High pitch feedback through sub that goes up in pitch when revving the engine

[two6sicks]

I have an 01 Mitsubishi Eclipse Gt V6 with a Kenwood deck, wired correctly to a jl audio 10" sub and a jl audio 200W amp.

Long story short. I get a feedback noise through the sub intermittently.

No audio at all. Sometimes I get an intermittent Crackle from the sub where it pushes itself out once and then back in.

I had a pair of 6X9's wired to a different amp a while back and got the same feed back noise (also dependent on RPM) but with the 6X9's I was able to hear some music but it was very feint.

I suspect a ground issue but have gone over the amp ground 100x's (exaggeration) but am positive it's not an amp ground

Alternator problem?

I should mention that I have a bad battery
(bad battery damaged alternator?)

Thanks guys

 

[synphul]

A bad battery can eventually wear out an alternator faster although it would be difficult to really tell without proper testing. I'd suggest a battery and charging system test to verify alternator output (amps) under load and check the battery. If the battery is bad or weak, replace it. It's difficult to sort out electrical issues with additional variables and there needs to be known good/reliable power to begin any other real troubleshooting.

It does sound like a ground issue (or shielding issue on stereo wires). Since you got the same feedback from two different amps, are you using the same power cable for both? If not I might be checking the deck since it would be the common denominator. Maybe see if you can try a different deck and check all the wires both power and speaker to make sure they're not pinched, rubbed bare, touching part of the car etc.