noice that follows the rpm?!

[gregus 10+ year member]

Hi, I just bought a pioneer dehp8600mp, and I'm having a problem with noice. It's a noice that follows the rpm that my engine runs at, and it's annoying as hell. I've got a stereo-system that I've had for about a year, except for the H/U, and there was no noice before, even though my old H/U just put out 5 volts on each channel, while the new one does 6 volts, or at least that's what they claim it does.. Does anyone have an idea as to what might be the cause of this? I've checked everything with the H/U wiring, and the RCA's, but nothing seems to work. Any though is welcome!!!

Thanx

Gregus

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[bigwheel15 10+ year member]

Do you have your power ran next to to your rcas and speaker wire, if so seperate them.Try different rcas, maybe yours are bad. Also check your ground, if this does not help try a search, you can find thousands of possibilities to try.

 

[pavengmike6 10+ year member]

You have what is known as GrOUND LOOP. You will need to redue your ground on your HU, and maybe your amp too. Instead of using the factory ground for you HU make a new one behind the dash. Take the time and clear all the paint away from the area.

Next you may look into doing the same thing for your amp. Like Big said saperate you power wire from all other wire. At least 12 to 16 inches. Granted you will not be able to do this near the amp. I know some people say you cannot pick up feedback from your power wire to your rcas. I SAY BULL POOP. Anything is possiable. And I would try everything.

If all else fails you can buy a ground loop isolator. It connects behind your HU or they make one that mounts near your amp.

I would bet your HU ground is not up to par, or your amp ground is not up to par. Oh one more thing. If you have not already done this change your ground wire and make it the same size if not bigger than your power wire (on the amp) Most kits give you a smaller size ground wire. This will help.

 

[forbidden 10+ year member]

My bet is on the crappy ground isolation in the Pioneer cd player. What cd player did you have before?

 

[helotaxi 5,000+ posts]

Next you may look into doing the same thing for your amp. Like Big said saperate you power wire from all other wire. At least 12 to 16 inches. Granted you will not be able to do this near the amp. I know some people say you cannot pick up feedback from your power wire to your rcas. I SAY BULL POOP. Anything is possiable. And I would try everything.

Well I'm going to say it one more time maybe just cause I'm ornery like that. You will not pick up noise from your power wire on your RCAs. If you could, then just moving the RCAs wouldn't help anyway. Think about it, where is the return current flowing in 99% of the systems? The chassis. If you are worried about the Pos wire radiating noise, shouldn't you be just as worried about the negative? Unless you have a way to move the RCAs "12-16 inches" away from the chassis, then what would the point be. The other flaw in your argument is that is takes a mag field of a large magnitude fluxuating at an audible frequency to induce noise in an AC signal transmission.

As forbidden said, I would look at the lousy signal ground isolation on the Pioneer unit. Without good signal isolation, the unit becomes especially suceptible to ground loops and any tiny resistance in the HU ground will cause the HU to seek ground through the RCAs. There is not a filter on the power supply of most HUs to eliminate tiny fluctuations in the input voltage caused by the rectifier in the alt.

 

[pavengmike6 10+ year member]

Well I got the response from the person I thought would have something to say about this topic

Well I tested your idea and again I got noise by moving my RCA"S closer to my power wire. SO again I SAY YES YOU CAN.

The field around the power wire is more consentrated than in the body of the car. As the return path comes back to the battery through the chassis it might be finding a easier path of resistance a good distance from the area near your RCA'S. I understand the relitive thinking you have behind your idea, but I have seen it and heard it to know it CAN HAPPEN.

Helo you are a very smart guy I will give you that. And with that you should also know that ANYTHING can happen when it comes to elec current. There may be 1000 laws that elec current is supposed to conform to but all I can say is it happend to me. All I did was move the rcas closer and further apart from the power wire and the noise got better and worse.

You and I have gone round and round about this topic 1000 times. I stand firm because I have seen it, heard it and lived it. Never say never.

About the other flaw you were talking about. Yes I know it takes a fairly large field to produce input into and AC signal. But again I DO NOT KNOW WHY I just know it DID. We are not hear to argue what did and did not happen. For some reason you always like contradicting things I say. I only say things I have lived and seen. If I have not seen them I do not open my mouth and tell lies. Then answer me this. Seeing A/C current is what is produced through the RCA cables. Correct?

You have a DC current in the power wire correct?

