et-ctsv
Junior Member
I need some guidance! I just finished installing a Clarion NZ500 headunit that runs to 5 Alpine Amps in the back. The headunit has a USB cable input to control, charge and play the audio and movie files on my ipod 160gb classic and iphone 4.
Everthing works great except when I plug in my iphone or ipod, I get loud static whining noise in my system that is audiable at all times. I can turn the music above the static noise, however when I'm at low volume the noise is really annoying. When I unplug the phone or ipod the noise goes away. I've been able to trace the noise down to my front left rca jack, when I unplug that jack then I get no noise. If plug the ipod or iphone directly into the 3.5mm input jack in the front I get no noise.
My assumption based on the testing I've done is that there is a ground loop from the charging circuit in the USB jack which causing the noise. For whatever reason the headunit is trying to ground the charging ciruit from the USB jack through this one RCA output cable. If I plug in a ground loop isolator inline with that RCA output then the noise reduces but is still audiable enough to be extremly irritating.
Other things I've tried so far:
1. splice in a noise isolator directly into the USB power wire running to the ipod
2. ground the USB power wire directly to the battery
3. splice in a noise isolator in the power wire running directly to the head unit
4. ground the rca shield to the headunit metal chassis
5. Ground the headunit directly to the battery
6. Turned the gain controls of my amps down to 1/4 (helped but noise is still there)
None of these had any impact on reducing the noise. The only thing that has successfully reduced the noise slightly is the ground loop isolator running between the headunit preamp and the amps inputs. One option I have is to just leave the front left jack unplugged from the headunit and run Y cables off the rear left output to run the amps. The problem with that option is that I end up splitting that signal 4 times to run all four amps and I'm concerned that this will have an impact on my sound quality. Am I correct in this assumption? Or will I be fine with splitting the signal 4 times?
Tonight I plan on trying to solder in a larger gauge ground wire from the headunit and run it to a new additional grounding location close to the front of the headunit.
Any other tips I could try?
Everthing works great except when I plug in my iphone or ipod, I get loud static whining noise in my system that is audiable at all times. I can turn the music above the static noise, however when I'm at low volume the noise is really annoying. When I unplug the phone or ipod the noise goes away. I've been able to trace the noise down to my front left rca jack, when I unplug that jack then I get no noise. If plug the ipod or iphone directly into the 3.5mm input jack in the front I get no noise.
My assumption based on the testing I've done is that there is a ground loop from the charging circuit in the USB jack which causing the noise. For whatever reason the headunit is trying to ground the charging ciruit from the USB jack through this one RCA output cable. If I plug in a ground loop isolator inline with that RCA output then the noise reduces but is still audiable enough to be extremly irritating.
Other things I've tried so far:
1. splice in a noise isolator directly into the USB power wire running to the ipod
2. ground the USB power wire directly to the battery
3. splice in a noise isolator in the power wire running directly to the head unit
4. ground the rca shield to the headunit metal chassis
5. Ground the headunit directly to the battery
6. Turned the gain controls of my amps down to 1/4 (helped but noise is still there)
None of these had any impact on reducing the noise. The only thing that has successfully reduced the noise slightly is the ground loop isolator running between the headunit preamp and the amps inputs. One option I have is to just leave the front left jack unplugged from the headunit and run Y cables off the rear left output to run the amps. The problem with that option is that I end up splitting that signal 4 times to run all four amps and I'm concerned that this will have an impact on my sound quality. Am I correct in this assumption? Or will I be fine with splitting the signal 4 times?
Tonight I plan on trying to solder in a larger gauge ground wire from the headunit and run it to a new additional grounding location close to the front of the headunit.
Any other tips I could try?
