Quoted from GraniteStatePin:So here's a question....is there a safe/reliable way to use the existing transformer I have and put something in the circuit/ in-line to step down the voltage from the winding that powers the sound board. I think its 18 volts and needs to be 12.
You probably could buy a small, cheap 12V transformer, put it in the cabinet, cut the 18V-wires from the original transformer (either at the transformer end or right after the connector going to the backbox) and splice in the 12V ones instead.
Remember to ground the new transformer and isolate the 18V coming from the old one.