# Noise Filter Question - Yes I searched!



## tspence73 (Oct 14, 2008)

Okay,

I still have alternator whine. I am going to use Crutchfield's tree to diagnose the problem:

When reading this I noticed that Crutchfield doesn't have any filters made for 80-amp and higher amplifiers. So, I went searching and found filters from a brand called "Newmar". They sell 80-amp and 150-amp line filters. Has anyone used these and found success? I'm having a hard time finding any reviews or feedback on these products. 

Here is the instruction manual on the product:
http://www.newmarpower.com/pdf/Manual-150A.pdf

Here are the products at their website (the 80-amp version is missing, but I've seen it for sale online, it's model# 80A):
http://www.newmartelecom.com/Noise-Filter/Noise-Filters.html

Does anyone have experience with these filters?


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## azngotskills (Feb 24, 2006)

IMO filters are just a band-aid to cover up the problem. You need to find out what is causing your problem then take steps to fix it. Common causes for problems are:

1) ground
2) RCAs
3) speaker wire
4) the components themselves, usually the HU or amp

I think the crutchfield tree is a good starting point, but not the only way. There are definitely more ways to figure out what is causing the whine and in your case you state is as alternator whine. The threads are here on DIYMA addressing similar problems, i have read them myself


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## Jimi77 (Jul 4, 2005)

tspence73 said:


> Okay,
> 
> I still have alternator whine. I am going to use Crutchfield's tree to diagnose the problem:
> 
> ...


I assume "still has noise" means you still have noise after swapping out amps, in which case that suggest the problem is something other than the amp. You might consider relocating the amp.


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## tspence73 (Oct 14, 2008)

azngotskills said:


> IMO filters are just a band-aid to cover up the problem. You need to find out what is causing your problem then take steps to fix it. Common causes for problems are:
> 
> 1) ground
> 2) RCAs
> ...


The amp is the effected component. Unplugged RCAs and the noise is still there. It's not just alternator noise. It's sounds like random little tiny popping noises along with what sound like very faint squiggly interference noises. I will unscrew the amp from the chassis of the car and see if that is the problem. I have completely re-run all power wire yesterday and re-grounded the amp. I was very thorough and careful in my amp install yesterday and was determined to make sure the cables were done by the book and clean.

I'm also looking for an 80-amp DC power conditioner but can't find any. I find it really strange that with so many audio enthusiasts who run car systems, the community hasn't demanded a high amp power conditioning product for cars. Heck, they could also make such a device a noise suppressor as well. I would pay hundreds for such a device to deliver noise-free, spike/dip-free and clean power to my amps. Heck, car voltage and noise is even more crazy than any home audio system would ever face. Spikes and dips in car systems are FAR more likely to cause audible audio issues. 

I have found some 20 & 30 amp DC power conditioners but that's it with no noise suppression built in.


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## ChrisB (Jul 3, 2008)

What have you done to diagnose the problem?

What have you done to isolate the source of your noise?

Automatically assuming it is your alternator without trying to diagnose the real problem is a good way to lead to an empty wallet, and FAST!

ETA: In after the op.


Please tell me the screws holding your amp down aren't going directly into the chassis/sheet metal of your vehicle.... In other words, please don't tell me you are making the heat sink on your amplifier a part of the circuit by using screws that are essentially grounding the heat sink to your vehicle....

ETA 2: What kind of vehicle do you drive? Older vehicles are more noise prone than newer ones. Especially Fords and GMs from the 80s!


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## tspence73 (Oct 14, 2008)

Jimi77 said:


> I assume "still has noise" means you still have noise after swapping out amps, in which case that suggest the problem is something other than the amp. You might consider relocating the amp.


It was more than just a swap. It was a complete re-wire too. After the install was completed and finding a speaker failure as well as pervasive alternator whine and other electrical noises, I had to postpone the final review of the amp until these problems are corrected. The review will be more than fair and extremely detailed. I promise it will make for good reading. I have already completed most of the first draft of the amplifier review. I think people will like it. For some reason I seem to entertain people on this board as my posts get so many hits. I think the DIY mobile audio forum should send me a t-shirt or mug or something, haha. 

