Ok, so just so have a little inside knowledge here is the setup:
2005 Chevy Trailblazer
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.
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.
well, in the process of ripping everything out after endless hours of troubleshooting, I stumbled upon the problem. The JL has an all steel construction, so when I used the sheet metal screws to mount it to my seat, it must have created some sort of loop by grounding the amp to the seat. I really am not even sure if this is what happened, just seemed like the most logical one to me, sense it stopped when the screws were removed. All i did was wrap the screws in vinyl tape, and voila! Problem solved!! Thanks for your help guys!
The first thing that comes to mind is exactly what you said, put the Hifonics in and see if the noise stops. I've heard excellent things about JL amps as well, but no manufacturer can claim they don't have any defective products. The noise you are describing seems like it is being generated by the head unit, but if it disappears with the old amp, you've isolated the problem.
I don't want to pinpoint it to this, but there have been a lot of issues with RCA whine at the Head Unit.
Your comment about running the JL amp with the ground disconnected is the exact type of thing that could cause this - I realize you did that AFTER the problem and you have a Kenwood and not a Pioneer, but it is something to consider.
Definitely makes sense to try the Hifonics to see if it's the head unit or the JL amp, though ....
Hope This Helps!!!
2002 Ford Focus Sony CDX-GT410u Sony XT-100HD HD Tuner Stock speakers, no amp, no subs
TigerHeli:Your comment about running the JL amp with the ground disconnected is the exact type of thing that could cause this - I realize you did that AFTER the problem and you have a Kenwood and not a Pioneer, but it is something to consider
Tiger-
What I meant was that was the only way to eliminate it. to eliminate power to the JL. When I remove the ground going into the JL, and the JL shuts down, then, and only then does the noise go away. I suppose I am going to head up to work on my day off and see if I can try a few more things, if nothing works, I suppose I will just have to go back to my old setup! I took it to a local sound shop, and they suggested I just live with it! There is no way I can live with that noise!
Okay - you would be better removing the fuse or removing the remote wire on the JL.
I have heard of user's removing the amp ground and the amp power then tries to ground through the RCA shields and back through the HU RCA shields and ultimately through the HU - sometimes causing the whine or hum issue that you are referring to.
Tiger---
Ok, so I removed the remote, and the same as removing the ground, the noise went away. what does that mean?
I figured it would - essentially - you are still at square one.
Swap the JL amp for the Hifonics amp, but it is looking to me like a defective JL amp and/or some setting on the Hifonics that filters the noise that is not set the same way on the JL. More likely a defective JL, though.
(As J Ro said - I don't mean to imply a quality issue with JL amps in general by the above statements).
Glad you got it sorted out.
Of course, it conflicts with the info on this page, which I consider highly reliable:
2.Some people say that an amplifier's case must be isolated from ground (mounted on a piece of wood). This, in my opinion, is a load of @#$%! Most amplifiers connect the case of the amp to ground internally. If there is no connection between the case and ground inside the amp, the case will be completely isolated from ground (and everything else) so it will not matter if you connect it to ground by mounting it down to a grounded piece metal. Do you think they would actually build an amplifier in a metallic case if it could not be connected to ground?
Then again, every day I seem to confirm that there are more guidelines than absolutes in Car Audio!!!
Tiger--
I would have to agree. THis goes against everything I have ever learned over the years. All that I do know for sure is... when I took the sheet metal screws out, the noise went away, so I came to my own conclusion. What is worth mentioning though.,.. is during my lat run at troubleshooting, right before I took the screws out, I disconnected the ground feeding the JL amp, and it did still power on. It seems as though it was like you said, and it grounded out through the RCA cables. I dont know. This has been one screwy set-up. I probably have about 8-10 hours of troubleshooting into this, and I stumble onto a solution while removing it!
But.. It is fixed now, so all is well!
This is a bit over my head as well, but I think you might still want to get the amp bench-checked.
I am now wondering if the ground terminal on the amp was possibly bad and it NEVER used that ground and was grounding out through the mounting screws and is NOW using the RCA shields.
I could be way off base, but better safe than sorry, and if it checks out fine you know how to avoid the previous problem now ...
When you say bench test, I assume you are referring to removing the amp and just doing continuity tests on the terminals to make sure that is grounding through the proper means?
Actually, I meant taking it to an audio shop and letting them hook it up to a test bench and check it out - usually with a power meter or an O-scope. Most shops won't charge a lot to do that.