for the past few days i have been installing a audio system into my car. when i got every thing hooked up and turned the car on (ACC). im getting a hisssing noise idk what it is. ill post a video of what it sounds like in a few

 

bad ground your hearing engine whine did you change your factory headunit

 

check it

http://www.youtube.com/watch?v=AvmFPJO4Q5o

if you put new interior speakers in ur car. did you tap into the rear signal?

 

Wow...definitely sounds odd...almost as if you are getting an antenna affect. Just for my edification....what is that wire/cable plugged into your head unit? Do you get the noise with that unplugged? Is it present on ALL audio signals (i.e. CD/AUX) or just the radio? I didn't notice if the noise changed with RPM but it also sounded that it came thru with the ignition (not acc) on in addition to running or did I miss something? Also, is the head unit and amp in the same unit or do you have cables running from the head to a separate amp? Sorry for all the questions, but last time I heard something like that was on an old tube amp I built where I didn't have the input impedance matched (I was using the line out instead of the preamp out and in addition to overdriving the amp, it was using isolated grounds on the preamp out and common on the line.)

 

i have my audio signal going from the car to a EQ from the EQ to a Crossover from the Crossover to 2 amps.

and no its not engine noise. it makes that noise in cd aux and radio im thinking i have a bad ground ill change it tomorrow and see if its still there

 

Could it be the High-Lows are connected to the wrong wires? - Does not hurt to double check =D