I know there is heaps of posts on here about this i have read them all, have just been through and rewired the whole amp to try and fix it, the car is a TS Magna V6 and the gear is as follows...

HU: Pioneer DEH-30MP (pretty old one had it for years)
AMP: Clarion APX4240 4 * 60 RMS
8 Gauge cable
Brand new Sony Xplod RCA's (small country town that was about all i could buy yesterday)
Pioneer 6 x 9s 60w rms (in the car when I got it

I have the power to the amp running down the Drivers Side of the Car, RCAs down passenger side and the remote wire down the center. The amp is earthed by 8 gauge cable to a threaded hole on the underneath of the parcel shelf (sanded back to bare metal). The head unit is earthed to bare metal directly behind the head-unit (sanded back also)

I have plugged an ipod directly into the amp rca's and get no whine so I am assuming the amp is fine.
When the key is in ACC position, the speakers are crystal clear. When key is in the ON position there is a high pitch whine no static just a clear high pitch whine, and when engine is running the alternator whine starts, I am satisfied the earths are good I have also checked the RCA ground (resistance between RCA and body of HU is .5-.7 ohms, which is fine? i think.

Is there anything I have missed where should I look next, maybe the voltage reg on the alternator although i'm getting 14.6v over the battery while the car is running which is pretty normal.

Any input would be much appriciated, oh gain is turned down to about 25% to try and minimize the whine and adjusting the gain does not effect the high pitch noise when the key is in the on position (car not running) it stays constant regardless of what the gain is set at

Any input would be much appriciated

Cheers

Sam

pictures of the amp wiring and earth

http://i733.photobucket.com/albums/ww332/sam_ang/IMG_0769.jpg
http://i733.photobucket.com/albums/ww332/sam_ang/IMG_0768.jpg
http://i733.photobucket.com/albums/ww332/sam_ang/IMG_0766.jpg

Have you tried doing a dry run with then amp not bolted to bare metal?
Double earthed?

No I haven't tried that will do it tomorrow morning. By double earthed do u mean the amp with be earthing on the mounts as well. When it was just the head unit in the car there what no whining at all so maybe that could be it

Thats roughly what i am getting at.
I have always mounted my amps on mdf which then bolts to the car, and never had a whining issue.
Have never mounted straight on to metal.
Just my thoughts.

Plus you have run the rca and power down on opposite sides of the car, so it should not be causing interference etc

OK mate thanks will give that a go tomorrow. Its really starting to annoy me lol

Have you run the speaker or any audio cables near the power cables? I couldn't see a problem attaching an amp straight to a car body as seeming three amp ground terminal will go straight to the amp housing anyway lol

Also try another set of RCA leads... I've seen Cheaper and/or Faulty RCA Leads give a similar result...

Yeah the ones I have are brand new but they are cheap ones not a whole heap of selection out here going to Toowoomba tomorrow so will grab some better ones there. Will I bet able to get decent ones from somewhere like auto barn?

Have you run the speaker or any audio cables near the power cables? I couldn't see a problem attaching an amp straight to a car body as seeming three amp ground terminal will go straight to the amp housing anyway lol

RCAs are on the left power on the right and remote it running straight up the centre of the car. I might try plugging my iPod into the end of the RCA's tomorrow as well that way I will know for sure if its the RCA's are an issue. I'm starting to lean towards the head unit having issues internally it is pretty old. So yeah I'll try those few things and see how I get on

This issue can be caused by faulty RCA's or RCA inputs.

If it were me however I would try,

-Mount the amp to an MDF board.
-Try another set of RCA's
-Try running the RCA's on the outside of the car.
-Earth the amp in a new area (eg: seat bolt)

See if that helps.

A couple of things to try as well...
Route the RCA's 30 cm clear of the ECU (or as much as possible)
Keep the RCA's away as much as possible from the loom of the radio...
Clean your Battery (Neg) -> Chassis Earths.. and check/clean the Alt -> Battery Positive Connections.

I also had an alternator whine and it turned out to be the remote wire. I did seperate the rca's from the power cables but had the remote wire on the same side as the rca's. Recently moved the remote wire to the power side and I've no noise since.

All fixed. Well not back together but the issue was the amp being bolted to metal. So thanks guys. I'll go get a piece of MDF tomorrow and it will be all sorted

Just sounds like double earthing. The earthing frequency on the amp and the earthing frequency on the headunit are different. They cause a mismatch which leads to interference on any signal lines. Any kind of signal sensitive equipment with multiple earthing on powered equipment does this.

As for RCA cables and quality. There is not much difference between a $20 and $200 set. Just keep an eye out for shielded cables as sound is like any other electronic principle and runs on conductors. The shielding helps reduce noise on a cable which obviously produces a clearer signal. You could even use Cat5E and add RCA adaptors :L

The shielding helps reduce noise on a cable which obviously produces a clearer signal. You could even use Cat5E and add RCA adaptors :L

Cat5E isn't shielded?

Cat5 is terrible cable for a car regardless of shielding or not, however most if not all Cat5 is not shielded.

I run about .125 of one volt through my rca's to my tweets, every pro in the industry said I need good rca's, but I had tbem already, so there is a difference between cables...But you can stick with good enough if you want.
I dont think I'll throw my solid core bass rca cables in the bin just yet.


Also, DC doesn't cycle, and has no frequency...

Also, DC doesn't cycle, and has no frequency...

Yes it does if it's from an alt. The wave should always be positive but it's still a wave none the less.

Batteries do not.

Cat5 is shielded..I work with it everyday lol. Of course you wouldn't use it in a car audio situation, it more of understanding the concept of RCA's and how signals travel. I guarantee if you bench tested it, you'd hear no difference in quality between using professional RCA cables and Cat5

Cat5/cat5e/cat6/cat6a UTP cable, 99.99% of all the cat cable you see, is unshielded. STP (and above) is the only shielded cable and it is only really used in noisy environments and where it really matters, think medical, broadcasting, some 10gig, and power station

Cat5 is shielded..I work with it everyday lol. Of course you wouldn't use it in a car audio situation, it more of understanding the concept of RCA's and how signals travel. I guarantee if you bench tested it, you'd hear no difference in quality between using professional RCA cables and Cat5

Im sorry but like I said not all Cat 5 is shielded, firstly im looking in a parts express cat right now that shows Cat 5e cable that is unshielded, then first paragraph below.
http://en.wikipedia.org/wiki/Category_5_cable, plus ive used it before.

Secondly I believe you will hear a difference from quality cable vs cat5, but its just word against word, from my experience I know what I hear, but there is also more to it than just the cable, connectors for one. Also if you use Cat 5 in a car environment it can be more subject to interference so if you count interference in terms of "quality" then thats a valid point that doesn't need testing (however I believe it has been done before)