I have read a lot about stereo upgrades in previous posts. Here is what I have.

1. MTX Amp 100*2 @ 4 ohms, 200*2 @ 2ohms under driver seat
2. MB Quart seperate speakers in doors
3. Stock head unit

Here is how it is wired

1. signal from head unit to amp is run along transmission hump.
2. signal from amp to speakers is run along transmission hump and under dash to each door. Crossover in door.
3. Power cable runs from battery through firewall on passenger side, under dash (behind radio as far as I could get) along driver door to under the driver seat. Cable is 10 gauge.
4. Ground cable is attached to front seat bolt. I sanded metal under seat until I got clean metal. Ground cable is on bolt between seat and metal floor.

Here is the problem...

I get alternator wine (varies with RPM). I know this is a symptom of bad ground so I pulled the driver seat out (again) and resanded the metal under the bolt. The ground makes direct contact with the unpainted chasis. This is as good as ground as I think I can get.

I did not do anything to the head unit ground. I assume it is good enough because I didn't get the wine before I installed the amp.

I also tried putting a 16V 2200 microF cap between the power and ground where they attach to the amp. Didn't notice an improvement so I removed it. I am not sure what an appropriate size cap would be, I just had this one lying around so I tried it.

Ideas

1. replace speaker cable with low level converter and run shielded cable. Unsure if the speaker cable is picking up the noise. Also, I assume the low level convertor in the amp is better than the passive PAC convertor?

2. Add a different PAC thingy to alternator. Anybody know about this? Is it just a cap?

3. Find a different path to route the power cable. I only see one way over the transmission hump and that is behind the radio.

Any knowledgable opinons would be welcome. I did all of the work myself.

 

I had this too when setting up my amps, but I did mine in the trunk. Where I think is best because of the heat from them. Its late so I can't really picture your setup fully right now, but its 2 things:

1. Your ground isn't that good, but it probably is.
2. Your power is too close to your speaker wire

If you did put it under a seat, the passenger would have been better. Your power is probably behind your radio which would do it.

 

Hunting noise down is the hardest thing to do! First off I have yet to do a system that works off the factory deck that does not have some noise.

That being said.....keep you power wires and speaker/RCA wires far appart from each other. Avoid internal wiring as much as possible as well.
Make sure all your connections are solid. See if changing out the hi-low converter makes a difference.

 

a 2200 uF cap isn't going to do much in helping rid you of noise...it will help power spikes of a very small order, but not whine.

 

But all do not. I have a PG amp and ADS speakers off the stock head unit with ZERO noise.

 

Quick test:

Remove audio input to amp (either RCAs or speaker level)... turn system on... if the sound is there then it is a grounding issue... if it's not and returns with the signal then you know it is signal related...

It's usually not that easy but I try to simplify things when tracking down noise... if I have numerous processors, crossovers, etc, I remove all components and add one at a time to see which adds noise...

Just an idea...

 

I'm not an expert auto installer, but it seems to me that a ground loop could act just like this. When the signal ground is removed (input unplugged) the noise disappears. When re-connected, a ground loop will cause the noise to re-appear.

Ground loop problems in other systems (CCTV for example) do not show up unless the signal wires are connected.

 

The amp should be on the right side of the car like the battery. I think he ran his power line BEHIND the radio and to the amp under the driver side (correct if wrong). If the power is too close to the speaker wire it will cause the alternator noise.

 

Good advice.

I ran my power on the right side and the signal wires on the left. (both under the door sills) I have a slight amount of noise in the speakers, but it's only noticable if the engine's not running and you lean toward the door. As soon as the engine is running, you can't hear it. I know it's a ground loop, but it's not significant enough to bother fixing.

 

I reran the power under the passenger door sil, behind the seats, and under the carpet to the driver seat. Doesn't go near the speaker wire now. Unfortunately noise still remains.

I believe my ground to the amp is good. I wonder if the head unit is grounded well? The amp is grounded to the seat bolt. I have sanded off the paint on the frame.

The only thing left that seems likely to help is putting a low level converter near the head and run shielded cable to the amp.

Thanks for everyone's help. I will keep working on this until I am satisfied.