Engine Noise from stereo

[Jasonva]

Hello all,

I was wondering if anyone has installed an aftermarket stereo with an amplifier in the trunk? If yes so you have engine noise? If No engine noise can you tell me how you installed your system...ie how you routed your power wire, RCA, and grounds. Do you have any ideas as to how I can get rid of these pesky ass engine noise? Thanks everyone.

 

[Briank]

Is it a noise from the ignition or an altenator noise. Is it just in when you play the radio or do you have it when playing a cd, tape, mp3 .... Goods grounds and proper shielding is all allways required for good sound.

 

[Jasonva]

I'm guessing its alternator noise...it varies with the rpms. Ignition noise is more of a buzzing sound. this is a whinning sound. I don't know if this matter but I do have my speaker wires running adjacent to the power wires...but I didn't think that would effect it. My RCA cables are running across on the drivers side of the car to the truck. The power, remote power, and speaker wire are running on the passenger side to the trunk. I have top of the line shielded cables. Man that sound is annoying.

 

[Arshad]

Yeah it's that dreaded alternator whine. I've run into this a few times on other cars when doing the install myself. Isolating the power line often helps. There is also a filter you can get that reduces the whine (it's fairly common, can't remember what it's called off-hand) but it also filters out some of your range so that's not so great. One thing you may also want to consider is swapping in a high quality amp just to see if it's the actual amp that's the problem (which has happened to me in the past).

There's a bunch of FAQ's on the net that go through this specific problem and how to address it, so take a look around. Good luck, that whine just ruins the whole experience...

EDIT: Look for the rec.car.audio FAQ

 

[fangtl]

Without getting into a wiring fiasco, what you should first do is turn down the gain on the amp and see if it's set too high.

 

[D'Ecosse]

First question - is this the stock head unit or an after market head?
I had the same problem with my original set-up I bought the car with - stock head & amp in the trunk - I think the ground at the head unit is insufficient. I put a better ground to the amp but it didn't make any difference - so I used this ground loop isolator & it eliminated it completely.
Note: you should not lose any signal frequency with this device - it does not decouple any frequency to ground like a passive filter might, just decouples the dc component between the amp & the head by transformer coupling the audio signal.
I did not try to improve the ground on the stock head unit, however, when I replaced it with after-market, I used a good thick ground wire directly to the chassis - there was no need for the isolator after that.
As fangtl says, turning down the gain may also help - it is good practice to set the gain only as high as you need it anyway. Set it all the way down, then adjust your volume control knob to about 80% - now slowly turn up the gain until the audible volume is about as loud as you would likely ever listen to it (assuming there is no distortion at that level - if so just reduce it further). If that doesn't do it, try improving the ground at the head (& the amp if it's marginal) & then use the isolator if it's still there.
Its been argued that you shouldn't need a ground loop isolator - true, but I certainly don't see any down side - they're cheap & you will not experience any performance deterioration.

 

[Jasonva]

I GOT IT!!!!!

Thanks for all the replies I screwed with it over the weekend and as usual it was a simple thing that I had overlooked. I have a rockford 750x running the mids and highs and what happend was when you put the end caps on the amp it was pushing the RCA's down and they were grounding to the steel on the amp. And Voil'a the dredded ground loop. once I took this cover off and move the RCA's around the engine noise disappeard....POOF...

Now it sound good and the amps are hidden in the trunk with no engine noise.

Now the only problem I'm having are the amp that is located were the NSX tool kit was located is getting so damn HOT it cutting off so might be cooling fan time.