1way

Cool story broI think it's ground related to... I just spent all day going over all grounds went over all connections everything is tight and down to bare metal. I have been putting systems in my cars for 14 years now and never once had any noise issue's. But I guess there's a first for everything.

I have a mechman 240a alternator with a xs power d5100 upfront everything wired up and running smooth. Now when installing my rear battery (another d5100) should I run both power and ground wires to the back battery or just the charge wire and ground in the trunk? Thank you in advance.

Do you have the big three done?Yes I have the big three done with all ofc 1/0 and a ground from alt casing to battery recommended by mechman for there alternators.

I have a digital design m2b running my sub a Fi BL 15 and I have a digital design s2b for mids. I hooked up the sub to the s2b to see if it was the m2b but the thump got louder. My other sub setup was a kicker 12 L7 and a jl e1800d and never had a problem. Now with the digital design amps I have problems.

I have the positive for the rear battery right off the charge post of the alternator then goes right through the firewall to the rear

It's a uni - body car so no beefy frame to go to. But all my grounds are on bare metal and tight. Everything was good until I installed the rear battery. I'm running active with a deh 80prs. I have the tweeter amp on the front battery and the mid and sub amp on the rear battery. The mid and sub amps are both on the same exact ground and same exact power and my mid amp is quite no noise on turn off but the sub amp thumps. Before with the one battery up front everything was good no noise no thump on turn off. But ever since installing the second battery in the rear along with new amp and sub I have this thump on turn off. I did notice when i ungrounded the tweeter amp it took way longer for the sub to thump

That was my next question should I also ground that rear battery in the trunk too?

Ok I have it that way now and now I get a pop/thump through my sub with no input signal so I'm pretty sure it's in the grounding not deck or rca related.

Will a 6" aero port be enough for a fully loaded BL 15 in a 3.5 to 3.8 box

2k rms max from a dd m2b