9
Tips for the power supply MPA 5.420
For the negative line (-), the same cable cross section must be guaranteed as for the positive pole (+),
in order to prevent potential differences as well as mass interference loops. The car body is due to the
high potential differences as negative pole not suitable for this application.
In order to avoid disturbances, all audio equipments must be layed on a central mass point. This mass
point will according to each vehicle type be determined during the testing of the installation. A direct
connection to the negative pole (-) of the battery is due to interruption technical reasons not always
an advantage. Please choose motor block or search the interruption minimum on the car body and
supply from this point all equipments with the negative pole (-).
The same criterion is for the positive pole (+). In order to prevent interference loops the battery cable
must be layed on a distributing cabinet. From this point all audio-equipments (also radio and CD-
player) as well as all memory cables will be supplied with power.
Must the positive line (+) be filtered due to screening reasons, then you only have to fit in a filter
choke with the corresponding total loading capacity in the positive (+) main current (pay attention
for the total power of all devices). Additional filters in the specific devices worsen the interference
filter effect.
In case of high reproduction loudness levels, especially in the woofer area, the amplifier can due to
the potential loss on the long cable clip early. This can be prevented with a large cable cross-section
and a minimizing of the transition resistance on the connecting parts.
Corresponding precautions with low deficiency battery clamps and distributing cabinets can be taken
by the initial installation.
In case of a too small cable cross section or high current supply in the impulse are of the bass
reproduction as well as through active operation of different amplifiers, an improvement of the
clipping can be achieved with an additional buffer capacitor. The buffer capacitor will provide in the
millisecond area with its high capacity (1F/40 V) enough current and achieves an additional
screening and smoothening of the supplying current and the power. The assembly will be effected
directly on the amplifier or on the distributing cabinet.
Determination of the „central mass point“ MPA 5.420
1. Install and check the system completely.
2. Prepare the negative (-) connection of the audio system provisional on the car body negative
(point 1). Lay the equipotential bonding line if not existing from the generator body to point
1.
3. Switch on the system, put in an empty cassette or CD (0dB-track) and adjust the loudness to
minimum.
4. Switch on the engine and take into operation all users, also light, heating for windows and the
fan. In case you hear a whistling after rev up, which will increase or decrease with the speed
in the frequency, than you have to adjust the mass connection.
5. Tear the antenna plug out of the car radio. Has the interference disappeared, then a potential
loss on the antenna base of the battery is existing. If the interference did not disappear, then
continue with the following:
6. Separate the negative pole (-) of the audio system from point 1 and connect to the motor
block.
Check if the interference has removed.
