Having played both of them (Siegfried / Fafner), neither one of them are a super-tall skinny bell classic “kaiser” B-flat.
The guy in the Vienna State opera Orchestra has his own version of the Fafner with an 18 inch bell (versus a 20 inch), but that’s still not a 16 or 17 inch bell.
They are both pretty big fat tubas, and about the same height.
The Miraphone might weigh a little bit more than the Fafner, but most all of the rotary Fafner models do not have a fifth valve, and the Miraphone is handmade - so even with five valves and being a B-flat, it only weighs 27 pounds.
I stated this earlier, but I’ve had several opportunities to pick up a Fafner for less than I paid for the Siegfried, and - having played both models - have passed on all of those opportunities. This is also redundant, but I like the piston version of the Fafner much more than the rotary version, but it sounds too much like my C tuba – a model 5450.
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As far as an update, and not just a bunch of rhetoric…
I am figuring out more intonation alternatives and workarounds towards perfect tuning on this instrument. I’m going to do some fairly significant alteration to the #1 slide circuit. It’s not going to reduce its tuning range – even though I plan to shorten its length in its shortest “closed” position, but it’s actually going to increase the tuning range.
I’m also going to go ahead with what I said I was going to do originally, which is to shorten the main tuning slide bow. It “just” plays at A=440 not warmed up (minuscule pull when warm), but think of what time of the year it is - and most orchestra jobs are in the fall and winter, are they not?
All of that having been said, I’m sort of pleased with my progress in mastering playing the thing.
I just have to remember to take gigantic breaths instead of large breaths. I’m pleased with my improvement in my B-flat reading ability.
Venting the valves will help my good-sounding-to-me slurs sound even better to others (those who decide whether or not to hire me back).