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Discussion Starter #1
I have a feeling that this is not too common but I figured I'd ask anyways. I'm wondering if a battery isolator will help in removing noise that I'm getting when I turn the car on. I should note that the car doesn't have to be on for the noise to appear simply, the key has to be on the accessory position 2 (the position right before turning the car on). Although there is also a little noise when the key is on accessory position 1, its not as noticeable as when its in position 2 when all the accessories are on.

My reasoning as to why a battery isolator might work is because I've tried everything else to remove the noise. I ran ground wires from the engine mount, to the battery, back to the amp and I still get noise (Big 3). I shielded the power wires with copper tape and I still get noise. I have shielded RCA's and I still get noise. I've re-routed the power and ground wires and I still get noise. I'm pretty sure its not a ground loop that's causing I believe the noise is being induced somehow by a relay in the engine compartment. I say this because I can clearly hear when the relay comes on when I put the key in accessory position 2 and that is when the noise comes on. When I move the key back to position 1, the relay turns off and so does the noise (for the most part). I'm guessing the noise is coming from one of the main accessory circuits, so if I can isolate my audio system from the car accessory circuits then I should have no noise. That's my theory anyways.

If anyone has experience with battery isolators please let me know if my theory would work or not. Also, I'm thinking about 12 volt line conditioner as well to clean up the power (don't know if that would work though) or maybe even a capacitor (as I'm guessing that it would filter at least some of the noise before it gets to the amp). Any suggestions are greatly appreciated. Thanks in advance.

- David
 

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what type of noise are you getting,alt whine ?? is it when running and engine off? i don't think the isolator will do much,all it has in it are diodes so you will still get any noise thru it from the power side of the car.
 

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sub'd having some issues myself so......
 

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Discussion Starter #4
what type of noise are you getting,alt whine ?? is it when running and engine off? i don't think the isolator will do much,all it has in it are diodes so you will still get any noise thru it from the power side of the car.
The noise is very much like alternator whine in that when the car is running the noise varies with RPM's. However, that is just because the engine running only makes the noise worse. In actuality, the noise is present when the engine is off and only the key is on so that the accessories (radio + amp) are playing.

I forgot to mention also that the noise is still coming through the speakers when I remove the RCA's from the amp. The noise only goes away when I disconnect the power (either by disconnecting the negative or positive wire) going to the speakers. That's why I believe its a power issue. I keep hearing that there is no such thing as "dirty power" but that is the only way I can describe as the culprit behind my noise problem. Which is why I was hoping that an isolator or a 12 volt line conditioner might help me. Believe me, I've tried just about everything to this point and I'm just tired of it.

By the way thanks for describing what an isolator consists of. like I said I really have no idea what other purpose it has other than allowing you to put a 2nd battery in line with the alternator so that you basically have a 2nd circuit. If an isolator won't do the job I'm thinking maybe a capacitor or line conditioner will.
 

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If the noise is still there when you remove the RCAs, then a ground loop is not likely. I would check to make sure you have good grounds though. seriously sounds the amplifier is going bad.

as for an isolator, no will do nothing. for car audio you DO NOT want to use diode isolators anyway. you will lose 1.4 Volts through all the diode drops on those things. only type that should be used (if at all) would be solenoid style isolators and those are just high power relays, essentially.
 

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Have you tried a cap? I'd get a used 1f or something and hook it up in different places in the car, like on the amps, on the HU, under the hood. Would be nice to figure out what is making the noise like heater fan/etc. If you have alt whine it may be a problem in your system I'd change out amps and test RCA shields on the HU and all that if you have not already. Just saying it is more common to have a noise from X item in the car like an alt, while if you have noise from everything then its more common to have a ground loop in your audio equipment.
 

