1 Power/Protect LED
The Power/Protect LED indicates the operating state
of the amplifier. A green LED shows that the amplifier is
ready for operation.
A red LED indicates that a malfunction has occurred.
A malfunction may have different causes as the HELIX B
FOUR is equipped with different protective circuits. These
protections shut off the amplifier in case of overheating,
over- and undervoltage, short-circuit on loudspeakers,
low impedance and false connection.
Please check for connecting failures such as short-cir-
cuits, wrong connections, wrong adjustments and over-
temperature. If the amplifier does not turn on it is defect
and has to be send to your local authorized dealer for
repair service. A detailed description of the malfunction
and the purchase receipt has to be attached.
2 Connecting the ground cable
The ground cable should be connected to a central
ground reference point (this is located where the negative
terminal of the battery is grounded at the metal body of the
vehicle), or to a bright bare-metal location on the vehicle
chassis, i.e. an area which has been cleaned of all paint
residues. Recommended cross section: min. 12 mm
2
.
3 Connecting the remote lead
The remote lead should be connected to the automatic
antenna (aerial positive) output of the head unit (radio).
This is only activated if the head unit is switched ON. Thus
the amplifier is switched on and off with the head unit.
4 Connecting the battery cable
Connect the +12 V power cable to the positive terminal of
the battery. Recommended cross section: min. 12 mm
2
.
5 Fuses
The input fuses are connected in parallel and provide pro-
tection against an internal equipment fault, i.e. the system
must be additionally protected by a further line fuse
located in the vicinity of the battery (max. distance from
battery: 30 cm / 12"). The fuse value for the HELIX B FOUR
is 2 x 25 Amperes.
6 Speaker terminals
To connect the speaker cables. See figures on next page.
Never connect the loudspeaker cables with the car chassis
ground. It damages your amplifier. Ensure that the loudspea-
ker systems are correctly connected (phase), i.e. plus to plus
and minus to minus. Exchanging plus and minus causes a
total loss of bass reproduction. The plus pole is indicated on
most speakers.
The impedance per channel should not be lower than
2 Ohms. In this case the protection electronics shut down
the amplifier.
7 Signal inputs
The HELIX B FOUR is equipped with four RCA inputs. They
can be connected with the pre-amplifier outputs / line out-
puts of the control device (head unit, processor etc.).
Please consider that all four RCA inputs must be connec-
ted to make sure that all four channels of the amplifier can
be operated. If your head unit only provides two outputs, a
RCA Y-adapter can be used.
8 Highlevel speaker input
The HELIX B FOUR is equipped with four extra highlevel
speaker inputs. They can be directly connected to the
speaker outputs of the head unit.
We recommend to operate the highlevel input only
with the enclosed connecting cable or with a HELIX wire
harness (optional).
9 Level controls for input sensitivity
These controls can be used to match the input sensitivity
of the individual channels to the output voltage of the con-
nected head unit. These controls are not volume controls
and are solely intended for the purpose of sensitivity trim-
ming. The control range extends from 200 mV to 6 V.
10 Bass-Boost control
To raise the bass signal from 0 to 18 dB at 45 Hz.
11 Highpass control
To adjust the crossover frequency from 15 Hz to 4000 Hz.
Hz
5K
2K
15 Hz
4 kHz
variabel
0 dB
18 dB
500
45
100
200
300
20
30
variabel
Hz
dB
