OFF and POWER
ON, the tubes internal components are allowed to warm up slowly before hitting them with the high voltage controlled by the
STANDBY being switched to ON).
3. Flip STANDBY to ON.
4. PLAY!
Following this startup procedure will lengthen the musical life of your power tubes and decrease the chances of untimely power tube failures.
BRIG HT
ACTI VE
NORMAL
INPUT
PULL
BOOST
GAIN
3
2 4
BASS MID TREBLE VOICE MASTER
51
PAGE 3
MUTE
PLAY
SIL. REC.
FULL
HALF PWR
D.I. PRE
POST
D.I. LIFT
GROUND
D.I.
LEVEL SOLO
Four:88
POWER
STANDBY
™
ON
ON
HELPFUL HINTS
IMPORTANT! The SPEAKER OUTPUT Jack’s AUTO-MUTE function is triggered anytime there is no Speaker Cabinet (Load) plugged into
one of the Speaker Jacks. The amp “knows” if a cabinet is not plugged into a speaker jack and mutes to protect itself from damage. If there is no
sound when you turn STANDBY to “ON” – ALWAYS and IMMEDIATELY – STOP PLAYING – and check to make sure there is a Speaker Cabinet
plugged in. The Front Panel MUTE LED will be illuminated red when either the MUTE/PLAY/SILENT RECORD switch is set to MUTE or SILENT
RECORD – OR – when there is no Speaker Cabinet connected to the Speaker Jacks. AUTO-MUTE is also ON when the Set Bias switch is on.
NOTE: IMPORTANT! MAKE SURE YOU HAVE A SPEAKER CONNECTED TO THE SPEAKER OUTPUT JACKS AT ALL TIMES! EVEN
THOUGH THE PRODIGY HAS BUILT-IN PROTECTION, DON’T RELY ON THIS ALONE – IT IS A HIGH POWER AMPLIFIER AND NEEDS
A LOAD CONNECTED AT ALL TIMES!
NOTE: IMPORTANT! NEVER UNPLUG THE SPEAKER LOAD (Cabinet) WHILE THE AMPLIFIER IS IN USE (BEING PLAYED)!
NOTE: IMPORTANT! DO NOT ATTACH OR USE A CABINET OR CABINETS WHOSE IMPEDANCE/LOAD IS LOWER THAN 4 OHMS. USE
OF A 2 OHM LOAD ON THE AMPLIFIER WILL DRAMATICALLY STRESS THE POWER TUBES AND OUTPUT TRANSFORMER, AND MAY
CAUSE EXTENSIVE AND EXPENSIVE NON-WARRANTY DAMAGE TO THE AMPLIFIER.
NOTE: WHENEVER POSSIBLE, AVOID USING THE HALF POWER SETTING WITH SPEAKER LOADS BELOW 4 OHMS! USING LOADS BELOW 4 OHMS WHILE THE AMPLIFIER IS IN HALF POWER WILL PUT UNECESSARY STRESS ON THE POWER TUBES AND TRANSFORMER.
NOTE: IMPORTANT! – Do Not flip the STANDBY SWITCH in and out of STANDBY mode (on and off) while the amplifier is being played or with
any type of signal being amplified. The large amount of current involved in this scenario can damage the STANDBY SWITCH.
Though it goes without saying, FULL POWER on the POWER SELECT mini toggle delivers the maximum headroom, punch and perceived
“speed” and control over the notes.
The VOICE Control is the most powerful single control on the PRODIGY and delivers many of the characteristics of several different manufacturer’s iconic amplifiers in one simple to use control. Use the VOICE Control to take a “broad aim” at the sound/playing style you are pursuing and
then focus in and fine-tune with the rotary Tone Controls.
