Wayne, Would you be so kind as to describe the various parts of the horn from the perspective of HornResp? I have a little trouble with knowing what the front chamber is, throat, mouth, etc. From the last picture (motor structure), it looks like your 12Pi has a ~1cu ft. front chamber and a fairly small (square hole) throat, which opens to the beginning of the horn in a very big jump in volume (compared to the square holes). I expected a smoother transition. Is the small throat where this "compression" comes from? Thx, Chris