hi all,
i have a 98 a4 non bose with an aftermarket head unit. when i turn the volume up, during radio or cd play, there is a loud crackling noise that doesn't sound like a blown speaker since the noise is only when the volume is up. (speakers sound fine at low volumes). i understand there is a small amp connected to the rear speaker, could that be the problem? any help would be great.

 

That's exactly the problem - you have a semi-Bose system (the rear speakers are amped, but the fronts run off the headunit at normal speaker-level voltage). With your aftermarket deck, you need to use a Metra harness - it has connections that allow you to wire your front speakers directly to the head unit's outputs, but to use your rear preouts on the deck to drive your rear speakers, since the amp requires a line-level input. Do a search on here for "metra stereo harness" or something along those lines, and you'll find it. It's around $17 or so online, and it'll take care of your problems.

 

thanks for the reply. the head unit was installed by the previous owner and it looks like they used a harness already. could the small amp be broken and if so could i wire in another small amp in its place? i have a 160 watt amp lying around the house for some reason, would that do the trick?

 

They'd have to use a harness, but it may not be the right type. You need one that gives you preamp plugs that become speaker leads, so you can send a preamp signal out to the rear speakers. On the back of the head unit, the rear preamp outputs should have RCA cables plugged in, and those should lead into the wiring harness. If you don't have this, it's not the right harness. The Metra harness that I mentioned is the correct one and will allow you to keep using your amped rear speakers with the aftermarket headunit.

If the amp is blown, and you put in a 160w amp in its place, you'll probably levitate the speakers into the cabin of the car.