Artist Ser ies
Owner’s Manual
Table of Contents
400RB-IV Series
Table Of Contents
Introduction..................................................................... 3
Safety Information........................................................... 5
Quick Start....................................................................... 6
Sound Tips....................................................................... 7
Settings and Sounds........................................................ 8
Installation and Maintenance........................................ 9
Front Panel Controls..................................................... 10
Rear Panel Controls...................................................... 11
400RB-IV Series Combos............................................. 12
Tech Talk....................................................................... 13
Specifications................................................................. 15
*All Features and specifications are subject to change without notice.
**This list is subject to change without notice.
Please read the Safety Information section on page 5 before continuing.
2234 Industrial Drive
Stockton, CA 95206
phone: 209.234.7300
fax: 209.234.8420
400RB-IV Series
Gallien-Krueger, Inc.
2234 Industrial Drive
Stockton, CA 95206
phone: (209) 234-7300
fax: (209) 234-8420
To get the most out of your new purchase please take a
few minutes to read through this manual. If you are in a
hurry, we suggest you at least read through the Quick
Start and Safety Information sections before setting
up your new rig. This will help get you started and
give you a few quick tips, but is not a substitute for
reading the rest of the manual.
We wish you a lifetime of good playing and remember to always have fun!
Your amplifier should have come with the following
items, please check the contents of the box to ensure that
you have everything.
Included with your 400RB-IV Head:
Rack mount Ears with Hardware
Power Cord
Owner’s Manual
Warranty Card
Safety Instructions Sheet
Included with your 400RB-IV Combo:
400RB/210 or 400RB/115)
Power Cord
Owner’s Manual
Warranty Card
Safety Instructions Sheet
If your 400RB-IV Series amplifier or combo did not
come with all the items listed above, or if you
encounter problems while setting up your new
equipment, please contact your local dealer, or us
as soon as possible at:
Your purchase of a new Gallien-Krueger 400RB-IV
Series product is surely the result of much careful
consideration on your part. For our part, we at
Gallien-Krueger are pleased that you chose us, and
are determined that you will be a satisfied customer.
In choosing a 400RB-IV Series product, you own a
unit with many unique features, which will allow you
to create your own distinct sound.
400RB-IV Series
GK Philosophy
I have never seen the point in doing things the way
others have done them. I also have not been very
interested in following the latest fad. I am a
Stanford educated engineer who worked his way
through school as a musician. Like all musicians, I
have lugged amplifiers up stairways and into car
trunks, always wondering why these things had to
be so heavy, bulky, and hard to handle.
As I am the principal innovator at G KK, our products
reflect my attitudes and life experiences. I don’t model
my designs after other manufacturer’s products (as
some of our competitors are proud of reciting).
Instead, I believe new and old problems are best solved
with new solutions. Having taken our own path, G K
products enjoy a unique, unmatched sound, allowing
the artist using them every opportunity to make an
original statement.
Having supported my products for over thirty years, I
have learned from the story they tell. Gallien-Krueger
is a reflection of that story, and has a commitment to
support that legacy. Just as the products I created
thirty years ago are still telling their story, the products
we create today will be talking to us tomorrow.
Robert Gallien
Founder & President
400RB-IV Series
Safety Information
To avoid safety hazards, use only the power cord supplied
with your unit. If a replacement cord is used, make
certain that it is of consistent quality and gauge as the
original. We do not recommend using extension cords
with this product. As with all electrical devices, do not
run power cords under rugs or carpets or place heavy
objects on them. Damaged power cords should be
replaced immediately with cords meeting factory specifications.
Your new 400RB-IV Series Bass Amp has been factory
configured for use with:
120 Volt/60Hz 20 Amp circuit for USA & Canada.
230 Volt/50Hz 10 Amp circuit for Europe
& Australia.
100 Volt/50Hz 20 Amp circuit for Japan.
Proper AC circuit for all other countries.
