I just got my new PA I bought from Ebay. No volume. I have tried both speaker jacks, I have tried all mic inputs (1/4" type... i have none of the other type of cable). I have tried many combinations of knob/eq settings. One other weird problem. It has low and high eq knobs. If I turn the low eq knob up on more than one channel at a time, the speakers start pulsing. ... Like every second they go pop, pop, pop... But if I turn up just one of the low eq... it does not do that. All of the other knobs produce no result at all. The speaker cab works. If I plug my mic into my Carvin amp, and into that speaker cab... it works fine. Any tips or whatnot would be greatly appreciated. I told the seller of this already and he said he would work with me either on getting it repaired, or returning it... whatever. I am pretty disapointed.