S4Dean

I have an '01 S4 with the stock Bose system. The previous owner had blown the rear deck speakers, so he added an aftermarket amp and 10" sub in the trunk. Over the past couple of weeks I can hear popping (like if you plug in to a turned on guitar amp)when I hit hard bumps or sometimes when I'm parked with the car running and I turn off or turn the stereo all the way down it will make that popping noise. The noise sounds like it's coming from the trunk. I just had that problem a few minutes ago where I'd turn down the volume all the way and the popping would occur everytime. I unplugged the ethernet looking cable running into the aftermarket amp to disconnect the sub. It then stopped happening. Is it possible it's a ground issue with the amp or something different? Thanks for any help. I really know nothing about aftermarket system components. I recently added an iPod Dice module behind the stock Bose unit a couple months ago. I don't know if that has anything to do with it.

HIS4

It doesn't turn off the amp. Did you have some kind of **** up front to adjust the volume of the sub? Did you notice that the sub got louder or softer when you unplugged that cable? What kind of amp and sub is it?

S4Dean

Looks to be an MTX Blue Thunder sub and Alpine MRP-M350 amp. Here are pics of the sub, amp, and connector:

<a href="http://s130.photobucket.com/albums/p266/adean1979/?action=view&current=DSC_6606.jpg" target="_blank"><img src="http://i130.photobucket.com/albums/p266/adean1979/DSC_6606.jpg" border="0" alt="Photobucket"></a>

<a href="http://s130.photobucket.com/albums/p266/adean1979/?action=view&current=DSC_6608.jpg" target="_blank"><img src="http://i130.photobucket.com/albums/p266/adean1979/DSC_6608.jpg" border="0" alt="Photobucket"></a>

<a href="http://s130.photobucket.com/albums/p266/adean1979/?action=view&current=DSC_6610.jpg" target="_blank"><img src="http://i130.photobucket.com/albums/p266/adean1979/DSC_6610.jpg" border="0" alt="Photobucket"></a>

HIS4

Oh okay, that's the power harness.

MacSub

You could try a GLI or similar between the feed to the sub amp and wherever they picked this up from on the Bose amp/HU.
The popping is caused by capacitor discharge whenever the HU does something electrically noisy, like turning the volume to zero or changing CD track.

S4Dean

Why would it be fine for 2 years and just start occurring now?

MacSub

No idea, just one of those bizarre Audi type issues

S4Dean

installed. I wonder if that ground connection is getting poor contact and causing an issue.

MacSub

Worth investigating, try grounding both the HU &amp; DICE to the chassis of the car