radio noise
Thread Starter
Pro
Joined: Nov 2006
Posts: 676
Likes: 0
radio noise
Car has a amp on stock radio and you get a wine noise from motor threw speakers anyone know how to stop.. is there a filter i can install or is hooked up wrong ..got it with the car.. trying to fix all little problems other owner did not take car of... thanks
Melting Slicks
Joined: Mar 2007
Posts: 2,100
Likes: 12
From: Frederick Maryland
Do you have the shielding in place around the coil, distributor and the spark plugs? They're there for radio noise suppression. Is the noise strictly on AM or FM as well? AM is far less noise resistant than FM, though if properly shielded you should't have problems with it.
If you do and still have noise, you need to identify the source of the noise. Does the whine go up and down with engine rpm? If so, it's alternator whine. If it's steady, it's probably ignition.
There are filters you can buy to go on the alternator or in line of the radio power lead. Sometimes even relocating the radio power lead to a different 12v source can eliminate or reduce the problem.
The car could have non-suppression spark plug wires on it, though that's less likely.
If you do and still have noise, you need to identify the source of the noise. Does the whine go up and down with engine rpm? If so, it's alternator whine. If it's steady, it's probably ignition.
There are filters you can buy to go on the alternator or in line of the radio power lead. Sometimes even relocating the radio power lead to a different 12v source can eliminate or reduce the problem.
The car could have non-suppression spark plug wires on it, though that's less likely.
Le Mans Master
Joined: Jul 1999
Posts: 9,206
Likes: 17
From: Sewell NJ
Many aftermarket radios are prone to noise from the electrical system. Some are better than others. I would recommend putting a noise filter on the junction block that the alternator lead goes to. It's located under the driver side front fender. You can get the filters from a number of vendors.
Team Owner
Joined: Jun 2000
Posts: 38,923
Likes: 1,482
From: Southbound
Cruise-In II Veteran
Radio cars have several noise suppression capacitors under the hood for filter ignition noise. These are shown in the assembly instruction manual (AIM)
The most common culprit is the alternator.
Per Roughrider: I get no ignition static with FM. I get a bit with AM.
The most common culprit is the alternator.
Per Roughrider: I get no ignition static with FM. I get a bit with AM.
Last edited by Easy Mike; Nov 4, 2010 at 10:12 AM.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
You can 'test' where your noise is coming from rather easily. The most likely candidates are ignition system and alternator. If you remove the belt for the alternator, that will eliminate it as the source. Listen to your radio while lightly revving the engine [in your driveway] to get a 'feel' for the noise in the radio. Then remove the alt belt and try it again. If the noise is still there and it varies with engine rpm, the noise is mostly from the ignition system. If it improves (or is totally eliminated) by removing the alt belt, add the radio noise "filter capacitor" to the alternator as suggested above to get some improvement. Also, try running through the blower fan speeds to see if that motor is causing problems as well. Cars from the factory had filter capacitors on motors/alternator and on accessory device switches (ie, brake light switch, etc) to eliminate 'pops' and 'whine' in the radio. Radio Shack has [or can get] appropriately sized noise filter capacitors at reasonable prices; if you buy restoration parts, they are very expensive.
Team Owner
Joined: Sep 2006
Posts: 31,279
Likes: 4,372
From: Westminster Maryland
Hi,
Many cars are missing the RFI shield that was under the distributor cap to shield the points. I'm not sure just what years used them; they started in late model year 70 when the distributor shield changed from the 'box' type... my 71 has one.
You can see if it's there by lifting the little metal door on the cap.
Maybe?
Regards,
Alan
Many cars are missing the RFI shield that was under the distributor cap to shield the points. I'm not sure just what years used them; they started in late model year 70 when the distributor shield changed from the 'box' type... my 71 has one.
You can see if it's there by lifting the little metal door on the cap.
Maybe?
Regards,
Alan
TheCorvetteBen
Joined: Feb 2007
Posts: 4,987
Likes: 144
From: Van Alstyne, TX
Speaking of radio interference, my radio has been acting up for a while. Sometimes it seems like I lose signal from the stations. this really only happens when my car is in motion. I even installed the antenna, so I think it might have to do with the sheilding. sometimes, it goes out and I cant hear anything, but then a few seconds later (like when I come to a hill) the sound is back again. what do you guys think it is?
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Melting Slicks
Joined: Mar 2007
Posts: 2,100
Likes: 12
From: Frederick Maryland
Speaking of radio interference, my radio has been acting up for a while. Sometimes it seems like I lose signal from the stations. this really only happens when my car is in motion. I even installed the antenna, so I think it might have to do with the sheilding. sometimes, it goes out and I cant hear anything, but then a few seconds later (like when I come to a hill) the sound is back again. what do you guys think it is?
Trimming an antenna is kind of a lost procedure since we went away from that style radio and to digital.
Instructor
Joined: Mar 2007
Posts: 173
Likes: 0
From: Avon Park FL
I had same problem with the whine noise.I called three different stereo installers they all said it was a ground problem .They also stated that the filters don't work waste of money. Also check your setting on amp too much gain will give you whine noise. My problem was amp setting.
Instructor
Joined: Mar 2007
Posts: 173
Likes: 0
From: Avon Park FL
Yea, I did the grounds also but like i said it was the gain .My amp has controls where I can make adjustments. Make sure radio itself is grounded . When I call the radio installer shops about filters thats when they told me about filters and what to check and they did not try to sell me anything.( that was a first ,lol ).
1969, 70, alternator, corvette, distributor, inducted, interference, noise, radio, reduce, rfi, shield, static, suppression, whine