The VOICE Feature “preset sounds” are assembled with these stylistic applications in mind:
1. Slight Mid Scoop/Huge Low End: Funk/Thumbing/Slap
2. Subtle Wide “Q” Bass Boost-Approximately 20Hz – 180Hz: Smooth R&B/Fingerstyle
3. Flat: Articulate Rock Punch/Fingerstyle
4. Mid Scoop/Bass Boost/High Boost: Classic Rock/Pick, Fingerstyle, Thumbing
5. Radical Mid Scoop/Bass Boost/High Boost: Aggressive Rock/Pick, Hyper Slap/Thumbing
Sometimes less is more. Don’t fall prey to the classic Tone Trap… EQ HANGOVER. Don’t chase great Tone around in circles. Instead use your
IQ and constantly reference a “less altered state of play”. By going back and forth to a more “flat” or “conservatively voiced” setting you will avoid
ear fatigue and end up with a more balanced sound.
The SOLO Feature can be used to not only boost your level for featured parts, but as an additional MASTER VOLUME to compensate for different footswitchable VOICE settings as well.
The D.I. OUTPUT will have signal present when in the PRE selection even when STANDBY is used to mute the signal to the power section
(STANDBY position) as this is the direct signal straight from your instrument before it goes through the amplifier.
The Cooling Fan is equipped with a thermostat that allows for different speeds depending on the operating conditions (temperature) of the output
transformer and tubes. Don’t be alarmed if the fan speed (and associated noise) increases while you are playing. This is normal and essential
to your amplifier’s wellbeing and reliability.
Now that you have an overview of your PRODIGY and some hints to achieve a great sound fast, let’s take a deeper look at the controls and
features of this mighty little Bass powerhouse.
PAGE 4
FRONT PANEL: (C F)
INPUT:
This jack is the instrument INPUT and it feeds the first tube stage in the tube preamp of the PRODIGY. Both passive as
well as active instruments are provided for with a specific setting on the 3-position INPUT SELECT switch.
BRI GH T
NORMAL
INPUT
INPUT SELECT: BRIGHT/NORMAL/ACTIVE
PULL
ACT IV E
BOOST
GAIN
This 3-position switch allows selection of three different Input configurations, two of which are voicing options and a third that offers an Input Pad for Active Instruments. Select the option that best suits
your tonal/stylistic needs and impedance/headroom requirements.
BRIGHT This is the normal INPUT (to us anyway)- and while “normal” is a relative term – this setting would usually be the first
choice for most Passive instruments. As you might imagine, the BRIGHT selection offers a brighter, more detailed Tone and can also
give the impression of a more responsive or faster feel – which Passive Instruments might benefit from. This Input Mode would be
the choice anytime you’re looking for a more present or forward sound with enhanced top end characteristics and a more detailed
spectrum of upper harmonics. While the name suggests that this position might be better suited to traditional or passive instruments,
don’t be afraid to try BRIGHT for an exciting sound with Active Basses as well. Just keep in mind that the range of usable, unclipped
headroom on the GAIN control will be lower if you use BRIGHT with an active instrument. BRIGHT provides a snappy, alive sound
that has more bounce and clarity for vintage style basses that is really fun to play. The impression of headroom and more full-range
EQ curve of the BRIGHT Input creates a crisp, superbly clean sound with these more traditional instruments that will likely take them
down some new avenues. You may also want to use BRIGHT if the cabinets you’re using don’t offer high frequency horns or tweeters
and you’re looking for more detail in the high end.
NORMAL provides a purposeful “Low-Fi” sounding alternative to the crisp and detailed sound of the BRIGHT Input setting. The
NORMAL input is also a great choice if your bass or cabinet (or both) leans toward being a little on the bright side or if you find the
Prodigy to sound bright with other elements of your rig. A quick flip of the switch and the Prodigy is tuned to your playing style or other
aspects of your rig. NORMAL features a rounder, warmer Tone that is perfect for old school sounds and classic passive Basses. This
setting may also be preferable for overdriven or clipped sounds as the less prominent top end will produce a more musical clip and
help avoid ratty or buzzy distortion characteristics. NORMAL can also provide a warmer sound for modern Basses with higher output
pickups, but will probably start to run out of headroom and break up sooner - possibly before you want them to. It will not hurt the
amplifier to run active instruments in the NORMAL Input and in fact, you may want to use this to your advantage in certain musical
scenarios. However, if you are looking for the most Hi-Fi tonal response and greatest headroom you will likely find better performance
by using the ACTIVE Input.
