400RB-IV Series
Tech Talk
Voicing Filters:Cool Running = Reliability:
Voicing filters are used to completely re-voice theThe 400RB-IV Series uses a ?dual rail power supply?
amplifier. In the case of the Contour and String Bassthat generates about half the heat of conventional
controls, the effect is dramatic.amplifiers. Low output signals run off a low voltage
supply, and high level signals run off a high voltage
The Contour is used to completely revoice the ampli-supply. This keeps the amp running a lot cooler and
fier. The Contour control tunes between two differentmakes it much more reliable. To cool the amp when
shaping circuits, with greatly different response. Withits being driven hard, we?ve designed a temperature
Tech Talkthe control all the way up, the low end is slightlysensitive fan cooling system. When the amp is under
boosted, the mids are dropped and the high end isa light load, the fan is off or running at a low speed,
pushed up. This is only found in GK amplifiers.reducing fan noise. As the amp works harder, the fan
speed increases to keep everything cool.
The way a Bass amp deals with the instrument low
string is a critical part of it?s sound. In fact, a fiveSmart Protection Circuitry:
string instrument requires an entirely different lowThe 400RB-IV?s protection circuitry constantly
end response than a four string instrument. Nomonitors for unsafe operating conditions such as
equalizer can make the necessary adjustments toshort circuits, miss-wired speaker cables, blown
accommodate both, however the String Bass buttonspeakers, improper ventilation, and incorrect speaker
on the 400RB-IV Series does just that. When it is out,configurations. In addition, protection is provided
the 400RB-IV is voiced like the 800RB. Push it in andduring power up/down. If the 400RB-IV senses any
the 400RB-IV is voiced for five string instruments. Forunsafe operating conditions, the output signal is
some playing styles you may want it in, even with aimmediately muted and the power light changes from
four string instrument.Blue to Red. The amplifier will remain muted until
the fault is removed. If the protection circuit activates
Low Noise Operation:while playing, turn the amplifier off and check the
The 400RB-IV Series uses a high gain, high head-amplifier speaker output connections. Be sure that
room, low noise input stage. It has such a largeyou are not exceeding the maximum recommend load
dynamic range (60v p-p) that very few instrumentsdescribed in this manual. If the problem persists,
can overdrive it. Even most basses with ?active?contact GK directly for technical advice.
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
?G.I.V.E.? Technology:how your new 400RB-IV Series amplifier works and
As in all GK pre-amps, the 400RB-IV Series pre-ampwhat advantages it can offer you in getting ?your?
incorporates what we call G.I.V.E (Gate Induced Valvesound. We thank you for reading the Owner?s Manual
Effect) Technology. We use field effect devices withand wish you the best of times! Please send us your
the gate biased in a way that emphasizes the optimumcomments via www.gallien-krueger.com or email us at
harmonic content of the signal. Working in
[email protected].
with our unique Four Band Active Equalizer, and
three stage Voicing Filter Section, G.I.V.E. technology
produces a consistently pleasing bass tone.
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ACEC
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