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High pitch ringing after amp install

814 views 15 replies 4 participants last post by  GOAT721 
#1 Ā·
Recently had a Rockford Fosgate amp installed for my door speakers. Problem is that the amp is picking up electrical interference from somewhere and relaying it to the full ranges in the dash. A constant high pitch ringing noise. If I disconnect the inputs to the amp, the noise goes away. So itā€™s the signal not the amp. Iā€™ve had this happen before on a previous vehicle with the same amp. The noise would stop if I turned off the DRLs. This time itā€™s not the DRLs and I canā€™t find anything that turns off the noise.

HOWEVER the noise does turn off when the vehicle is turned off for about 30 seconds but with all the audio and infotainment still running. Ground loop isolators didnā€™t work, different RCAs didnā€™t work, moving wires around didnā€™t work. Any thoughts or solutions?
 
#3 Ā·
Could it be a module that is going to sleep at around the 30 second interval that makes the noise stop? Maybe try pulling fuses for various systems to see if you can isolate the source?
 
#5 Ā·
You can't eliminate the systems on the truck. But perhaps you can wire your amp to a different circuit that isn't a part of what is causing the noise?
 
#7 Ā·
The amp shouldnā€™t be hooked to anything but the battery, ground, rca, pos/neg to the sub, and the signal wire that turns it on and off. Iā€™ve hooked up so many different styles of systems and Iā€™ve never once had this particular problem. Even with using a line output converter. Sounds like something was done wrong during installation for this issue to arise.
 
#10 Ā·
Forgot to mention, the amp gain is all the way up. I know I knowā€¦ however it is the only way to achieve no input clipping from the factory signal. If I back off the gain the noise goes away but itā€™s not loud enough to really listen to with the windows down on the highway. 100+ rms watts of power with 90+ db speakers, that shouldnā€™t be a problem. So I guess the new question is why does the amp have to be turned up so high to get the level of volume itā€™s supposed to do at half-2/3rds of gain? Is the factory signal just that bad and nothing can be done?
 
#15 Ā·
Sounds like a wire interference or some kind of bad connection. If they used cheap wire and ran them too close to the power wire, that would cause it. Loose or bad connections on the amp or stereo could cause it. If the amp is up against bare metal, that could cause it. Could be cheap or bad rca cables. Long list of things could cause it tbh.
 
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