|
||||||||||
|
||||||||||
Technical
Help
Personal
& Marine
Home
Stereo &
Auto
Electronics
|
The
Genesis of Noise
Alternator
noise is a high pitched whine that is synchronous with the car's engine acceleration.
When the engine turns the alternator rotor, the alternator induces an AC voltage
that is converted to DC and distributed to the electrical system.
How alternator noise becomes audible
1.
Induced noise
: When current
passes
through a wire
, an electromagnetic field
radiates from it. This field will carry with it all the noise imposed by the system,
and any noise created by peripheral devices
such
as factory harnesses, car computers, navigation and phone systems, and other electronic
equipment
as well.
Repairing this problem is very simple: DO NOT run power and signal wires in close parallel! Never allow power and signal wires to run in parallel closer than 8 inches. When they must cross, try to place them at 90 degree angles perpendicular to each other. Run power wire from the battery to the amp on one side of the vehicle, and the signal wires along the other side of the car. On most cars it is better to run signal wires on the passenger's side, and power wires on the driver's side.
2.
Ground loops
: The metal chassis and body of the car
serves as a ground. If the battery and alternator are under the hood, and an amplifier
is connected to the body at the trunk area, it is highly likely that the ground
potential may be just a few millivolts off from what it would be at the front
or middle section of the same car body. Allthough theoretically, the car's metal
has little or no resistance, and it should not matter where grounds are connected
for amplifiers, radio, battery and alternator, the metal in the car does have
resistance, and there is a potential difference from the front of the car, where
the battery is, to the middle of the car, where the radio is, and the back of
the car, where most amplifiers are situated. The small difference in electrical
potential
is sufficient to allow noise to intrude at undesirable levels. Differences of
as little as 1/5 volt, can create noise problems.
Troubleshooting Tips
If
everything is configurred using the above guidelines and you still have noise,
then try to figure out what is causing the noise . First, double check all grounds
at amplifiers, crossovers, radio, etc. Make sure the antenna is well grounded.
Try to isolate the source of the noise.
Bypass
crossovers, signal processors, equalizers,
etc, by connecting RCA cables straight from the radio to the amplifier. If the
noise goes away, this is an indication the problem may be RCA wires or grounds
hooked up to crossovers/equalizers.
Noise
filters
Noise filter devices should be considered once you have exhausted all the remedies
we suggest above. These usually go in the battery + line. Active filtration is
better than a passive filter. For a selection of such filters see our page
here.
The
Ans-80
is one of our most effective and popular models.
|
MAIN
PAGE
|
ENCLOSURES:
Theile/Small AMPLIFIERS: About Installing Install Tips Power Ratings RECEIVERS: Installing NEON/LED: Installing TOOLS |
|||||||
|
||||||||||
-- | -- | |||||||||