Car Stereos: car audio, watt amp, stock radio

Question
what if you got a stock radio hook up with 1200 watt amp and the amp is working perferctely but the sound in the woofers 2 12 inch keep going in and out . I hooked up another amp just to make sure and the same thing continues to happen to this amp as well it is also hooked up to a high and low already  

Answer
There are many things that could be causing the problem.  99% of the time, it is not the speakers.  If they do not have little circuit boards right where you hook up the wires, the speakers have no option to not work.  They are mechanical.  So the problem would lie in the amp or the radio.  Since you tried 2 amps, doesn't mean it isn't the amps.  If you are trying to bridge your subs, or wire them for more power, they may not have enough resistance for the amp, and it is shutting down from overheating, which is really bad to keep doing.  If the subs are wired individually to the amp, and the inputs from the stereo are going into RCAs or speaker level inputs, then the problem may lie in the radio.  Are any other speakers shutting off besides the ones powered by the amp?  If so, the problem is probably a short of some kind in the stereo.  If I had to guess, I would probably double check all the wiring, including ground wires, and make sure all connections are right and tight.  Then go from there.  Hope this helps, Scott