Grounding issues

[Turbinesurgeon]

Did you get the ground issue solved? I installed an amp and tower speakers on a boat I had previously. I grounded the amp directly to the negative battery terminal. I had a slight buzz that I could never stop. After some reading, I finally re-ran the amp ground to the same ground bus bar the radio was grounded to and that cleared it up instantly.

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Thanks for the info, I did move the ground to the same buss the amps are grounded to with no change. I installed some triple shielded rca and reset settings on the amps which seemed to cut down on the feedback a bunch but I can still hear when you start trimming or let go of the trim switch. Same with the lights but way less noise so it is an improvement.


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[HFarr]

Hmmmm.... Maybe some ground isolators might be worth a try. They aren't expensive.

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[qwertykerr]

Hmmmm.... Maybe some ground isolators might be worth a try. They aren't expensive.

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if you run the ground of your head unit directly to where the ground wire inserts into the amp you remove the loop and will eliminate the noises. Worked for me. the blower noise was the most noticable... but the alternator whine was bad too. Both gone once i did this. The Rockford Fosgate actually suggests this. As did another forum.

Right now i still do have the issue of a slight white noise from the speakers. The 6 inch you can barely hear it with volume at 0. The wake cans it's very low volume. Trying to solve this...

[MLA]

As noted earlier in this thread most people to not understand what ground loop is, thus they only focus the DC B-. Takes two to tango, so dont ignore the B+.

[HFarr]

I think it was already suggested to make sure amp and head units are sharing the same ground point. I had that problem on an older boat, and doing that took care of it. However another post on here with white noise in the speakers recommended making sure you only have ONE battery selected if you have a multiple position switch. That seemed to solve their problem with noise.

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[MLA]

I think it was already suggested to make sure amp and head units are sharing the same ground point.

So different B+ points are ok? Either way, theres a potential for a voltage differential.

[Holdmybeer]

If everything is isolated to 1 battery, all grounds made at single point (i.e. bus bar or battery terminal), all positives are made at single point, RCA's replaced, then it is time to start thinking about the unit itself.
2006 Supra, was this original or replaced over a decade ago?
Do you have a transom remote? Is it corroded from being in water 90% of the time?

TEST
1. Can you get a 3.5mm headphone jack to RCA adapter (or lightening connector to RCA, or usb-c to RCA) and plug a device directly in and play music? The amps will work and you should hear music. If the noise is gone, the amps, rca, etc. are all good. Turn the volume on device all the way up. If it still happens, we need to start looking at the amps.

2. Now while still using the handheld device, use the device charger and then 12V port near the radio (assuming it has one). If the noise returns, you have a ground loop or power problem. If it does not come back, reconnect the head unit and see if it comes back. That would point to the radio.