Subsonic:
The intern subsonic filter deregulates the subwoofer and amplifier from all frequencies below the
potentiometer „Subsonic“ (6) adjusted frequencies (15 Hz up to 35 Hz at 18 dB slope per octave).
This enables that the frequencies which cannot be reproduced by the woofer will be kept away which
ensures an unnecessary stress of the subwoofer and amplifier.
Subwoofer-adjustment DPA
1.2500
In order to find the correct adjustment of the loudness, dividing frequency and the phase position,
you should have much time, patience, know-how and your favourite CD.
In the first step you have to locate the installation place of the subwoofer. The preferred boot corners
and close to the dividing wall situated positions on the boot floor will only slightly increase the
electron beam resistance. Therefore the expected increase of the efficiency and an improve of the
dynamics for the desired 3 dB cannot be completely achieved.
The adjustment of the Dividing frequency, phase position and the loudness level is only relevant for
the stipulated installation place. All adjustments should only be optimised by the user only when the
front and rear systems are operating. The single operation of the subwoofer without front- or rear
system is not advisable and will lead to the mismatching of the level, the dividing frequency and the
phase position.
Adjustment of the dividing frequency:
The dividing frequency of the subwoofer must be matching to the dividing frequency of the front-
and rear system. Will the front- and rear systems get a 80 Hz high-pass signal, than the dividing
frequency of the subwoofer should be matched to the high-pass frequency. But the dividing
frequency should not be essentially higher. A maximum of 80 Hz – 100 Hz are advisable, in order
that the locating of the subwoofer can be excluded and a clean roll-off at 80 Hz – 3 dB at both
dividing frequencies can be guaranteed.
Adjustment of the phase position:
The relative phase position between subwoofer and the front- and rear systems is relatively
independent to the dividing frequency of the subwoofer. It is advisable to find for the second step the
correct and optimal phase position of the subwoofer to the front- and rear systems. This results in the
correct adjustment and in case of correct polarity from the summing up of the sonic part of the
subwoofer and the front- and rear systems and can be recognized by a more dry and voluminous
bass. In case of a incorrect or wrong polarity of the subwoofer or the front- and rear system, a
subtraction of the sonic parts which can be recognized by a weak level and a mat bass. The amplifier
DPA 1.2500 has no phase invert circuit. The adjustment of the phase can be effected through a
change of the poles of the loudspeaker cables on the subwoofer (+ to – and – to +).
Adjustment of the loudness level:
The last step is the adjustment of the loudness of the subwoofer to the front- and rear systems. Adjust
the level controller of the front- and rear system in order that together with the fader of the car-radio
an optimum loudness can be guaranteed. Switch the front- and rear system with a title of your
favourite CD on medium loudness. Adjust the subwoofer loudness on the level controller of the
amplifier to silent (minimum loudness), not on the radio. Then adjust the level controller of the
subwoofer while music is playing and increase the volume slowly until the subwoofer will be
pointed out of the acoustic pattern. Then reduce the subwoofer loudness with the level controller
until the subwoofer will just not point out from the acoustic pattern anymore. Don’t change the level
controller of the subwoofer anymore.
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