Car Stereos: Subwoofer Phase, theft security, problem thanks

Question
My son's car stereo is a Sony Xplod.  Not sure of the model number but on the Subwoofer Phase setting it has Normal and Reverse.  Can you explain what this Normal and Reverse is?  My son has an amp and two 12" subs hooked up to it and I just want to make sure something doesn't go wrong with it due to the fact that we had a Theft Security issue already in which we were able to get the light to go off but the wire from the amp to the radio was hindering the car from accepting the code.  This was a real pain to deal with just to find out that one tiny wire was causing the car to not accept the code so it would start and I would rather not have that same problem.  Thanks for any help you can give.

Answer
Hi Anna,

Explaining subwoofer phase isn't something I can quickly or easily explain here.

What I can tell you is that the subwoofer phase being set to either setting should not affect the safety or health of the car stereo.  It's used to switch whether the bass in the subwoofer hits in phase with the midrange and highrange speakers, or out of phase.  There're many things involved with the acoustics of sound, and playing around with the phase on your speakers is a large part of it.

The easiest suggestion I can make is to suggest your son puts in a CD with a noticeable, clean bass line in it.  Then, switch the subwoofer phase on and off during the song.  Leave it on the setting that makes the song sound fuller.

If he doesn't notice a difference, leave it at off.

But if your only concern is the safety of the stereo, whichever selection it's set to is just fine.

Justin