I have a 160 amp alternator thats supposed to be running 14.8 volts at 1000 rpm but stereo is only getting 8 volts but everything else is getting the 14.8 . At times the voltage will increase to 14.8 at stereo then for no given reason drop back to 8, which is where its at most of the time. I have a 5 farad capacitor and pretty relative with electronics but this one stumps me. help please!
Having a guess maybe you have a bad earth or a bad positive wire, arcing out or corroded over time (nothing to do with the alt but the car wiring). I had this problem with my amp a few years ago and it turned out to be high resistance through a 60amp fuse (it wasnt blown) just where it went into the holder it wasnt getting a good connection which caused a simalar voltage as your getting. I replaced the fuse and fuse holder and it was fine.
Good luck with it, Your probly going insain with it cos i know i was.