You know what? Despite the teasing and some people being downright awful to me at times, I love this hobby now. I am getting more and more info everyday to help plan and complete my car audio project. I'm even finding new ideas and goals to meet. I am going to post here and document my journey of trials, failures, successes and eventually show a system that I'll be proud of. For now, I'm learning, sometimes the hardway but if I can post it all here, maybe I can save the next guy the trouble. I know you guys say that there is plenty of information, but not information layed out the way an average joe can learn it. I am trying and I will eventually get to a point where I can give solid advice to others and not make fun of them or bully them just because they don't understand some of the concepts right away.


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## tspence73 (Oct 14, 2008)

06BLMUSTANGGT said:


> What have you done to diagnose the problem?
> 
> What have you done to isolate the source of your noise?


Oh, last night after the install, I diagnosed the effected product. The amplifier is it. I disconnected the RCAs and the noise is still there. I'm going to unscrew the amp from the car chassis next to see if it still has noise.



> Automatically assuming it is your alternator without trying to diagnose the real problem is a good way to lead to an empty wallet, and FAST!


Why do you think I'm posting here? My health? No, my wallet! 



> ETA: In after the op.
> 
> 
> Please tell me the screws holding your amp down aren't going directly into the chassis/sheet metal of your vehicle.... In other words, please don't tell me you are making the heat sink on your amplifier a part of the circuit by using screws that are essentially grounding the heat sink to your vehicle....


Um....well.....yeah. I had to in order for the amp to fit.  I had to squish down the foam stuff far enough that the amp could clear the seat underneath. Anyway. If I find by unscrewing the amp the problem goes away, then I'll find some rubber grommets to prevent contact with the amp chassis and the car chassis.



> ETA 2: What kind of vehicle do you drive? Older vehicles are more noise prone than newer ones. Especially Fords and GMs from the 80s!


I am driving a 2007 Nissan Sentra. 120-amp alternator. 4awg power lines standard from the alternator to the battery and chassis. It's a pretty good electrical system, capable of running an optional high powered rockford fosgate sound system. So, putting in a good aftermarket system shouldn't be problematic.


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## tspence73 (Oct 14, 2008)

While I'm waiting to do the diagnosis on the noise, back to my original question. Has anyone bought a noise-filter product made for a high output system that worked well for them?


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## capnxtreme (Feb 5, 2008)

No, we prefer to install our systems properly in the first place.

A noise filter is a band-aid, PERIOD. A band-aid on a wound that requires stitches.


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## tspence73 (Oct 14, 2008)

capnxtreme said:


> No, we prefer to install our systems properly in the first place.
> 
> A noise filter is a band-aid, PERIOD. A band-aid on a wound that requires stitches.


I've read stories of people who did everything right and still couldn't get rid of it until a filter was used but my equipment requires filters that are designed for more amps. I might be able to get away with a 60-amp filter.


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## guitarsail (Oct 12, 2007)

I think you should listen to all of the advice given above...like...ungrounding your heatsink to the chassis, making sure you have a GOOD ground point...HU ok...etc..

then throw it all out the window and ignore it, because I think this is a hands down, case of violent bass air getting to your amplifier!


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## capnxtreme (Feb 5, 2008)

tspence73 said:


> I've read stories of people who did everything right and still couldn't get rid of it until a filter was used but my equipment requires filters that are designed for more amps. I might be able to get away with a 60-amp filter.


The answer is no, ok dude? Assuming your search wasn't as dumb as your posts, there's a reason you didn't find anything on it. If you didn't want to hear the answer, don't ****ing ask.



> For some reason I seem to entertain people on this board as my posts get so many hits.


Ever hear of a trainwreck?


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## tspence73 (Oct 14, 2008)

capnxtreme said:


> The answer is no, ok dude? Assuming your search wasn't as dumb as your posts, there's a reason you didn't find anything on it. If you didn't want to hear the answer, don't ****ing ask.
> 
> 
> 
> Ever hear of a trainwreck?


