AC current stands for alternating current witch means that the power changes from positave to negitave and then back to positave and the other wire being ground.
DC stands for direct current and means that one wire is always positave and the other is always negitaive or grond
AC is not as usefull as DC but things like transfourmers cannot run off DC and it is easyer to convert AC to DC so mains power (the power that is supplyed from wall plugs) supplys AC.
AC wich is a problem for us becausThe transfourmer supplys e batterys olny supply DC, and DC it is harder to convert into AC.
Luckley the circuit that was in my speeker had four diodes aranged as a bridge rectifyer. A bridge rectifyers purpose is to convert AC to DC witch is what our batterys supply. This means that what looks like our board draws AC the board its self actually converts it into DC before it reaches anything so we can connect our batterys directley to the input.