ACTIVE provides the proper padded Input sensitivity for instruments that incorporate an on-board preamp and/or pickups that utilize
active electronics. This jack can receive the highest signal level before clipping and therefore provides the greatest headroom for
these higher output instruments. EQ-wise, ACTIVE is voiced much like the BRIGHT setting and provides the full spectrum of upper
harmonics. This clarity and detail nicely reinforces the higher headroom nature of this Input setting. While there is more headroom
- and therefore, ACTIVE requires a hotter signal to bring the whole amp to full power - don’t be afraid to try it for a different sound
with passive Basses as well. One thing is for sure, you won’t be running out of clean headroom at the INPUT if you run your passive
instrument in the ACTIVE setting. You can use this to your advantage when looking for the cleanest possible sound with traditional
Basses. Just keep in mind you may see higher settings on both GAIN and MASTER than you’re accustomed to in order to achieve
the volume you want for this hyper-clean Tone.
PAGE 5
THE CONTROLS
GAIN
This control determines the overall character of the sound along with input gain and sensitivity. The lower regions of the
control (below 12:00) offers the cleanest sounds and greater headroom with a scooped, brighter personality. The upper harmonics
BRI GH T
PULL
ACT IV E
BOOST
come through more prominently in this area of the control making the top end sound more transparent
and crisp. This region is especially useful for funkier stuff when thumbing is in order. It keeps the rubberband feel intact in the lows and mids while voicing the snap just high enough to avoid harshness, or the
NORMAL
INPUT
dreaded “gak” when the G string is plucked.
As the GAIN control is increased past 12:00 a richer, “well-rounded” and more blooming voice becomes
dominant. Headroom starts to diminish in increments until eventually, a tube overdrive sound appears
GAIN
as the 12AX7 input preamp tube is driven into saturation.
The region between 12:00 and 2:30 is where classic, warm tube sounds reside. Within this narrow band, you will discover a world of
old-school tones. Tiny increments here produce subtle, but important differences in the attack characteristic, which in turn, can feel
like changes in the time domain.
By experimenting with the setting of the GAIN control, you can actually voice the amp to feel as if it bounces just ahead of the groove
(10:30 – 12:00) - or lays back a little deeper to produce a more ‘Fatback’ feel with tube drive (12:30 – 2:00). The difference in attack
and sustain produces striking results as to how the bassist - and in fact the whole band - perceives things in the time domain.
PULL BOOST - Your new amplifier has an update to the original feature set. The GAIN control now includes a PULL BOOST Feature
that increases the gain early in the preamp and creates a region of tube saturation toward the upper end of the control’s taper.
This boost in gain created when the GAIN control is pulled fattens up the sound, adds natural tube saturation and compresses the
attack. The higher the GAIN control is set, the more these characteristics become dominant in the mix.
For maximum overdrive levels, set the GAIN Control in the upper region of its sweep (3:00 – 5:30). For more subtle overdrive applications try the region between 12:30 – 3:00 on the GAIN control. This zone will retain a more urgent attack and the natural sound of
your instrument and provides a smooth transition between really clean and the point where tube overdrive begins.
BASS
This control is responsible for the basic mix of low frequencies in the tube pre-amp. The BASS control is an “active” control
- as opposed to a “passive” style control. This means that a center “Q” point has been chosen for this control that allows you to either
boost or cut a range of low end centered on that frequency. While there is a specific frequency that
the Bass control “centers on”, the frequencies and harmonics on either side of this center Q point are
affected in a diminishing “bell shaped” curve as you sweep it one direction or another.
The BASS control is actually a gain and frequency control all rolled into one with the “Q” center at 55Hz.
