My subs stop after a while when they are running?

Question

I have 1 15 inch 7500 MTX and im running it off a 1000 wat x plod amp i have 4 gauge wires that go through a distribution block to 8 gauge wire but the on 15 will be bummping ang goinng very very veryyyy well! and then it will just like sorta stop, like u can still sort of hear it but its alot quieter then it was and i have to turn it down and wait a lil bit before it will go back to the loudness it was at

Answer 1

be very aware of the sub. It sounds like the voice coils are overheating and the sub may blow.  

Answer 2

sounds like your amp is clipping.  

Answer 3

Clipping

Clipping occurs when an amplifier is asked to deliver more current to a speaker than the amp is capable of doing. When an amplifier clips, it literally cuts off the tops and bottoms of the musical waveforms that it's trying to reproduce, thus the term. This introduces a huge amount of distortion into the output signal. Clipping can be heard as a crunching sound on musical peaks.

distortion is the main cause of speaker damage

you dont have enough RMS wattage, when you match speakers and amps you need to pay attention to the RMS wattage not the peak/max wattage