scratchy speakers

hey guys i havea little problem and having been a profess. car audio installer i have never encountered this before. i have panasonic head unit with dvd cap. and it has a mosfet 52x4 internal amp which i run all 4 alpine 6.5 2 ways. just recently i have been having trouble when the volume gets above 25... the music is clear up until then and then starts getting really scratchy and sounds like fingernails on a chalkboard...wierd and my subs do not get a proper signal and sound very rough like they are not hitting at all...anyways i think there is something wrong with the head unit amp i guess but has anyone run across the same problem?

is it an output problem?

Start by unplugging the feed to the sub.

If that doesn't stop it, use the fader/balance to drive one speaker at a time. See if you can isolate the problem ...

ok i will hopefully there is an impedienance prblem somewhere in my wiring like a short touching the body...thanks

well two speaker wires were touching now thats fixed but subs are hitting but sound like sh.. ... what should i look for? they are moving a lot but not hitting at all! help!

i adjusted the level and bass boost on the amp and still nothing is making clean loud bass...they are moving like crazy but not hitting still

Wired out of phase ?

Check polarity.

subs were out of phase- checking all my wiring took forever... problem solved

thanks! im kinda lazy but whats wierd is that i take the time to do it right on other peoples cars but on my jeep i overlook little things like that... oh well