What the hell? I thought this place was somewhere someone could ask a question. The thread is legit and so was the question, ABOUT A NOISE FILTER. Jesus, you guys are real jerks. If you don't like helping people then just don't reply. I'd rather not hear from you guys again if that's the way you're going to answer legitimate questions with non-answers and giving me a hard time. I already stated at the very beginning that I was going to go through a series of steps using the Crutchfield site. Then people started repeating the same steps already listed on the site, which is okay, but then I get insulted and my thread railroaded for no good reason. So, in the future, if you aren't going to to be helpful and be nice about it, then just don't post anything and move on.

I think there are people that like my threads. People that like things a bit easier to understand. People who are probably afraid to post the questions because of flamers like you. You may underestimate me, but in my own way I'm learning and will have a nice system eventually put together with hard work. If you don't like me I can't help that. I won't stop being who I am just because someone acts like a jerk. I don't think people are viewing my threads because of the 'trainwreck' effect. I think maybe the 'know-it-alls' fall into that group. But I think there are as many or more people reading my threads and learning something new or reading because they wanted the same clarification I did but were afraid to ask.


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## tspence73 (Oct 14, 2008)

capnxtreme said:


> No, we prefer to install our systems properly in the first place.
> 
> A noise filter is a band-aid, PERIOD. A band-aid on a wound that requires stitches.


A noise filter is a tool. A tool used by professional and commercial companies for ambulances, boat electronics, etc. When someone has interference or noise on their electrical it could happen even if you do everything right. That's why the filters are made. If achieving a noise-free mobile electronics enviroment was as easy as just "doing it right" then filters wouldn't be used by the pros.


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## Oliver (Jun 25, 2007)

The amplifier may be missing some extraneous circuitry that helps in dealing with some prevalent issues [ turn-on, turn-off pops, etc.., ] this helps the amp manufacturers wallet.


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## capnxtreme (Feb 5, 2008)

tspence73 said:


> A noise filter is a tool. A tool used by professional and commercial companies for ambulances, boat electronics, etc. When someone has interference or noise on their electrical it could happen even if you do everything right. That's why the filters are made. If achieving a noise-free mobile electronics enviroment was as easy as just "doing it right" then filters wouldn't be used by the pros.


Doing it right ain't easy, that's the point. If you haven't gone through the steps, you shouldn't be asking this question, yet. I am hostile because you clearly haven't, and you are wasting all of our time (yet again).


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## tspence73 (Oct 14, 2008)

capnxtreme said:


> Doing it right ain't easy, that's the point. If you haven't gone through the steps, you shouldn't be asking this question, yet. I am hostile because you clearly haven't, and you are wasting all of our time (yet again).


You don't have to respond if you don't want to. If you feel like I'm wasting your time you can simply not read it. You seem to want to help me, but go out of your way to act annoyed when you do.


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## guitarsail (Oct 12, 2007)

boy do these threads provide fantastic laughs


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## Lothar34 (Oct 6, 2006)

tspence73 said:


> You don't have to respond if you don't want to. If you feel like I'm wasting your time you can simply not read it. You seem to want to help me, but go out of your way to act annoyed when you do.


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## bobduch (Jul 22, 2005)

No experience with those filters. But the others are correct. I'll bet you can get rid of the noise w/o a filter. 

First, I always ground everything in the system to the same point. The amps have short ground runs and the other pieces maybe longer. I run a 4 gauge ground from where the amps are grounded to the dash area for the pieces located up there. For example, the HU, which draws almost no current, but I want to be sure that I don't add resistance in that ground wire. So I overkill with the 4 gauge.

Second. Never use the seat bolt for ground. I've seen this written in several places over the years. The threads may have paint on them (and hard to get off w/o messing up the threads). And the bolts may be zinc plated. Why does this matter?

Glad you asked. I had noise that changed by moving things around (like xovers). Could not get rid of it. Ground spot was good. Sanded shiny metal. What could be wrong? Zinc plated screw. But all the screw does is push the ground wire spades (or ring terms) to the shiny metal. Or so I thought. Replaced the screw and the noise was gone. All, as in 100% of it. Werewolf gave me a very technical explanation as to why it matters. Who would have thought? Also, many use a star washer with the ground screw.

