74 beetle help wanted!

[beetlejuice74]

OK so i do not know a whole lot about this car because i just bought it about two months ago. The past few days it has been dying. And when it starts to die the stereo turns off, then makes a loud noise, the noise kind of sounds like youre sucking out of a straw. I have been jump starting it, since it is my daily driver. It will last about ten minutes and die. I know it is the alternator, because i put in a new battery. I have subs in it, which could be using all of the power in the car. What should i do? Should i buy a new alternator? and if i do what kind should i get? I need one with a lot of power so it can handle the subs and everything else. And what is this straw noise? Is it normal for the blinker to stop working when it starts to die? I am madly in love with this car. Helllp