Tuba/Rotary vs. Piston Valves
TubaSoldier wrote at 2007-09-21 23:51:28
Rotary valves are faster that pistons due to a few factors: 1. the springs are lighter on rotary valves, 2. rotary valves are smaller, so there is less surface area in contact with the valve casing, 3. rotary valves use a lower viscosity (lighter grade) oil, so there is less friction to overcome, and 4. there is a shorter lever throw on rotarys than on pistons (unless you have a Conn 20 series piston valve tuba). Rotary valves also tend to be quieter than pistons, because the torquing action gives a gentler valve return against the bumpers.
I hope this helps clarify your question an add to Mr. Mitchell's answer.
Mr. Weaver wrote at 2008-10-17 15:02:46
Piston valve can also be front action (horizontal). And also have 4 valves. Rotary valves are actually much harder to push and often sluggish not to mention very hard to do any work on. Fixing or cleaning your own horn is a nightmare. In my opinion the only pro to a rotary valve is that the distance the valve has to move is a little less than that of a piston. But it still take twice the effort to move the valve half the distance. Not worth it. There really isn't much better than a front action piston horn. and a top action isn't bad either. I would personally take one over a rotary valve.
Air Force Tuba guy wrote at 2009-08-19 17:58:54
Actually, piston valves work faster because you are not exerting energy through the rotary button, rod and the action of turning the rod. A piston takes the energy and force directly from your finger, causing it to act quicker on demand. Also, 4 valve piston horns are readily available. Another factor in piston reaction time is the amount of spring pressure. Their are various spring tensions available for piston horns, heavier springs cause the piston to move quicker but make it harder to press. Softer springs move quicker when pushed but move up slower. All in all, piston or rotary is definitely a measure of preference.
Dave Weston wrote at 2012-11-16 14:24:04
I have purchased a rotary valve tuba and have played piston valves before and after my purchase. Any difference in the pressure need to press the valves is next to zero. The biggest advantage to rotary valves, in my opinion, is the distance your fingers need to travel to operate the valves. This is less on rotary valve. I recently played piston valve as a one off and I really noticed the difference. When playing fast passages, I find rotary valves much easier. It is however a matter of personal preference. Having played both, if I were to buy another tuba I would go for rotary valves again.