I noticed the other day my sub cutting in and out. It would hit for a few minutes then stop and would come back on again. I checked everything and found out that my terminal cup had melted. The area around the negative port where you plug in the wire was literally melted. I recently bought a new one and have not had an issue, but I am curious as to why or how this happened. I have a Jl12w7 in a sealed enclosure built to specs powered by hifonics brutus 1500d (i know not the greatest amp) with 4gauge wire. No alt/batt upgrade.