Connecting the amplifier to a line with specifications
other than indicated above can create a safety and fire
hazard, and may damage the amplifier. If you have any
questions about the voltage requirements for your
specific model, or about the line voltage in your area,
contact your dealer before plugging the unit into a wall
Handle The AC Power Cord Gently:
When disconnecting the power cord from an AC outlet,
always pull the plug, never pull the cord. If you do not
intend to use the amplifier for a considerable length of
time, disconnect the plug from the AC outlet.
Mains Disconnect:
Verify AC Circuit Capacity Before Use:
If the AC mains has to be completely disconnected, the
plug/power cord is used as the mains disconnect
device and shall remain readily operable.
The high power output of your amplifier may require
heavy current draw under Full-Load conditions. To
insure proper performance and avoid potential safety
hazards, we recommend connection to line circuits with
Amperage specified “as above”. Connecting multiple
amplifiers to the same circuit, or connecting the amplifier to the same circuit used by other heavy-power
devices, such as high-wattage lights, may cause circuit
breakers to trip. It is always a good idea to avoid using
any audio equipment on the same AC circuit as equipment with motors, such as air conditioners or refrigerators. This will lessen to possibility of power variation and
electrical start-up noise affecting your sound.
Do Not Open The Amplifier Enclosure:
There are no user-serviceable components inside this
product. Opening the amplifier enclosure may present a
shock hazard, and modification to the product will void
your warranty. If liquid enters the unit, or any metal
object such as a paper clip, wire, or staple accidentally
falls inside the enclosure, disconnect the unit from the
AC power source immediately and consult an authorized
service station.
Warning: Do not disconnect or plug in the instrument/speaker cable with the amplifier power on.
Be sure the amplifier unit is turned off before
connecting to the speaker.
The carton and packing materials used in shipping your
new amplifier were specially designed to cushion it from
the shocks and vibration that occur during transport. We
suggest that you save the carton and packing materials
for use in shipping, in the event you move, or the
amplifier needs repair.
Safety Information
Do Not Use Extension Cords:
Verify Line, Voltage and Amperage Before
400RB-IV Series
Quick Start
Quick Start
The 400RB-IV is designed to be simple to operate. All
controls have a well defined purpose and are well
behaved. These directions will take you through the
basics and give you a good start for setting up your
1. Plug it in:
At this point:
Set the power switch to Off and connect the supplied
power cord, from the amplifier AC receptacle, to an AC
power outlet of proper voltage and power rating (see
safety information on page 5 for details).
You should be hearing your bass quite well. You can
use the Volume and Master to achieve a comfortable
sound level. R e m e m b e r : If you need more volume,
turn up the Master control first.
2. Connect your cabinets:
Connect your speaker cabinets to the amplifier
outputs marked 280W AMP ONLY. Be sure not to
exceed the recommended speaker load below.
Maximum Recommended Speaker Loads:
One 4 Ohm or two 8 Ohm cabinets.
If you are using a RBH Series cabinet, set the crossover switch to Full Range.
3. Initial front panel control settings:
Set all EQ controls and the Boost control to 12
o’clock. The Voicing Filters should be turned all the
way down to get a flat response. Set the Level and
Master Volumes at 0. If you have a five string bass,
push the button marked String Bass in.
4. Plug in your bass:
Using an instrument cable, connect your bass to the
Input jack and press the power switch on. If you have
active tone controls on your bass, turn all of the
controls to the middle or flat position and turn the
volume all the way up. If you have conventional,
passive tone controls, turn all tone and volume
controls all the way up.
5. Level and Master Volume settings:
Set the Master Volume to 12 o’clock. Turn the Input
volume up as you play. Try not to turn it past 1
o’clock unless you want an overdrive effect. If the
yellow clip light turns on, press the -14db button in.
If it is still on, try turning the volume down on your
400RB-IV Series
Sound Tips
The Equalizer:
The Equalizer is used to fine tune your sound. When
adjusting it, do it just a little at a time. These are
active circuits, and small changes can make a big
difference in your sound. With a little experimentation you will find that this equalizer is very easy to
use, never sounds weird and provides you with a large
variety of great sounds, unique to GK.
