Rep Power: 304

..well more like wooooo woooo-ing

i was running a old panasonic head unit, with no preout for a sub.
everything was fine, except i couldn't control sub levels only bass levels.

i recently changed head unit to a indash screen with a sub out.
it worked fine in like the first few hour after install, however now i hear a deep wooooooo sound like a low bass type (sorry hard to describe) it goes on whenever there is music/sound, but if i mute it it will be gone.

this only happens when i start my car and play music/dvd etc, however, if i run my car just off the battery, it wont do that.

any ideas? i tried tuning my amp, and i got to make the woooo sound a bit lower by adjusting the gain, but it's still there.. my subs dont even pound like they used to

 
Rep Power: 255

Make sure your power wire and RCA wires arent crossing each other or near each other

 
Rep Power: 304

ok, think i might have figured it out
will confirm later on...thanks for pointing me in the right direction
=)