2nd blown sub in 4 day

hi this is my first post here, english is my second language so be lenient, :)

i have a serious problem i explain, i buy a 200 watt amplifier 2 channel with a 350 watt rms 12 inch subwoofer, i install it in my car all go nice and smooth but 2 day later the sub start to rattle and the amp goes on protect ,try to stop and start her back but the amp just make a pop in my sub and go on protect again .i try a speaker on my amp and it play great i ve got my sub exchange for an other one identical. same thing produce again 2 day after i install it

what is the prob  the amp????  or the sub????

dont know what to do helppp???

I do the wiring myself and i double chek it ( its not my first install )

what brand amp and sub, what are the setting on the amp and how is the sub wired to the amp.

its a cheap brand (legacy)

the amp have an internal crossover tha is set on low with a bass boost and the volume of the amp is about half the way to the max and the sub is wired in bridge mode to the amp

thanks for the solution i now have a new door stop and a portable heater

ill try to get it back to the store for some better stock

Maybe the amp sucks but how did you wire it?  Is it a dual or single VC sub?  bridge a dual VC the wrong way and it'll send that amp protecting itself.  What ohm sub is it?  Drop that legacy at 2ohms and I guarantee it's clipping for sure.  Even though it might be rated at that.  A 4ohm speaker will drop lower than 2ohm's while moving (if bridged of course), therefore making some of the lesser quality amps go into protection.  Find out the details before you junk it. 

Maybe some people cant or dont want to pay for the good stuff.   You can make the cheap stuff work if your on a budget.  Just wont sound as good.

the sub is a single vc 4ohm

and the amp on bridge mode push 4 or 8 ohm (that what said the manual that comes with it)

anyway ill trow it back to the store and get something else