Turning up the Boost control, will add a little growl to
your tone. This is an unmistakable GK trade mark
sound, that you will grow to appreciate. Raising the
Boost while lowering the Master will add more growl
while keeping the sound level the same. Growl is
actually a small amount of even order harmonic
distortion, that sounds great through a woofer, but
horrible through a horn. For most playing situations,
the Master is set between 12 & 3 o’clock. The cleanest
sound is obtained by setting the Master above 12
o’clock, and going above 3 o’clock for maximum
power situations.
Increasing the Contour level will scoop out midrange frequencies while boosting the highs and lows.
The sound, once again, is unique to GK and unavailable on any other Bass amp. Lower contour settings
are recommended for midrange clarity at higher
playing levels. For 800RB voicing, set the contour
control either on 0 or 10 (Off, On on 800RB).
Direct Out:
The 400RB-IV provides a low noise, high quality
balanced direct out for connection to PA and recording consoles. With the Pre/Post EQ switch set to “Pre”
(Out), the direct output signal is fed directly from our
low noise, high headroom, FET input stage providing
a low noise output superior to external direct boxes
and impedance transformers. In addition, this output
is calibrated for 1.0V (0 dBV) output. With the switch
in the Pre position, the Direct Output signal is only
effected by the -14dB Pad and Tuning Mute controls.
This allows you to adjust your tone and volume on
stage without changing the Direct Output signal level
and confusing your sound man.
String Bass:
The way a Bass amp deals with the instrument low
string is a critical part of its sound. In fact, a five
string instrument requires an entirely different low
end response than a four string instrument. No
equalizer can make the necessary adjustments to
accommodate both. However, the String Bass button
on the 400RB-IV Series does just that. When it is out,
the 400RB-IV is voiced like the 800RB. Push it in and
the 400RB-IV is voiced for five string instruments. For
some playing styles you may want it in, even with a
four string instrument.
Changing the Pre/Post EQ switch to “Post” ( In),
sends the “GK sound” and preamp response to the
Direct Out jack. This gives you complete control over
the Direct Out’s tone and volume. In addition, a
Ground (Gnd) Lift switch is included to remove hum
and buzz when connecting to equipment powered by
a different ground system.
Sound Tips
The 400RB-IV Series has several unique features
which, if used properly, will obtain that sound you
have been searching for.
400RB-IV Series
Settings & Sounds
Settings and Sounds: 400RB-IV
The 400RB-IV is versatile in its sound and tone. Below
are a few suggested amp settings that can be used as
starting points to define your own sound.
* Contour note:
At higher playing levels the contour should be set lower for mid-range clarity.
To get 800RB voicing, the contour should be set to 0 or 10 only.
* VVoo l u m e n o t e :
Adjust volume before playing these recommended settings.
Both pickups recommended.
Both pickups recommended.
Front pickup recommended.
Both pickups recommended.
400RB-IV Series
When the unit gets dirty, clean only with a dry cloth.
Never use benzene, thinner, alcohol, or other volatile
cleaning agents. Do not use abrasive cleaners, as
they may damage the finish of metal parts. Avoid
spraying insecticides near the unit.
To insure proper operation and to avoid
potential safety hazards, place the unit on a
firm, level surface. When installing the unit
in a rack, be sure the mounting hardware can
support the amplifier’s weight. To save space
in your rack, the 400RB-IV’s feet can be
removed using a Philips head screw driver.
Make certain that proper space is provided for
ventilation. The 400RB-IV Series
requires at least ½ inch clearance above for
proper ventilation. Never block the fan vent
holes in the top or front of the amplifier. If
the amplifier will be installed in a rack or
other enclosed area, make sure that there is
sufficient air movement within the enclosure
to allow proper cooling. Consult your dealer
for more information.
Avoid installation in extremely hot or cold
locations, and areas that are exposed to direct
sunlight, or near heating equipment.
Avoid moist or humid locations.
Remember, power amplifiers generate heat.
