I'm not sure what section to put this thread so I'll try here. I had a gig this past Saturday night at a small "dive" of a place. Since we were limited in space I used the following: Standard Jazz Bass(MIM) GK MB210 Combo GK 210MBE ext cab speakon cable to connect cabs instrument cable About a month ago I used this same "combo" of gear for practices. Everything sounded good until my practice last week. I started getting crazy loud feedback. The only changes I had made from previous practices was changing from "flats" to "tapes" for my strings. When using the tapes I got the feedback. I have read that tapes could cause feedback at times so I went back to the flats. Saturday during the 1st set I experienced the loud feedback again. I turned off the amp quickly just to get rid of the noise. I didn't get the noise anymore that night. I'm not sure what's causing the problem now...I was hoping it was the strings but that must not be it. On break I looked the amp over, visually, and the only thing I saw was I had the horn engaged on the amp but the ext cab's horn was off. I wouldn't think that would cause it but not sure. Now what....check the cables being used, have the bass checked, have the whole set up checked out by a shop....? I can't simulate the problem at home. Not really sure what to do. Thanks Note: we were playing with no PA support. Only vocals were going through the PA.