TubaForum.net

If you are interested in auditioning for an orchestra you should know about "Musical Chairs." It's a comprehensive website for professsional jobs and auditions.

https://www.musicalchairs.info/jobs

There are currently two auditions, both in Germany. Bb tuba would be required for one as would fluency in German.

If I may add to the above, here is another great resource for auditions.

https://www.lastrowmusic.com/tuba-and-e ... auditions/