Ok so a few months ago I went all out and bought a really nice nice
setup for my car. 2x12" subs, a 1500 watt 4 chanel amp, 16cm components
and tweeters, and a new head unit. All 'Mac Audio' and a Pioneer BT70
Head Unit) Myself and a mate installed it in a weekend and it was
savage.

Got a new car, same car- honda civic, newer better model, did the
install again, but this time serious problems. When the engine is on
I'm getting interferance in the subs and speakers. It is a high pitched
whine that goes up and down with the revs of the engine. Also, When I
put in a new cd you can hear it searching through the cd on the
speakers, its very annoying. I took it to a shop and the guy spent ages
working on it, installed some little box between the RCA's and the head
unit - to ground it, which helped a bit but the noise is still there.

Possible Reasons for the problems:
- The ground and power cables are aparantly not big enough. They are ok
but I was told I should have huge cables to handle the power.
- The RCA's and the power cable are going down the same side of the
car, I was told they should be on oppasite sides.

These are unlikely to be the sole reason for the noise, but they may
contribute tot he problem. I'm going to redo the whole thing, at the
weekend.

However what was suggested to me is that the alternator is where the
noise is coming from - aparantly the bearings can start to go and cause
this noise, long before you notice anything wrong with the car.

Everyone I talk to has a diffent idea on what the problem is - but as
they say: "Opinions are like Arseholes - everyone's got one"... I need
someone who Really knows exactly what they are doing. I've put over
€1500 into this system and having it less then perfect is killing me!

If anyone has any proper advice I'd love to hear it.
Thanks

wrote in message
oups.com...

Possible Reasons for the problems:
- The ground and power cables are aparantly not big enough. They are ok
but I was told I should have huge cables to handle the power.
- The RCA's and the power cable are going down the same side of the
car, I was told they should be on oppasite sides.

What size power cable do you have?
Can you read the fuses on your Amplifier? What's the total number of amperes
the fuses are rated at? (I.e. 3 x 20AMP fuses?)

Definitely run the RCA's down the opposite side of the car to the power
wire. Definitely do this first as it may well fix the problem.

Cheers.

I will second that. Run the battery power cable down one side, and the
remote wire and RCA lines down the opposite side. That sound is called
electromagnetic interference (EMI) and it happens because your amp draws a
ton more current than your RCA lines are putting out which creates magnetic
waves in the battery cable line. Also, make sure that you have a really
nice ground for your amp.

--
- AUSTIN BECKER
"Mark" wrote in message
...

wrote in message
oups.com...

Possible Reasons for the problems:
- The ground and power cables are aparantly not big enough. They are ok
but I was told I should have huge cables to handle the power.
- The RCA's and the power cable are going down the same side of the
car, I was told they should be on oppasite sides.

What size power cable do you have?
Can you read the fuses on your Amplifier? What's the total number of
amperes
the fuses are rated at? (I.e. 3 x 20AMP fuses?)

Definitely run the RCA's down the opposite side of the car to the power
wire. Definitely do this first as it may well fix the problem.

Cheers.

That sound is called
electromagnetic interference (EMI) and it happens because your amp draws a
ton more current than your RCA lines are putting out which creates
magnetic
waves in the battery cable line.

True, EMI can be a cause of what we affectionately call "alternator whine",
but in my experience, it is WAY MORE often caused by ground loops. Ground
loops happen when the negative potential of one component (let's say your
head unit) is different than the negative potential of another component
(the amp let's say). The difference between these potentials creates a
small voltage that travels across your RCA's and is amplified by your
amplifiers (of course). The reason it fluctuates with the RPM of your car
is that, well, it's complicated to explain. Suffice to say that when you
rev your car it increases the output of your alternator and this changes
pretty much all voltage potentials of the car (whether positive or
negative).

The problem with fixing ground loops is that very often it depends on the
car. What works for one car may not work for another (or as you have seen,
even the same model of car can have different problems). This is because
(among other reasons) the car's body is, in a sense, a large piece of wire
back to the negative terminal of the battery (or negative terminal to the
alternator). With many cars, you may actually have different negative
potentials at different points on the car body.