As mentioned above, though it is centered here, frequencies (harmonics) in both low and high direc-
BASS MID
tions are affected because of its broader-band nature. Twelve o’clock (NOON) on the BASS control
delivers a basically “flat” response (no boost/no cut). As the BASS control is increased past 12:00
(NOON), it produces a 6db per octave boost in gain starting at the center point of 55Hz and tapering
gradually to the edges of the broad Q’s bell-shaped curve from 20Hz on the low side, all the way up to
321Hz on the high side. At 5:30 on the bass control a +6db increase in gain is possible. As the BASS control is dialed below 12:00,
55Hz and all associated harmonics are reduced and eventually notched almost completely out of the signal path. This lower range
of the control delivers a 6db per octave “cut” centered at 55Hz going down to 20Hz with an overall “cut gain” of -10db possible as the
control reaches 7:30 (off).
This type of active rotary control makes it possible to achieve bass control and characteristics far beyond that of a conventional passive type control. It can increase the low end to an almost absurd level and then, with a flick of the wrist, dip it to near transistor radio
PAGE 6
THE CONTROLS (Continued)
skinniness. Needless to say, with any control this powerful a certain amount of finesse must be applied to achieve musical results.
MID
This is the only passive style control in the string of rotary tone controls. This scheme was chosen for its inherently musical
blend and for the way the passive style midrange control - with its wide footprint and smooth taper - fills in the “holes”. Unlike the
BASS, this control is a cut only, and while it can competently remove this broad spectrum of midrange
from the mix, it cannot provide the extreme focused attenuation of an active style control.
You will find that this passive, broad-band control works really well for shaping the midrange frequencies and imparting a natural earthiness and character that is the perfect counterpart to its active style
neighbors. It’s hard to dial wrong with this more forgiving approach - as it gives you the ability to punch
BASS MID
through a mix or sweeten and smooth out the sound by adjusting just one control.
Another useful property of the Passive MID when used above 12:00 is that it starts to impart a furry,
tube growl as it is increased and actually pushes things toward the threshold of clip at higher settings… especially in the #3 “Flat”
VOICE Position. Use this to your advantage when searching for aggressive Rock sounds with an edge or R&B Tones that have just
a hint of tube saturation.
For radical and specific scooping of the midrange frequencies in modern R&B and Funk styles, there is plenty of notching power that
is infinitely more accurate stylistically, to be found in the VOICE Control. Because of this, we opted for the tried and true passive style
midrange control that has been working great in all of our amplifiers for decades. It’s hard to improve on a classic.
TREBLE
The TREBLE is also an active-style control like that found in the BASS and it was chosen for its ability to radically shape
the upper harmonic region. Like the BASS, it also has a center Q point with frequencies (harmonics) above and below, responding in
harmony in a bell-shaped curve as it is dialed for either cut or boost.
3
2 4
As the TREBLE control is increased past 12:00 (NOON), it produces a 6db per octave boost in gain
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starting at the center point of 3.2KHz and tapering gradually to the edges of the broad Q’s bell-shaped
curve from 723Hz on the low side and all the way up to 6KHz on the high side. The maximum boost
available from 12:00 (Flat) is 5db. Dialing the TREBLE below 12:00 produces a 6db per octave cut
TREBLE
VOICE
centered at 3.2KHz and decreasing in strength down to 723Hz and out to 6KHz. The maximum “cut” attenuation of -10db is reached at the bottom of the control (7:30/off). The ability to cut these frequencies
more radically makes it possible to obtain incredibly rich and warm old-school R&B and Jazz sounds
that rival any of the classic recordings of the day. This broad Q scheme lends a sweetness of sound when boosted while retaining all
the focus and simple usability associated with a traditional passive TREBLE control.
The active TREBLE control completes the rotary tone control string to create a powerful and extremely accurate network to use as
your fundamental tools for Tone shaping. It’s no wonder many first-time PRODIGY players make the comment that just these three
controls (even set at noon) — combined with the GAIN — create the best tone they have ever heard!
NOTE: As with the BASS control, may we remind you that a control of this type, with its increased power, should be used with finesse
(in the TREBLE’s case, almost more so, because higher frequencies seem louder to the ear and are generally more painful when set
to extremes). Another reason to use care is that high frequencies tend to increase the ambient noise floor when set too high. This is
then exacerbated if the MID control is combined for added top end boost. Dial with care and music in mind.
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