Re: Rotary versus Piston Valves


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Posted by Johan Gustafsson on November 20, 2003 at 15:39:02:

In Reply to: Rotary versus Piston Valves posted by Darrell Pugh on November 18, 2003 at 14:17:36:

As others have stated; it is more the total feeling of the tuba that matters, not if the valves are of piston or rotor type in their construction.

In my personal experience:
* it's the quality of the design, manufacturing and maintenance of the valves that makes them fast, silent, divine etc. or not, not if they are rotor or piston.

* rotor valves are a bit more tricky to dis/re-assemble to clean and lube, but then they generally last longer than pistons till the next time they need attention. You can also add oil to them between clean-ups without taking them apart.

* too small diameter on rotor valves or too crude design on the windways in the rotor puts too sharp bends in the windways to not affect the characteristics of the horn (lots of negations - sorry!). Too small diameter is mostly a problem on trombones, though. Most rotors are just made of massive brass cylinders with "ditches" milled into them. I once came upon a 4v F-tuba by Ahlberg & Ohlsson where the rotors were built up like pistons - hollow pipes with short bits of tubing inside connecting one hole with another, like on a Hagman valve. This was a great horn!

* piston valves are somewhat sensitive to not being pushed straight down. If you push at too large an angle they might stick.

* large bore tubing results in long throws for piston valves, for ultra-large bores (20 - 22mm; 0.787 - 0.866" or more) you find almost only rotor valves. I personally don't find a long stroke a problem however. Rotor valves always turn 90 degrees regardless of the bore size, i.e. no difference in spatula travel due to bore sizes. As for rotor valve spatulas leveraged for a short stroke, I usually have to push them quite hard. I don't find this faster, just tiresome.

I personally prefer a tuba with a compensating system (4v, 3v is ok too if i don't need the extra range), and those are (to my knowledge) only available with piston valves.

So far my 0.15 Sw. Crowns.
Johan


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