I currently have a 2001 Dodge Dakota extended cab. I took out the back
seat, and replaced it with 2 12" Infinity Perfects and 3 amps (1 to
front speakers, 1 to back speakers, and 1 for subs). The amps are all
Rockford Fosgate Punch series, 2 attached to the seperate custom
speaker boxes and one to the back wall. This is the second
configuration I have had in this truck, run in the same manner as my
previous system. The previous system ran without any problems, so I
know the power and ground connections are solid.

The problem I am having did not show up immediately after
installation. It was a few weeks later, I started noticing a "hum" in
the system, that soon grew to a definite buzz that would change
frequency with RPMs of the motor. This has lead me to believe that the
noise is only introduced by something in the dash or could be over the
power cable, because how else could the amplifiers pick up engine
noise when they are in the back of the truck?

Anyways, I performed a series of tests, and concluded that somehow it
has to be coming through the power wire. My question is, how can the
power produce a result such as this? Since it was not present in the
beginning, could it be caused by a low battery, or a dying alternator?
Any other suggestions?

The problem I am having did not show up immediately after
installation. It was a few weeks later, I started noticing a "hum" in
the system, that soon grew to a definite buzz that would change
frequency with RPMs of the motor. This has lead me to believe that the
noise is only introduced by something in the dash or could be over the
power cable, because how else could the amplifiers pick up engine
noise when they are in the back of the truck?

90% of the time this is a ground loop, the result of an insufficient ground
somewhere.

"archangelwar" wrote in message
om...

Anyways, I performed a series of tests, and concluded that somehow it
has to be coming through the power wire. My question is, how can the
power produce a result such as this? Since it was not present in the
beginning, could it be caused by a low battery, or a dying alternator?
Any other suggestions?

Sounds like something is loosening or settling over time, and metal is starting
to make contact with ground where it shouldn't. Try to isolate some of the
components so they're not touching any metal on your truck. For example, remove
your head unit and run your stereo with the head unit on your seat or the
carpeted floor.

Pull the ground off and re-ground the amp and HU to the chassis of your
truck. Another thing you can try is to ground all the components to the
same spot.
"jeffc" wrote in message
...

"archangelwar" wrote in message
om...

Anyways, I performed a series of tests, and concluded that somehow it
has to be coming through the power wire. My question is, how can the
power produce a result such as this? Since it was not present in the
beginning, could it be caused by a low battery, or a dying alternator?
Any other suggestions?

Sounds like something is loosening or settling over time, and metal is
starting
to make contact with ground where it shouldn't. Try to isolate some of
the
components so they're not touching any metal on your truck. For example,
remove
your head unit and run your stereo with the head unit on your seat or the
carpeted floor.

"Trader" wrote in message
et...
Pull the ground off and re-ground the amp and HU to the chassis of your
truck. Another thing you can try is to ground all the components to the
same spot.

I've found isolating everything (meaning the grounds of all components,
including any metal chassis) and then running grounds directly to the battery
negative works best. At least, in terms of avoiding noise.

In article ,
(archangelwar) wrote:

I currently have a 2001 Dodge Dakota extended cab. I took out the back
seat, and replaced it with 2 12" Infinity Perfects and 3 amps (1 to
front speakers, 1 to back speakers, and 1 for subs). The amps are all
Rockford Fosgate Punch series, 2 attached to the seperate custom
speaker boxes and one to the back wall. This is the second
configuration I have had in this truck, run in the same manner as my
previous system. The previous system ran without any problems, so I
know the power and ground connections are solid.

The problem I am having did not show up immediately after
installation. It was a few weeks later, I started noticing a "hum" in
the system, that soon grew to a definite buzz that would change
frequency with RPMs of the motor. This has lead me to believe that the
noise is only introduced by something in the dash or could be over the
power cable, because how else could the amplifiers pick up engine
noise when they are in the back of the truck?

Anyways, I performed a series of tests, and concluded that somehow it
has to be coming through the power wire. My question is, how can the
power produce a result such as this? Since it was not present in the
beginning, could it be caused by a low battery, or a dying alternator?
Any other suggestions?

A current carrying ground connection may be faulty or the signal ground
may be shorted. Both can send current through the low-level audio
connection (ground loop).

