Alternator Whine - Detailed Post

[Mike4068]

Thanks for the diagram. Although I have not personally had issues using the stock hu ground, it is not usually recommended. I also had to go around to all the factory ground points and grind down to bare metal. They were all painted, I don't know how anything worked before that but it made a huge difference. You could try grounding to your frame instead of that long 2awg run. The theory is that the huge mass of the frame will have less resistance than the small 2awg wire. There are other things that can be done but come with drawbacks so I'd try this first. 

[Blast12345]

Unfortunately I don’t have other head units at my immediate disposal 🙃. I think my dad has some lying around I could try.

I plugged my phone into the RCA up near the head unit - but to my surprise I hear the problem!

I suppose that rules out the head unit. It is quite strange that without anything connected to the RCAs - no noise. With mute plugs/dead short RCA - no noise. With my 3.5mm to RCA hooked up - with or without phone - noise.

I’m going to begrudgingly remove the rear seat and try my phone directly plugged into the amp. If it still makes noise I’m going to try removing the sub amp from the system.

[Joshdashef]

Try this https://www.amazon.com/PAC-SNI-1-Noise-Isolator/dp/B000K50HJE

[Blast12345]

@Joshdashef - Thanks for your suggestion. I'll try that if I can't find any other way to address the issue.

@Mike4068 - I tried grounding my amp to the chassis (the ground is temporarily shoved into a seat bolt hole). To my surprise - no whine. When I plugged back into the distribution block (for the ground I ran from the battery) - the whine returns.

So it definitely seems to be an issue with the grounding point - but I'm extremely surprised that a dedicated 2 gauge ground straight from the battery is causing a problem. I'm curious why this may be happening so that I can avoid it in the future. I was under the impression that grounding directly to the battery is the best option, but most people don't because the chassis/frame is (usually) sufficient and far easier.

The only thing I can think of is that the ground is picking up noise...but I figured noise in a power line wouldn't matter.

Update: 
I just considered something I read a couple nights ago. Basically the other of the post made the cause that if the connection between the battery ground and the chassis fails - your dedicated line becomes the new ground, but it requires all of your vehicles energy to flow through your equipment.
While I certainly have an intact line from my battery to chassis, perhaps there is corrosion that is reducing its effectiveness and thus some unwanted current is flowing through my amp?

If this is the case - I could ground my ground (at the front) to the place where my battery grounds to my chassis. This saves me from that risk, my solve my problem, and has a lot more direct/low resistance connection to my battery. 
I'll give it a try - but in the meantime I'd like to hear your thoughts.

[Joshdashef]

2 hours ago, Blast12345 said:

@Joshdashef - Thanks for your suggestion. I'll try that if I can't find any other way to address the issue.

@Mike4068 - I tried grounding my amp to the chassis (the ground is temporarily shoved into a seat bolt hole). To my surprise - no whine. When I plugged back into the distribution block (for the ground I ran from the battery) - the whine returns.

So it definitely seems to be an issue with the grounding point - but I'm extremely surprised that a dedicated 2 gauge ground straight from the battery is causing a problem. I'm curious why this may be happening so that I can avoid it in the future. I was under the impression that grounding directly to the battery is the best option, but most people don't because the chassis/frame is (usually) sufficient and far easier.

The only thing I can think of is that the ground is picking up noise...but I figured noise in a power line wouldn't matter.

Update: 
I just considered something I read a couple nights ago. Basically the other of the post made the cause that if the connection between the battery ground and the chassis fails - your dedicated line becomes the new ground, but it requires all of your vehicles energy to flow through your equipment.
While I certainly have an intact line from my battery to chassis, perhaps there is corrosion that is reducing its effectiveness and thus some unwanted current is flowing through my amp?

If this is the case - I could ground my ground (at the front) to the place where my battery grounds to my chassis. This saves me from that risk, my solve my problem, and has a lot more direct/low resistance connection to my battery. 
I'll give it a try - but in the meantime I'd like to hear your thoughts.

Do you have upgraded grounds for your battery underhood? as in the big three? Throw some 1/0 or atleast 4 gauge between battery negative and chasis, battery negative and engine, alternator positive and battery positive.

[Blast12345]

I’ve not done the big three. I’ve got plenty of left over 2 and 4 gauge cable to do it (albeit I need adequate mounting hardware).

I’m skeptical as to whether not it will fix this current ailment, but it would certainly be beneficial to do. 
 

Update on my other test:

I moved the ground line (for the amps) from the negative battery terminal to where the battery grounds to the frame. Whine persists.

So - same as my previous post - the only situation where I don’t have whine is grounding to the chassis at the rear of the vehicle.

[Mike4068]

So you have your solution. Enjoy your system. 

[Blast12345]

Turns out that the whine came back when I reconnected to the HU - even using chassis ground.

But I think I found my problem. The manual for the amp says it’s gain range is 0.25v to 8v. On the website it says the range is 0.25v to 5v.

So - my gain was setting assuming an incorrect range (0.25-8.0). The music sounded fine, but obviously had that noise. I lowered the gain and - while I’m sure the whine is still somewhat present - it is now inaudible.
 

TLDR - I think the gain was wrong because of inconsistent documentation. The audio sounded fine though, so I had no way to know that the gain was wrong 🤷‍♂️
 

I’m going to reassemble the system with the modified gain. I feel like I kind of wasted everyone’s time with something as simple as a gain issue - but the takeaway (for others that come across this thread) is to double check the documentation.

Im going to email Zapco and ask for clarification and - if the documentation is incorrect - request they change it for future buyers. I’ll post back with my results.

 

Update:

Nah. It’s still there, just more quiet because of the adjusted gain. I’ve now run a ground from the battery ground to the HU so that the amp and HU are definitely on the same ground.
I still emailed Zapco to ask about the gain range because their documentation did seem inconsistent. 
I don’t think it is the problem, but I’m going to humor using a second set of RCAs ran through the center of the cabin. I’m also going to try a different amp.