Hmmm... Do you think they'd be any different from a regular rotary valve? It kinda looks to me like they just rotated the casing 45 degrees to accommodate a more direct entry angle for the pipes. Then again, I don't build horns for a living, so perhaps others might be seeing something here that I'm missing.harold wrote:I would certainly like to see how the actual rotors look when removed from the casing.
I don't think the issue is so much dynamic flow resistance as it is with unnecessary bends detracting from the resonance of the horn; i.e., the concern is one of acoustics more than fluid dynamics.harold wrote:I disagree.
I don't think that any of the angles make any difference on virtually any horn.
This is the same argument used by people that reverse the direction of their valves or remove the spit valves because it allegedly decreases the wind resistance through the instrument.
I think you've nailed it down pretty well, Chuck. The resonance of the column of air as it interacts with the pathway that contains it is probably far more important than any airflow considerations.Chuck(G) wrote: I don't think the issue is so much dynamic flow resistance as it is with unnecessary bends detracting from the resonance of the horn; i.e., the concern is one of acoustics more than fluid dynamics.
A large organ pipe that had been mitered to fit into a smaller space doesn't speak as well as one that has been left straight. I'd speculate that the fewer contortions a souind wave has to go through could only improve resonance.
No, the valves are oriented the same as a regular rotary instrument. Look at a rotary tuba and you'll see that the openings in the casing are the same. The difference is that this tube has no curve in the tubing knuckle attached to the side of the casing.poomshanka wrote:It kinda looks to me like they just rotated the casing 45 degrees to accommodate a more direct entry angle for the pipes.
Oops, I have one leg out on my chair, and was actually looking at it *at* a 45 degree angle. My bad. See, I got so wrapped up thinking about the sound, I lost track of the appearance.Rick Denney wrote:No, the valves are oriented the same as a regular rotary instrument. Look at a rotary tuba and you'll see that the openings in the casing are the same. The difference is that this tube has no curve in the tubing knuckle attached to the side of the casing.
Rimshot for dave!poomshanka wrote: <snip> See, I got so wrapped up thinking about the sound, I lost track of the appearance.
I *will* solve this mystery in my lifetime, and deliver a full report to the forum.
...Dave
Your pictures show the difference very well -- thanks, Sven!sbring wrote:I've tried to picture the difference in "angularity" between an ordinary tuba and the one on Daniel Kunst's site. Hopefully there are two pictures below, in both cases attempting to illustrate the airstream with no valves or all valves open, respectively.
Regarding organ pipe mitering, that is true for only one class: open flue pipes; they are essentially whistles. They are half-wave resonators. Mitering brings open end to less than half a wavelength from the mouth of the whistle, and the resonance does not work as well. [The acoustic circuit exists both inside and outside the pipe.]Chuck(G) wrote: ...A large organ pipe that had been mitered to fit into a smaller space doesn't speak as well as one that has been left straight. I'd speculate that the fewer contortions a souind wave has to go through could only improve resonance.
[/i] 
