Help! Alt Noise Question - Driving Me Nuts!

[madmoomoo]

Hey folks,

I've got this stupid noise coming through my audio system and it's making me go bananas.

I'm presuming it's alternator noise because it correspondes with RPM. I've got an R33 series one with 2 amps in the back. I've put one of those noise suppresor things in, I've currently got the back seats out for other purposes, so I can see that the rca cables are laid down the left side of the car and under the passenger seats - so as far as I can see they are far as possible away from any power cables.

Are there any things I could try that I've missed? It's really annoying. I have to have the music up loud so I don't hear the silly whirring...

I've had a look at the front of the car - the rca cables are lead underneath the passenger footwell, and at the base of the middle console there are a couple of smaller powered lines going through to my fog lights and powering my aif/fuel meter thingy, so they have to sort of cross at some stage. Would it work if I used aluminium foil to wrap the rca cables at this point to try and shield them? How far away does a power cable have to be to avoid interference?

If anyone has any advice it would really be appreciated; I'm at my wit's end with this problem...

Thank you in advance (i hope).

cheers!

[R33S2]

I was reading a thread where they were discussing spark plugs and if you got the wrong ones (no R in plug no.) this happens and is also not good for ecu.

[madmoomoo]

Yikes! Wouldn't have thought of that. Thanks. I got the guys at autobarn to find the spark plugs for me so hopefully they looked it up right. I'll have a bit of a look.

Anybody got any other suggestions?

[Dose Pipe Sutututu]

have you used one clean earth point for both amps?

if your using two seperate grounding points for each amp it can cause alternator whinning as well...

also ..... ! the whinning could be from your deck, when you installed your deck did you use the earth wire in the harness?? thats a big NO NO... run a new earth point and drill it into the body...

hope that helps.. ...

[madmoomoo]

I've got both amps earthed to the same point, but I bought the car with the head unit already installed. Appears as though they've done a decent job, but I'll get in and have a look at the gounding for it.

Thanks. Hope that fixes it...

[Mercury]

I've got a similar problem on my '33 S2. 2x alpine amps in boot w/ direct to amp earth wiring.

I've narrowed my problem down to the fog lights. Seems everytime i turn 'em on, i get alt-whine.

Oh well, no driving with fog lights on low music listening?

Hope this helps.

[rocketboy]

Check earths as stated, also sand paint back if earths on chassis is not direct to bare metal. Or try a different earth point.

And would agree that checking head unit earth is grounded direct to chassis, again, sand paint back for good contact if need be.

Faulty RCA's could be the cause also. I had an intermitant noise problem that I eventually tracked down to a faulty new RCA - they were half decent ones too. So perhaps run some other RCA's to see if the noise is still there.

[Edge]

Thanks for the headunit earth tip. Been having the same problem - quiet whirr, I'm buying an A'PEX Super Ground Stabilizer but maybe I should try this first.

edit - I tried to shorten the blank space,

and what happened to the delete post option?

Edited March 1, 2006 by Edge

[ferni]

I had the same problem once. I upgraded my amp to something bigger and got the whine. With my old alpine amp (which i still currently have) there is no whine, i tried all sorts to fix it, different ground points for the amp, those power supressor things, no luck. took it back in the end.

The suggestion of the ground fromt head unit is a good one, i'll have to check that, i'm pretty sure its a proper ground earth, but i'll double check to be sure next time my dash is out.

Ohh and to the OP, check your spark plugs have the R in, eg, BKR6E.

[RANDY]

Just been tooling around with my old amp. Installed it with thick cables etc etc. Good RCA's and so on.

I get whine and static.

Most of the whine seems to come from a factory harness that runs across and behind the A/C unit, and down the left hand side of the head unit (where it goes to a yellow plug), then across the bottom of the head unit. The ciggy lighter wiring joins into that harness too.

If I hold the RCA cables close to that factory harness, the whine is incredibly loud! I tried aluminium foil over both sets of cables, no change. If I keep the RCA's well away, the whine dies down considerably. Now i'm stuck in the same situation where the sound is JUST there, and annoying me. None of my previous cars have ever had any troubles with this amp, or any form of RCA wiring that i've put through it.

