TubeNet

If you checked all the usual then you may need to take it into a shop and have it looked though.

Also check to see that any random soldering didn't come undone (even between tubing, not just braces).

While holding the note try grabbing parts of your horn or squeezing (lightly) on different places. Play a sorta-like "you're getting hotter/colder" kinda game and you may be able to at least locate where the problem is.

Good luck!

BP

Be sure to check the threaded rod on the 1st valve tuning slide stop. It can rattle inside the support at times. I found some tiny nylon bushings at a hobby shop that worked well to reduce the size of the hole in the support and the problem went away.

I would make sure that your 5th valve is well oiled. On my horn, if the rotor dries out those notes will rattle.

Keep an eye on that 1st valve slide stop, though. Mine buzzes on all Bs. I don't even think about it anymore - my finger moves to stop it now on autopilot

Congrats on finding the buzz - the DSs are idiosyncratic, but worth the trouble!

J.c.

Will do, thanks for the advice bloke.

MIne had a buzz also. After some hunting I found out it was the 1st valve spring. I pulled it out and gave it a very light tug to unwind it a little and it completely quit. Just a suggestion.