So keep playing detective before going the filter route. Can you plug in (via rca's) a home system to the car amp? Still noisy? Change the rca's. Change the speaker wire. Can you run the car HU into a home amp connected to the car speakers? Still noisy? Have you thought about checking (and cleaning) the ground wires under the hood. Like the battery terms to the engine block/chassis. I mean check every link of the chain. You will find the problem. As said above, make sure your not grounding your amp chassis. But this goes for HU and procsessors too.


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## Jimi77 (Jul 4, 2005)

Take Bob's or Lothar's advice....


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## tspence73 (Oct 14, 2008)

Jimi77 said:


> Take Bob's or Lothar's advice....


Okay. I will. I don't want to blow $150 without needing to. I want these noises banished!


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## tspence73 (Oct 14, 2008)

HA!

I did it! I fixed the noises! 

VICTORY!









It was a pain in the butt. First, I thought it was just the amp only. Naw naw naw. I isolated the amp and the alternator whine went away. BUT! There were plenty of other squiggles, tiny pops, hums and noises still there!!!  Then I unplugged the RCAs and these 'other' noises went away.  

To make things more confusing me and my friend were probably looking like cavemen trying to use fire for the first time.  I was listening close to the speaker because it was windy and hard to hear the noises with the doors open. We tried double shielded 75-ohm video style RCAs and the noise was reduced by a good amount. Then we were stretching and moving cables in odd places and listening to the noises get better then come back. We played the game of 'find the quiet route through the car cabin'.

When only one set of RCAs were plugged in, the noise disappeared. It didn't matter which set. As long as only one set was plugged in, the noises vanished. And when the noises were there, getting the RCAs anywhere near the power line or the car chassis made the noises worse. We found one good route. Suspended in the cabin at least a foot above the floor of the car. 

Finally we settled on routing the cables above the floor, just under the steering wheel, down the kick panel, wrapped the RCAs in aluminum foil where they passed the left speaker wire and then to the amp. We wrapped more foil around the amp's power line to try and isolate the interference as much as possible. We got most of the noise to a bare audible level where all that could be heard was a midrange-frequency hum through the din of the car motor and traffic. 

On the way home I still wasn't satisfied. The battle was not over. I decided that I would try an RCA ground loop isolator at the amp connection. I initially bought two of them but discovered that one was all that was needed. With only one of the RCA sets connected to the RCA ground loop isolator, the noise vanished completely with all four channels connected to the amp. I simply returned the leftover one after that. Whew! I won!


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## chad (Jun 30, 2005)

What headunit again?
Are the original RCA's shielded or those damn twisted ones with no shield?


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## tspence73 (Oct 14, 2008)

chad said:


> What headunit again?
> Are the original RCA's shielded or those damn twisted ones with no shield?


Headunit is on my sig under this post. Originally I was using non-shielded zipcord RCAs. We tried dual-shield video-use RCAs and it helped but didn't eliminate the problem. An RCA ground loop isolator on just one RCA set of plugs was all that was needed. Noise gone. Alternator whine was cured by isolating the amp's chassis from the car's chassis ground. My system is now quiet.


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## chad (Jun 30, 2005)

The noise you were getting after isolation, especially pops with the brake lights, twirrs, etc was likely induced noise but it can only be induced if the shield is not tied to ground. Next time you have the headunit out check and make sure that the sleeve of the RCA on the headunit is tied to ground or damn close to ground, I'm wondering if there is not an issue there.


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## tspence73 (Oct 14, 2008)

chad said:


> The noise you were getting after isolation, especially pops with the brake lights, twirrs, etc was likely induced noise but it can only be induced if the shield is not tied to ground. Next time you have the headunit out check and make sure that the sleeve of the RCA on the headunit is tied to ground or damn close to ground, I'm wondering if there is not an issue there.


Do you have a picture of what this should look like?


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## chad (Jun 30, 2005)

The outside shell of the RCA, on the headunit, with the RCA cables disconnected, see if it's ground, I don't have a pic but that's about as clear as I can describe it


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## tspence73 (Oct 14, 2008)

chad said:


> The outside shell of the RCA, on the headunit, with the RCA cables disconnected, see if it's ground, I don't have a pic but that's about as clear as I can describe it


There are 3 sets of RCA jack outputs on the back of the head unit. None of them are grounded from what I remember. That's not to say that there wasn't a ground of some other kind that I didn't notice.


