My subwoofer in my car pulses when i turn my car on.

[Mr_Beastly12]

Hi i hooked up a scar audio 12 inch sub in my car. I hooked it up to the speakers using speaker imputs in a planet audio amp since i couldnt find a scar one with speaker imputs. But i used the speaker imputs since i didnt put a new head unit in. And it works perfectly when i just turn the ignition on. But as soon as i turn the car completely on the sub starts pulsing for like a minute then stops. I know its not the amp or the sub because i swapped out a different sub and amp from another vehicle that works perfectly and it has the same problem. Do you guys have any idea what my problem could be?

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[dragon.breath 10+ year member]

That sounds like a ‘ground loop’ . I have had the same problem when trying to use the speaker level inputs on an amplifier. You can try moving the ground wire for the amplifier to a different location. But in my case, the fix was to use a separate line output converter.

 

[Mr_Beastly12]

That sounds like a ‘ground loop’ . I have had the same problem when trying to use the speaker level inputs on an amplifier. You can try moving the ground wire for the amplifier to a different location. But in my case, the fix was to use a separate line output converter.

I just got the line output converter and put it in, and i have the same problem.