jeffgt14

I think I have a ground loop somewhere that I can't figure out. I had a little powered all in one sub installed previously but I just upgraded to a new Alpine type S sub with an Alpine MRV-M500 amp. I'm getting a stat-icky, popping noise coming through my tweeters which is especially bad when accelerating. My TL also seems to be running a little off and if I watch it as it's idling, every now and then the lights will dim for a second. I figured this is probably a grounding problem but when I check the resistance of my ground (using the red painted bolt in the trunk) it's measure about 0.2 Ohms which should be fine. Voltage on my battery seems fine at 12.4V. I did measure the resistance of my actual battery to the chasis and it's at 0.79 Ohms so I'm not sure what's normal there. I never had any issues before I installed the new amp. When I first installed the amp, my battery was dead for some reason when I connected everything back up but it's been working fine it seems after a jump. I'm kind of stumped right now.

thoiboi

I was just going to suggest installing a ground loop isolator or sanding your grounding points to promote lower resistance. But then i saw that your lights are dimming, that leads me to believe there's too much draw on your alternator and it is either dying or you need a bigger one.

jeffgt14

The alternator is actually under 2 years old. It’s only a 500W Amp. It should be drawing too much.

thoiboi

Then fix all your grounds. What kind of wire did you use for the Amp?

jeffgt14

That was the only other thing I could think of but I’m hesitant to re-run wire if there’s no need. It’s only 8ga wire as that’s what I was using before. I know 4ga is recommended for this amp but I think 8ga should be sufficient. Also, wouldn’t smaller wire draw less power making it less likely to be too much of a power draw?

I just don’t see any problem with my grounds so I don’t know what to fix. The resistance on my amp’s ground should be fine.

Bchester6

It could be so many things... Your only addition is the amp and the sub so the static in your front speakers leads me to believe it's a systemic problem since it's not been affected by aftermarket changes. Battery ground or something in that vein I suspect. Is 12.4 volts on your battery when the car is on or off? You should be seeing somewhere well above 13 volts at idle so my guess is battery and/or clean your terminal posts.Your amp is only 500 watts and class D efficient (regulated power supply) so upgrading to 4 gauge power wire seems like a bit of stretch for me unless your talking 25+ feet but even then...I run good 4 gauge for a 1000 watt A/B Audison amp and have no issues whatsoever with current draw or voltage drops and it's no where near as current friendly as that Alpine your running.

jeffgt14

12. 4 is off. It was around 13.2 idle.

jeffgt14

Sorry that should be 13.9V running

jeffgt14

Still struggling with this like crazy if anyone can be any help. I replaced the battery mainly because I wanted a bigger one anyways. Upgraded all my amp power and ground cables to 6 gauge full copper. I'm actually not even sure it is the new amp anymore because it still does it even with the amp completely unplugged. The noise whine completely goes away with my stereo off or volume at 0 but comes back if the volume is even at 1. I've read numerous other threads where people have had alternator whine that goes away with the the stereo volume at 0 and the cause was bad capacitors in the factory amp. I've replaced my factory amp and it made no difference.

Bchester6

Grounding your HU to the same ground as your amplifier will sometimes does the trick. The more common grounding points you have the better in most scenarios. Couldn't hurt.

Jackass

I "thought" that if the factory amp was failing, the noise would still be there since it was injected at the amp? Just thinking it through....even if the HU volume is at 0, the amp is still doing it's thing and amplifying anything coming into it which in theory when at "0" is nothing. So if this theory is correct, and it is silent on "0" but noise on "1", wouldn't this be the HU that is at fault somehow?

jeffgt14

You know where the ground is for the HU? Anyway to get to it without removing the entire dash?

jeffgt14

Just to follow up on this. After spending months trying to figure this out, I changed the spark plugs and all my ground noise stopped. My car is running a hell of a lot better too. I had NGK Iridiums in there and they only had about 50k miles on them so I’m not quite sure why they were bad but I guess they were. I’ve never really known spark plugs to cause a whining noise and certainly never even read that in my months of searching as a possible solution.

thoiboi

thanks for updating us.. that's bizarre...

Bchester6

Yeah weird. Been doing this a long time and haven't heard that one yet.