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## chad (Jun 30, 2005)

They should have some reference to ground, so one probe to the chassis, one probe to the shell.


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## tspence73 (Oct 14, 2008)

chad said:


> They should have some reference to ground, so one probe to the chassis, one probe to the shell.


Okay. So, you're saying that the HU chassis needs a ground and then at least one of the 3-sets of RCA plug-in's needs a wire soldered to it's outer-metal and the other end of the wire grounded at the common grounding point?

Do you think I should disconnect the RCA ground loop isolator and do this? The noise is gone. Is it worth the effort? Or is this more like an excercise in 'doing it right'?


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## chad (Jun 30, 2005)

The shell of the RCA should already be grounded, SOME units (pioneer) have an internal fuse that protects this path and will blow if you look at it funny. I tend to believe it's fine because without it the isolator would not work as you would not have a complete circuit to drive the primaty of the transformer in the isolator, but it's worth a look. Losing that ground is a dead giveaway for the noise you are expieriencing.


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## tspence73 (Oct 14, 2008)

chad said:


> The shell of the RCA should already be grounded, SOME units (pioneer) have an internal fuse that protects this path and will blow if you look at it funny. I tend to believe it's fine because without it the isolator would not work as you would not have a complete circuit to drive the primaty of the transformer in the isolator, but it's worth a look. Losing that ground is a dead giveaway for the noise you are expieriencing.


The crazy thing that got me was that when I had only 1 set of RCAs connected, it didn't matter which set, front or rear, there would be no noise. Plug in the second set and the noise is there. I only needed the ground loop isolator on one set of RCAs. That's what's got my head itching.


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## chad (Jun 30, 2005)

Because the shields are all tied together as they are at the amp, the isolator breaks any electrical (DC) bond to the amplifier and uses galvanic isolation to get the audio from one to the other. Since these are all tied together, when you introduce a direct connection you lose the isolation effects of the transformer.

You have a ground loop, there is a funky ground somewhere and the 2 grounds are not at the same potential.


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## tspence73 (Oct 14, 2008)

chad said:


> Because the shields are all tied together as they are at the amp, the isolator breaks any electrical (DC) bond to the amplifier and uses galvanic isolation to get the audio from one to the other. Since these are all tied together, when you introduce a direct connection you lose the isolation effects of the transformer.
> 
> You have a ground loop, there is a funky ground somewhere and the 2 grounds are not at the same potential.


Must be. I've checked all my grounds though. I've kept all but one ground to a common point. Perhaps that could be it?


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## tophatjimmy (Dec 16, 2005)

Unfortunately I have a touch of the noise too.....

I can attest that sometimes doing everything you can think of still doesn't always work.
My amps are mounted to an MDF board, grounded to the same place on the frame as my battery. 
The RCA's are unshielded, but they aren't the cause. I ran a new set up and over the vehicle to the amp and still got noise. 
The radio was using the factory ground, so I ran a 16g wire back to the same spot on the frame as my battery and amp were grounded, still got noise.



I'm gonna check my radio as Chad suggested and make sure all RCA shields reference to ground. If they are ok, my next step is gonna be an RCA GLI.....

So I hate to play devils advocate...but **** happens.


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## TrickyDIck (Aug 22, 2008)

First off-

why is this thread in the trash bin (you should have searched) ?

Next -

I've got noise like crazy on my W505. Only RCAs I am using are from the processor to the amps. Using an optical cable and AINet cable frmo HU to the processor. I get the pops with turn signals, brake lights, etc. As far as I know, there is no ground from the chassis to the RCa shields, but in my case there are no shields because there are no RCA cables. There is a rear view camera. I may try disconnecting this guy to see if that's the culprit, though there is no audio RCA, suppose a ground loop wouldn't care what the RF is ..

Is the AI Net cable sufficiently shielded and internally grounded?


TD


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## chad (Jun 30, 2005)

TrickyDIck said:


> Is the AI Net cable sufficiently shielded and internally grounded?
> 
> 
> TD


I BELIEVE (disclaimer) that some have had issues with 3rd party AiNet cables, is yours 3rd Party?

Is it run anywhere near the stock car wiring?