The heat sink fins and ventilation slots that
form part of the enclosure are specially
designed to remove this heat. Placing other
electronic equipment near these heatdissipation systems may possibly affect the
long-term reliability of both your amplifier
and the other equipment.
Your new amplifier is rugged. It was built to give you
a lifetime of trouble-free operation, if it is operated in
accordance with the instructions contained in this
manual. The only maintenance required is cleaning.
If you are going to move your amplifier around
frequently, we recommend a road case to protect it
from scratches and road wear.
Moving the Unit:
Before moving the unit, be certain to disconnect any
interconnection cords with other components, and make
sure that you disconnect the unit from the AC outlet.
Installation & Maintenance
Installation and Maintenance
Front Panel Controls
400RB-IV Series
Front Panel Controls
Adds edge and definition to higher frequencies.
Active Equalization:
Boost and cut at 7 kHz +14dB shelving type. Add or
remove edge and definition.
8-High Mid:
Boost and cut at 1 kHz +6dB/ -10dB, “Q Optimized,”
band pass type. Works on lower string harmonics,
and effects the punch of your sound.
9-Low Mid:
Boost and cut at 250Hz +6dB/-10dB, “Q Optimized,”
band pass type. Works on the main body of your
Boost and cut at 60Hz +10dB, shelving type. Controls
low end push.
A post EQ gain stage using GIVE technology which
adds “growl” as it is turned up.
Controls the output level of the amplifier.
13-Effects Loop:
Send and return jacks provided for the insertion of
effects after the EQ, but before the boost section.
Some effect units have gain, turning the BOOST
down, will compensate for this.
14-Tuner Output
Output comes directly off the input stage and can be
patched to a tuner with a shielded patch cord. This
output is unaffected by the Tuning Mute Feature.
15-Power/Protect LED:
The LED is red at turn-on for five seconds while
the amp powers up. The LED turns blue when
the amp is ready to play. Should the amp
experience a fault (over heat, over current) the
amp will mute and this LED will switch to red
until the condition is corrected. This LED turns
off when the power switch is turned off.
16-Power Switch:
Turns the amplifier on or off. Should a problem
occur during operation press this switch out
first. This turns the amp off, but does not
completely disconnect the power from the AC
mains. The power LED should be off at this
1-Balanced Direct Out:
An electronically balanced output, that you can run
to your P.A. system.
This switch disconnects the ground on the balanced,
XLR output to eliminate hum and buzz when
connnecting to equipment that is running on a
different ground system.
Pre/Post EQ Button:
Selects the direct out signal before or after the EQ.
A standard ¼” input jack to plug in active or passive
basses using a shielded cord.
4- -14dB Pad:
Input attenuator button. The button is generally left
out, except in rare cases when the clip LED flashes.
This switch should be pressed if the CLIP LED stays on
continuously. It may be necessary to “pad” the input
if you are using a bass with active electronics or very
high output.
Clip LED:
LED lights yellow when the input stage is being
over-driven. If -14dB PAD is pressed and clip
LED still stays lit, turn down the volume on
your bass.
Tuning Mute Button:
Set this switch to “On” when tuning up. No signal
will be sent to the speakers, or the P.A. system.
Mute LED:
LED turns on when “Tuning Mute” is switched
to the “ON” position.
Sets pre-amp gain after the input stage. It is used in
conjunction with the input pad, to optimize the
amplifier’s headroom.
6-Voicing Filters:
4/5 String Bass:
Setting this button to the “ON” position, voices the
pre-amp for basses with “B” tuning (5 string bass).
Leaving it in the “Out” position will voice the amp
like the 800RB, for a 4 string bass.
Drops the mid-range frequencies while boosting lows
& highs.
400RB-IV Series
Rear Panel Controls
1- AC Receptacle:
The power cord is detachable and plugs in here.
2- 280W/180W Amp Only:
280W/180W power amp output for Full-Range
operation only. They deliver 280W/180W into 4
Ohms. Lower impedances should not be used.
Higher impedances such as 8 Ohms, 16 Ohms, or No
Load are acceptable. One 8 Ohm cabinet is okay. One
4 Ohm and one 8 Ohm is not recommended. No
damage will result from operating the amplifier with
the speakers disconnected.
