I played on the stage pictured below and had a heck of time dialing in a decent tone on stage. I was using the Home County Folk Festival rental amp. I'll be sure to bring my own in future. The stage is concrete, the walls are brick. Very boomy. No matter what I did to the amp it just sounded like chicken-doody on stage. FOH was great according to reviews after the set. I tried cutting freq I wanted less of. And eventually just gave up and lived with it. Does anyone have any suggestions for a stage like this. I really enjoyed the gig all the same. Great crowd. Largest for me in many a year.