problems after sub install

Hey guys, I just installed a ported box with 2 alpine 10" and a 250 watt MTX amp. It sounds pretty good but when I go to crank it up the speakers off of the deck stop. You can still hear the subs and you can mess with the channels etc of the deck. I know I need a new alternator but when it is cutting out the ScanMaster show 13.5-13.2 volts running. Any ideas? The gain on the sub is only at about the 10 o'clock postion any higher the sub clip and bottom out(that's another problem all together)

[Audiowizard]

1) What kind of head unit is it?
2) how are the mids and highs hooked up?
3) Are mids and highs deck powered or ext. amp powered?
4) What are your tone controls set at (bass,treble,balance)?
5) What exact position is the amp gain at (1/4, 1/2, 3/4)?
6) What is the voltage at battery with DVM ?
7) what is voltage at idle and engine off?

If you can answer these questions for me, I may be able to figure out exactly what may be going on. There may or may not be an internal problem with deck. It could be possible low voltage. The scanmaster reads voltage but can be inacurate sometimes, thats why I wanted to know what voltage is at the battery with DVM.

[mr_85regal]

I JUST FIXED THIS PROBLEM ON MY CAR! do u have a pioneer head unit? if u do .. then its over heating.. mine was doin that and all i did was bridge bolt front speakers into the left channel and didnt hook up the right... i know it sounds wierd and stupid to do but it works.... using the RCA jacks and all 4 channels on the head unit gets it hot..killing that one channel it wont get as hot and it doesnt cut out.. i havent had a problem since. and if u read one other of my post for MrEIGHTYTWO's post i tell everyone my whole set up.. im goin to bed.. peice