I have a noise whenever I turn on my system that sounds like a belt moving, it goes faster when your rev it up...etc. I heard its called alternator whine and i think that makes sense because when i turn the car off it doesn't make the noise also. I heard that its caused by your RCA cables touching metal or an object carrying noise, is this correct?. And if that is correct then if I move the RCA cable it should go away right?

If you want to check out waht equipment I'm using you can check it out on my car domain site, if that helps any.

http://www.cardomain.com/membe...age=1

 

The most common cause of engine noise (alternator whine) through the amp is improper grounding. Make sure the amp's ground wire is securely attached directly to the chassis. Also, the grounding point should be to bare metal and free of paint, undercoating, etc.

For more troubleshooting tips...
http://www.bcae1.com/audiots.htm

 

I have an update. I have a 4-channel amp (speakers) and a 2-channel amp(subs). The RCA cables arn't the problem, i checked them all today and there not it. I guess it must be my ground then. What I don't get is, I heard some whining before but only enough to hear if you really really listen in to it. Then last night I pluggen in my new rear speakers and about 5 minutes after I had them installed then thats when this problem started with the loud whining. The amp is set at 4 ohms and the rear speakers are 3 ohms, could this be the problem, or when hooked up the amp should automatically go to 3 ohms, right?

 

Whine can be caused by a bunch of things. Clean and tighten the batterey terminals. Dont take short cuts. Actualy remove the cables from the bat and take a wire brush to both the cable end and the terminals, use water and baking soda. Reinstall and tighten. If the whine is still present disconnect all of the rca cables from the amp. If you still have the whine it is being picked up by the power/ground wires, and it is almost impossible to get rid of. Maybe a better amp. If the whine went away after disconnecting the RCAS you might have a bad ground in one of the cable. How big of a gnd wire to the amp. Are the new speakers better at high freqs? Maybe you had this problem all along just never heard it.

 

I just tried the test with the RCA cables, when i un-plug the RCA's the sound goes off. So i guess it is my power/ ground wire. I'm gonna clean my battery terminals today also. Thanks for your help!!!!

 

also, when I turn on my system it pops. Its a pretty loud pop also, and my volt meter shows me a huge spike in power when it does it. So, does this also have something to do wiht my problem? thanks

 

If you have the remote wire from the amp hooked to 12 volts instead of the remote on from the head unit you will get a pop at power up. The whole purpose of the remote on is to power up the amps AFTER the head unit.
If the noise went away when the RCA's are disconnected that implies the RCA cables are picking up the noise. Can you ohm out the RCA cables? Look for open GND. If not hook up one channel at a time and see if the problem is only with one RCA. If everything checks out move the gnd for the amp back to the batt. They sell batt cables that have extra clamps for this purpose. Be sure you are using heavy enough guage wire, power and gnd are the same guage.

 

I just tried it today, and it seems that all 3 sets of my RCA's have this noise, so I moved the RCA's to the whole other side of the car away from the power and remote wires. And it still makes the whining noise, I even re-ran every cable carefully as to avoid power sources/etc. I seriously have no clue what it could be...

 

Where are you speaker wires ran? Are they anywhere near the power or ground wires? Some people say where you run the speaker wires doesn't matter, but in my case, it did.

When I installed my stereo system 3 months ago, I ran my speaker wires next to my power wires, and I had whine just like you. I tried everything... rerunning RCA's all over the place, changed grounds, upgraded the Big 3 and upgraded all of my engine grounds while I was at it, etc, but the whine didn't go away. Last week, I reran my speaker wires away from the power wires, and it definitely made a difference. Instead of whine always going on, I only hear a faint whine at night when i have my headlights, foglights, and rear defroster on.

So anyway, if your speaker wires are anywhere near any power wires, fix that. If you still have minimal whine like me, maybe it's the amp that's the culprit.

As far as turn on pop goes, you can still get turn on pop if the remote wire is correctly connected to the head unit remote wire... it has to do with the amps. To fix it, you can get a delay module that hooks up to the remote wire. It's made by Stinger, and you can get it from cardomain.com.

