Engine noise through speakers

[Paulyy]

Okay i have installed a new Eclipse headunit in my car and have connected it to a 4 channel Kicker amp to run all 4 speakers. The headunit has 3 5V preouts (front, rear & sub). The amp is mounted in the boot and since my battery is in the boot I’m running 8 gauge cables to + & - from the battery. I’ve got 2 RCA cables running on the passenger side (left hand side since I’m in Australia), 2 sets of speaker cable to run the front 2 speakers & also the trigger cable to turn the amp on and off.

When the car is off it sound crystal clear but when the car is running it's got this high pitched noise coming from the speakers and when I rev it the tone goes higher. It’s not a loud noise but gets annoying.

So does anyone have had this problem? Or something like it?
Or have I done something wrong with the wiring?

Cheers,
Paulyy

[John_AZ]

Age of spark plug wires? Check the spark plug wires for arching in a dark garage. Check the cap and rotor for arch trails.

[Paulyy]

Didn't think of that. il give it a go tomorrow morning, thanks

[Makis]

Usually cheap amplifiers will do this. Car amplifiers need to have special input stages to help reduce noise caused by ground loop induced noise. You can minimize the effect by carefully wiring the amp and headunit, but an amplifier with good ground isolation will remove the noise completely. I would experiment with some passive ground isolation transformers to confirm that ground isolation is the problem here.

[Paulyy]

yeah, i was thinking of taking - off the termal of the battery and bolting it on the body of the car see if makes any difference. & no cheap amp for me $350 Kicker 75W rms x4.

but thanks for some advice makis

[Makis]

Depends on which Kicker amplifier you have. ZX series are OK as they have special input circuitry according to the specs I just seen. If you have older KX series this may not be the case.
If your amp has the special circuitry then the problem will be something simple, like the RCA linking wires nor connected properly. Get an Ohm meter and measure connectivity of wires. A broken ground wire in the RCA connector will route the ground through the main ground supply to the amp which in term will induce the noise you experience. The special input amp circuitry will not be able to remove this noise.

[krystar]

it's the grounding on the amp or the headunit. they should be grounded at the same location if possible. or cheap fix is to get a ground loop isolator.

[924RACR]

I've had just such a problem on my 931 plaguing me for over a year now... became a problem when I installed a 4-channel amp and new headunit. Had a different pair before, without issues. Very pissed, think I'm gonna off-load the 4-channel amp and just run the headunit. Not as loud as it needs to be, but lighter and clean.

That is, once I've rebuilt the engine in the spring! LOL

[flash968]

sounds like alternator noise due to a ground loop issue

keep power and ground cables away from rca cables - NEVER run them parallel - they can cross over, but do not run them alongside each other

ground directly to the chassis, NOT to the car's wiring harness, and keep the ground lines as short as possible, and the same gauge wire as the power lead

use wire of large enough gauge for the power needed

use good sheilded rca cables for long runs (over 4')

make sure you have resistor plugs and suppression wires

[wild man]

If all else fails, they sell something called a "noise filter" that goes in line with the power wire (and ground wire) of the amp. If it is of good quality, it should get rid of the alternator noise. Just make sure that it is of a sufficient amperage rating for what the amplifier will draw. It is what is commonly known as a "pi" filter.

[rmcdonnell]

Try powering the amp off a separate battery to see if the noise from the alternator or ignition system is getting into the system through the DC supply to the amp. If this is the problem, you can filter the DC supply to your amp as suggested by wild man.

If it still breaks through, unplug all the speaker loads and attach one speaker on a short lead at the amp, to see if the speaker wires are picking it up.

Shielding is the best bet for input/output wires.

Check the caps across the alternator, coil, resistor plug wires etc as these are probably making the row in the first place.

cheers
Rissole

[Paulyy]

Thanks for all your help guys ill be tinkering with it later on.

makis, mines a ZX series amp

[flash968]

filters and such gadgets rarely work on alternator whine - ignition crackle they can help with occasionally, though resistor plugs and suppression wires do a lot more - i have also had some limited success with a capacitor grounding from the alternator

alternator whine is almost always an issue due to EMI via cable leakage, or bad grounding

the two main causes are:
1. routing of power cables cables along side other cables (speaker or rca)
2. inadequate or improper grounding

i have about a 95% success rate solving these kinds of problems with the methods listed in my posts above

[Paulyy]

since i didnt get time today to look at the car tomorrow morning after i fix the interior bits il check the system out.

flash, i like the way you think..
il check the alternator and the grounding. im going to move the negative cable from the battery terminal and ground it properly as i would in any other system.

the noise is so annoying i took the car up the street to see how its running since i was playing with the AMFLink on idle (didn't idle well) i just heard the noise and im like wtf is that. i thort it was pressure leak from the AFMLink box untill i revd it and head it was from the speakers.

924RACR, i don't know how you can deal with such a noise! and for about a year. i cannot handle it for 5 minutes

[Makis]

Originally Posted by Paulyy

Thanks for all your help guys ill be tinkering with it later on.

makis, mines a ZX series amp

This is good and should exclude the amp and you should not have the noise really.
I would double check the wiring as suggested first.
Then I would check the matching between you head unit and amp as you said the headunit is high output. Also you need to confirm that the noise is not created at source. Try the suggestion mention to power the amp from a different battery and run the system. If you get noise then the headunit could be causing your noise.

[924RACR]

I dealt partly by dialing back the amp gains, since that's where the noise originated - run more gain on the headunit instead. That at least kept it tolerable, mostly. Was also heat-sensitive; worse with a cold amp in the AM, better in the afternoon driving home from work!

Was all alternator whine; went through a puddle once which splashed the alt belt and briefly had no whine! LOL

No rerouting of wires or ground loop isolators etc. made a difference. I even tried replacing the voltage regulator, no change.

[flash968]

lol - some amps are just crap - been there - i think i have one around here i'm using as a door stop

but i've been able to solve the problem in almost every car, and i've been able to improve it in every car - it has almost always been wire routing or bad grounds

sometimes i've had to use better rca cables - the shielding on the little skinny ones that radio shack sells is pretty cheesy - they work fine most of the time, but some cars bleed a lot - a good braided shield will do a lot in preventing EMI - if your rca run is over 4' i would definitely invest in a good cable

sometimes i've even had to shield the amp or even run caps from the shield of the rcas to ground - but that is a last resort

good luck

[Mike C5]

I had what sounds like the same problem when I installed an Eclipse (around 5 years ago). The audio shop I bought it from had some magic filter that worked wonders.

[flash968]

while such filters can occasionally solve small problems, i know of quite a few shops that will sell you such a filter, and even go so far as to install it (for a fee of course), but what they really do is fix the problem of the bad ground - nice way for them to make an extra $100 and is a lot easier than explaining how what really fixed the problem was cutting the long ground wire and grounding the amp right next to the amp

[Paulyy]

all fixed!! thanks guys for your help
the amps wernt grounded properly. i powered them with another battery and noticed it went down but was still there. i grounded it to the chassis and it was still the same. i played with the headunit grounding and all fixed!!