[email protected] wrote: > But I can think of reasons why a builder might want to experiment with doubled valves. > One possibility is that it would allow an air path without sharp turns. The air flow through the main body of the horn (past the leadpipe) is so slow that anything short of mashing the tubing flat-as-a-pancake shouldn't have much effect. Forget "air flow" and think "take care of the standing wave," and you'll be much closer to home.
Umm, I believe in my original message I never used the term you quote, "air flow". I used "air path" which is a different thing with a different focus. When we play horn, there is a DC (0 Hz) flow through the horn because the only way we have of making the embouchure vibrate is to put an air pressure difference across it. The volume of air through that drop in pressure is what provides the energy tat the embouchure converts to acoustic energy, and which the horn resonates in interesting and wonderful ways. However, there are other methods by which a horn can be acoustically excited, and it has been done as part of acoustical experiments. (Sorry, no citations at hand.) A small electronic speaker can be affixed to the mouthpiece and used to as an acoustic "buzz" overtone source at any desired frequence, but with which the DC air flow will necessarily be zero. I believe such a mechanism is used experimentally to plot the impedance response of a horn against frequency, useful to measure the `Q' of those pesky high harmonics. The standing wave does not (based on horns I've played, some with sharp turns, some with gentle "air flow friendly" crooks) care about what the airflow is up to. Precisely. The effect of many sharp bends with which I was concerned is not the effect on D.C. air flow. The question is whether the nature of the _standing wave_ is affected by those turns. Almost certainly it is. Would reduction of the number of sharp bends improve the consistency and playability of a horn? (Remember, the Urhorn (Waldhorn) has approximately zero sharp bends.) Thanks to Bob Osmun for the reminder about the Veneklasen horn. Are there more details about its valves anywhere? If brass instruments relied on "air flow" to play well, the Thayer valve would be the hands-down winner, and no rotary (or piston) valve would even be a feasible alternative. But brass is about taking care of the standing wave that sets up when we play, and NOT about airflow. Therefore the Thayer valve is just one more possibility, and is most certainly not an advantage... just another way of doing it. (I follow intently all happenings in the trombone world). All valve types have certain advantages balanced with certain drawbacks, but some work well in spite of (or because of?) their non-concern for "air flow." _______________________________________________ post: [email protected] unsubscribe or set options at https://pegasus.memphis.edu/cgi-bin/mailman/options/horn/archive%40jab.org