I dunno why it's int he trash, people got on a spree at one point.


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## TrickyDIck (Aug 22, 2008)

chad said:


> I BELIEVE (disclaimer) that some have had issues with 3rd party AiNet cables, is yours 3rd Party?
> 
> Is it run anywhere near the stock car wiring?
> 
> I dunno why it's int he trash, people got on a spree at one point.


my AiNet cable came with the Alpine equipment.

Turns out my noise emanates from the KCE900e device to mix nav prompts into the audio stream. Turning NAV MIX to off removes the noise. Turning it ON and increasing the level makes it worse, the higher the level is set.

I suspect a grounding issue and if this won't fix it, I will replace the unit.

TD


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## subwoofery (Nov 9, 2008)

I read somewhere that Nissans were noisy cars... around the headunit that is.


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## ErinH (Feb 14, 2007)

back from the dead, because I searched...


I’ve got alt whine from Hades plaguing me. ALL my grounds share the same location (via distro block); even the headunit. Whine is still there. Move headunit ground to battery (outside of car)… whine still there. Move main ground to 3 positions throughout the car, ALL bare metal and THICK… whine still there. I could get it down to acceptable levels (see: where most people would say ‘good enough’) but that’s not good enough for me: I want it GONE!

I also get an EMI issue via the daytime running lights (buzzzzzzzz until I flip the headlights on). 

After speaking with Chad on the phone last night I’m going to try a ground loop isolator. If it works, then I have direction, even if I don’t keep the GLI in my car. Another direction I'm going is to ground the RCA shields to the common ground as well.

I can see running a single amp in a car and swearing up and down that you didn’t get the problem solved right, but IMO, running 4 things in the trunk and spending countless hours searching down the culprit to not find it, and then resorting to a GLI does not equal a failure. It’s part of trial and error. And, after speaking with Chad, then doing some research, I, quite frankly, have completely changed my viewpoints on GLI’s (which were solidified in audio-myth because I accepted internet knowledge as Gospel).

And I tell you what... once I do this, IF the GLI solves the problem, I'll run RTA with and without it, then post the results here. I'll even do it at 1/24th scale and sum the responses.


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## Jimi77 (Jul 4, 2005)

bikinpunk said:


> back from the dead, because I searched...
> 
> 
> I’ve got alt whine from Hades plaguing me. ALL my grounds share the same location (via distro block); even the headunit. Whine is still there. Move headunit ground to battery (outside of car)… whine still there. Move main ground to 3 positions throughout the car, ALL bare metal and THICK… whine still there. I could get it down to acceptable levels (see: where most people would say ‘good enough’) but that’s not good enough for me: I want it GONE!
> ...



Did you try a different source (ie Ipod)? Good luck


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## ErinH (Feb 14, 2007)

yep. every source.


GLI didn't work. Didn't even make a dent.

thus, it begins...


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## Jimi77 (Jul 4, 2005)

bikinpunk said:


> yep. every source.
> 
> 
> GLI didn't work. Didn't even make a dent.
> ...



A different source eliminated the possiblity of a ground loop. That pretty much means it's the amp. Make sure no part of the casing is grounded.


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## ErinH (Feb 14, 2007)

huh?

if it's all sources I don't see how that really tells me anything. 

There's a set of RCAs running from the headunit to the processor. It carries all analog signal including ipod & radio. I get noise from both sources. 

I'll have to make muting plugs tonight


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## Jimi77 (Jul 4, 2005)

bikinpunk said:


> huh?
> 
> if it's all sources I don't see how that really tells me anything.
> 
> ...



I thought you tried a completely different source - ie plugging the ipod directly into the amp.


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## ErinH (Feb 14, 2007)

oh, I misunderstood. I thought you asked if I tried a different source on the headunit (aux, cd, radio).


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## Jimi77 (Jul 4, 2005)

bikinpunk said:


> oh, I misunderstood. I thought you asked if I tried a different source on the headunit (aux, cd, radio).


Good luck troubleshooting. Muting plugs or an alternative source should get you pointed in the right direction. 

Make sure your amp casing isn't in contact with sheetmetal. Sometime a screw can go thru your mounting board into sheetmetal and cause ground loop symptoms.


