Voltage going crazy!!!

[bl0wn3ur0]

Ok so here's the situation, my 2000 S4 has a 1200w Orion amp wired to one ohm pushing a 12 3000w alpine sub optima red top and a 2.2 farad(can't remember for sure) capacitor. Now when I really crank the volume the voltage needle in the car starts dancing between 12-14v if I'm stopped at a light or something but if I'm moving, the needle doesn't go all the way back over to 12 but it still moves around. My question is this, am I looking at needing a new alternator or could it be something else? And if I do need a new alternator, would a new oem one do the job or do I need a higher voltage one and if so where can I find one?


PS: car has a four channel for interiors also and a line driver for the sub

[WB650]

Where are your grounds for the amp? I believe I read the rear seat belt bolt is the best for these cars, and make sure paint is sanded down.

Do your lights dim too when bass hits?

Ditch the POS capacitor and do the Big 3 upgrade, it actually stabilizes voltage unlike a cap which is just a band aid fix.

[bl0wn3ur0]

Thanks for the response. The sub ended up cooking in about 3 days so I think something's up with my amp, gonna recheck all grounds and replace the amp and sub