Weird sub hitting when turning off

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Weird sub hitting when turning off

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Ok, so I've had a job 250 watt amp and a 10. I upgraded to a 1200 watt and two twelves. Ran all new wiring. My problem is if it's been running for a few minutes and I turn off the radio via the button or turn the key off I get a very loud low bass rumble. And the amp won't cut off. But, if I have my drivers door open it doesn't happen. I have a good contact ground to the body under my rear seat, the same place I had my old amp grounded with no issues. Using stock HU, with loc, rcas are not anywhere near power or ground wires or remote wire. If I cut the remote wire it cuts off normal. I don't really want to put a switch on the remote. Just thought it was weird that if my door is open. It doesn't happen. It all works normal besides this issue. Thanks

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  • Update. If I unplug the left rca cable from the amp. The issue goes away. But the subs naturally have less power running to them. Can't find any issues with my wiring behind the HU.

  • Chances are the vehicle has retained power until the door is open, very common on newer cars. If such is so, then the amplifier is still receiving power on the remote wire telling it to stay on after the radio/ignition is turned off. Then since it's on with no signal, if may be amplifying any interference it's picking up in the wiring to the input on the amplifier.

    Now you say removing the left RCA cable, it works as it should. Perhaps you can use a Y-splitter to get two identical right channel signals to the amplifier. Bass is generally recorded in mono, besides, your amp and/or how it's wired is probably for mono operation anyway.

    No idea what the actual gear was you had and now have are, as far as model numbers.

  • The issue with it retaining power, is that it does it while the car is still running as well. I bought a ground loop isolator. Hopefully it works. Thank you for your help

  • Does it with the car running and radio playing?

    I know you said you have a good ground, but I must inquire as to the mounting location and how the location was prepped.

    You say your old 250W worked no problem, but the 1200W has this issue. No idea what the RMS ratings are of those amps or if they are respected brands, but based on what you've given, that's nearly 5 times as much power being produced, so you need a much stronger electrical ground connection.

    Hope the ground loop isolator resolves the issue, though I'm not so sure it will.