Very nice looking woodwork, rendoman, but I don't think you will get an acoustically pleasing result. The purpose of a horn is to smoothly transform the acoustical impedance of the (relatively) small throat of the driver to the acoustical impedance of the free air at the mouth of the horn. For this to be accomplished smoothly the horn must have an exponential flare, not a conical flare. This is why you see most, not all, brass and woodwind instruments having an exponential flare. I am not near my library right now but, as I recall, the classic book, "Elements Of Acoustics" by Harry f. Olsen discussed the properties of horns many decades ago. The rate of flare is also critical to smooth transition from the impedance of the driver to the impedance of the throat of the horn. The flare rate of your conical horns looks much too great in the photos. Obviously, making exponential horns is far more difficult than making conical horns, especially in wood.
awright