The front chamber volume is larger than some others, but it can be partially filled with solid material to reduce volume, if necessary. The front chamber acts as a low pass filter, so on a basshorn, it isn't a bad thing. That will serve to reduce harmonics even further, just like the horn folds do. All the other characteristics of this "push-pull plenum" horn are the same as any other horn. It's just the harmonics cancellation feature that's different, and that's done with a very simple mechanism of turning one driver around.