Grounds ran to frame, swapped RCA cables, etc. Still noisy.

[Papermaker85 5,000+ posts]

I've been working on this issue for a couple of weeks now, gradually upgrading components in an attempt to get it to go away.
After an amp and speaker upgrade to the base factory stereo, I had:

1. Static.

2. Whine.

3. A radio station in the background with the radio off. Seriously.

I focused on grounds, grounds, and more grounds with everything I'd installed. I even bought some top shelf RCA cables and better line out converters, going so far as to connect them directly to the speaker level output at the factory head unit.

After two weeks of no success, I just accepted that the problem was with the factory head unit and/or wiring. Since I'd already torn into it, I knew that I couldn't expect help from the dealership for a warranty issue.

I shelled out some serious coin for a PAC dash kit with harness, and a double DIN head unit.

After the swap last weekend, I was left with the static and whine. The background radio station vanished confirming that at least some of my problems were from the factory set up.

Again, I focused on grounds, grounds and grounds.

Only after I wired the head unit to get power directly from the battery did I make any headway.

But you'd think that a good ground is a good ground and that a solid frame connection would be as good as the factory one, which was noisy in a previous troubleshooting step.

Oh well...score one for Easter egging your way through a problem. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

**** alternator ground SON

 

[los33]

stupid you are, know electrical you do not. shut up you will.

... You really always gotta post some dumb sh1t huh.
Enjoy talking to yourself.

Sent from my Moto G4 using Tapatalk

 

[Papermaker85 5,000+ posts]

... You really always gotta post some dumb sh1t huh.
Enjoy talking to yourself.

Sent from my Moto G4 using Tapatalk

im not the one posting dumbshit.

shitforbrains

 

[longbedbob]

Passenger side fuse box ground post was only finger tight.

New unit didn't fix it.

It was only by checking the resistance at various points did I finally get a clue what was happening. My grounds (fasteners to the cab floor) read 0 ohms while the factory head unit ground to amp ground read 7 ohms. Upgrading and sanding down the cab to frame ground didn't sort it. So I then removed interior body panels until I found wires that I didn't even know existed. Lo and behold, not too far from the interior fuse panel I found its ground terminal only held in place by a nut that was just finger tight. It has probably been like that since rolling off the assembly line.

That being said, I still have some static and it's slightly louder than before. Some of that is to be expected. The new unit has a 5V preout whereas the old had 4V. So, at the same gain settings it will be louder.

However, the only reason that I can think that I'm having noise to begin with is, once again, grounding issues. Think maybe that now my factory wiring harness is back to snuff I simply need to connect my amp grounds to factory terminals instead of wherever was convenient? Although the resistance from nearly any location on the body to ground is no nearly 0 ohms, it seems like a good first thing to try.

 

[HighlanderAudio]

How long are your ground wires?

 

[Papermaker85 5,000+ posts]

A perfect power loop allows for the electricity to ground out correctly.
Sent from my Moto G4 using Tapatalk

In a positive DC system current starts at the ground. similar to loosing a return.

 

[longbedbob]

How long are your ground wires?

Amp grounds are 1 foot or so, but screwed (x3) to a sanded spot in the cab floor. If I stretch out to 2 - 2 1/2' then I can tap a proper ground post.

Head unit ground is the factory harness, so who knows? Wire is on the thin side. I've thought about getting some 10 gauge wire and running it 3-4' to the same factory ground terminal as the interior fuse panel. I suspect that it's already running there, anyway, as that is the nearest ground post. I'd just do it with thicker wire.

 

[longbedbob]

Additional problem identified: Sound Ordnance sub amp had a defect allowing the slight alternator whine to permeate through the entire system. Replaced with a JL Audio JX 500/1 and that problem has disappeared.

Only remaining issue is some hissing that can't be heard when the truck is running and volume at 0. I have to dial it up to midscale before it overcomes road noise. But it does come through quite passages of music and when the truck is turned off.

I will be replacing the 8 gauge CCA amp wire with 4 gauge welding cable. Even though I'm realistically below the max amperage allowed for 8 gauge (and that's what the Infinity Reference 704A calls for anyway), I will open the pipes if, for no other reason, to have more current available for a planned 300-500 watt inverter install. I'll also shorten the 12v constant and accessory power wires. This should eliminate any power issues as the source of my static.

 

[Boomin_tahoe 5,000+ posts]

Augh...CCA. Some people don't mind it others hate it. try to use OFC if you can.

 

[longbedbob]

Final problem, static, resolved.

Replaced Infinity Reference 704A amp with JL Audio RD 400/4.

Replaced 2 ohm Infinity Kappa 6x9 coaxials with 4 ohm Focal 165KR components w/separate cross over.

Either one or the other was the culprit, but that it could be that 2 ohm speakers are more susceptible to passing on any noise.

I'll still upgrade the wiring as I'd like to add a true sine wave inverter at some point. It's a matter of finding one thin enough to mount in what little space that remains behind the rear seat.