[J. FO]

here's the deal, i'm the drum tech/percussion instructor at a local high school. for their marching band show, they are doing a large mallet ensemble and we are miking 2 marimbas, vibes, and 2 xylophones. here's the rub, the power for the board, speakers, wireless mic receivers (for woodwind soloists) comes from a portable battery, because an extension chord tends to trip people tyring to march over it (go figure). the battery is causing the speakers to hum a great deal. the speakers are powered JBL's, but don't hum at all when plugged into a wall outlet. now, i'm new to the live sound reinforcement biz, but am i correct in assuming a power conditioner or rack mountable power supply unit help to get rid of this hum/buzz? thanks for your help.