Maximum Recommended Load:
One 4 Ohm or two 8 Ohm cabinets.
Rear Panel Controls
400RB-IV Series
400RB-IV Series Combos
The 400RB-IV Series combos deliver the 400RB-IV’s
unique features and distinct sound by using a variety
of internal speaker configurations, GK’s RBH cabinet
technology and a unique Lock N’ Roll transport
Speaker Configurations:
One 8 Ohm 15" speaker.
Two 16 Ohm 10" speakers
(wired in parallel for an 8
Ohm equivalent load).
The 400RB-IV combo electronics are identical to the
400RB-IV head and are rated for the same maximum
power output and speaker load (280W into 4 Ohms,
and 180W into 8 Ohms). Maximum power is achieved
by connecting one 8 Ohm extension cabinet (such as
the 210RBH, 410RBH, or 115RBH) in addition to the
combo’s internal 8 Ohm speaker load. To drive more
than one extension cabinet, the combo’s internal
speaker can be disconnected by unplugging the 1/4"
jack connected to the combo’s back panel. Below is a
detailed description of the maximum loads the
combos can drive.
Maximum recommended load with the
internal speaker connected:
One 8 Ohm cabinet.
Maximum recommended load with the internal
speaker disconnected:
One 4 Ohm, or Two 8 Ohm cabinets.
The 400RB-IV Series combos are designed for maximum setup versatility to accommodate a variety of
playing situations. For practicing and close monitoring situations, tilt the cabinet back into its “Rock
Back” position. For stronger bass and audience
projection, leave the combo in the upright posit
400RB-IV Series
Tech Talk
The 400RB-IV Series is a flexible, state-of-the-art Bass
Amplifier, designed to deliver maximum performance,
and be simple to operate. This is accomplished
through a few, very important features:
Extremely high current power supply and
power amp circuitry, gets the sound out of
your head.
Four, Bass specific bands of active
equalization for precise tone control.
Three voicing filters for shaping and
customizing your sound.
Balanced direct output with level control
eliminates need for a direct box.
Continuously variable fan cooling.
Standard tone controls and graphic equalizers give
you plenty of variation, but they don’t provide what
the instrument really needs. The fact is, graphic
equalizers are intended for room equalization. The
equalization in Gallien-Krueger amplifiers reflects 30
years of continuous development and refinement. The
GK equalizer is unique to the industry, it’s not just a
normal four band equalizer, each section is a special
circuit optimized to perform a Bass specific job in its
range of operation. These sections are wired in Series,
so they add to one another creating a tremendously
flexible equalizer, that doesn’t sound weird at any
setting. Now it is possible to obtain the sound you
Current Output & Bass Response:
When a power amplifier is pushing several speaker
cones, and a high-power transient like a string slap
comes along, the amp has to tap into a large power
reserve to maintain cone control. If the amplifier
doesn’t have this ability, the sound is unresponsive
and less out front. The amp loses it’s punch and feel
at higher playing levels. Instead of responding to
your every command, the amplifier simply cuts those
transients off, leaving you with the feeling that
something is missing in your sound.
Since most amplifiers have limited output current
capacity, they need “current limiting circuits” to
protect against self-destruction. High-power transients trigger these circuits, which rob the amplifier of
it’s ability to control speaker cones. This creates a
mushy, unresponsive feel to your sound.
The 400RB-IV Series has extremely high current
capacity, so it doesn’t need current limiting circuits
for over-load protection.
There is nothing in the 400RB-IV Series power amp to
come between you and your sound except faithful,
raw power.
Tech Talk
Characteristics of the 400RB-IV:
400RB-IV Series
Tech Talk
Tech Talk
Voicing Filters:
Cool Running = Reliability:
Voicing filters are used to completely re-voice the
amplifier. In the case of the Contour and String Bass
controls, the effect is dramatic.
