HELIX M FOUR DSP Manual page 29

mandatory to connect the remote input (REM).
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
M FOUR DSP and your connected amplifiers.
This may cause severe damage to your
speakers. We strongly recommend to use an
optional remote control for adjusting the volume
level of the digital signal input!
Information: The HELIX M FOUR DSP can
only handle uncompressed digital stereo
signals in PCM format with a sample rate be-
tween 12 kHz and 96 kHz and no Dolby-coded
digital audio stream!
4. Connection to power supply
Make sure to disconnect the battery before
installing the HELIX M FOUR DSP!
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 DSP = max. 45 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
metal location on the vehicle chassis, i.e. an
area which has been cleaned of all paint res-
idues.
5. Connecting the remote input
The remote input (REM) has to be connected to
the radio remote output if the amplifiers lowlevel
Line Inputs or the Optical Input is solely / are
used as signal input/s. We do not recommend
controlling the remote input via the ignition
switch to avoid pop noise during turn on / off.
If the Highlevel Input is used this input does not
need to be connected as long as the car radio
has BTL output stages.
6. Configuration of the remote input
The M FOUR DSP will be turned on automati-
cally if the Highlevel Input is used or if a signal is
applied to the remote input terminal (REM). The
Auto Remote switch (page 26, item 10) allows
to deactivate the automatic turn-on feature of
the highlevel inputs.
The feature should be deactivated (Auto Re-
mote = Off) if there are e.g. noises while switch-
ing on / off the amplifier.
Note: If the automatic turn-on function is deac-
tivated it is mandatory to use the remote input
terminal to power up the amplifier! The high-
level signal will be ignored in this case.
Note: The automatic turn-on feature of the
highlevel inputs is activated ex works.
7. Configuration of the internal DSP
The general DSP settings should be con-
ducted with the DSP PC-Tool software be-
fore using the amplifier for the first time.
Ignoring this advice may result in damaging the
connected amplifiers / loudspeakers. Informa-
tion about connecting the M FOUR DSP to a
computer can be found on page 33.
8. Adjustment of the input sensitivity
Attention: It is mandatory to properly adapt
the input sensitivity of the M FOUR DSP to
the signal source in order to avoid damage
to the amplifier.
If you want to change the input sensitivity use
the "Input Gain" menu of the DSP PC-Tool soft-
ware.
The factory setting of the input sensitivity is
20 Volts for the Highlevel and 4 Volts for the
lowlevel Line Inputs. Only if the head unit / car
radio doesn ́ t deliver enough output level, the
input sensitivity should be increased carefully.
The "Input Gain" function can be found in the
"Signal Management" tab of the DCM menu of
the DSP PC-Tool software : "Main Input → Input
Gain".
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