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Have you tried a cap? I'd get a used 1f or something and hook it up in different places in the car, like on the amps, on the HU, under the hood. Would be nice to figure out what is making the noise like heater fan/etc. If you have alt whine it may be a problem in your system I'd change out amps and test RCA shields on the HU and all that if you have not already. Just saying it is more common to have a noise from X item in the car like an alt, while if you have noise from everything then its more common to have a ground loop in your audio equipment.
he said it does it with the car off. so fan motors and alternator whine are out. it also does it with the RCA disconnected. has to be the amplifiers.

I forgot to mention also that the noise is still coming through the speakers when I remove the RCA's from the amp. The noise only goes away when I disconnect the power (either by disconnecting the negative or positive wire) going to the speakers. That's why I believe its a power issue. I keep hearing that there is no such thing as "dirty power" but that is the only way I can describe as the culprit behind my noise problem. Which is why I was hoping that an isolator or a 12 volt line conditioner might help me. Believe me, I've tried just about everything to this point and I'm just tired of it.
that is not a real test. would be like saying "everytime I unplug my lamp the light goes out, whats wrong?" of course the noise quits when you disconnect the speakers, lol.

you are right, there is no such thing as dirty power in a car. the battery pretty much filters out anything that can be called "dirty" add to the fact that the amplifiers themselves will further filter out more DC noise and you would have to have many volts of noise on your DC to cause any kind of noise. (most noises in a car DC system are in the mili-volts)

I would be looking at RCAs, bad grounds, bad amplifier. check your speaker wire and make sure it is not getting grounded to the chassis anywhere (chafed speaker wire)
 

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Discussion Starter #8
If the noise is still there when you remove the RCAs, then a ground loop is not likely. I would check to make sure you have good grounds though. seriously sounds the amplifier is going bad.


as for an isolator, no will do nothing. for car audio you DO NOT want to use diode isolators anyway. you will lose 1.4 Volts through all the diode drops on those things. only type that should be used (if at all) would be solenoid style isolators and those are just high power relays, essentially.
Cool thanks for the heads up. I guess the isolator is pointless for my issues. That leaves me with the option of installing a capacitor or a line conditioner. Hopefully that will clean up the noise a bit. By the way I've tried different grounding points and they are all rather good. I'm getting only about 0.04 drop in voltage
 

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Discussion Starter #9
he said it does it with the car off. so fan motors and alternator whine are out. it also does it with the RCA disconnected. has to be the amplifiers.



that is not a real test. would be like saying "everytime I unplug my lamp the light goes out, whats wrong?" of course the noise quits when you disconnect the speakers, lol.

you are right, there is no such thing as dirty power in a car. the battery pretty much filters out anything that can be called "dirty" add to the fact that the amplifiers themselves will further filter out more DC noise and you would have to have many volts of noise on your DC to cause any kind of noise. (most noises in a car DC system are in the mili-volts)

I would be looking at RCAs, bad grounds, bad amplifier. check your speaker wire and make sure it is not getting grounded to the chassis anywhere (chafed speaker wire)
Since this the second time someones mentioned "bad amplifier" I'm going to switch it out to see if that works. I don't really think that's it since its rather new but worth a try. I'm planning on running new speaker wires so that should take care of the possibility of a wire touching a metal surface. i'll check the amp first later today and post results. Thanks for the info on batteries. Very much appreciated.
 

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Cool thanks for the heads up. I guess the isolator is pointless for my issues. That leaves me with the option of installing a capacitor or a line conditioner. Hopefully that will clean up the noise a bit. By the way I've tried different grounding points and they are all rather good. I'm getting only about 0.04 drop in voltage
only reason to use an isolator is if you have a second battery and you want to listen to your system with the engine off and you DONT want to use the starter battery. keeps you from having a car that wont start. :)
 

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Discussion Starter #11
Sorry, I haven't had a chance to swap out the amp to find out if its actually the amp causing the noise or something else. Don't know if I mentioned this or not but the noise is still present, although you have to really pay attention to it because its not loud at all, even with the amp off. That is, when the car is running, but the amp has no power going through it, there is still a bit of alternator whine but its not very noticeable. Which is why I'm guessing that the power/ground wires might be picking up some noise.

