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2005 chevy
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256 Posts
Discussion Starter #1
Ok, so just so have a little inside knowledge here is the setup:

2005 Chevy Trailblazer

  • Kenwood DDX812 Headunit
  • JL Audio 1000/1
  • Alpine Type X Sub 12"
  • Alpine MRP-F600 (4-channel amp)
  • Alpine Type R Components Up front
  • Alpine Type R Coaxials in the back doors
  • Kinetics HC-600 battery

Ok, so for about a year I had the same setup, except I had a Hifonics Amp pushing two Kicker L7 Solobarics, everything else was the same, had all the tweeters and same 4-channel amp. The only issue I ever had was a ground loop which I suspect from having the extra battery grounded at a different location, but I purchased a ground loop isolator, slapped it in the Sub RCAs, and voila, solved the problem.... Well, about a month ago, I decided to ditch the solobarics and upgrade my subs and amp. So I purchased the Alpine Type X 12" Sub, 1000watt RMS 3000 Peak and also got a JL Audio 1000/1 amp to go along with it. After I got everything hooked up and swapped out I noticed a TERRIBLE ground loop when the radio is at low volume. What is strange is that I get the noise coming from my midrange/tweeter combo up front, and my coxial speakers in the rear. It never did this before I upgraded to the 1000/1. The only I have found to remove the noise is by disconnecting the ground to the JL amp, but obviously this is not a solution. here is a list of what I have tried, so you guys know what has already been done.

  • New RCA's to both channels of the 4 channel Alpine
  • Tried grounding both amps to seperate ground locations.
  • tried running a ground from the headunit back to the alpine.
  • inspected all RCAs to make sure there is no pinch.
  • Tried Ground loop isolators on all 4 channels

I have tried everything I can possibly think of, and it is DRIVING ME NUTS! I am to the point where I am ready to slap my old system in it and be done with it. I have heard excellent things about the JL amps, but everything leads me to believe it is something with the amp. everything works flawlessly with the Hifonics. It is just so strange that it is causing some kind of interference to my 4-channel....

so.... has anyone ever ran into a similiar situation? any tips, or guidance would be GREATLY appreciated.
 

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2002 gmc envoy_slt
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3,552 Posts
have you tired grounding the battery and the 2 amps at the same point? and make sure it is a good ground.
 

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2002 gmc envoy_slt
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3,552 Posts
to clear something.

the static movied from the sub to the 4 channel?
 

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2005 chevy trailblazer_ls_ext
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255 Posts
have you tried to get a thicker/shorter ground wire for the battery itself?
i used to have an explorer with a really nice/loud/hard system...no cap, really good alternator, and had an optima yellow top, with a ground wire as short/thick as possible, never heard whine at all.
try that and see if it helps
 

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2009 chevy trailblazer_ss_3ss
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3 Posts
Check to see if that Kenwood head has an internal fuse on the output stage, typically the RCAs. Pioneer has an issue with an internal fuse blowing and when it's blown, it will allow/create noise in the system similar to a ground loop. You can also try grounding the shield of the RCA to some point and see if the noise goes away. just strip a wire, on both ends, ground one end of the wire to a good, solid metal point in your truck, and touch the other end of the wire to the outside, exposed barrel of the RCAs.
 

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2005 chevy
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256 Posts
Discussion Starter #8
Yes, the noise transferred to the 4 channel, which has been the same amp since I have got my TB. but....
I kind of stumbled onto a solution while I was mad and just switching it to my old system. To make a long story short the sheet metal screws that I used to mount the JL were creating some sort of loop. I dont even know if thats what it was, all that I do know is that when I took the screws out, the sound went away. All I did was wrap the screws in vinyl tape, and voila! No more noise!
I seriously have about 8-10 hrs of troubleshooting into this, it kind of aggrevates me that it was something so stupid, but, at the same time, I fixed it.
Thanks guys, I really do appreciate all your help!
 

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2002 gmc envoy_slt
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3,552 Posts
if your mounting screw was the problem, then it would suggest that the case of the amp is charged.

i wanna see a pic. espically one of the power and ground wire into the jl amp.
 

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2005 chevy
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256 Posts
Discussion Starter #10
Gavin--
I will post pictures tomorrow, I have to take all the pics on my lunch hour then post after work. If the case of the amp is charged do you think that maybe something internally on the amp is not right?
 
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