Installed ground loop isolator now no sound
 

Okay so here is my situation. I completely replace my OEM Bose system with a new F90b HU, Infinity Kappa front and rear componet speaker, Alpine R sub, 4 channel Infinity amp for front and rear and Infinity Sub Amp. I also ran all new speaker wire for everything. I ran my power wire on the opposite side of the car from the RCA cables that run from the HU to the amps. I have the HU grounded to the ground location behind the 3 insturment cluster of the center stack. My amps are mounted in the factory sub location behind the drivers seat and grounded to the mounts in the back top of that space.

I am getting altinator hum that can be heard at low volumes. So i figured I had a ground loop problem, I installed two sets of groupd loop isolators from Radio Shack between the RCA cable and the input to the amp. One for the front channela nd one for the rear. With those plued in I go sound at all from the speakers. No music no anything. Am i installing them wroung? How do I get rid of the hum?

IMHO the Z has a noisy alternator/power system. My 2005 took too much work to get acceptable and even after following all the normal procedures wasn't able to completely remove the whine.

1. First make sure your gains are set properly. Rule of thumb is to turn your headend's volume control to 3:00 and adjust the gain of your external amplifiers to the point where clipping occurs and then back down a bit. Technically there's a pretty good step-by-step procedure on the JL Audio site on how to do the gains with a volt meter.

2. Ground everything together at one point. I ran everything forward toward the headend and used the factory grounding point behind the triple cluster. This removed about 70% of the whine for me. I kept a jolly big 4 gauge cable from the amplifier stack down to the frame for power and ran a ground ribbon cable forward.

3. You can use an iPod to see if the noise is coming from the amplifiers (like mine) or the headend. If you connect an iPod in and the whine goes away it's the headend/cables producing the noise. If the whine remains it's the amplifiers(s).

Good luck.

Paul - thanks for the input. I am using three ground points. I will change that to one. I never thought about using the iPod to elimante the HU for noise. Willl try that also.

off topic but does this RCA cable looks like it shielded to you guys?

http://www.monstercable.com/mpc/prod...C.asp?pin=2934

I think this is the cause of my hum as well.

+1 In my previous car, I took it apart and search for endless hours of why I had ignition noise and couldn't figure it out. Swapped out the Pioneer headunit which was only a year old for a Kenwood Excelon and no more ignition noise!

btw - those noise isolators will really diminish sound quality if you ever get them to work

He already wrote what head-unit he's running it seems like it's a Panasonic unit.

Wherever you ground, make sure the ground wire is as short as possible (1ft max for mines), make sure that the paint is scrapped away from wherever you are grounding to as well.

A ground loop isolator really is a ghetto/bandaid way of fixing the alternator whine imo. Find out where the real bad ground it.

My Head Unit is a Pioneer Avic f-90b not a Panasonic. Will the grounding system suggested by bigaudio still be useful?

I just read the link http://www.caraudio.com/forum/showthread.php?t=198477 posted by bigaudio. It says it is a fix for Pioneer. I am guessing that Panisonic above was a misprint. I will try grounding the RCS's as shown.

Thansk