I have a curved soprano that is good but the bottom C is very flat B and Bb too though somehow I feel C is flattest. It is like the bell joint is too long and those last two tone holes are a little further away than they should be. I took it to an excellent technician and he couldn’t correct it. He described perfectly what I was doing to bring it in tune (“honking in a subtone”). I asked about shortening the bell joint from the joint end to bring the last tone holes in closer. He was resistant to that idea, no doubt sensibly so. The rest of the notes are pretty good and relatively easy to play in tune. It is a Bauhaus curved. Any “sharp” ideas to improve this issue gratefully received as it is portable, a great fun piece of kit and paradoxically has good tuning higher up. Thanks Ed