HELIX M FOUR Instruction Manual page 13

Initial start-up and functions
1 Line Input
4-channel lowlevel line input to connect signal
sourc es such as head units / radios / DSPs.
Important: It is strictly forbidden to use the High-
level Input and lowlevel Line Input at the same time.
This may cause severe damage to the lowlevel line
outputs of your head unit / car radio.
2 Highlevel Input
4-channel highlevel loudspeaker input to connect
the amplifier directly to the loudspeaker outputs of
OEM / aftermarket radios that do not have any low-
level line outputs.
The Highlevel Input is equipped with our proprietary
ADEP circuit (Advanced Diagnostics Error Protec-
tion) which ensures that the car radio detects the
amplifier as a speaker and thus neither any function
of the radio (e.g. fader) will be deactivated nor any
error log in the CPU of the car will be created.
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.
Attention: Solely use the pluggable screw-terminal
for the highlevel connector which is included in de-
livery!
Important: It is strictly forbidden to use the High-
level Input and lowlevel Line Input at the same time.
This may cause severe damage to the lowlevel line
outputs of your car radio.
3 Input Level
These controls are used to adapt the input sensi-
tivity of the channel pairs A/B and C/D to the output
voltage of the connected signal source.
This is not a volume control, it´s only for adjusting
the amplifier gain. The control range of the RCA /
Line Input (lowlevel) is 0.5 - 6 Volts and 1.3 - 13 Volts
for the Highlevel Input. If the Highlevel Input is used
in combination with a standard car radio we recom-
mend an input sensitivity of roughly 9 Volts. For this
purpose, turn the control from max. CCW position to
9 o'clock position.
4 HPF
This control is used to adjust the crossover frequency
of the highpass filter from 15 Hz to 4,000 Hz. This
control is activated if the X-Over switch of the spe-
cific channel pair is set to HPF (highpass filter). On
channel pair C/D it is also activated in LPF / Band-
pass and its adjustment is mandatory.
5 X-Over
This switch allows to set the internal crossover to
highpass, fullrange or lowpass / bandpass mode.
The filter options depend on the channel pair.
Channel pair A/B: Highpass filter or fullrange
If this X-Over switch is set to HPF (highpass filter)
the crossover frequency for the highpass can be ad-
justed with control 4 of the channel pair A/B.
At switch position FULL (fullrange) the crossover is
bypassed.
Channel pair C/D: Highpass filter, fullrange or low-
pass filter / bandpass.
If this X-Over switch is set to HPF (highpass filter)
the crossover frequency for the highpass can be
adjusted with control 4 of the channel pair C/D. At
switch position FULL (fullrange) the crossover is
bypassed.
At switch position LPF (lowpass filter / bandpass)
the highpass is always active. That means a band-
pass is created in any case.
By adjusting the highpass (control 4) and lowpass
(control 7) filter any bandpass between 15 Hz and
4,000 Hz can be realized.
Caution: To avoid a loss of gain make sure that
the crossover frequencies of the high- and lowpass
filters do have an interval of at least two octaves
when generating a bandpass.
That means if the lowpass signal is adjusted to
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