New radio/amplifier alternator wining noise

[tolum]

Guys;

Just installed my kit. Works great when engine not running. When I start it I can ear the engine wining noise in all speakers. What is the best solution to eliminate that noise?

Thierry

[Cassiebox]

you have what's called a ground loop caused by your radio, components and amp having different grounds. You can try either a power filter, GLI (ground loop isolator), or creating a common ground for all the components.

[tolum]

Done some troubleshooting. The problem is comming from my pre-amplified subwoofer. I have a very small Blaupunkt THB200A. When I unplug the RCA cables from back of the radio, humming stops. I try another thing. Unplug actual RCA cable both ends and try another RCA cable, no change. Next try will be for tomorrow, I will look to the sub ground. Maybe it is not good! Will use another cable and ground it solid and make another try... There should be a solution! I don't want to use a bandaid like a GLI...

Thierry

[Cassiebox]

Agree GLI is a band-aid solution and changing RCA cables will be of little value.

I presume your amp, pre-amp sub and h/u all have different grounds. That most likely is the problem. Try creating a common ground for all of them, most preferably at the amp (which needs the most power and as such is preferred for having the shortest ground cable). Another cause could be the multiple channel grounds from your h/u to the pre-amp sub and amp. If you recall, when taking apart the OEM wiring, they used a common ground for all the channels coming from the head unit (FR, FL, RR, RL all had a common -). By now using RCA cables for each channel, you've isolated their grounds from each other and from the grounds of each of the components.

As I said, try using a common ground for all your components at the amp and see if that clears it up. You can also try and ground the RCA cables to the h/u which will then tie them in to the power ground for the h/u (making it common)

BTW - what kind of h/u are you using?

:)

Edited October 24, 2008 by Cassiebox

[tolum]

No better result. I have an Alpine CDA9885 deck, an Alpine Mrpf-250 amplifier and Blaupunkt THB200A amplified subwoofer. I use RCA cables from deck to amplifier (front & rear) and RCA cable for subwoofer. When I unplug the RCA's on sub, no more wining. When I plug amplifier RCA's but unplug amplifier RCA's no more wining. I did try to plug all three ground together at the same point, No change, still wining. I can ear wining not only when engine running, but just with the contact on prior to start the car I can ear noise in speakers produced by pumps & car electric components...All 3 RCA cables are good quality Monster Cable.

I'll try a ground loop isolator for the sub RCA and see the result.

Do you have any idea for a solution?

[Cassiebox]

Sooooo the noise entering the system is from your amplified sub. Where is it getting it's power from -same sources as h/u & amp? Are your RCAs to the sub running parallel to it's power cord? If so, separate them out by at least 18"s or so and see if that doesn't solve the problem.

If it does not, you can try jumping the RCA grounds at the h/u, for the sub, to the h/u (which will then tie them in to the power ground - making it common as well). I hesitate posting this picture as it's a really bad example of how it can be done (it's not mine BTW either), but I think you'll get the idea so you can test it for a solution:

Edited October 25, 2008 by Cassiebox

[Beelzy]

Yep, that will end the issue.

I so had that pic in mind, I wonder who's it is??

[tolum]

To answer the questions: 1- Both amplifier & subwoofer are getting there power individually, directly from the + battery pole with an individual fuse holder. 2- I did use an other RCA cable that was passing from deck to sub over the seats (clearly out of the power field). No change.

New step. I'd try the RCA ground loop isolator at sub RCA input. It works but I'm clearly loosing power.

[Cassiebox]

Try my solution above in post #6 (obviously a little more cleaned up or you can split the shielding in the RCA cable and ground it that way). If that doesn't solve it, then I think you have internal grounding issue w/ the amplified sub.

[tolum]

Did try it. It cut noise for about 50% but not more than that!

[Ross1]

Ground your subamp to the chassis! Cassiebox is correct about ground loop problems. The hissing noise is caused by the amp trying to find a common ground, so it travels through the RCA cables and creates the noise. Make sure your main amp is also grounded to the chassis. Your head unit can most likely still use the factory ground wire. This solution has worked for several people in this forum.

[tolum]

Do you mean grounding the amplified sub itself to the chassis using a screw that is on the sub enclosure??? Tried it, no result.

I did another test. Unplug the RCA cable from the amplified sub, engine running & a cd running in the deck. No noise.

Still with RCA cable not plugged in the sub, when I touch the negative side of the RCA male connector, I mean the outside pin of the connector, same humming noise starts.

Does it sound something for you?

Edited October 27, 2008 by tolum

[tolum]

Finally changed my RCA cable and did what cassiebox says on post #6. This is very acceptable. Still a little wining, but it doesn't go higher with RPM so with volume at 2 or 3 no noise is disturbing...

Thanks a lot to all of you. There's nothing like sharing experiences, good and bad.

Thierry

[Ross1]

Do you mean grounding the amplified sub itself to the chassis using a screw that is on the sub enclosure??? Tried it, no result.

I did another test. Unplug the RCA cable from the amplified sub, engine running & a cd running in the deck. No noise.

Still with RCA cable not plugged in the sub, when I touch the negative side of the RCA male connector, I mean the outside pin of the connector, same humming noise starts.

Does it sound something for you?

You need to take the actual ground cable for the amp and bolt it to the chassis! If that doesn't fix your problem, then experiment with some extra wiring and try connecting all your grounds together. There's no reason why you should have to settle for just a little humming noise. After a while that will even start to bug you! You can do it!

As a side note. You can buy high end RCA cables that have external grounds on them!