So, how to fix it. First, always use the biggest ground wires you can. You
want to make the negative potential of your components as close to the
negative potential of the car body as possible, so they all match up. You
also may want to try grounding your components at different spots on the
car, for the reasons I already pointed out.

But the best fix I have ever found is to ground every single component
(including head unit) to the same spot, with large gauge cable. In my
experience, this fixes about 95% of all ground loop problems. That way you
are GUARANTEED to have the same negative potential for every component. If
that is very difficult or impossible, simply run an 8 gauge cable from the
ground of your amp to the chassis of your head-unit. You would be surprised
how often that little trick solves the problem.

MOSFET

I second what MOSFET said. Also, if no one has already suggeted this
(sorry...I read through all the posts fairly quickly) just try grounding
your head unit and/or amp at a different location. And make sure the
grounding location is a good ground, with clean, bare metal. Scrape any
paint away from the surface if you have to.

Rerouting the RCA cables is not as much as issue as proper grounding. If
grounding doesn't work (which I suspect will eventually fix your problem)
then try rerouting cables....but I don't think you'll need to, and it's a
lot of work to boot!

Tony


--
2001 Nissan Maxima SE Anniversary Edition
Clarion DRZ9255 Head Unit, Phoenix Gold ZX475ti, ZX450 and Xenon X1200.1
Amplifiers, Dynaudio System 360 Tri-Amped In Front and Focal 130HCs For Rear
Fill, Image Dynamics IDMAX10 D4 v.3 Sub

2001 Chevy S10 ZR2
Pioneer DEH-P9600MP Head Unit, Phoenix Gold Ti500.4 Amp, Focal 165HC
Speakers & Image Dynamics ID8 D4 v.3 Sub

Tony F wrote:
I second what MOSFET said. Also, if no one has already suggeted this
(sorry...I read through all the posts fairly quickly) just try grounding
your head unit and/or amp at a different location. And make sure the
grounding location is a good ground, with clean, bare metal. Scrape any
paint away from the surface if you have to.

Rerouting the RCA cables is not as much as issue as proper grounding. If
grounding doesn't work (which I suspect will eventually fix your problem)
then try rerouting cables....but I don't think you'll need to, and it's a
lot of work to boot!

I'll give that a third. First thing: try regrounding the deck. If it
has a poor ground wire and is grounding through the antenna or chassis,
you can easily get ground loops. Or disconnect the deck's ground wire
so it ONLY grounds through the antenna and/or chassis. Or hook a ground
wire to the deck's chassis... several easy options to try.

Having the power and RCA feeds to the amp separated will help avoid
other types of induced noise getting to the amp, but it's not related to
alternator whine or to the "CD loading" noise.

FYI, I had similar noises in my system, until I added a crossover
between the deck and the amp... then the noise vanished. I rigged
everything to a common ground, to a common filtered power, added a relay
for the deck so it was drawing power directly from the battery...
nothing worked until I put in the crossover. Noise problems can be very
strange and elusive sometimes.


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FYI, I had similar noises in my system, until I added a crossover between
the deck and the amp... then the noise vanished.

That's interesting. Usually it's the other way around (I had an EQ that
always created ground loop problems when it was installed between the deck
and amp).

MOSFET

MOSFET wrote:
FYI, I had similar noises in my system, until I added a crossover between
the deck and the amp... then the noise vanished.


That's interesting. Usually it's the other way around (I had an EQ that
always created ground loop problems when it was installed between the deck
and amp).

Yeah, I know, that's what really weirds me out about it... I was putting
off adding the crossover because I was afraid it would make matters
worse (especially as it's a really cheap-cheap unit), but when my
Punch75 sub amp blew up and I had to rewire things to run the sub off
two of the four channels on the main Kenwood, I had to add the
crossover... and bingo, the noise was gone.

I'm not gonna argue with success though, as long as it works!


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