Hughes & Kettner BASSBASE 250 User manual

.:. :
BASSBASE 250
BASS AMPLIFIER / COMBO AMPLIFIER
Hughes &Kettner Musical Instruments GmbH Magdeburgerstr.6 6690 St.Wendel
Telefon
( 0 6851) 20 21
Telefax ( 0 68 51)4886

Congratulations on your choice,
the Hughes
& Kettner BassBase 250!
The BassBase 250 was designed by a group of musicians and technicians to
meet the needs of the professional bass player.
Superb tonal characteristics and sophisticated features define the Bassbase 250 as
a professional bass amplification system. Both the compact, easily transportable
combo and the elegant head versions of the Bassbase
250 are at home on stage and,
thanks to sophisticated signal routing possibilities, in the studio.
The Basebass 250 is available as a combo or an amp head. The amplifiers are
identical in both versions, with the exception that the combo comes with a speaker.
Sound quality through tube technology.
The Bassbase 250’s preamp is constructed utilizing the classic ECC 83 tube. This
tube is responsible for a lively, dynamic bass tone through it’s innate compression
characteristics and carefully dosed upper frequency range. The basic tone of tube
technology is most convincing; from a dark warm jazz tone through to an articulate,
punchy rock sound, down to the high attack of funk, the
Bassbase 250 can do it all.
Carefully balanced tone controls with a parametric midrange.
The four tone controls enable you to quickly and efficiently dial in your own basic
tonal characteristics and allow for dramatic modifications to suit your needs. The
midrange of the musical spectrum is paramount to a good baas sound therefore,
the
Bassbase 250’s midrange can be adjusted parametrically.
250 Watts of dynamic power with "DynaClip".
Bass amplification demands a great deal of power. The explosive dynamics created
when you play with a heavy attack drive conventional bass amps to the limits of
clean sound reproduction. Annoying distortion, apart from endangering the speakers,
restricts the output potential. The Bassbase 250’s newly developed "DYNACLIP"
circuitry suppresses the distortion created through dynamic peaks without limiting
the dynamic spectrum.
1

Specially developed 10” speakers in the combo version.
Two speakers developed specifically for the Bassbase 250 ensure a powerful,
percussive reproduction of the amp’s output, replete with precise transient response.
Additional tweeter for upper frequency response.
An additional tweeter provides transparent highs and accurate harmonic
reproduction.
Ergonomic, back lit front panel controls.
The front panel controls are- arranged for maximum accessibility and simplicity.
Potentiometers, function permitting, are center notched for a “memory effect”.
Back lighting provides for visibility on even the darkest stages.
The
Bassbase 250 was engineered to provide you with the opportunity to
comfortably create your personal sound. This manual will give you some insights
into the
Bassbase and familiarize you with it’s features, enabling you to do just
that.
Have fun with your Bassbase 2501
2

3
FRONT PANEL CONTROL FEATURES
(1) INPUTS:
The Bassbase has two input jacks with different input sensitivities to accommodate
basses with passive as well as active electronics. LO INPUT is designed for active
basses with active pickups. HI INPUT has a higher sensitivity rating for the more
traditional passive pickups.
(2) TUNER:
Directly above the two input jacks you will find the TUNER jack. This jack is
suitable for sending a signal to an external tuning device. Connect the TUNER jack
to the external tuning device’s INPUT jack.
(3) MUTE:
The MUTE switch silences the Bassbase. When the MUTE is activated (MUTE
LED illuminates), no signal is sent to the power amp/ Line out/ PA out; only the
TUNER jack receives the signal.
The MUTE function is especially convenient for silent tuning between songs or sets
when it is less than desirable to have audience participation. MUTE is also recom-
mended when switching the power off, changing instruments, etc.
(4) GAIN:
The Bassbase’s preamp is constructed with tube circuitry, lending the amp a
dynamic, warm sound typical of classic tube technology. The GAIN control sets
the preamp’s input sensitivity and fine-tunes it to the instrument’s output.
Higher GAIN settings add a nuance of overdrive and harmonic distortion.
The intensity of the compression effect inherent in tube amplification is also
adjusted with the GAIN control.
PLEASE NOTE: Tubes need to reach a minimum operating temperature; a few
seconds delay between turning the power on and reaching operational readiness are
the norm with the Hughes
& Kettner BASSBASE 250.

