Strange radio noise
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=13480
Printed Date: August 22, 2025 at 1:20 PM
Topic: Strange radio noise
Posted By: jaxman
Subject: Strange radio noise
Date Posted: May 13, 2003 at 1:48 PM
Well , after solving (80%) the alternator noise now I ended up with some other NOISE.
Now I ran into another problem.
Yesterday I installed also the front speakers trough the amplifier and the sound is great(Had the front speakers firectlly on the head unit).
Today on my way to work I noticed that the sound it is noisy when I listen to radio (this problem has not been before) and it is not engine noise.
I disconnected the antenna and I plugged into the antenna jack just a short wire in the middle.The signal quality got better and without noise.
If I put back the antenna then the signal it is perturbed again.
Bought an extra antenna cable and run with it outside the car to the antenna in the back , same problem.
Bought a brand new antenna to mount on the windshield and the same noise.
If I just put the core of the antenna cable the sound it is ok but not so powerful and the signal gets lost once in a while.
Tried to take out the front speakers from the amp and let only the ones in the back like it was before …same thing.
What could be the problem ?
Replies:
Posted By: jaxman
Date Posted: May 13, 2003 at 2:20 PM
By the way , this is happening with the engine off also.
Posted By: esmith69
Date Posted: May 13, 2003 at 6:06 PM
Sounds like your antenna is not properly grounded, or a ground loop exists between your head unit's grounding point and the antenna's grounding point. Most likely you just need to ground the antenna to a good, solid, paint-free spot of bare metal on the vehicle's chassis, and it should sound okay. BUT I should ask, what kind of vehicle is this? (year/make/model) Is it by any chance, a VW? ------------- Ethan
-----
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Posted By: jaxman
Date Posted: May 14, 2003 at 12:25 AM
The car it is a Mitsubishi Carisma (EU)
The noise on the radio is more like some kind of interference or something like the signal it is strong but perturbed just like then when you manually search after a TV stationon on the TV and then the image it is clear but the sound has some kind of windy noise.
I have tried to change the antenna with another one but the signal it is the same and the only thing I have changed since the signal was ok it was adding the front speakers to the amplifier.
Now let me ask you all a question :
1. Can the power cable influence radio reception ?
2. Can the RCA Cables go on the same side with the Speaker cables that come from the amp to the front speakers ?
3. If the amp it is running 1 ohm on the subwoofer can this have any influence on the speaker output ?
4. Can I run with the speaker cable (not rca) beside the power cable ?
5. Will the gear case produce any noise if I run with the RCA or speaker cables in the midle of the car ?
Posted By: jaxman
Date Posted: May 14, 2003 at 1:21 AM
It will be a good ideea to isolate the RCA cables with aluminium foil ?
Should I have a ground on the head unit's install frame ?
Posted By: DYohn
Date Posted: May 14, 2003 at 8:39 AM
I suspect esmith is right, you have a ground loop of some sort that is interfering with your reception. In addition to making sure your antenna is securely mounted, make sure your head unit and all amps have good, paint-free and common grounds. Since you say the only thing that changed when you first noticed this sound was adding the front amplifier and speakers, I would begin by improving the ground connection for the front amplifier. Make sure your speaker wires for the new front speakers are not shorting to the frame of the car somewhere.
Posted By: jaxman
Date Posted: May 14, 2003 at 4:46 PM
I have tried to take out from the amplifier the new wires but the noise it is still there.
Tried to pull out the RCA cables also together with the speaker cables. Interference still there. 
Posted By: esmith69
Date Posted: May 14, 2003 at 10:10 PM
What about if you remove tha main fuse on your amp's power cable? Is the interference still there? As for the question about the speaker wires causing interference...I have yet to experience such a thing--the reason being speaker wires just don't handle the amount of current that power cables do. now if you have some MONSTER setup that requires something ridiculously huge like 6 or 8 gauge speaker wire, then I suppose it might be possible but still even then it's pretty unlikely. Although it's not as big of a problem as when you're running RCAs, running speaker wires next to power cables can sometimes cause interference to occur. I would say to avoid running them (speaker and power) together whenever possible. ------------- Ethan
-----
"Patience, persistence, and perspiration make an unbeatable combination for success"
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Posted By: jaxman
Date Posted: May 15, 2003 at 1:16 PM
If I remove the power from the amp I can't hear the interference as all the speakers go trough the amp :)
Posted By: esmith69
Date Posted: May 15, 2003 at 2:09 PM
jaxman wrote:
I have tried to take out from the amplifier the new wires but the noise it is still there.
Tried to pull out the RCA cables also together with the speaker cables. Interference still there.
I thought when you said that above, you meant that you unplugged the speaker wires from the amp and the interference was still there. But now I think I know what you're talking about. You might wanna try something like the N-AI from david navone as I think it might do the trick. ------------- Ethan
-----
"Patience, persistence, and perspiration make an unbeatable combination for success"
Donate to the12volt.com
Posted By: jaxman
Date Posted: May 18, 2003 at 1:18 PM
Don't you think the head unit can be the problem ?
The noise came out of nowhere. It's actually not a NOISE , it is more like the radio signal it is perturbed by something or like the frequency it is not 100% in the position. The station it is all the time there but I can hear some perturbance all the time , the sound is not clear.... damn I hate this and it's a brand new Pioneer.
I'll try to go to the dealer and borrow another one for 5 minutes , set it in the car and see if there is any difference , this will show me if it is a head unit problem or antenna.
Thanks all for the input.
Posted By: DYohn
Date Posted: May 19, 2003 at 7:55 AM
I have had a similar problem in professional audio equipment using balanced DIN cables with XLR connectors for microphones. If one end of the cable is wired properly (+, -, shield) and on the other end, the shield is on the wrong pin (swapped with either + or -) OR the shield is on the correct pin but also shorting to a signal pin, usually through a stray conductor strand, the cable becomes a pretty good AM radio antennea at a very low level. It usually self-tunes to about 1440 Khz. A radio station comes through sounding off-channel, as you describe, and at a low level that the amplification equipment makes audible during quiet passages. I have had this effect ruin the audio track on video tapes and cause long delays in live sound setups. If this sounds similar to what you are hearing, you might check to see if any of your RCA or antennea cable shield connections are shorted to chassis ground or to + signal. This is a long shot, but your symptoms suddenly sounded familiar!
Posted By: jaxman
Date Posted: May 19, 2003 at 7:59 AM
Thanx for the tip.
I justc checked the head unit on the bench and it sounds ok so the problem it is somewhere in my car.
I will check the RCA cables today...
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