19
Installation
Connection of HELIX C 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 13). 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 head unit / car radio. It is not mandatory
to use all lowlevel line inputs. If only two chan
-
nels will be connected we recommend to use
the channels A and B and set the
Input Mode
switch
to “2-CH”. When all channels will be
used please choose switch position “4-CH” (see
page 17, item 12;
Input Mode switch
).
2. Connecting a digital signal source
If you have installed the HELIX Digital Input
Module HDM 2 and have a signal source with
an optical digital output you can connect it di-
rectly to the amplifier using the appropriate in
-
put.
It is not mandatory to use both digital inputs.
If only one digital input will be connected we
recommend to use the input of the channel pair
A / B and set the
Input Mode switch
to “2-CH”.
When both inputs will be used please choose
switch position “4-CH” (see page 17, item 12;
Input Mode switch
).
Important:
The signal of a digital audio source
normally does not contain any information
about the volume level. Keep in mind that this
will lead to full level on the outputs of the HELIX
C FOUR. This may cause severe damage to
your speakers. We strongly recommend to only
use volume controlled audio sources!
Information:
The C FOUR can only handle
uncompressed digital stereo signals in PCM
format with a sample rate between 28 kHz and
96 kHz and no MP3- or Dolby-coded signals.
3. Configuration of the digital signal input
If you have installed the HELIX Digital Input
Module HDM 2 and connected a digital signal
source you have the possibility to route the dig
-
ital signal of the individual channel pairs directly
and loss-free from the integrated DA convert
-
er to the respective internal power amplifier.
To activate the direct signal routing you have
to change the position of the respective
SPDIF
Direct In switch
to “On” (see page 16, item 2)
as well as the position of the
X-Over switch
to
“FULLRANGE” (see page 18, item 16).
Note:
These switches only affect the signal
routing of the optical inputs-.
4. Adjustment of the input sensitivity
Attention:
It is mandatory to properly adapt
the input sensitivity of the C FOUR to the
signal source in order to avoid damage to
the amplifier.
If you want to change the input sensitivity of the
individual channels use the four
Level controls
(see page 17, item 10;
Level controls
).
5. Connection to power supply
Make sure to disconnect the battery before
installing the HELIX C 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 (C FOUR = max. 90 A RMS at
12 V power supply). If your power wires are
short (less than 1 m / 40”) then a wire gauge of
16 mm² / AWG 6 will be sufficient. In all other
cases we strongly recommend gauges of 25 -
35 mm² / AWG 4 – 2!
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.