TUNER MUTE
@ & GAIN BASS FREQ-MIDiLEVEL TREBLE FX- MIX MASTER B /;,_
LO - *I HI
00
El3
Q@
Q Mi
BASSBASE 250
(1) (2) (3) (4) (5) (6) (7) (8)
(9) (10)(11/13/14)(12) (15) (16)
THE BASSBASE 250'S TONE CONTROLS
The BASSBASE's tone controls are designed to produce dramatic changes in the
tonal spectrum by using only the essential control features. A minimum of effort by
you, the player, can achieve maximum effect.
(5) BASS:
The BASS pot adjusts the lower frequency range and specifically influences the
frequency response of the low B, E and A strings. The center position is neutral; turn
the pot to the right to increase the low end, to the left to decrease it. The adjustment
values are approximately +/- 15db. The center frequency is
90hz.
MID - THE PARAMETRIC MID CONTROL
The Bassbase 250’s mid-range control is semi-parametric, allowing you to freely
choose the frequency range which you want to influence. The semi-parametric tone
control has two pots, one to determine the frequency range that is to be adjusted, and
the other to increase or decrease said frequencies. This allows the mid-range to be
custom tailored to your personal tastes.
(6) FREQ:
This pot dials in the frequency you want to adjust; app. 2000 bz rotated completely
right and 140
hz at the far left position.
(7) LEVEL:
Determines the amount of boost or taper to the frequency you have dialed in with the
FREQ pot. The control range is +/-15 db.
The parametric tone control enables you to adjust the entire mid-range spectrum. The
mid-range is the most essential indegredient in a good bass sound, the entire tonal
character is determined in this frequency range. We advise you to familiarize
yourself with the variety of tones the FREQ and LEVEL controls have to offer and
experiment with these pots to hear all the possibilities.

(8) TREBLE:
The TREBLE pot adjusts the high frequency through a wide band and determines
the amount of bite and harmonics. The center frequency is app. 8khz.
(9) FX-MIX:
The Bassbase 250 is equipped with an effects loop switched in parallel for
external effects devices. Conventional effects loops, switched in series, send the
entire signal through the effects device, whereas the Bassbase’s FX-MIX pot
allows you to determine the precise amount of the original signal you want to
send through an effects device.
FX-MIX: The far left position allows none of the signal to be sent down the
effects loop path. Rotate the pot to the far right, and the entire signal is sent for
processing. (The effects path functions now in the same fashion as in a
conventional effects loop).
NOTE: If you choose not to connect an external effects device, ensure the
FX-MIX pot is rotated completely left!
The effects loop can be switched on and off via a footswitch.
(10) MASTER VOLUME:
controls the overall volume of the BASSBASE 250.
(11) DYNACUP:
A control LED illuminates when DYNACLIP is operational.
DYNACLIP is a power amp circuit that was developed exclusively for the
BASSBASE. It efficiently suppresses power amp clipping without sacrificing
peak dynamics, as opposed to peak limiters. Unpleasant and potentially speaker
damaging distortion is avoided and the effective power output is increased.
(12) BAL.PA OUT:
This XLR output jack sends a transformer balanced signal to feed a PA board.
(13) DIRECT:
Depress the DIRECT switch to bypass Gain, tone controls and the effects
loop to send an instrument signal via BAL.PA OUT.

(14) GROUND:
Depress the GROUND (LIFT) switch to sever the ground between BAL.PA OUT
and the PA board. Choose the position that
has the least amount of audible noise.
(15) PHONES:
Headphone jack. Connect headphones here for silent practice sessions. if the
PHONES jack is used, the speaker in the combo version is automatically dis-
engaged.
(16) MAINS: .
Main power supply switch. The front panel inscriptions will illuminate at the
ON position.
REAR PANEL FEATURES AND FUNCTIONS
Located on the BASSBASE 250’s rear panel, you will find the AC power supply
socket for the factory supplied Euro-mains lead. Integrated into the AC power supply
socket is the FUSE bracket.
In order to change a fuse, depress the fittings on both sides of the bracket and pull
the fuse out. The appropriate fuse amperage for each model can be determined by
reading the value annotated below the fuse bracket.
VOLTAGE SELECTOR:
All European models can be adjusted to operate at 220V or 240V. Rotate the insert
in the fuse bracket to the desired position. The correct voltage is determined by the
number visible in the upper region of the fuse bracket. Ensure this number
corresponds to the voltage specifications of your country. Also ensure that the fuse
bracket is completely secure after changing a fuse or adjusting the voltage.
SPEAKER
This speaker jack is suitable for connecting an external speaker. The combo
model’s speakers are factory connected to this jack. The Bassbase’s speaker
combination was designed to take advantage of the amp’s maximum output; thus the
overall impedance of 4 ohms. External speakers for the combo version should be
used as an alternative, not an addition
.W
6