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## wenkebach (Jan 13, 2009)

I think I blew a Pico fuse in my Pioneer FH-P8000BT HU. The noise is terrible and started suddenly after I accidentally grounded a speaker to metal (I was just tightening up the connection and replacing) while the system was on. I know, bad move.

Anyway, I have been studying the Pico fuse issue, and I think that's my problem.

At this point, will grounding the RCA plugs fix the problem?


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## chad (Jun 30, 2005)

wenkebach said:


> I think I blew a Pico fuse in my Pioneer FH-P8000BT HU. The noise is terrible and started suddenly after I accidentally grounded a speaker to metal (I was just tightening up the connection and replacing) while the system was on. I know, bad move.
> 
> Anyway, I have been studying the Pico fuse issue, and I think that's my problem.
> 
> At this point, will grounding the RCA plugs fix the problem?


Yeah but, what speaker output did you ground, off of the deck or off of an external amplifier?


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## wenkebach (Jan 13, 2009)

The speaker was being fed by an external amp.

When it touched metal, there was a very loud BUZZ for about 1 second. Afterwards, I insulated the speaker leads, and re-mounted the speaker.

It was immediately after this that the problem occurred.

With key "on" and engine "off" and HU turned on at zero volume, and no matter the HU Source, there is a medium frequency melodic HUM. It is really obnoxious.

I can turn up the radio (or whatever source I'm using) and it works, but the noise is a constant and does not vary with the HU volume control.

I tried swapping amps - this didn't change the problem.


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## chad (Jun 30, 2005)

Your problem is larger than you think, the loud buzz pulled a ton of current, likely the ground for the amp could not handle it and started going for the headunit ground. This popped the fuse. Find a solid ground for the amplifier or at least REALLY look into this.


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## wenkebach (Jan 13, 2009)

Chad - Thanks for your help with this.

I have ordered a replacement HU assuming the worst (after I figured out that the amp was ok).

I got the HU for Christmas, so I can get a refund. The new one will be here tomorrow.

I am a newbie here - have done a few installs, but obviously have a lot to learn.

The amp is grounded to a seat bolt. I used a grinder to grind the paint down to shiny and a ring terminal for the 8 g ground wire that is about 8" long.

Here's what I have learned after studying the board this morning. Please add to this whatever I leave out:
1. Never ever work on any component without disconnecting power from the battery.
2. RCA cables are the last things to be plugged in to the HU before energizing.

What else?


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## chad (Jun 30, 2005)

Man, sometimes you just never know. For example, I was CERTAIN that the seat belt bolt on the same chunk of metal as the rear-strut-tower would make for a DAMN solid ground point but I was wrong, it was noisy, I found a better one.

I rarely disconnect my battery, well I only disconnect it to replace the battery to be honest and even then I keep the car "powered up" with a power supply. I'm not saying that's right though. I DO power down to disconnect and re-connect RCA's but ONLY to reduce noises that could harm an active rig. (I don't use pioneer)

I really don't consider myself lucky but rather a thinker. I just think about what the ramifications of what my actions could be.


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## chad (Jun 30, 2005)

Auto-dupe


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## wenkebach (Jan 13, 2009)

Let's assume that the ground to the amp is OK.

Would what I did have blown the pico fuse in the HU?

In other words, if the amp was grounded properly, would I not have blown pico fuse in the HU?

If the ground is really adequate, and I just need to replace the HU, then I'd just as soon pop the new HU in and be done with it.

BTW - the system was working great, noise free prior to the incident.


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## wenkebach (Jan 13, 2009)

chad said:


> Auto-dupe


Auto dupe?


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## Jimi77 (Jul 4, 2005)

wenkebach said:


> Auto dupe?


It means he double posted.


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## wenkebach (Jan 13, 2009)

Well - IT WORKED !!!

I grounded the RCA's just as outlined in this thread. Absolutely NO NOISE !!!!

I am blown away how easy this was !!!

So in post-mortem, if you have a Pioneer HU, and your system suddenly develops Buzzing, Humming, etc...consider a blown Pico fuse as the culprit. The fix is simply to ground the external RCA jacks.

Wow - still can't believe it. Thanks to this thread.


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