im having problems with getting the right voltage to my amp. over the past few months it has been cutting off when you turn it up to a certian volume. its been getting worse and worse over the past few months as in cutting off at lower and lower volumes. i have 2 JL 12W6's in a scion tc with an alpine PDX 1.1000 amp. worked fine when i first put it in. i just bought a new optma yellow top and i was told by a few people that would solve the problem. when the amp shuts off its shutting off at around 10 volts. when it shuts off the voltage at the battery is still high 13's. all the connections are good. grounds good. everything else. anyone have any ideas on whats going on with this? also my amp gets really hot. seems like its hotter than it should be. could i just have a problem with the amp?
That should be fine with true 4 awg wire, no need for 0/1 or a capacitor. If the battery is still at 13+ when the amp is only getting ~10 volts it sounds like a faulty amp to me. I would try to return it and get a replacement/repair for it.
If the battery is over 13 volts it could be the amp or a high resistance somewhere else. I would disconnect the amp and measure the voltage to see if it matches the battery voltage. If it does than it's the amp if not it's somewhere else.
Your amp is likley shutting off due to voltage drop, and is also getting hot due to low voltage.
What ohm do you have your subs wired to? Do you have any other amps in your car or anything that is drawing alot of current? Where does your voltage stand when your car is at idle? and at 2000 rpms?
If your alternator is charging correctly and your battery is good I don't see that amp straining your vehicles charging system. If comes down to it, try upgrading your big 3 (just google it). You could also have a slowly dying alternator maybe.
What size is the in-line fuse? You've got to be drawing a load of current to drop 3V across a piece of wire. Try disconnecting one of the subs and see if it does the same thing. Those amps are supposed to output the same power regardless of the load but there might be something wrong with the amp. Bring it back. If you disconnect the amp from the circuit then you should have 0V drop from the battery to the connections on your amp (open circuit = no current flow = no voltage drop)