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I would like to know as well. I am not familiar with whatever is being described here.

Rob, turning the valves referrs to changing the rotation so that all the valve rotate in the same direction. As to scooping the valves, next time you see Pritchard ask him, I think he's had it done to his PT6. I don't exactly what it is, post back after you talk to him please.

HI-
Turning the valves--example-#3 & 4--allows them to all move in the same direction. Many newer rotary tubas now do this, but older ones had valve 1& 2 moving in one direction-counterclockwise, and 3&4-clockwise (or visa versa)--imagine having four doors in a tunnel, and having air coming through--if two of the doors needed to be pulled forward to open, and the other two doors needed to be pushed to be opened, it would interrupt the air stream--if all four doors were just needed to be pushed to be opened, it would be smoother--and as for playing, think 1st movement of Prokofiev #5 for smoother, silkier, slurs on some of the passages--I hope this makes some sense.

Scooping the valves allows them to be lighter for one--less metal, and allows more air to go through the valves and align with the ports. First off, many horns have too much metal on the rotors, which makes them heavier, slower, and doesn't allow or hinders as much air to flow through. Some older rotary horns had valves that were smaller than the tubing bore of the horns--opening up the ellipse (the depth part esp.) allows for lighter, faster valves (less metal) but also allows for more air to flow through the horn--'opening' up the horn--again, I hope I make some sense in this (I should have learned never to try to be detailed on a Sunday morning....).

The old King rotary tubas--ala Bill Bell's, Joe Novotny's, etc.-had the valves moving in the same direction, and had hollow copper valves--very light weight--somehow makers started to make rotary tubas with 1&2 moving one way and 3& 4 going the other way--cosmetics? Who knows. However, as stated above, today many makers of new horns--even the Chinese, have their rotary valves moving in the same direction.

Time for coffee....

mark

Any guesses why the old style was to have 1 & 2 go one way but 3 & 4 the other way?

bort wrote:Any guesses why the old style was to have 1 & 2 go one way but 3 & 4 the other way?

Because back then everything was harder...at least that's what my dad tells me...

bort wrote:Any guesses why the old style was to have 1 & 2 go one way but 3 & 4 the other way?

The rotor stack is longer than the paddle bridge. By letting the lever arms act on the lower side of the two first axles and on the upper side of the lower two axles you avoided off-setting the lever arms too much under the bridge. Mechanically you got a more direst power transmission from the paddles.

Klaus