15
Installation
Connection of HELIX M FOUR to the head unit /
car radio:
Caution:
Carrying out the following steps will re-
quire special tools and technical knowledge. In or-
der to avoid connection mistakes and / or damage,
ask your dealer for assistance if you have any ques-
tions and follow all instructions in this manual (see
page 11). It is recommended that this unit will be
installed by an authorized HELIX dealer.
1. Connecting the lowlevel line inputs
Use the correct cable (RCA / Cinch cable) to
connect these inputs to the lowlevel line outputs
of your car radio. It is not mandatory to use all
lowlevel line inputs. If only two channels will be
connected we recommend to use the channels
A and B and set the
Input Mode
switch to “2CH”.
When all channels will be used please choose
switch position “4CH” (see page 14, item 6;
In-
put Mode
). The automatic turn-on circuit does
not work when using the lowlevel line inputs. In
this case the remote input (
REM
) has to be con-
nected to activate the HELIX M FOUR.
Important:
It is strictly forbidden to use the
Highlevel Input
and lowlevel
Line Input
at the
same time. This may cause severe damage to
the lowlevel line outputs of your car radio.
2. Connecting the highlevel speaker inputs
The highlevel loudspeaker inputs can be con
-
nected directly to the loudspeaker outputs of an
OEM or aftermarket radio using appropriate ca-
bles (loudspeaker cables with 1 mm² / AWG 18
max.).
We recommend the following channel assign-
ment:
Channel A = Front left
Channel B = Front right
Channel C = Rear left
Channel D = Rear right
Actually it is not mandatory to use all highlevel
speaker inputs. If only two channels will be con-
nected we recommend to use the channels A
and B and set the
Input Mode
switch to “2CH”.
When all channels will be used please choose
switch position “4CH” (see page 14, item 6;
In-
put Mode
).
Make sure that the polarity is correct. If one
or more connections have reversed polarity it
may affect the performance of the amplifier. If
this input is used the remote input (
REM
) does
not need to be connected as the amplifier will
automatically turn on once a loudspeaker signal
is applied.
3. Adjustment of the input sensitivity
Attention:
It is mandatory to properly adapt
the input sensitivity of the M FOUR to the
signal source in order to avoid damage to
the amplifier.
If you want to change the input sensitivity of the
channel pairs use the two
Input
Level
controls
(see page 13, item 3;
Input Level
). The settings
of the controls affect both the lowlevel line in
-
puts (
Line Input
) and the highlevel speaker in
-
puts (
Highlevel Input
)! If the
Highlevel Input
is
used in combination with a standard car radio
we recommend an input sensitivity of roughly
9 Volts. For this purpose, turn the control from
max. CCW position to 9 o’clock position.
4. Connection to power supply
Make sure to disconnect the battery before
installing the HELIX M FOUR!
Connect the +12 V power cable to the positive
terminal of the battery. The positive wire from
the battery to the amplifier power terminals
needs to have an inline fuse at a distance of
less than 12 inches (30 cm) from the battery.
The value of the fuse is calculated from the
maximum total current draw of the whole car
audio system (M FOUR = max. 60 A RMS at
12 V power supply). If your power wires are
short (less than 1 m / 40”) then a wire gauge of
10 mm² / AWG 8 will be sufficient. In all other
cases we strongly recommend gauges of 16 -
25 mm² / AWG 6 – 4!
The ground cable (same gauge as the +12 V
wire) should be connected to a common ground
reference point (this is located where the neg-
ative terminal of the battery is grounded to the
metal body of the vehicle), or to a prepared met
-
al location on the vehicle chassis, i.e. an area
which has been cleaned of all paint residues.
5. Connecting the remote input
The remote input (
REM
) has to be connected