The thing is I've already tried re-routing those wires to see if the noise would go away and it didn't work. In actuality, I disconnected the power and ground wires and then used jumper cables to feed the amp the appropriate power and ground. My reasoning was that if the noise was coming from inside the car then I would run the wires outside of the car and then that would eliminate the noise. However, it didn't work. So basically other than swapping amps (which I don't think will work but I'm going to try anyways), installing a capacitor, or installing a line conditioner, I'm all out of ideas. If anyone has any experience with line conditioners or knows if a capacitor would work for my situation please let me know. Thanks in advance.
 

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Okay, I swapped amps and the noise is still there. So its safe to assume its not the amp. I guess my only options left are to rewire the power/ground wires and possibly get a capacitor. Think I'm going to get a capacitor first just in case, seems like it would be easier to do that instead of rewiring everything. Any suggestions please let me know.
 

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you can try it. if you have alot of noise on the DC, it will filter it.

I dont remember (not gonna go read it all again ;) ) but does the noise stay if you pull the RCAs off?
 

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Discussion Starter #14
you can try it. if you have alot of noise on the DC, it will filter it.

I dont remember (not gonna go read it all again ;) ) but does the noise stay if you pull the RCAs off?
I bought a capacitor off of ebay, will probably get it next week so I will have to wait until then to see if it works. And yes the noise is still present when the RCA's are pulled off. Even with the amp off and car on the noise is present (although not as much). It seems to me that the more power (accessories are on) the louder the noise is. If not a lot of electrical current is being used then the noise is minimal. I've never had any issues like these in my previous installs. I thought I had a good understanding of electronics but all of this has me really just baffled.
 

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Do you live next to a power plant lol ?? You still have noise with the rca's off and the amp off with the car running ? This is what you should try,remove the speaker wires from the amp and hook them together to short them and start the car with amps off no rca's and see if you still hear noise from the speakers.
 

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Discussion Starter #16
Do you live next to a power plant lol ?? You still have noise with the rca's off and the amp off with the car running ? This is what you should try,remove the speaker wires from the amp and hook them together to short them and start the car with amps off no rca's and see if you still hear noise from the speakers.
I tried this and of course no noise is made but that is because there is no power going through it (since its disconnected). I actually did this with the RCA's on but it would have made no difference with them off since like I said before there is no power going through.

Like I've said before I do believe its a power issue. I'm thinking that the power wire is picking up noise somewhere along the line and in turn the amplifier is increasing the noise once it is turned on. I'm still waiting for my capacitor to arrive, will install to see if that helps matters. Thanks for the suggestion anyways.
 

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Discussion Starter #17
Well, I've installed a capacitor and the noise still persists. So I guess I will re-route my power and ground wires to see if it goes away. Its kind of weird though because the noise gets louder as more accessories are turned on so maybe its a ground issue as well. Really don't know though, I guess I just have to try different things until it goes away.....
 

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I don't know how an amp could make noise when it is off, unless you have noise getting into the speaker wires somehow. Anything is possible but if the outputs are off they are off, the speaker wires are not connected to anything really. Unless the amp is not really shutting off.

Starting to wonder if whatever that relay runs is messed up. You could try inductors on the amp power lines, but many amps have some internally.
 

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Being a mechanical person and not a very good sound system guy, maybe I've got a different perspective. Have you tried unplugging the fuse for the fuel injection or the fuel pump? I've seen it happen that when a fuel pump goes bad or starts to go bad, it sends all kind of weird noises through the car. Some fuel pumps are just inherently noisy, like the Walbro. Just a thought. That's the only thing that would give a whine when in ACC2 since that turns the fuel pump on.
 

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Exactly what i was going to say, fuel pump. Also how is your head unit grounded? I know some Pioneers can suffer from earthing problems.

Gav
 
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