Well correct me ( I know you will ) if I am wrong, but A/C means alternating current, and D/C means direct current. With that A/C is pulsing, or alternating to push the signal down the path (rcas). If the D/C (power wire) is produing a field around the wire with 1000000000 of stray electrons forming the field (each one looking for a place to go GROUND who is to say that everytime the A/C electrons pass through that field they do not grab a stray D/C electron and take it with them? Thus the stray electron produces a difference in input causing a noise to be heard. If electricity follows the path of lease resistance and that just happens to be the RCA cables then all the stray electrons will want to find a new home. Then cannot get through to the body of the car, Seeing mine is coated with a rubber coating so they cannot go back to the NEG terminal that way, so they attach themself to the least insulated source (the rca cables) and find a ride back to a neg source.

To answer you, yes my truck body is coated with a rubber coating FROM THE FACTORY about a 1/4 inch thick. So that is acting as an insulator keeping the returning electrons from comming through the chassis and going into the RCA's . That is the only explanation I have for you saying the nosie would come from the chassis if my theory was true.

 

[gregus 10+ year member]

Hi again,

thanx for all your replies! To answer some of your small questions, I have the rcas running down the left side of my car, and the speaker and power-wires running down the right side, so they're so far away from each other as possible. I have had a pioneer deh-d77 earlier, and nothing has been changed in the wirering since then. I have the biggest awailable cables for both power and ground on my amp, but the amp is grounded to the battery, which is maybe too far away. I also have a 1 farad condensator (or whatever it's called in english?), and it's grounded by a couple of midsized cables, that should add up to be approximately the size of my power-wire. Also, the rcas should be of good quality, at least they were the next to top model by monster cable, and cost me more than 100$ each, but i will test them just to make sure.

Anyways, I will try to test the ground on the amp, and also replace the factory-ground on the h/u, and see what happens. I've also heard there is something that i can connect to the rcas and the ground on the h/u to remove noice. Have anyone tried this?

Thanx again

Gregus

 

[helotaxi 5,000+ posts]

You and I have gone round and round about this topic 1000 times. I stand firm because I have seen it, heard it and lived it. Never say never.

What kind of RCAs are you using and what type of design and shielding do they use?

About the other flaw you were talking about. Yes I know it takes a fairly large field to produce input into and AC signal. But again I DO NOT KNOW WHY I just know it DID. We are not hear to argue what did and did not happen. For some reason you always like contradicting things I say. I only say things I have lived and seen. If I have not seen them I do not open my mouth and tell lies. Then answer me this. Seeing A/C current is what is produced through the RCA cables. Correct?

Correct

You have a DC current in the power wire correct?

You are on the righ track so far...

Well correct me ( I know you will ) if I am wrong, but A/C means alternating current, and D/C means direct current. With that A/C is pulsing, or alternating to push the signal down the path (rcas). If the D/C (power wire) is produing a field around the wire with 1000000000 of stray electrons forming the field (each one looking for a place to go GROUND who is to say that everytime the A/C electrons pass through that field they do not grab a stray D/C electron and take it with them? Thus the stray electron produces a difference in input causing a noise to be heard. If electricity follows the path of lease resistance and that just happens to be the RCA cables then all the stray electrons will want to find a new home. Then cannot get through to the body of the car, Seeing mine is coated with a rubber coating so they cannot go back to the NEG terminal that way, so they attach themself to the least insulated source (the rca cables) and find a ride back to a neg source.

...and now you've lost the right track. You seem to have a field and a potential confused. A potential is caused by excess charge (electrons). A field is created by potential. A field will surround any wire carrying current, but a field does not have any electrons associated with it. You can't pull electrons out of a field, because there aren't any there. The electrons are confined by the insulation of the wire. If there were electrons in a mag field, you would have sparks flying every time you started a car, turned on a light, played any stereo equipment.
If you are getting radiated noise from your DC power wire, then I will say it again, your DC isn't. You are getting pulses in the power caused by a noisy rectifier in the alternator. This is actually one place that a cap can help out. A large cap wired in parallel with the battery will act as a shunt and filter that noise out.

I'm not trying to be contradictory here. I'm not acussing you of lying. I'm just trying to dispell some very common misconceptions that have been around the car stereo world for a very long time that just don't stand up to science.

