I have large sub amp installed in my Bonneville, run off a line input converter, that receives its input from the amplified outputs that went to the stock 6x9's in the rear. This seems to work fine and I have no issue with my subwoofer.

The stock 6x9's are no longer there, they've been replaced with a set of aftermarket co-axials. I installed a secondary amp for these new 6x9's. That amp has internal line-level inputs, so I tapped into the (blue and brown?) wires that are inputs for the factory amp for the line level inputs. I believe this blue and brown wire is the rear output for the factory deck.

After I installed this small amp (it's 200 or 300w, can't remember), I've introduced a ground loop, or a constant hum coming from the rear 6x9's that increases pitch with engine RPM. I'm certain the power feed and ground wires are solid and secure, they only travel two or three feet past the rear seat. I don't run the signal wires along side the power wires. Wire size is 3 ga for sub amp, 6 ga for small 6x9 amp.

The line level inputs all have a + and - for the audio signal (for each channel) and then a seperate ground wire that I'm not sure where it goes to. I've attached that to the vehicle chassis.

Any help in identifying this unwanted noise would be appreciated!

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Inferno Red 2009 Dodge Caliber SRT-4 125k

are the runs of pos for the amps on separate sides of the vehicle?

where are the grounds bolted down to?

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95 bonny sse WALLED.
-new build in progress-
Iraggi HO alt - 320 amp (added "sense" wire and 5k pot, 15.4v)
2 DC Level 5 18s
Cactus Sounds K12
4 runs of 1/0
14 batts.
Mtx 4244 and (2) kicker ix404

YouTube.com/user/pitchdarkshadow

POS of both amps are run straight to the battery. The amps are 2-3' apart, though for obvious reasons they run parallel the closer they get to the battery.

One amp is grounded to the OEM factory ground, where the negative battery terminal meets the chassis. The sub amp is grounded to one of the seat belt fasteners, which is a large 17+mm bolt, bolted directly to the chassis. I made sure to sand down any paint if there was any question-- I know both grounds are good.

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Inferno Red 2009 Dodge Caliber SRT-4 125k

you just answered your own question and probaly dont realise it..lol


basically you need to run all grounds to one secure ( unpainted ) spont on the frame.

having more then one ground 9 times out of 10 will cause a ground loop. having more then 1 ground lets the ground current travel through the entire frame of the car and pick up the alternator wine noise you hear coming from your speakers when you step on the gas..


try switching it and putting both grounds to the same exact location ( one ontop of the other and bolt them down like that.

if that does not work, go to radio shack and buy a ground loop isolator for about $20.


but before you waste any money you can also try grounding out the rca wires them selfs.. if unsure how to do this let me no and i will explain it to you.