Alternator whine and static in speakers

Finally got my system fully installed. DDX9907Xr, 12" subs, rewired all door speaker cable to 12 gauge for previously installed Focals.

Been trying to fine tune it all and I'm catching alternator whine and some static. Alternator whine happens whether the head unit is on or off when RPMs get high. Speaker static is noticeable if a song isn't playing. When I pull the RCA's from the amp the static goes to a bare minimum so I assume that's from the amp power and unavoidable. Noticeably louder with RCA's in and gets worse with a gain increase.

Both amps are under seats and grounded below seats also. Drilled a hole on driver side off of the side where the front left seat leg bolts. Used an existing hole on the passenger side. Sanded both grounding points to remove paint.

Just looking for opinions before I tear the truck apart again. Power cables to close to RCA's? Bad ground? Should I use GLI's? Spent too much time and money at this point to settle with the noise.

See attached diagram for how I routed cables.

 

Only thing I can think of is replacing the 8 gauge wire with 4 gauge and make sure the power wire to the 4 channel isn’t in direct contact with your RCAs where they cross.

 

Replace the 8 gauge ground or both?

 

I used 4 gauge for all amp power and ground. Its probably not the issue but cheap and easy enough to cross off the list as not contributing to the problem.

If I crank the gains towards max I get some white noise but even having them dialed back to get silence at 0 volume I can only get the volume to 30/50 before it feels like my ears are going to bleed.

 

Yea I thought upping the ground to 4 gauge might offer an improvement. I know the 8 gauge is plenty of power for that short run with Infinity recommending 10 gauge.

 

Besides what s already been mentioned, from what I ve read about various noises in speakers, they can be caused by poor grounds including; grounding to body of cab rather than running ground through body, and grounding to chassis, or insufficiantly tight connections. Running speaker wires next to power wires, (if speaker wire needs to cross power wire make sure it crosses at a right angle, or 90 deg to power wire. This is partially solved by running power wires/cables on one side of vehicle, and speaker wires on other side of vehicle. Myself, I ran zero gauge to distribution block, and ran the recommended input size to each device from block. Keeping output grounds as short as posible helps. Also, some systems respond better when using a common ground. Other systems like seperate grounds. Only way to know is to try each way.

 

If you don t mind my suggestions: After looking at your diagram I would route rca s differently, or if you mount amps on 1 inch stand offs, and run power cables around back, and under amps rca s never cross power wires. The idea is no crossing of those two. Try a common ground. Run both amp grounds to a common ground like

$11 Fastronix 5/16" Single Stud Ground Junction Block

this, then to frame.

 

Most likely you have power cables running to close to another signal wire for something in the truck. Running power wires outside the cab along the frame would be my recommendation. Also any speaker wires that are running in parallel with any power or ground wires will cause that condition also. Always run power wires 90 degrees to any speaker cable.

 

I appreciate all the advice. Tried to limit the crossing as much as possible but I think I’m gonna reroute the 4 channel rcas around the glove box instead of the center console.

Also gonna detach the headunit ground from the Maestro box and find a place on the dash frame to bolt it. First started noticing the static noise after I installed the head unit and I increased the gain a hair on the little 45 watt alpine amp I had installed at the time.

From there I’ll address the amp grounds if needed.

 

After reading your posts, I am of the opinion that your amp ground/s is probably the issue. Not sure the size or power output of your amp/s, but I would do a minimum 4awg and ground them BOTH TO THE SAME LOCATION as to avoid a "ground loop". Also be sure that wherever you ground them, that you remove any paint at that location as paint inhibits contact.

 

Trouble shooting ideas.
https://www.youtube.com/watch?v=Q8dpucdxs6Y

 

Sub- 500 W RMS, 4 Channel - 280 W RMS

4 gauge ground from sub and 8 gauge ground from 4 channel. I was going to use a distribution block to ground them and still have one but other posters said to ground them separately so I did. I did sand the paint off to achieve metal to metal connection.

 

Well, I cannot comment on what other's have done. All I can say is I have installed more aftermarket systems than I care to remember. And for my amps (I'm running a 4chan and a mono), I have 4awg hots and grounds both going to distribution blocks and merging to 0/1 gauge (hot going directly to battery and ground going to floor/frame), each with a tinned copper 0/1awg terminal lug. Oh, and I am using 100% oxygen free copper (as copper clad aluminum is utter shit and will only get you into trouble later). So, both my amps are merged and grounded a the same location. And I have ZERO alternator/background noise coming through my speakers.