 

[pavengmike6 10+ year member]

What kind of RCAs are you using and what type of design and shielding do they use?
At the time I was using a set I got in an install kit. They are the standard cheap RCA with a think rubber coating. I did not tear into them and see if there is any type of shielding.

I moved to a gold series from radio shack. They have about 4 times the insulation and I am sure better shielding. It helped, but it did not go totally away. I then moved the wire as far as I could (it is run on the same side of the car) and it went away. I had read your posts before about the noise and it not being able to happen, so I played around with it. They only thing I did was move the wire closer and further away. The sound got louder as I got closer and weaker as I pulled it away.

I totally understand the concept you have been saying all along. I can only say what I see. I have been installing stereos for 20 years, and I have always heard of this being a problem. It was not until I started reading these posts that people say it cannot happen.

The only reason I tell people to move the wire is to take any chance away ( know there is not much of one) that they may have the same problem I did. It is not supposed to work the way it did, but I cannot explain it any better than you can.

I would hope nothing is wrong with my ALT, seeing it is BRAND NEW from the factory. Who knows my DC current may Be DC and A/C. KIDDING

 

[pavengmike6 10+ year member]

Sorry back to the topic. Yes you can buy a ground loop isolator. It plugs into the rcas. There are 2 different types on the market. One that has a Ground wire with it, and the other that does not. They both seem to work ok, but I have had better luck with the grounded one.

As for you ground, YES THAT IS WAY TO LONG OF A GROUND. Your ground should be as short as possible. I would not go more that 12 to 18 inch's

 

[gregus 10+ year member]

I have now tested another h/u in my car, same as the one i had before. A pioneer deh-d77 or something, i can't quite remember. It came out with no noice whatsoever. I have also tested my new h/u in another car, which has an alpine h/u installed, and there was a noice which isn't there when the alpine is used. The noice was different in the two cars, with kind of a loud drumming sound with a high-frequent more quiet noice in the other car, and just an annoying high-frequent noice in my car.

As for my car, I've changed the ground. Removed all painting from a point in my trunk, and I now have a big ground cable that's about 10" long, but the noice doesn't go away. I'm going to return my h/u tomorrow, and say it's something wrong with it. Does anyone think there can be something other than the h/u?

Just to be thorough, the other car has expensive monster cable rca's, and is grounded with a big ground cable near the amp, which is an Alpine V12.

Thanks

Gregus

 

[Davbret]

It's definitely the headunit. You blew a ground trace on the preamps. It's a cheap ($50) fix for any audio repair shop to take care of. Typcially happens when you pull/connect RCA leads when the headunit is powered on.

The "drumming" is digital feedback and the whine is from your alternator. When both are heard it's all but a dead ringer diagnosis of a blown ground trace in the headunit. Unfortunately I know all too well about this..... //content.invisioncic.com/y282845/emoticons/bawling.gif.6287aa5d1d447c8af063fc9466e822ef.gif

R

 

[gregus 10+ year member]

Thank you. I sent the h/u in yo get it fixed, and they did it for free, so now everything works like a charm!

 

[joshpoints 10+ year member]

Well I'm going to say it one more time maybe just cause I'm ornery like that. You will not pick up noise from your power wire on your RCAs. If you could, then just moving the RCAs wouldn't help anyway. Think about it, where is the return current flowing in 99% of the systems? The chassis. If you are worried about the Pos wire radiating noise, shouldn't you be just as worried about the negative? Unless you have a way to move the RCAs "12-16 inches" away from the chassis, then what would the point be. The other flaw in your argument is that is takes a mag field of a large magnitude fluxuating at an audible frequency to induce noise in an AC signal transmission.
As forbidden said, I would look at the lousy signal ground isolation on the Pioneer unit. Without good signal isolation, the unit becomes especially suceptible to ground loops and any tiny resistance in the HU ground will cause the HU to seek ground through the RCAs. There is not a filter on the power supply of most HUs to eliminate tiny fluctuations in the input voltage caused by the rectifier in the alt.

I've heard amp companies actually say that you should move the power cable away from the rca's if you are having this problem. Amp companies also say it can be caused by a bad ground.

 

[Davbret]

Thank you. I sent the h/u in yo get it fixed, and they did it for free, so now everything works like a charm!

Awesome, schweeeet!! Glad I could help! //content.invisioncic.com/y282845/emoticons/veryexcited.gif.c26a15f316d23068607f36ddacd7a7ab.gif

R