Amp help

Stretch

TJ Enthusiast
Joined
Jul 22, 2019
Messages
204
Location
Alberta
Hi all,
Installed an amp this weekend to aftermarket stereo. Amp was def improvement to sound/loudness etc … however I noticed interference when the car is on vs running system via battery only. I get humming/whining that aligns with engine revving…
Any advice from the folks who understand this better than me?
PS I used the mounting suggestion under the steering column … damn that was hard to mount in there but does keep it clean!
Thanks
 
Power is coming straight from the battery off a heavy gauge Rockford Fosgate.
To ground I used a location on the floor board on the drivers side under the carpet that had a nut/washer in the tub that looked like a good spot.
 
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It's called a ground loop. 99% of the time it is caused by a poor ground of your amp. You can try moving the ground to a different location and make sure you have a a good metal on metal connection.

If you aren't to concerned with perfect sound quality, you can just buy a noise isolator (PAC SNI-1) which will probably solve your issue.

Some other things you can try to chase it down (i had to do all of them in my case)

-some amps have a chassis ground - so try floating the amp away from any metal and see if it makes the sound go away
-try disconnecting the antenna connector at the head unit
-ground your amp and stereo to the same location
-a bad alternator can introduce noise in the electrical system

@skrelnik may have more ideas.
 
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The above advice is solid: check your grounds.

In the case that comes up empty, check if any of your RCA cords are running next to a wire carrying power (e.g., the power cable running to the amplifier). In the past this was what caused my alternator whine, and moving the RCA cables away from the amplifier power wire was all it took to solve it.
 
I’m taking bets 😁… winner gets a one year annual subscription to the wrangler forum 😂

I actually took a dremel with a grinding stone bit to shave the paint off the tub where the ground location was. As @Hopper mentioned, check those wires to make sure they are not crossed with other wires.

Check the connections at the amp as well.

Check the gain on the amplifier, what position is that in?
 
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I had this exact issue in an old F150, it seemed like it HAD to be a ground issue. Tried everything related to ground, but no change. THEN swapped out the amp for a new amp and the problem disappeared. Weird, but solved it for me.
 
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Is your ground wire a couple fee long? That could be it as well, you can ground the amp on the firewall, the run would be like 10 inches.
That length of ground wire will absolute not cause any problems so long as it is the proper gauge and properly connected to an appropriate ground point.
 
That length of ground wire will absolute not cause any problems so long as it is the proper gauge and properly connected to an appropriate ground point.

Correct, you can have a five foot long ground wire but the fact is, shorter the better, and the firewall is a better placement than under the seat since it is a shorter run, easier to run, and hidden out of the way.

The gauge is also important and should generally match the size of the power wire, and one should follow what gauge the amplifier's manual calls for.
 
If you just used a bolt, and didn't clean the paint to bare metal, then the issue is most likely a poor ground. I'll collect my prize money after he fixes it this weekend with a bit of sandpaper and elbow grease
 
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And the winner is … Ground!
Congrats to @Wingback73 @Jerry Bransford @LJGreg @skrelnik and pretty much everyone!
I didn’t sand the tub down at all as pictured below … used the suggested sandpaper and elbow grease to remove some paint to show bare metal (who knew that bare metal really means bare metal… everyone I guess)
Anyways thanks for your help everyone … please contact admin for your winnings 😂 2320F438-C2A7-4E0E-A08A-1483DB8FB64E.jpeg