Thank you
The two tubas are also extremely similar in size. Since I have sold the Alex I can not measure it, but to me there is no difference. And they are not 3/4 tubas. At least 4/4 size tubas or even 5/4 tubas. To give you an idea of the size, here is a picture of the Alex flanked by my B&S F and a Besson New standard BBb (currently owned by Klaus)
And it looks down to the strap holders like the Alex, though all the small supports clearly are B&S made. Here you see the logo on the BBb, which is just like the one I have on my B&S F Symphonie.
My B&S F and BBb Model Symphonie side by side
And the intonation is superb! And as some of you speculate, just as good, or even better than that of a standard Miraphone. And the response is just as good as on my F.
And commenting on the tone compared to the Alex. I think that they sound more or less the same. The sound I get out of this even with a Kellyberg is much more interesting and colourful than on any other tuba I have played. That being said, my Alex might have needed a new leadpipe, and that would probably have helped the sound a bit.
And one thing that also struck me was the entering the first valve at an angle of 45 degrees. It seems not to be a common thing on rotary tubas, though it is found on both the Alex and this B&S