User manual HELIX DARK BLUE FOUR

[. . . ] For safety reasons, the amplifier must be secured in a professional manner. This is performed by means of four fixing screws screwed into a mounting surface offering sufficient retention and stability. Before drilling the holes for the screws, carefully examine the area around the installation position and make sure that there are no electrical cables or components, hydraulic brake lines or any part of the petrol tank located behind the mounting surface - otherwise these could be damaged. [. . . ] 4 Fuses The input fuses are connected in parallel and provide protection against an internal equipment fault, i. The system must be additionally protected by a further line fuse located in the vicinity of the battery (max. Never connect the loudspeaker cables with the car chassis gound. The impedance per channel should not be lower than 2 ohm as overheating could cause a shut down of the amplifier. 6 Signal inputs The DARK BLUE amplifiers have RCA connectors for RCA cables that can be connected with the pre-amplifier output of the lineoutputs of the headunit or with a pre-amplifier. This connectors are gold-plated to ensure a better signal transmission. 7 High- and low level signal switch To change the input signals from low level (head unit or preamplifier) to high level (speaker outputs of head unit). 8 Level controls for input sensitivity These controls can be used to match the input sensitivity of the individual channels to the output voltage of the connected head unit. These controls are not volume controls and are solely intended for the purpose of sensitivity trimming. the control range extends from 200 mV to 8 V. 9 Bassboost control To raise the bass signal from 0 to 18 dB at 45 Hz. If this switch is set on HPF Highpass the crossover frequency for the highpass can be adjusted with control 10. That means a bandpass is built in any case. With switch 10 adjust the highpass and with control 12 adjust the lowpass. Thus every desired bandpass between 15 Hz and 4000 Hz can be adjusted. To avoid a lost of sound pressure make sure that the crossover frequencies of high- and lowpass are separated of 2 octaves when building a bandpass. That means: If the lowpass signal is adjusted to 320 Hz the highpass should be adjusted 2 octaves lower on approx. (1 octave = double frequency or half frequency) If a subwoofer is connected we recommend to use highpass control 10 as variable subsonic filter or turn it counter-clockwise to 15 Hz to get a subsonic filter. [. . . ] This must be notified to your dealer within 5 days of purchase. c) Defects caused by incorrect installation or connection , by operation errors , by overloading or by external force. D) Products which have been repaired incorrectly or modified or where the product has been opened by other persons than us. [. . . ]