Audio Systems: engine interference, jeep grand cherokee, dynamic headroom

Question
HEy what's up, i was hoping maybe you could help me out. I just installed a system in my 2000 Jeep Grand Cherokee. the issue i'm now having is engine interference noise. It's coming through all of the speakers, and the sub. I have a 4 gauge power wire, running on the passengers side of my car, All the rca wires run up the drivers side, and i get no interference, when the rca's are unplugged from my amps. I have a 4 channel, and a mono channel amp, both good Quality, and i used good quality Tsunami twisted Rca cables. I've tried everything with what i have. I moved the rca's away from the power. I moved the ground leads, shortened them, and grounded both amps out to the same post. everything works, but the noise is unbearable. Do you have any sugguestions as to what i can do to solve this issue, or any way for me to atleast cut down the nosie so that i can listen to my system? Please help! thank you, Scott

Answer
ok..
"no interference, when the rca's are unplugged from my amps"

You may not realise it but you just isolated it to something in front of the amps :)   
Like the deck or crossovers ect.

A device ahead of the amps is picking up the noise and sending it down the rca's.

If the grounds are solidly hooked to the chassis:

The #1 prob is usually that the amp levels are way too high. This does nothing but increases noise and reduces the dynamics. It will NOT give you one iota of a power increase. You will lose massive dynamic headroom and can easily damage speakers and amps even at moderate volumes.

Center all controls bass, treble, loudness/bass boosts off ect.
With the amps all the way down, turn the deck up to about 75-90% (use good source cd like dark side of the moon by P. Floyd).
Bring the amps up slowly and tune it to the weakest link in the system (likely the mids and highs) rather than going for 'balls out' bass ect.
You should be able to have the volume up nearly all the way with ZERO clipping or distortion..  once you are in this realm, you have the amps set pretty much correctly. You will find that this type of dial-in hits like mike tyson once ya crank it up andwill sound super smooth throughout the volume range compared to too high of amp levels.

If reducing the levels does not cure it (it WILL help), you may want to use a PAC line level ground loop isolator as a last resort (this goes inline with the rca's). I would NOT put in a noise suppressor before the head unit if at all possible!


Hope this helps out.. it may still be a ground problem. So be sure you use larger than normal ground wires and have them as short as possible and SECURELY tightened to bare metal.


J Mael