Car Stereos: car stereo, installing a capacitor, noise filters

Question
QUESTION: ok, so i got this hissing in all speakers and also my sub woofers. i have not tried changing my gain levels yet. i have tried new grounds and i understand a ground is a ground. i had a jacked up constant power and i just hardwired it straight to the deck. nothing changes except when i turn the car on and i can hear it getting louder when the car is at idle and even louder when rpms increase. also i can hear glitches when i turn on the wipers. this is mind boggling to me. i checked my ground at my amps and when i swapped them nothing changed. there was something done to the wiring but i am pretty sure i eliminated it by cutting the main power wire going to it all. all my speakers run though an amp and my subs do as well. idk what is going on??? any help???

ANSWER: Joshua,

Since the hissing is heard throughout the system, the problem is somewhere around the radio.  The amp wiring should be ok.  I would double check all of the connections to the radio, and be sure everything is tight and correct.  If you have checked all connections to the radio, then you may want to take the radio in to have it tested.  Hope this helps, Scott

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QUESTION: Thanks Scott,
what do u think about installing a capacitor and subwoofer, do u think those could make a difference ? Are there filters for subwoofers?

Answer
Well, You have an open ground.  It means there is less resistance for the power from the alternator to get to your radio than it is for the power to get to the battery.  Your electronic components need to have a shorter ground wire than the ground from the battery.  Usually it is pretty short.  If you cant make the grounds that short, you may need to buy a "noise" filter.  This is an inline resistor that absorbs the added voltage.  That will quiet the humming for sure.  I would concentrate on calming the humming sound before adding more components.  The only "noise" filters that you need would be placed on the power wire of the radio.  That should take care of the problem.  Good Luck, Scott