I just installed a new stereo in my 1993 ford ranger why is it really staticy?

[That guy]

i had a 200watt pioneer cd player in it but it was a little staticy but when playing a cd it was good so i checked the antenna and sanded the connections and made sure they were good but it didnt help any so i decided to get a new stereo its 200watts doesnt have a cd player but has a ipod dock and the radio stations along with anything i play off the ipod are really staticy so it must be in the wireing right? also i just installed new sony speakers in the doors and there are new pioneer speakers in the rear. so does anyone know why im getting this static its even worse with the new stereo.