The 400RB-IV Series uses a “dual rail power supply”
that generates about half the heat of conventional
amplifiers. Low output signals run off a low voltage
supply, and high level signals run off a high voltage
supply. This keeps the amp running a lot cooler and
makes it much more reliable. To cool the amp when
its being driven hard, we’ve designed a temperature
sensitive fan cooling system. When the amp is under
a light load, the fan is off or running at a low speed,
reducing fan noise. As the amp works harder, the fan
speed increases to keep everything cool.
The Contour is used to completely revoice the amplifier. The Contour control tunes between two different
shaping circuits, with greatly different response. With
the control all the way up, the low end is slightly
boosted, the mids are dropped and the high end is
pushed up. This is only found in GK amplifiers.
The way a Bass amp deals with the instrument low
string is a critical part of it’s sound. In fact, a five
string instrument requires an entirely different low
end response than a four string instrument. No
equalizer can make the necessary adjustments to
accommodate both, however the String Bass button
on the 400RB-IV Series does just that. When it is out,
the 400RB-IV is voiced like the 800RB. Push it in and
the 400RB-IV is voiced for five string instruments. For
some playing styles you may want it in, even with a
four string instrument.
Smart Protection Circuitry:
The 400RB-IV’s protection circuitry constantly
monitors for unsafe operating conditions such as
short circuits, miss-wired speaker cables, blown
speakers, improper ventilation, and incorrect speaker
configurations. In addition, protection is provided
during power up/down. If the 400RB-IV senses any
unsafe operating conditions, the output signal is
immediately muted and the power light changes from
Blue to Red. The amplifier will remain muted until
the fault is removed. If the protection circuit activates
while playing, turn the amplifier off and check the
amplifier speaker output connections. Be sure that
you are not exceeding the maximum recommend load
described in this manual. If the problem persists,
contact GK directly for technical advice.
Low Noise Operation:
The 400RB-IV Series uses a high gain, high headroom, low noise input stage. It has such a large
dynamic range (60v p-p) that very few instruments
can overdrive it. Even most basses with “active”
electronics do not need the input attenuator to be set.
The benefit to you is less hiss from your horn, and
over all, much less noise.
In Closing:
You should now have a thorough understanding of
how your new 400RB-IV Series amplifier works and
what advantages it can offer you in getting “your”
sound. We thank you for reading the Owner’s Manual
and wish you the best of times! Please send us your
comments via or email us at
“G.I.V.E.” Technology:
As in all GK pre-amps, the 400RB-IV Series pre-amp
incorporates what we call G.I.V.E (Gate Induced Valve
Effect) Technology. We use field effect devices with
the gate biased in a way that emphasizes the optimum
harmonic content of the signal. Working in concert
with our unique Four Band Active Equalizer, and
three stage Voicing Filter Section, G.I.V.E. technology
produces a consistently pleasing bass tone.
400RB-IV Series
Block Diagram
400RB-IV Series Specifications:
Output Power:
Amplifier Protection:
Full short circuit, thermal,& RF protection.
Stable into reactive and mismatched loads.
Five second muted warm-up.
180W @ 8 Ohms
280W @ 4 Ohms
Input Section:
Maximum Input Level
With -10dB pad
Input Impedance
Send output impedance
Return input impedance
Tuner Output Impedance
Direct Output Impedance
Dimensions (HxWxD):
3 1/2” x 17” x 8 ¼”
(2 Rack Spaces)
0.6V Rms
1.6V Rms
1M Ohm
220 Ohm
50k Ohm
10k Ohm
500 Ohms
Power Requirements:
700RB-II: 570W(full power), 210W(average power)
+10db @ 60Hz
+6db/-10db @ 250Hz
+6db/-10db @ 1kHz
+14db @ 7kHz
700RB-II: 570W(full power), 210W(average power)
Voicing Filters:
String Bass Button
700RB-II: 570W(full power), 210W(average power)
+2db@50Hz /
-10db@500Hz /
-90db referenced to 700W/480W,
“A” weighted
Continuously VariableSpeed Fan
700RB-II/1001RB-II Series
400RB-IV Series
Owner’s Manual
Part #160-0003-C
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