Pistons vs. Rotors: an age old debate
This is a question that gets argued frequently. Tuba players will go back and forth with each other on this subject, and I really haven't heard many convincing arguments for one over the other, so today I will try to provide some insight to how each system works and you can make a decision for what is best for you.
1 - "Which is faster?"
This is a trick question. The answer is neither are truly faster when cleaned, adjusted and lubricated properly. Both systems need to be perfectly clean before assembly. Pistons need the proper spring for light quick action without feeling too stiff, and strong enough to avoid "bounce back." Rotors have to have all of the moving parts thoroughly cleaned and lubricated with the proper oil (and there is more than one). Rotors also need to have the linkage mechanism adjusted for proper action and to eliminate lost motion so the rotors are quiet.
Piston vs. Rotors 1: DRAW
2 - "Which is easier to maintain?"
Pistons are easy to take apart. For Tubas and Sousaphones it is as easy as unscrewing the piston top cap. Piston casings need to be swabbed with a clean cloth and oiled regularly. If your horn is going to be put into storage for an extended period of time, it is important to clean the oil from your pistons and casings. You do this because the oil will evaporate leaving a residue which will cause the pistons to stick.
Rotors SHOULD NOT be disassembled by young students without trainging from a tech or an experienced Tuba teacher. There are many different parts, and if they aren't properly reassembled or if they are mixed up, your horn might not work. That being said, once a rotor valve horn has been cleaned and oiled, it needs re-oiling regularly, but rarely requires rotor disassembly. As long as you properly oil your rotors, you will have quick, quiet rotors for a long time.
Pistons vs. Rotors 2: DRAW
3 - "____________ sounds better."
Again, this is a trick question. In the musical instrument retail business, SOUND is kind of a dirty word. This is because sound is ultimately subjective and is different from player to player. People who like rotor horns might argue that the bore remains more consistent with rotors allowing the sound wave easier passage through the horn where as pistons might cause more resistance. I have not seen any convincing evidence in either direction for this argument.
Pistons vs. Rotors 3: DRAW
At the end of the day, the choice is ultimately yours. In my opinion when properly adjusted neither system is faster nor is one system any easier to maintain than another. Many major Tuba manufacturers offer many of their models with piston or rotor options.
What do you prefer and why? Let me know.
(I think the picture is from Dan Schultz's (the Tuba Tinker) collection, but I am unsure.)