Feedback reverb???

[wonchya]

I have a Memphis box set up with 2 12” subs and a Memphis amp (can’t remember the exact model off the top of my head will update soon) set up in the trunk of my car. I have the rca cables ran through a metra output line converter. My problem is that when I have the radio off and the car running whenever I close the hatch on my trunk it starts to feedback and keeps ramping up on volume until it’s shaking my whole car. Does anyone know any probable causes for this or any fixes?

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[Buck 5,000+ posts]

Unplug the RCA’s from the amp and see if the amp still does it.

I believe I’ve had this happen with ground before, the ground to the sub amp. I’d check everything wiring related and make sure nothing is loose.

Does it seem like closing the trunk starts the initial feedback problem?

 

[Buck 5,000+ posts]

Some sort of signal is clearly making it into your amp. Maybe shutting the hatch/trunk lid starts the initial vibration that make the subs move and the subs keep vibrating the problem even worse, like a snow ball. I really wonder if it’s a loose ground. I would definitely check all amp wiring. I’d also try to test the sub amp with a different source than RCA’s from the converter, like if you can play tones off your phones or something, and see if the problem still happens.

 

[1aespinoza 10+ year member]

Does anyone know any probable causes for this or any fixes?

I had this same issue with an Audiopipe amp. It happened when I would close drivers side door which amp was closest to. It would go into a loud humming. Odd thing about this one was that it would do it with rhe system off. After exhausting methods, I switched it out. Has only happened with that amp.

 

[Buck 5,000+ posts]

I know this can happen when RCA wires break inside of the RCA's. Closing a door can cause broken wires to touch, and that can cause signal noise, which bumps the subs, which shakes the RCA's and amp, which then vibrates the broken wires even more. I've personally had that happen on my home audio subwoofer, and when I turned the AC down at night, that temp change caused the metal to shrink/expand, and my sub would slowly start getting louder and louder. It'd scare the crap out of me in the middle of the night.

 

[1aespinoza 10+ year member]

It'd scare the crap out of me in the middle of the night.

LOL! This reminds me of a few times I have left the compressor connected at clients homes. Because of slow air leakeage, it would come on between 3-4 in the am! Them telling me the story had me laughing and apologizing at the same time. I've mostly had cool clients, so never a biggie.