My setup: Premier 630 HU, Memphis 1000D sub amp, Eclipse 3640 4-channel, Memphis Coaxials all around, Audiobahn DVC 12" Sub.

Wiring: 0-gauge all the way back, fused front and rear. 4 gauge going to the Memphis amp, 8 gauge going to the Eclipse. American Bass wiring for everything. Power wire ran on opposite side of car from speaker wire and RCA's. 0 gauge ground reinforcement at the battery.

Problem: When driving the car, you get a sort of alternator noise. As the RPM's rise, so does a bit of whine through the mids-highs. When you turn on the AC/Heater fan, you really notice the whine coming from the fan through the speakers. This exact setup never used to do this, but has been for a while now (I honestly can't pinpoint when it started doing it ).

So, I figured it must be a bad ground. My amps were both grounded to the same place, at a factory ground (that I cleaned all the paint off of for a better ground). Well, I tossed in a new ground wire on my Eclipse amp, w/ a new connector, and grounded it to a new spot. Ground wire is about a foot long. Same exact problem.

Okay, maybe it's the alternator. So I turn the car to the on position w/out starting it, and turn the AC/Heater fan on.......noise clearly coming through. I unhook the ground from the Eclipse and carefully listen to my sub to see if any noise is coming through there, and I couldn't hear any noise from it.

I'm kinda stuck on where I should go from here. I fear something might be wrong w/ my 4-channel Eclipse, but I really can't afford to fix/purchase a new one. Any other ideas on things I can check? Other than the little bit of whine, the system sounds great.

 

get a good ground loop isolator, it will help, part of the problem is probably the radio ground especially if you used a factory ground, I haven't found one yet that didn't make noise when hooked to a factory ground

 

i recommend one of those isolator boxes too. i had that same problem in my car and they took care of it. i know they sell em at our local best buy for like 10-15 bucks a pop i think, im not too sure if anyone else will sell them too.

 

Do a search for "muting plugs" on this forum. Use these to trouble shoot the problem and try to fix it before you go using band-aids like ground loop isolators.

Did you use RCA cables that use "twisted pair" construction? This is a must if you didn't.

 

Look very closely at what wires are near your RCA cables as they come out of the radio. I had a very very similar problem... it was intermintent. It would come and go spontanously and would be just as loud whether or not I had the radio up or down... only time it would go away completely is if I had the radio off or on "0" (my radio sends an "off" status signal to the amps at 0 volume, not many do this though)

If your problem sounds like mine, this tells you its not the source, because that would vary with the output voltage going ot the RCAs. So your problem is somwhere between your radio's RCA outputs and your amp's RCA inputs. Check to see if the noise is coming from just one speaker, or all of them. If it's just one or a couple of them it's the aforementioned problem. If it's coming from all of them then it's most likely the amp's ground or internal circuitry (as you mentioned)... and as others mentioned, factory grounds don't always work so great- many times because there are other devices grounded there as well.

 

I had to EXACT same problem. (And I mean EXACT!) Ground loop isolator was the only thing I could find that fixed it. Got it for about $15 at Radio Shaq.

 

try grounding your altenator. gms are real good at not grounding them for you. hope this helps

 

Upgrading the big three as well as the head unit ground will usually help get rid of alternator whine. And isolator is just a bandais the problem stil exists. Make sure you ground all your amps to the same point also.

 

i had a similar problem and i switched my rcas to monster cables competiton series rcas and it stoped the noise. the rcas are like $80 so make sure you troubleshoot the problem before you go and start spending cash. just thought id add that in. good luck!

 

Slayer made me think, what RCA's are you running? Are they sheilded and or twisted?

 

I honestly can't recall what RCA's I'm running. I know they are American Bass RCA's to my Memphis amp, and god knows what to my Eclipse. But I don't toss cheap crap in my car, so it's nothing too cheap.

I haven't had a chance to work on it, but I did check out a couple of things. My Premier HU mutes the system at 0 volume.

It seems the noise comes through the same level regardless of where the volume is set, and through all 4 speakers. I even tried fading and balancing the HU to just one speaker, and it was still the same......that kinda rules out the HU IMO.

A ground loop isolator isn't really an option for me. #1 I don't have any money I should be spending on the car, and #2 IMO it's nothing but a patch for the real problem. Guess my next step is to move the ground to the amp in a totally different place, and see how that works out.

Obviously this can't be an alternator problem, since the fans do it when the car is off; off = no alternator noise. My worry is since it never USED to do this w/ the same setup, that something internal on my amp may have given up. If that's the case, I'll just live w/ the freaking noise.

 

Update:

Well, I decided to go out in the garage and work on her some more.

Step #1: ANOTHER new ground. New hole drilled, paint removed, and this is about as solid of a ground spot as you are going to find. I did this to 100% rule any chance of a bad amp ground out of my mind. Result = same noise as always.

Step #2: So, I got this idea in my head. I turned my head unit off. Then, I took a wire and toched it from power to my remote lead, to turn my amp on. I then turned my AC/Heater fan on (with the car NOT running). What do we have here, but the same damn noise as usual. Well, this 100% rules out the head unit. And the noise comes from all 4 speakers. I also am running 2 different brands of RCA's it looks like to my amp (car has been broken into before, and idiot theives think it is easier to cut the RCA's than to just pull the plugs so each set of RCA's is different.

Step #3: While I was typing this, I got an idea. Unhook the RCA's from the amp (w/ the head unit off and powering up the amp), and see if the noise is still there. I unhook them and *SILENCE*!!! So I try each on of the RCA cables; all four cables (to the same amp jack to make sure) made noise, but the cheaper of the cables seemed to make a bit more noise.

Hmmm, so now what? Looks like I proved it is my RCA's. Should I yank them and run them down a different part of the car (I have them running down the passenger side of the car, near the door sill)? Any other tricks I might be able to get away with?



So now what?

 

Until you know for sure whether or not your RCA's use twisted pair construction it doesn't matter what you do to your existing cables. You can pick up a set of Stinger's Hyper Series twisted pair RCA's from Sound Domain for a good price. Twisted pair RCA's are a must when it comes to trying to rid your system of noise.

 

I would suggest picking up a new set of RCA's and/or making sure you run them down the opposite side from the power wire. Sounds like it's the RCA's. Pick up, or borrow, one nice set and see if that fixes the problem. If not the it's more than likely the amp. You can try plugging in a borrowed amp to check it out, this is why I usually have an amp or tow laying around .