TubeNet

Mike,
It was likely built in High Pitch, so it' probably about a half tone sharp.
The valve slides can likely be pulled out for A=440, but for my High Pitch horns I've made new tuning slides for them so that they can be pulled out for 440 and not modify the originals.

These horns often came with two tuning slides, one for High Pitch and one for Low Pitch (A=440). In 1910 York parented an extra loop for the difference so that one could use the same tuning slide for either.

If you don't care, you can just do something like have the original ferrules extended so that it is now long enough to play in modern pitch.

I think that every pre-1920 York that has come through this shop has needed main tuning slide work to bring the pitch to modern standards. They typically were built with an extra loop and slide on the small side of the main slide, which is too flat if you use the optional loop and too sharp if you don't. My solution for a number of horns has been to remove the loop and split the difference in total length, which translates into cutting and using parts of the loop to extend the small side of the main slide, then finding larger tubing to extend the ferrule and slide on the large side. The valve slides generally do not need to be modified.

Which model or size? 20" bell? If it sounds like a euphonium must be a smaller model? Pic?
thanks
Joe