User guide

ABH120C Combo and ABH180H Head Features and Controls
INPUT
– Mono !” Jack socket for instrument input. Use a
properly screened “guitar” cable for interconnection. There
are many different makes of guitar cable available, ranging
from fairly inexpensive to very expensive. Each have
different characteristics, and depending on your particular
guitar will give different results, so experimentation and
help from your dealer is the best advice we can give.
-10dB INPUT PAD
– normally the input jack connects
GLUHFWO\WRWKHLQSXWJULGRIWKH¿UVWYDOYHDPSOLI\LQJVWDJH
DW KLJKLPSHGDQFH 0HJRKP 7KLV LV WKH VZLWFKRXW
position, and is suitable for most purposes. However,
in the case of high output active guitars and preamps,
the signal level may be too high for the input stage to
handle without distorting. By pressing the -10dB PAD
VZLWFK ,1WKHLQSXWFLUFXLWLV UHFRQ¿JXUHGWRDDWWHQXDWH
WKH LQFRPLQJ VLJQDO E\G% DQGE DGMXVW WKH LQSXW
impedance to a more suitable value for active guitars
DSSUR[.RKP
INPUT GAIN
– this control determines the amount of
VLJQDOWKDWWKH¿UVWDPSOL¿HUJDLQVWDJHOHWVWKURXJKWRWKH
rest of the amplifier. It is pretty straightforward in use –
lower settings are clean – high mid settings are in the start
of distortion range – and high settings are in the overdrive
range.
OUTPUT VOLUME
– this quite simply controls the
output of the preamp, giving you the required sound level
and balance that you require.
4
INSTRUMENT INPUT STAGE
EQ CONTOUR EXPANSION SWITCHES
±WKH(4
system of the
ABH
bass system is very wide ranging
and very versatile in its own right, but the use of the four
expansion pushswitches opens up even more possibilities.
EQUALISATION STAGE
LOW BOOST
– conversely the Low Boost switch
UHFRQ¿JXUHVWKH LQSXWVWDJHFLUFXLWWRERRVW WKHYHU\ORZ
frequencies in a very warm and musical way.
HIGH BOOST
– as its name implies this switch boosts
the high frequencies adding great “presence” and “cut”
required for modern bass playing styles. It adds “snap”
without adding harshness.
BASS & TREBLE EQ ROTARY CONTROLS
–
DOWKRXJKWKH7UHEOHDQGEDVV(4FLUFXLWLVYDOYHGULYHQLW
LVRIWKHFXWDQGERRVWYDULHW\DQGWKHUHIRUHLVÀDWLQWKH
mid position.
MIDDLE EQ & RANGE CONTROLS
– as stated
earlier the Middle circuit is after the valve preamp, and
again is of the cut and boost variety. The Range control
continuously varies the Mid centre frequency between
200Hz, and 2kHz. Because it is independent of the Treble
and Bass circuits, even bigger variations in how the
middle frequencies react are possible.
DI OUTPUT LEVEL
– This rotary control gives an
independent output level for the DI output.
DI FEED PRE/POST SWITCH
– This push-switch
connects the DI circuit to either run in parallel with the
DPSOLILHU LQSXW FLUFXLW 35(RU LVIHG IURP WKH SRZHU
amplifier output derived from the speaker connection
3267
GROUND LIFT SWITCH
– This switch lifts the DI
socket ground connection from direct ground connection
to be higher impedance. This is used to eliminate any
mains ground hum that could be generated between the
DPSOL¿HUDQGRWKHUPDLQVFRQQHFWHGHTXLSPHQWVXFKDV
a mixing desk.
series
ABH120C ABH180H & BLS1215
Front Panel
ABH120C ABH180H & BLS1215 User m4 4 2011-4-21 17:32:09