I have a 1986 Rx7 and when I got it the back speakers where not in the tubes. Anyway there are some cuirtit boards in there and there all broke and stuff..What are these electronics and what do they do?

 

yours was originally set up with a bose system. if you still have the working head unit you could just replace the speakers with bose. bose system is different than regular system. you'll find extra power leads and also a different ohm level sent to the speakers from the stock bose head unit. if you are not familiar with a bose system get someone who really knows their stuff nit some beanhead at cicuit city. good luck