Emergency help needed!!!

skyhighZJ said:
The RCA’s next to power supply can also make an interference issue. Battery power (plus or minus) needs to be separated from anything carrying voice signal (RCA, speaker wire).
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If they do have to occupy the same space, running power and signal at 90 degrees to each other (instead of parallel) will help with induced noise.
 
Fabrik8 said:
If they do have to occupy the same space, running power and signal at 90 degrees to each other (instead of parallel) will help with induced noise.
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While certainly true, thats really more relevant to AC and DC crossing. As the sine wave harmonics cause pulse inductance/ pulsed magnetic resonance so by crossing at 90 the pul is in one spot and doesnt cause hamronic distortion
 
Ron said:
While certainly true, thats really more relevant to AC and DC crossing. As the sine wave harmonics cause pulse inductance/ pulsed magnetic resonance so by crossing at 90 the pul is in one spot and doesnt cause hamronic distortion
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I'm talking about AC and DC crossing. Well, DC that apparently has AC noise riding it from something.
 
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RatLabGuy said:
What kind of feedback? Squelch? Engine noise? Does it change in pitch or volume w rpms?
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Just routed the yellow (constant) to the battery. Still doing it. It does change with rpms.

The ground is not to the battery. It's grounded to the metal dash.

This is a new radio but I feel sure I would have had this issue before now. I did not move the ground on the amp. None of that was touched.
 
McCracken said:
Just routed the yellow (constant) to the battery. Still doing it. It does change with rpms.

The ground is not to the battery. It's grounded to the metal dash.

This is a new radio but I feel sure I would have had this issue before now. I did not move the ground on the amp. None of that was touched.
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Run you a ground directly to the battery, just a test first to see if it fixes it. Then if it does you can properly run it, but for quick testing I’d just Ron over the dash right to the battery.
 
Ran ground to battery. Nope. Still doing it. I went and turned the input level down on the amp and that's the only thing that has made a difference. Of course, the radio isn't as loud now but it got rid of it mostly.
 
McCracken said:
Yes, that is how it is currently connected.
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Are you saying they're connected with RCA cables, or that they are connected with twisted pair RCA cables with no shield?

Those Rockford Fosgate cables are not shielded, they are a twisted pair. You would need a 3-pin connector to shield a single twisted pair.

You likely need to move the amp and radio grounds to the same point (same screw, bolt, etc., attached to the vehicle chassis/body), and see how that works. That will somewhat make the two devices have the same ground potential, and the RCA cables won't be carrying current across a difference in ground potential from device to device. That is very important if you're chasing probable grounding issues, because those differences in ground potential is what makes things susceptible to noise, and also moves noise from one device to another.
You may also need to isolate the radio chassis from the dash, but there are other things I would try before that.
You should not be grounding the radio at the battery unless the amp is also grounded directly to the battery. Even then, the ground wire length for both devices would make that a bad idea.
Wire length creates resistance, and resistance in a wire that carries current creates voltage differences, and voltage differences breed noise.
 
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Fabrik8 said:
I'm talking about AC and DC crossing. Well, DC that apparently has AC noise riding it from something.
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yep.
Sound = AC signal ;-)

Also - ferrite choke or other loops are your friend.
But really its all about the ground plane
 
My bad @Fabrik8 i guess I didn’t look closely at the link. I meant to link a shielded RCA cable set. Guess I just looked at the pic and it wasn’t just the black rubber Walmart special set.
 
Here is the simple way to troubleshoot the issue, turn the radio on to where it is making the feedback, then start moving wires around.

Sent from my SM-G965U using Tapatalk
 
McCracken said:
So do I just need to search for shielded RCA cables?
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Any RCA cable you buy is shielded. It's inherent in the design of a coaxial cable. But all shielding is not created equal. Avoid tight turns which may break solid (foil, etc) shields or cause braided shields to separate.

If the cable is old and well loved, you might see an improvement with just replacing the cable. I wouldn't expect any miracles, though. Focus on similar ground and line voltage power paths and places where AC gets involved (ignition and electrical motor inductance, line source from head unit to amp, etc).
 
McCracken said:
So do I just need to search for shielded RCA cables?
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It should help if you twist the cables around one another. Also, you can create a shield w/ a strip of aluminum foil. Or put them through EMT etc. But you'd need to ground that too.
 
I tried to do that today.
RatLabGuy said:
It should help if you twist the cables around one another. Also, you can create a shield w/ a strip of aluminum foil. Or put them through EMT etc. But you'd need to ground that too.
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I actually considered aluminum foil but I thought that might be too janky
 
RatLabGuy said:
This is likely the best solution, if it is going a long way.
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It's the only solution. I didn't know twisted pair RCA existed until five minutes ago. I can't think of a good application for them, but this definitely isn't it.
 
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