The BASSBASE's power output is 180W at 8 ohms, 250W at 4 ohms.The
DYNACLIP circuitry increases the effective power output by about 25%. Do not
connect any speaker combination with an overall impedance of less than 4
ohms.
COOLING DEVICE:
Please note that the cooling device heats up considerably, especially after extended
sessions at peak power. Ensure that there is plenty of space behind the amp to allow
for adequate air circulation.
LINE OUT:
The LINE OUT jack is used to drive additional power amps.
FX-LOOP:
The FX-LOOP jacks are suitable for connecting an external effects device. The
processed signal is mixed with the original via the FX-MIX pot on the front panel.
Connect SEND to the effects device’s INPUT and RETURN to the effects device’s
OUTPUT
The voltage level of the FX-LOOP can be adjusted with the -10db switch from
1v down to 300mV in or&r to accommodate different types of effects devices.
NOTE: If you don’t connect an effects device, the RETURN jack can be used to
connect an additional instrument (guitar, bass, keyboards) or another signal source
(drum machine, tape recorder, etc.). The volume of this second signal source is
regulated with the FX-MIX
pot.
FX FOOTSW ITC H
The EFFECTS LOOP can be switched on and off with a footswitch connected to
the FX FOOTSWITCH jack.
NOTE: If no effects device is used, the FX FOOTSWITCH can be used to
switch from one master volume to another.
n Use the connected footswitch to turn the FX LOOP off.
n The volume is now regulated with the MASTER VOLUME pot. =

n Now turn the FX LOOP back on via the footswitch.
n The second master volume is regulated with the FX MIX pot on the front panel.
n You can now switch back and forth between two seperate master volumes.
CARE OF YOUR AMP AND WARRANTY CONDITIONS
A WORD ABOUT VALVES
n Valves need to reach a certain operating temperature. They need a few seconds
after the power has been switched on to warm up before they will work.
n Valves are sensitive to shock. Once you have switched the amplifier off, give it a
few minutes to cool down before transporting it.
n The sound characteristics of valves will also tend to change with time.
Occasionally, they will need replacing. The ECC 83 valve used in the BASSBASE is
one of the most commonly used, and the most affordable. Generally speaking, a
change of valves is only necessary every few years.
Before opening the amplifier casing, ALWAYS remove the mains plug!
WHERE TO USE THE AMPLIFIER
do not use the unit under following conditions:
n extremes of temperature or high humidity
n poor ventilation or insufficient cooling
n extreme vibrations or impacts
SERVICING AND REPAIRS
if your amplifier suffers a failure or fault, refer the matter to your authorised Hughes
& Kettner dealer. Do not try to rectify the problem yourself; servicing and repairs
are jobs for experts. Please note: any interference with the amplifier by unauthorised
persons or workshops will render your guarantee invalid.
every Hughes
& Kettner product is accompanied by a warranty card showing its
serial number and a card showing proof of inspection.
8

BASSBASE 250 SIGNAL ROUTING
I
\
J’
FOOTSWITCH M FOOTSWlTCH
(FX ON/OFF)
w EXTERNAL
SPEAKER CAB.
0
0
(01
0
II;
0
0
TUNER
-w TUNER INPUT
PHONES
M PHONES
FX-SEND
-b FX-INPUT
FX-RETURN a- FX-OUTPUT
SPEARER
LINE OUT
BALANCED
PA-OUT
-w EXTERNAL
POWER AMP &
CASINETD
SlGNAL FOR PA
APPLKATIONS
n
0
0
0
SIGNAL FOR
RECORDING
/
STUDlO
APPLKATIONS