Adjusting The Input Sensitivity - HELIX C-DSP Competition Manual

Adjusting the input sensitivity

The input sensitivity of the line and highlevel inputs can be adjusted separately for each channel pair. The
potentiometers for adjusting the input sensitivity are on top of the C-DSP.
Each control knob is assigned to one channel pair, f.g. the first control on the left adjusts the sensitivity
for input channel A and B, second for C and D and so on. This counts for the line inputs as well as for the
high level inputs. The adjustment range of the line input is 1,8 - 6 Volts and of the high level input 6 - 20
Volts.
Before you begin with the adjustment turn all controls to left stop.
To adjust the input sensitivity to your signal source connect the source to the C-DSP. Please note that at
this point no amplifier should be connected to the C-DSP. Now start playing a „0 dB" signal on your car
radio / head unit. You find a „1 kHz / 0 dB" signal on our homepage which can be used for this process
(www.audiotec-fischer.com/pc-tool.html). All other 0 dB signals can be used as well. Now turn your car
radio / head unit to approx. 95% of the maximum volume to reach highest possible output voltage of your
car radio.
To start now with the adjustment of the first channels (A and B) turn the left control knob slowly clock-
wise until the green clipping LED lights up red. At this point turn the control slowly counterclockwise until
the clipping LED lights up green again and then keep this position. Now the channels A/B are adjusted.
Repeat this procedure for all input channels which are connected to a signal source. Also if you are using
only one channel of a channel pair you have to adjust the pair.
The clipping LED should not be light up red in any case because this could result in distortion of the A/D
converters.
If there is one channel pair which isn't used turn the assigned control to left stop.
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