Could we hear from people that have run one or two sets of RCA cables from the HU to the boot without any issues?

[AdamsR33]

Just take it to a car stereo installer they should be able to fix it quickly and easily

[RANDY]

Naww.. i read over 50 search results on SAU, and noone ever seems to get it fixed.

On other sites I came up with a few good ones.

1) HU not earthed well enough

2) RCA ground fuse blown in HU

3) Amp ground fuse blow

So anyway, yesterday I bought even better RCA cables from Jaycar (hifi ones, not their car ones) and ran them from the boot, outside the car, into my HU. My rear RCA outs were perfect. No noise no whine nothing! The front outputs were hideous with static, but no whine. I turned the gain on my amp down, and now there is no noise at all! I suspect that my HU has a blown ground fuse, but I can't find it. (might be a resistor that is stuffed).

There were guides about checking the resistance (ohms) across the RCA cables etc, which mine all passed.

Anyway... my fix was simply to replace the RCA cables and turn the gain down. I ran them down the same path as they were before, and my problem is solved.

I did hear people mention that some amps did it for them, and others did not. Some cheaper, some more expensive.

In any case, here is the list of "to try" (in order)

1) Run new, high quality RCA outside the car.

If noise persists, it's not your cables

2) Use a 3.5mm stereo mini-jack to RCA cable and play your ipod or whatever through the RCA cables.

If noise persists, it's not your Head Unit

3) Swap amps

If noise persists, you might have grounding issues or two dud amps.

I hope it helps, but i'm stoked that I finally have my setup nailed after 3 full days of ripping shit apart!

[rocketboy]

Good stuff, checking amp earths first may be easier than some of your tips though. Also check that suitable sized cable is being used for power requirments.

Another strange one is for you Pioneer headunit owners. Apparently there is a fusable link in the RCA line outs, this can blow causing system noise. That'll be a beyatch to find if you don't know to look for it. It's an easy fix if your unit is under warranty.

[Damo Monster]

Good stuff, checking amp earths first may be easier than some of your tips though. Also check that suitable sized cable is being used for power requirments.

Another strange one is for you Pioneer headunit owners. Apparently there is a fusable link in the RCA line outs, this can blow causing system noise. That'll be a beyatch to find if you don't know to look for it. It's an easy fix if your unit is under warranty.

Can tell you from personal experience about the pioneers... if you ever get alternator noise and you own a resonably late model headunit, check this first!! most common cause is not having a good enough earth for your amps, or having your gains set at the wrong level on your amp... its not a major to repair tho, but its knowing to check it... funny though, i like my pionner, but who the hell would put a fuse on an earth of all thing?! definitly fused power lines, but the earth? yikes...

cheers,

damo

[RANDY]

Well... when you run long RCA's, and they get cut on the car body... they can short each other... so you get 2volts or more going back into your negative RCA...

This can kill a head unit or amp pretty fast! I think that is why they're earthed. =-]

[Trooper]

Im having the same problems

Tried almost everything, ran the RCA's outside the car and the noise still there, re-grounded the amp (this helped a little bit)... My headlights also dim in time with the base (when the sub is drawing power) would a capacitor fix this problem? and would this also possibly reduce the whine? My whine is much worse when the lights are on and even worse if the fog lights are on too. I cant afford new RCA's at the moment (saving for all my performance upgrades to be put in) but i dont think i went too cheap when i bought them.

Cheers

[Bl4cK32]

anyone tried these -

http://www.jaycar.com.au/productResults.asp?FORM=CAT

?

Edited March 17, 2006 by Bl4cK32

[RANDY]

Linky no workie!

Heath: yeah, one of those large capacitors should fix your dimming problem. I beleive your main earth should be bigger than any other earth wire you run, so it might pay off to have an auto sparky make up a really thick grounding cable for your battery.

Jaycar noise suppressors made absolutely no difference for me, if that's what the link was for.

[Bl4cK32]

yer it was the jaycar noise supressors.

http://www.jaycar.com.au/productView.asp?I...x=&SUBCATID=563

[FUR105]

those noise supressors r crap!