Eddy968

I have a 1997 Audi A4. The PO raped the wiring, but I managed to restore it. The original Bose speakers and amp are still intact. (the amp has been reconnected) I replaced the pathetic HU with a Blaupunkt Hamburg MP57. Everything is great now EXCEPT: There is a loud boom or popping noise coming from the speakers every time I turn on my radio or just switch radio stations.
As I understand it, the Bose system expects blanking transistors in the HU, which should ground the output signals to eliminate the switching noise.

Is there a way to eliminate this booming/popping noise?

MacSub

as it introduces noise via 2 amps rather than one. the other way is to solder capacitors across the RCA's. Explanation in the attached thread. It's actually the other way round, the Bose system doesn't like the fact that aftermarket HU's ground the RCA's to eliminate electrical switching noises. It is the grounding of the RCA that causes the capacitor array on the input stage of the Bose amp to discharge quickly that causes the popping.<ul><li><a href="http://www.audi-sport.net/vb/showthread.php?t=26307">http://www.audi-sport.net/vb/showthread.php?t=26307</a</li></ul>

B5S4_Oz

Rip out the crap Bose speakers &amp; amp, replace them with something decent.

MacSub

Well that was the other option!

AUDI GT1

on my 3rd audi to retrofit with new speakers and the nokia system has no rear speakers if you order a v-900 harness they provide you with two wires which i think are for this but i just toss the worn out paper cones and wiring out and wire the rears like an amp directly to the new head unit. my suggestion for quality is kenwood replace both front and rears and cap the tweeters with the capacitors in the amps or inline giving you better quality without loosing the tweeters and note leave the black box in the door skin it helps the bass i made the mistake of throwing one aside only to put it back in the acoustics suffer a lot without it. have fun