 

I did another test today. I pulled out my deck and attached all 3 of my RCA's to the back and let them sit on top of my seats back to the amp, and plugged them in there, and it STILL made the alternator whine. I even plugged in and out each one to figure out if one was hte culprit but there all like that. Even if I have only one RCA plugged in then the sound will come out of that channel. So i assume that I have a power problem now. My ground is good and close, while touching bare metal.
I was gonna upgrade to 1/0 gauge wire anwayas, so i'm gonna install the bigger wire on Sunday, right now I have 4 gauge. So i'll take extra time and care with the battery terminals and everything then just to make sure that thats all right. Does anyone have any more ideas.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by YAMAHAtrueracer &raquo;</TD></TR><TR><TD CLASS="quote">I have an update. I have a 4-channel amp (speakers) and a 2-channel amp(subs). The RCA cables arn't the problem, i checked them all today and there not it. I guess it must be my ground then. What I don't get is, I heard some whining before but only enough to hear if you really really listen in to it. Then last night I pluggen in my new rear speakers and about 5 minutes after I had them installed then thats when this problem started with the loud whining. The amp is set at 4 ohms and the rear speakers are 3 ohms, could this be the problem, or when hooked up the amp should automatically go to 3 ohms, right?</TD></TR></TABLE>What kind of HU, what kind of amp and what kind of RCAs, It sounds to me like the problem is at the HU, if you are running a 4ch amp, what did you do with the speaker wires out of th HU, and what kind of ground do you have for the HU. 94

 

-Pioneer AVH-6400CD Deck
-2-12" Audiobahn Flame Q subs
-Audiobahn A2300 2-channel amp
-Audiobahn A6004 4-Channel amp
-Audiobahn ACAP301Q 3 Farad Capacitor
-Pioneer 6.5" 3-way coxial speakers (Front)
-Audiobahn ACX653 3-way 6.5" speakers w/ crossovers. (Rear)

 

If you can, try this, get another brand of HU and try it, I have run into noise problems when trying to drive some brands of amps with a Pioneer HU, the problem has always been a groundloop that I could only get rid of with groundloop isolaters on the RCAs , [ not the best for SQ] 94

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by selasornayr &raquo;</TD></TR><TR><TD CLASS="quote">Where are you speaker wires ran? Are they anywhere near the power or ground wires? Some people say where you run the speaker wires doesn't matter, but in my case, it did.

When I installed my stereo system 3 months ago, I ran my speaker wires next to my power wires, and I had whine just like you. I tried everything... rerunning RCA's all over the place, changed grounds, upgraded the Big 3 and upgraded all of my engine grounds while I was at it, etc, but the whine didn't go away. Last week, I reran my speaker wires away from the power wires, and it definitely made a difference. Instead of whine always going on, I only hear a faint whine at night when i have my headlights, foglights, and rear defroster on.

So anyway, if your speaker wires are anywhere near any power wires, fix that. If you still have minimal whine like me, maybe it's the amp that's the culprit.</TD></TR></TABLE>

 

You have a ground loop problem. Find and isolate it most common places are:
1. poor head unit grounding.
2. poor amplifier grounding.
3. poor processor grounds.
4 poor chassis grounds.

This site isn't PDA friendly lol

 

There are two things that made a huge difference on my systems when I built it.

1) I ran a 10awg line from the negative terminal on the battery back to the grounding point near the amps. This will entirely eliminate any case of poor chassis resistance short of running the same awg of wire for the ground.

2) Take a different approach: turn up the source output to lower your signal/noise ratio. This can be accomplished with a high line output HU, 4V is what I have or one that can adjust the output. So turn up the HU output and turn down any gains on processors and amplifiers.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PupaScoopa &raquo;</TD></TR><TR><TD CLASS="quote">There are two things that made a huge difference on my systems when I built it.

1) I ran a 10awg line from the negative terminal on the battery back to the grounding point near the amps. This will entirely eliminate any case of poor chassis resistance short of running the same awg of wire for the ground.
</TD></TR></TABLE>

A better choice would be to run that from where the deck is grounded to where the amplifier is grounded.

 

"A better choice would be to run that from where the deck is grounded to where the amplifier is grounded."

I disagree.
When trying to eliminate noise you want only one path to gnd and you want the gnd from the hu and the gnd from the amp to be as close to the battery as possible. This is whats called a "star gnd".

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by matt_in_sd &raquo;</TD></TR><TR><TD CLASS="quote">I disagree.
When trying to eliminate noise you want only one path to gnd and you want the gnd from the hu and the gnd from the amp to be as close to the battery as possible. This is whats called a "star gnd".

</TD></TR></TABLE>
The different paths to ground is not what causes noise (i.e. ground loops). Ideally you would want all paths going to the same point as close to the battery as possible. The key here is why is this the "ideal" situation. While the small wire from the battery ground to amp would work very well you still have the possibility that the stereo and amplifier are at different ground potentials. Doesn't really matter what you call ground, its all a matter of reference. Now if you tie the stereo ground and amplifier ground together it won't matter if those ground points are up .1v from the battery ground because they both will be. So the ground is still 0 to the amplifier and the stereo.

