Light dimming after big 3 and H.O alternator..

It's dimming because you're actually seeing the same voltage at the front of the car and the back of the car whereas before the front was ~14v and the back was ~12v and now they're both 12-13v or whatever it is. 

You're likely clipping the amp a little bit too. Buy a cheap voltmeter for $10-20 and wire it into the amp input terminals and then stick it on the dash somewhere. See what your voltage actually drops to when the lights dim.

SHADE575 said:

I have a voltmeter wired to my battery that i have under the dash, it was cheap so ill just buy another one and wire it to the amp too. Its possible im clipping the amp, ive set the gains by ear since i dont have that device thing the pros use lol. Could the voltage drop from the battery to the amp from the cable being so long? Its an 18 foot long car, both wiring kits ive had in it were just barely long enough..

Would a heavy duty battery help me out here voltage-wise? Ive been thinking of buying an optima yellowtop for under the hood.

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Optima has been low quality for 5+ years now. They live on the reputation they used to have and clearly it works because you thought it was worth the premium lol

If the battery is relatively new and functioning properly then no it won't help to add a large battery as you'll still drop below 13v. Going from 14-15v to below 13v is the dimming you see. I doubt you want to throw a ton more money at it so check the voltages when it dims (it'll work during the day too you just won't see the dimming). Report back with your lowest voltage at the alternator/front battery, and also the amplifier input terminals. 

Your gain probably is clipped, which is fine to some extent but if it stops getting louder with each click of the volume you need to turn it down. 

Without adding even more alternator output, a huge bank of batteries (or lithiums), the only thing I've found to help is adding a single bank of ultracaps. Not the big single cap, I mean legitimate ultracaps. After you report back with the voltage you find I'll give you a recommendation

I'm having the same issue voltage only drops from 14.5-13.8 and only on quick snappy bass but the old style incandescent lights dim easily.

Since the voltage overall on my vehicle is staying in the safe range I'll likely just get led headlight since they are regulated and dont dim.

I am very curious if the new style ultracapacitors would help this. I dont notice dimming on long notes where the voltage drops but only on the quick bass notes