I suspect that the reason for this is that the piston F's have the same bore in the fourth valve, while the most popular rotary F tubas have a larger bore in the fourth valve (at least). There is a reason for this. The rotary F tubas were intended as general-purpose tubas--they were the default tuba in German orchestras. Contrabass tubas were only used for certain works. A general-purpose F needs to sing in the high register but it also needs to play loud in the low register. Those larger bores in the longer valve branches had the objective of preserving the tone when played loud and low. But they do require a specific approach. The piston F's I've played (including the one I own) are easier in the low register but they don't sing as much in the high register. Once I learned how to blow that low C, the B&S is the most balanced F tuba I've ever played.Mary Ann wrote: ↑Fri Jan 06, 2023 3:52 pm Even the best rotary F has, by virtue of how it has to be constructed, "that problem." The piston ones, for the same reasons, apparently do not. I understand why you would want a piston one. I played an early 45SLP and frankly it was not as good, except for the accessibility of "that range," as my MW 182. And it was a piston tuba.
Of course we can get back into the dropped mouthpiece dent and resultant fix of the nodes, but no maker has seemed even vaguely interested in applying that fix to a standard instrument. I mean, who wants a brand new shiny tuba with a dent in it, even if it does make it suddenly playable? Seems like someone could just weld an appropriately shaped piece of metal on the INSIDE at that spot and have the perfect rotary F tuba. Why am I the only one who talks about this?
I have observed that the low C on an F tuba plays the same as the low F on a Bb rotary tuba. The Holton 345 has a larger bore in the fourth valve, and the low F on that (piston) tuba is more difficult to blow than on my Hirsbrunner, which has that same larger bore throughout the valves. Low F's veritably jump out of my smaller Bb tubas in comparison. Learning how to play the low C on a B&S made playing low F's on my rotary Bb tubas easier. Hmmm. We just get asked to play low C's more often and with more facility than low F's.
My first F tuba was a cheap rotary with four valves, so it was limited in repertoire application from the start. I bought it to learn F tuba fingerings and get some experience with bass tubas. The low F on it was oinky, but easy enough to blow. (I'd like to try that tuba again with what I now know.) My next F tuba was a Yamaha 621, which plays bigger than its looks and which has an easy low register. But it doesn't sing like a B&S, and it isn't as nimble in the upper register despite its small size. The B&S, once I committed to it, was a revelation--it had the nimble, singing quality up high like a small classic F, but a big sound in the low register allowing it to be used for a lot of orchestral lit. My first B&S was a 5-valve Symphonie, which I traded for a six-valve last-generation (unlabeled) Symphonie.
Rick "let low-C fear steer him away from the B&S for too long" Denney
......At Jim Laabs it is called a Schiller Frankfurt...... 
But finally, "What is in a name", as the famous father of English poetry said.......?? The Schmid plays rather well and that is what counts for me..... 