Guest cattmann Posted July 29, 2011 Share Posted July 29, 2011 I really didnt know where to post this question so here it is.Can anyone tell me why I have interference in my speakers. I have installed a cd player independent from my original 6 volt ,positive ground system. I even mounted it in a wooden box.When I start the car the volume breaks up badly to the point you cant hear it . As soon as I shut the engine down it is fine. The speakers are also independent and not touching any part of the body.I have a 12v battery in the trunk ,also not touching the body what so ever.One item I must mention is that the interference is not the same as the engine coming over the speakers.It is sound breaking up badly.Thanks Gary Link to comment Share on other sites More sharing options...
Rusty_OToole Posted July 29, 2011 Share Posted July 29, 2011 Could be interference from the ignition or from the generator. You can add a capacitor to the generator to quell the sound.Sound breaking up badly, could be a bad connection somewhere in the 12V system making intermittent contact due to vibration as you drive. hard to say without hearing it . Link to comment Share on other sites More sharing options...
Guest Bob Call Posted July 29, 2011 Share Posted July 29, 2011 GaryThere is nothing wrong with your stero system. What you are hearing is the engine ignition system. Modern ignition secondary cables (plug wires) have built in radio frequency (rf) interference suppression in the core and insulation. I suspect that your car probably has original style wire core cables. Changing to modern fabric and graphite core cables, including the coil to distributor cable, will fix the problem. I remember back when I had a 59 Chev with a tripower 348 equipped with Packark Electric 440 cables (copper core) you could hear the iginition through the radio at all speeds. I bought an igition noise suppressor at Radio Shack that fit in the coil to distibutor cable and it eleminated all but idle speed rf inerference. Link to comment Share on other sites More sharing options...
Guest cattmann Posted July 29, 2011 Share Posted July 29, 2011 Bob I am inclined to agree with what rusty said in regards to vibration but at the same time do agree with you in regards to engine sounds over the speakers. I have experienced this my self years ago in older cars in regards to engine sound. This is nothing like that. It is simply the sound is cutting in and out . I installed another speaker using the extra rear speaker wires and layed it on the front seat1 foot away from the stereo. It sounded great until I started the car and it cut out completely.No matter if I held it in my hands or wiggled it around there was no sounds until I killed the engine.I dont have to move the car to make it break up ,Just have it idling in the garage and that old flat head is some smooth.Tomorrow I will remove the stereo from its holder and fire it up lying on the front seat with a speaker wired directly to it .If it is indeed the old wiring I should know tomorrow. Thanks for the input guys.It is appreciated Link to comment Share on other sites More sharing options...
Guest bofusmosby Posted August 2, 2011 Share Posted August 2, 2011 I agree with the engine noise, but if that doesn't take care of it, try lining the inside of the wooden box (where you have your radio) with metal. Tin would probably work OK. This will "shield" the radio from the noise, if the other suggestions do not work. Since you are using a seperate ground, I don't know if the metal inside the box would have to be grounded, and if so, which ground. The Car ground, or the 12 volt battery in the trunk.Just an idea. Link to comment Share on other sites More sharing options...
Guest cattmann Posted August 2, 2011 Share Posted August 2, 2011 What I have discovered is if the wires are tucked up under the firewall insulation I have issues with the sound cutting in and out . I played the system with it lying on the front seat and it works great with the engine running I had a friend of mine that is into electronics, moniter what I was doing to trouble shoot the issue and he said it is EMF Electrical Magnet Frequency issues.I was in town today with the car and pulled the power and ground wires away from the firewall as with the speaker wires and Never had one bit of sound interruption at all ,not even engine noise.What I did find is that my antenea cannot be any where near the stereo or my problem worsens and it is not grounded to the body .Oh well at least we are getting somewhere .Thanks again everyone Link to comment Share on other sites More sharing options...
jdome Posted August 2, 2011 Share Posted August 2, 2011 I thought you just had a CD player. You are receiving EMI, Electromagnetic Interference from either the coil (on the firewall), distributor, spark plugs, plug wires or all of the above. Does the unit work OK with a CD? You are most likely picking it up through the antenna but it is possible to get it from the speaker wires or power wire too. Try grounding the antenna mount to the car and also grounding the - of your 12v radio battery to ground. It won't cause any problems with the car's electrical system (either + or - ground) as long as both hot sides are isolated from each other. Making a common ground might help. It might also help to run a good heavy ground wire from the hood to ground. That might help shield some of the under hood interference from getting to the antenna. Long parallel power lines to the radio/CD player can also act like an induction coil (EMI antenna) so I would also suggest using a twisted pair wire for your power run and/or make the power line as short as possible. Twisted speaker wire is also better than parallel cord in this case too. Link to comment Share on other sites More sharing options...
jdome Posted August 2, 2011 Share Posted August 2, 2011 Another thing. You say taht it works better if you move the antenna away from the radio? Is that also because you are moving the antenna away from the engine bay? Link to comment Share on other sites More sharing options...
Guest cattmann Posted August 3, 2011 Share Posted August 3, 2011 Thanks for the info. I am using an extension cord for my positive and ground. It is a heavy commercial type. It runs from the trunk and is not coiled up at all. As far as the speaker wires go I actually used a roll of automatic garage door opener wire.I have 2 grounds and 2 positives twisted together running from the rear speakers to the stereo and again no extra coiled up. I pulled the speaker wires away from the firewall this morning and still had sound breakup so I pulled the power /ground wire away from the firewall also and everything is great.In regards to the antenea ,It doesnt have to be mounted anywhere,I just held it in my hand and held the end that plugs into the unit close to it and I have breakup. I just coiled it up and left it unhooked from the stereo It doesnt seem to matter whether I have the radio playing or a cd in or just using a USB stick .I even tried wrapping my wires up in tin foil at the firewall with no luck. I also grounded both the positive and negitive connections one at a time as you suggested with no positive results. Link to comment Share on other sites More sharing options...
jdome Posted August 3, 2011 Share Posted August 3, 2011 Is this a car radio or is it a portable boom box type of radio? You may have to install some modern resistor plugs & wires and some radio frequency capacitors on the coil and dist. to get rid of it but even that is no guarentee. Link to comment Share on other sites More sharing options...
Guest cattmann Posted August 3, 2011 Share Posted August 3, 2011 It is a new JVC indash player. Link to comment Share on other sites More sharing options...
Guest cattmann Posted August 3, 2011 Share Posted August 3, 2011 Here are 2 pics Link to comment Share on other sites More sharing options...
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