Check for a short to ground in the signal wires. Only the HU should
have grounded RCA shields. When the HU is disconnected, there should be
at least 100 Ohms of resistance between the amp's RCA shields and the
car's chassis. If there's less resistance, inspect the audio cables and
speaker cables for cuts. Remove wires one at a time until the problem
is isolated.

Power up the amp and compare the RCA shields of the HU to the chassis.
More than 0.3V indicates a poor negative power connection. Compare the
(-) power connector on the amp to the chassis. It should be less than
0.1 volts.

If you've still found nothing you'll need a battery powered amplifier.
Radio Shack sells one. Connect it directly to the HU output and listen
for the noise. If it's there, the HU has probably has a blown capacitor.

"Kevin McMurtrie" wrote in message
...
If you've still found nothing you'll need a battery powered amplifier.
Radio Shack sells one. Connect it directly to the HU output and listen
for the noise. If it's there, the HU has probably has a blown capacitor.

A blown capacitor that changes frequency with the RPM of the motor?

In article ,
"jeffc" wrote:

"Kevin McMurtrie" wrote in message
...
If you've still found nothing you'll need a battery powered amplifier.
Radio Shack sells one. Connect it directly to the HU output and listen
for the noise. If it's there, the HU has probably has a blown capacitor.

A blown capacitor that changes frequency with the RPM of the motor?

Specifically, the capacitors on the power line and virtual grounds that
filter ripple.

Electrolytic capacitors do wear out. The aluminum oxide dielectric on
the anode occasionally cracks and then heals over when the exposed
aluminum underneath oxidizes. Some last for decades, some for only a
couple of years. Their lifespan depends on their build quality and the
strain placed on them.

Kevin McMurtrie wrote in message ...
In article ,
"jeffc" wrote:

"Kevin McMurtrie" wrote in message
...
If you've still found nothing you'll need a battery powered amplifier.
Radio Shack sells one. Connect it directly to the HU output and listen
for the noise. If it's there, the HU has probably has a blown capacitor.

A blown capacitor that changes frequency with the RPM of the motor?

Specifically, the capacitors on the power line and virtual grounds that
filter ripple.

Electrolytic capacitors do wear out. The aluminum oxide dielectric on
the anode occasionally cracks and then heals over when the exposed
aluminum underneath oxidizes. Some last for decades, some for only a
couple of years. Their lifespan depends on their build quality and the
strain placed on them.

I really don't think that the capacitors are an issue, as these amps
were bought brand new, and the noise is in two of them. I have not
checked the third, as it runs to the subs. I was hoping there was some
quick fix, as I do not want to have to remove all the stuff.

So I am guessing it must be the ground. All the grounds run to a block
and combine to a four guage wire that is bolted to the metal
backwall... This has always been sufficient in the past... What would
be a better ground?

In article ,
(archangelwar) wrote:

Kevin McMurtrie wrote in message
...
In article ,
"jeffc" wrote:

"Kevin McMurtrie" wrote in message
...
If you've still found nothing you'll need a battery powered amplifier.
Radio Shack sells one. Connect it directly to the HU output and listen
for the noise. If it's there, the HU has probably has a blown
capacitor.

A blown capacitor that changes frequency with the RPM of the motor?

Specifically, the capacitors on the power line and virtual grounds that
filter ripple.

Electrolytic capacitors do wear out. The aluminum oxide dielectric on
the anode occasionally cracks and then heals over when the exposed
aluminum underneath oxidizes. Some last for decades, some for only a
couple of years. Their lifespan depends on their build quality and the
strain placed on them.

I really don't think that the capacitors are an issue, as these amps
were bought brand new, and the noise is in two of them. I have not
checked the third, as it runs to the subs. I was hoping there was some
quick fix, as I do not want to have to remove all the stuff.

So I am guessing it must be the ground. All the grounds run to a block
and combine to a four guage wire that is bolted to the metal
backwall... This has always been sufficient in the past... What would
be a better ground?

Usually the chassis is a better ground but no perfect power ground
exists. That's why the signal ground must not connect with the power
ground at more than a single point, which is usually inside the HU.
Connections between the signal ground and two imperfect power grounds
will result in a flow of current through the signal ground (ground
loop). This is the most common problem so it's the first thing to
check. Only the HU should have a low impedance path to the power ground.