I have a 2004 Mazda 3 wagon with factory head unit. I had some local audio shop install a 4 channel Blaupunkt amp (cheap) and alpine coaxial speakers up front. Front channel powers front components, rear channel powers small sub. Well after 5 days and 4 different trips back to the shop, they finally have it working, sort of. First issue: horrible alternator whine. Ground is fine, paint removed. Goes away when I remove rca's from amp. Second problem: factory tweeters are still producing sound- loud, ugly blaring treble due to being fed way more power than designed. When I disconnect them, the alpine's shut off as well. The alpine's are coax and I do not want the factory tweets playing! A line out converter was used to get rca level signal to the amp. Any ideas about either issue? Thanks!
