Hello, I'm currently planning a box which will have 2 15" PA Drivers. Normally I'd just go for a standard one on top of the other box (ported) but I was wondering if anybody had any other suggestions as to a design that might be more effective. I've seen Foldback speakers with what looks like wooden square ports, with a sloping 'floor' of the port and a small gap for air coming out of the box. Does anyone know what this type of design is called? I might be confusing a lot of people somewhat so I'll just clarify what I mean for the first thing. I plan to make the box like this: I---------------I I I I 15" I I I I 15" I I I I Port/s I I---------------I Never before have I seen such fantastic ascii art thanks if anybody replies to this.