Subs play immediatly after car turn off

My two Rockford Fosgate 12 in. punch subs get as loud as they can get right after i turn my car off. It only lasts about a second but its starting to get annoying. The signal is coming from my rear 6 x 9's and my 12 volt remote turn on it connected to a 12 volt souce that comes on when the car is on. I know that isn't the correct thing to do but i don't turn off my stereo at all. Does anyone know why my subs get really loud for a second or two right after i turn my car off.
(The 12 volt source turns off when the car is turned off-spliced from a ciggarret lighter plug)

The amp's input is totally dependent on the signal supplied to the rear speakers, so the head unit (the original OEM, I take it?) is the source of the signal surge....and the high level input of the amp adds to the problem because it isn't able to suppress it.  (And I'm going to presume that's what you're using.)

Switch to a high quality aftermarket line output converter, such as one of these adapters here.  The circuitry contained within the adapter should stop that surge when you power off the deck (it goes off when the car goes off).

Also, it's fine to get the turn-on power from a switched source.  It's a good idea also to put a small inline fuse holder and 1/2 amp fuse near where you have it soldered to the car's wiring.

-------------
Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

i've got one of those already put in, would adjusting the knobs on the end help solve that problem, or maybe i've got a shhhty one but i'm sure its good because my rockford amp only allows preamp input

If it has gains it should probably be good enough...so maybe I didn't hit the spot with that answer.  But to answer your last question, yes, those gains should be tweaked until you get the best quality sound.  This is generally done while you're setting up the system and getting the deck volume and amp gains in sync.  An adjustment to the LOC gains creates a difference in voltage input to the amp, which then necessitates an adjustment to the amp gains.

-------------
Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

so does that solve my subs from blasting each time the car is turned off?

btw thanxs for the help

If your gain controls are set too high, this can happen.  This would be the first thing to check.

If that checks out, then many times all it takes is a slight delay to power down the amp before the radio.  What you can do is cut your radio's accessory lead, and install a diode inline (put the stripe side toward the radio).  Now, install an electrolytic capacitor (220-1000 microfarad) on this line after the diode (on the radio side).  The bigger the value, the longer the delay.  Make sure to observe polarity on the cap (it'll pop if you get it backwards)- there'll probably be an arrow with a "minus" sign in it identifying the negative terminal.  Connect negative terminal to ground, and positive to the accessory lead.

Now, when you cut off the ignition, the diode will keep voltage from leaking back into the accessory circuit where the amp is tied on, and the capacitor will discharge into the radio, keeping it on until after the amp shuts off.

-------------
My ex once told me I have a perfect face for radio.

i would've never thought to do that.

thanks for the help everyone!

...uh....don't be so happy, jcmathis88.  Read his sig line.

-------------
Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

oh shoot

Thanks a lot, Steve, maybe now it's time again to change it.  Still, that was pretty funny now that I think about it.

-------------
My ex once told me I have a perfect face for radio.