Getting a whistling noise through back speakers with RCA hookups.

[jakeg1210]

Hey all,

I just hooked up a new small JBL 4way channel amp in my trunk to normal aftermarket coaxial front and a set of rear speakers. I'm loving the audio when it's turned up, sounds pretty good, but I get a crazy whistling noise from my back speakers when volume is low (probably high but the music drowns it out), these are set up through RCA cables running down the side with the speaker cables while the main power cable is in the center. My fronts sound fine but I have them wired through the high level input on the amp as my stereo doesn't have front preamp hookups. I figured first thing to try was the ground as my old one seemed a bit shady, so I sanded up a nice spot on the frame til it was shiny as hell, hooked it all up and no change. This occurs when gains are all the way down on the rears, could this be an RCA issue? I can't figure this out even watching plenty of car audio videos and trying to take advice. Anyone got any suggestions here?

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[Lasherž]

Hey all,

I just hooked up a new small JBL 4way channel amp in my trunk to normal aftermarket coaxial front and a set of rear speakers. I'm loving the audio when it's turned up, sounds pretty good, but I get a crazy whistling noise from my back speakers when volume is low (probably high but the music drowns it out), these are set up through RCA cables running down the side with the speaker cables while the main power cable is in the center. My fronts sound fine but I have them wired through the high level input on the amp as my stereo doesn't have front preamp hookups. I figured first thing to try was the ground as my old one seemed a bit shady, so I sanded up a nice spot on the frame til it was shiny as hell, hooked it all up and no change. This occurs when gains are all the way down on the rears, could this be an RCA issue? I can't figure this out even watching plenty of car audio videos and trying to take advice. Anyone got any suggestions here?

Usually this is an RCA issue caused by alternator whine caused by power being run close to (especially coiled) near the RCA cables (especially coiled). Does it still occur with the car turned off? One thing I would suggest trying is getting a 3.5mm to RCA adapter and using your phone to play music through it. If the whine is gone then expect RCAs or the source (Active noise canceling module for example?) to be the culprit and if the whine remains then expect an internal issue with the amp or grounding.

If I were you and that ended up getting rid of the problem, I would use the same source for all 4 outputs. The loss will be your fader no longer working forward/backwards on the head unit, but provided the signal source to the speakers has good range on it it will sound better with less complication.