 

If your going to spend the time chasing down a noise problem why screw around. For the extra 20 minutes and $10 in 10 ga wire you eliminate a lot of variables.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by matt_in_sd &raquo;</TD></TR><TR><TD CLASS="quote">If your going to spend the time chasing down a noise problem why screw around. For the extra 20 minutes and $10 in 10 ga wire you eliminate a lot of variables. </TD></TR></TABLE>
Don't know what you were trying to say here, I agree that the wire would help. I just know that their is a better location to put it. The idea is to have the resistance to the battery ground be the same. Which it never will be but you can come extremely close.

 

Here's a link to a thread that's probably the most helpful with system noise that I've ever read...

http://forum.sounddomain.com/u...08251

 

When trying to eliminate noise that is propagated through the ground network you want to keep the ground path for a given system (amp+hu) as isolated from other systems as long as possible. The battery is essentially the center of system gnd. So the closer you are to the battery the less noise the amp+hu will pick up from other sources. If you have never used an oscilloscope to look at signals you might think gnd is a constant level, but it isn't. All of the computers, motors, switches create spikes on the gnd plane. The farther from the battery you get, the more contaminated the gnd becomes. So if you have a noise issue with the amp/hu the closer you get to the battery the quieter the gnd is, the better your system will sound.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by matt_in_sd &raquo;</TD></TR><TR><TD CLASS="quote">When trying to eliminate noise that is propagated through the ground network you want to keep the ground path for a given system (amp+hu) as isolated from other systems as long as possible. The battery is essentially the center of system gnd. So the closer you are to the battery the less noise the amp+hu will pick up from other sources. If you have never used an oscilloscope to look at signals you might think gnd is a constant level, but it isn't. All of the computers, motors, switches create spikes on the gnd plane. The farther from the battery you get, the more contaminated the gnd becomes. So if you have a noise issue with the amp/hu the closer you get to the battery the quieter the gnd is, the better your system will sound. </TD></TR></TABLE>
This isn't what a ground loop is. If you have a noisy ground you have a noisy ground it doesn't mysteriously amplify itself further away from the noise source. If you have noise then you’re going to have noise in everything you connect it to. Best way to fix this is to eliminate the noise.

Now when you have two different current paths you have the potential to have two different ground potentials. This is more common when you have high current paths, which an amplifier is. The deck is a low current path. Every piece of wire has a very small amount of resistance associated with it. The problem with the car chassis is that it goes all over the place the resistance from one point to another will be different. So if the deck ground resistance is .02 ohms from where it is grounded to where the battery is located and the deck draws 5amps then this will raise the ground up .1 volt. Now if the resistance from the rear of the car where the amplifier is grounded is .04 ohms and the current is 80 amps this will raise its ground up 3.2 volts fairly significant difference. These are exaggerated to show my point. Now when you connect a set of RCA's from the deck to the amplifier you have now tied the two together. The ground on the RCA provides a current path for current to flow. Current flows from the highest potential to the lowest potential. So the difference between the two points will flow down the RCA's and be mixed with your signal. This is where the noise comes from.

So what do ground loops isolators do?
These are usually transformers that separate the connections. Isolating the two components from each other so the only current that can flow is the AC signal current. They don't really fix the problem IMO.

How come they don't completely eliminate the noise?
For the same reason that the AC signal is able to transfer.

 

If gnd potential is the source of the noise the noise would remain the same even with the ignition off. You are right noise doesn't amplify itself. but every computer module, every motor, solenoid, ADDS noise. the farther you get from the battery the more of these noises you will see. Every time DC is switched, ie. a motor turning, solenoid firing, or even a microprocessor there will be a noise spike on the gnd plane. This is the source of the noise, not gnd potential. And the closer you pick up gnd to one of these sources of noise the more noise you will hear in the amp. If you want to get more technical low resistance is not the only factor dictating noise in a system. There is a term called impedance. It is similair to resistance but takes into account the frequency of the noise. Also something called skin effect, which has to do with how effectivly frequencies move in different types of wire. Engineers spend a lot of time dealing with gnd noise, its not simple to eliminate.
RCA's are not meant to carry gnd current. I have fixed many HU where the amp was not grounded, used the RCA's as gnd and fried the trace in the HU.