How to eliminate electrical hum in stereo

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fionntan

Banned
I installed a stereo in my car a while ago and the ground to the head unit was bad. I ran a new wire from the head unit and connected it to where the stereo frame and the floor pan meet (the bolt that holds the dash to the floor). Now I get hum in the speakers occasionally. Is it just that where it is ground is not a good spot or could it be something else? Where is a good ground spot? Would finding a better spot fix the problem.
 
as long as its on the metal of the car it should be fine, but beef up the wire, it sounds like it dont have a good connection
 
Hey Conan, I JUST saw this post. What your getting, I have learned, is called "alternator whine". What gauge wire are you using? I would suggest at least using an 8 gauge, though personally I usually go with 4 gauge, just in case. I'm trying to remember how my audio guy fixed mine which I think he moved where my power wire was routed in the engine bay as well as where my ground wire was connected to. I'm not sure if this will help but that is what I can recall. Good luck my friend. :thumbsup:
 
I dont remember what guage it is exactly, but I know it was thicker then what was used in the original harness. I might not have to work today so if I dont I will take a look and try to fix it.
 
get a bigger ground wire and sand clean the spot your ground is attached too and make sure its nice and snug on there. make sure you didnt route your power wire along the same side of the car as that audio wires.
 
I am not using an amp or subs, just factory size speakers and a head unit.
 
Whoa - dont ground any of the signal/power wires jackass. And you dont need much more than 12 guage wire to ground a freaking headunit guys.

Are you getting just a hum or is it like a whine that changes frequency with your rpms? One is just a weird electrical loop while the other is noise from the alt (which im guessing you dont have). You said you only get it "occasionally" - can you elaborate on this?
 
It is actually alternator whine (changes frequency with rpms). I dont usually notice it while driving forward, but if I reverse there is no mistaking that it is there.
 
Whoa - dont ground any of the signal/power wires jackass. And you dont need much more than 12 guage wire to ground a freaking headunit guys.

Are you getting just a hum or is it like a whine that changes frequency with your rpms? One is just a weird electrical loop while the other is noise from the alt (which im guessing you dont have). You said you only get it "occasionally" - can you elaborate on this?

who said anything about grounding the signal or power wires?
 
To get rid of alternator whine you need a bipolar bypass capacitor, also the ground point to the frame of the car make sure it's got a really good contact sand away a bit of the paint and use dielectric grease. Also it might be quite possible that the point you chose for a ground is creating a ground loop.
 
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Another common problem with ground wires is their length. Just somethin to consider.
 
the bipolar cap is a very small one just to block the alt. noise. It's not one of these overly huge caps used in monstrous audio systems.
 
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