noise filter question....

Pugsly · 01-10-2005, 11:11 AM

since i installed my pie amp an sirius sportster i get an alternator whine now. i moved the pie amp ground a few times and have reduced it but not eliminated it. it increases with engine speed. I am going to install a noise filter like this one
Click me from Crutchfield

or this Radio Shack version?

I am assuming since i have not touched the HU at all the whine is being casued from the pie amp. if i install this by replacing the HU in the install instructions (basicly it says you install this inline between the fused power wire and the head unit, so i want to install it in the pie power wire) would it matter if i grounded it to the same ground as the pie amp or go find a new ground attachment ?

Do you audio experts think this will work?

LittleBuddha19 · 01-10-2005, 11:33 AM

I had that same Whine from my alternator.
I just installed a Ground Loop Isolator from the stereo to the amp right at the amp. NOT at the stereo.
Don't use the one that you're looking at on the Crutchfield web site.
I bought mine at wal-mart, around $10.
But i bought the one with the RCA plug in Jacks (red+white).
It works better than the wired ones.
Good Luck

Pugsly · 01-10-2005, 11:51 AM

i tried a ground loop isolator, these are not those. thanx though.....

bestatchess · 01-10-2005, 12:14 PM

I think the HU has at least three paths to ground: through the chassis to the bracket, through the harness ground, and through the antenna cable shield. When I disconnected the harness ground from my RF HU, it still worked. When I ran a 0 gage ground wire to the region of the bottom of the firewall, I created alternator whine, when I thought I would just improve the HU ground.

I think if at all possible, you are better off trying to solve the whine through proper grounding, as those filters just chop certain frequencies.

Also, in connection with the installation of amplifiers, I used a Matrix pre-amp from Audio Control, which has three pairs of RCAs in and out, with separate gain adjustment for each pair. I used one for the front speakers, one for the rear speakers, and one for the AUX jack. The Matrix did not produce noise in the AUX jack. There maybe some inherent deficiency with the PIE amp that causes the noise.