lights dim with bass

hey can someone tell me what you think i need to do, for some reason it just started last night, but my head lights are dimming with the bass, and its really getting on my nerves, i tested the alt. and it was all good charging between 16 and 18 volts so i decided to run a 4ga. wire from the alt. to the bat. than run a 4ga. from bat to amp and from amp to ground........wich helped some what acutally helped alot, but still seems to be dimming a lil bit.
any suggestions will help.

First thing to do is to get some good 2awg or 0/1awg and wire your alt to battery, battery to ground, and engine to ground.  I know you said you upgraged some of this already but a nice guage wire will help out a ton.  Next check your grounds, make sure all grounds in your charging or audio system are ground in the shortest possible distance and onto clean rust and paint free metal.  After all of this if your lights are still dimming then look into some other options...  If you are planning on upgrading your stereo with more amps and such in the future then consider adding a second battery and an isolater.  If you dont want to go that route you could possibly look into a capacitor, the general consensus on this board is that capacitors dont do crap, I havent had THAT bad of luck with them in the past, but I can tell you they arent really going to fix your lights if they are dimming more than just slightly.  Try upgrading those wires and most importantly check for good grounds, post back and let us know if it helps.

Jeff

hey man i just wanted to say thanks, adding a 4ga  ground from the bat. and motor helped and a whole lot, you can hardley see it now, but i also figured out that my alt. is a 105 amp and my system is pulling 106 amps so well i think i am going to get me a bit of a bigger alt. i think a 130 amp should work fine, how about you.?

It depends if that 106 you metered was with all electronic devices on, if you didnt have your headlights on or any interior lights then you could be pulling more than 106 amps.  If you are definetly pulling that amount and dont plan on adding any other pieces to your stereo then 130 should be fine.  What kind of car is it going into, what kind of equipment are you using?  Also where are you getting the 130 from, I just ordered a 200 amp for my expedition but they havent even shipped it yet (ordered a week ago), so if the product isnt perfect Ill be looking for a new source pretty soon.