HELIX DSP PRO MK2 Manual page 20

Installation
Connection of HELIX DSP PRO MK2 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 15). It is recommended that the device will be
installed by an authorized HELIX dealer.
1. Connecting the pre-amplifier inputs
Use the correct cable (RCA / cinch cable)
to connect these inputs to the pre-amplifi-
er / lowlev el / cinch outputs of your car radio.
Each input can be assigned to any output us-
ing the DSP PC-Tool software. The automatic
turn-on circuit does not work when using the
pre-amplifier inputs. In this case the remote in-
put has to be connected to activate the HELIX
DSP PRO MK2.
Important: It is strictly forbidden to use the
Highlevel Input and pre-amplifier inputs (Line
Input) at the same time. This may cause severe
damage to the pre-amplifier 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
assignment if a common car radio will be con-
nected to the signal processor:
Channel A = Front left
Channel B = Front right
Channel C = Rear left
Channel D = Rear right
Actually it is not mandatory to use all high level
speaker inputs. If only two channels will be con-
nected we recommend to use the channels A
and B. Make sure that the polarity is correct. If
one or more connections have reversed polar-
ity it may affect the performance of the signal
processor. If this input is used the remote input
does not need to be connected as the signal
processor will automatically turn on once a
loudspeaker signal is received.
20
3. Adjustment of the input sensitivity
Attention: It is mandatory to properly adapt
the input sensitivity of the DSP PRO MK2 to
the signal source in order to avoid damage
to the signal processor.
If you want to change the input sensitivity you
have to open the device at first. Dismantle the
side panel where the USB input is located by
removing the five Phillips screws and pull out
the bottom plate sideways. Now you have ac-
cess to the eight trim potentiometers that allow
adjusting each channel individually. The assign-
ment of the trim pots to the respective channels
is shown in figure 1 on page 19.
Please note: The setting of the trim potentiom-
eters affects both the lowlevel and the highlevel
inputs!
If the sensitivity range of the highlevel input may
not be sufficient it is possible to change it by re-
positioning a jumper (see figure 2 on page 19).
The sensitivity range of the two pre-amplifier in-
puts G and H can also be changed to connect
even mobile devices with significantly lower
output voltage (like smartphones) by reposition-
ing a further jumper (see figure 3 on page 19).
Important: To change the position of a jumper it
has to be removed by pulling it straight upwards
and plugged into the desired position. Make
sure that the jumper is reinserted properly and
all pins are fully inserted. The position of each
jumper can be changed independently.
Follow the subsequent steps to perfectly adapt
the signal processors input sensitivity to your
audio source by using the internal trim poten-
tiometers:
1. Don't connect any amplifiers to the outputs
of the HELIX DSP PRO MK2 during this
setup.
2. Turn on the signal processor.
3. Adjust the volume of your radio to approx.
90 % of the max. volume and playback an
1 kHz full scale test tone (0 dB) via CD drive.
4. The adjustment will be easier when you con-
nect and adjust one input channel after the
other.
5. If the Clipping LED already lights up, you
have to reduce the input sensitivity via the
respective trim potentiometer until the LED
turns off.