Please see this topic in our forum
This message was posted by Gus Pratt on the Onelist TUBAEUPH discussion list several years ago. It is still a good discussion.
When tuning the valves the most critical thing is that you think about whats going on with the horn from a techincal aspect. If you tune the first valve first, then when you adjust your main tuning slide the note you tuned with the first valve is now out. Here's the order that I would use, some of which will need a tuner.
1. Tune to concert
The Wick numbering system for baritone and euphonium can be a little confusing. The numbers are like "4AL" or "6BM" or similar.
The number refers to the diameter of the rim. If I remember correctly, a 4 is about 26mm across inside the top of the cup, and the numbers a roughly the same as Bach for rim diameter. So a Wick 4AL is about like a Bach 4G on the chops.
The first letter, "A" and "B" in the two examples above, refers to the cup depth. "A" is deep, "B" is medium,
I rarely use a mute in my euphonium. However, some important band, orchestra, and solo pieces call for mute so it is important to have a quality mute on hand. It is also useful to have a so-called practice mute for situations when you want to practice but can not make much noise.
STANDARD STRAIGHT MUTE: The best mute I have found for general use is the Denis Wick DW5513 Euphonium Straight Mute. It has one of the best mute sounds I have found and holds up well to loud playing.
The most common mouthpieces in use for euphoniums are made by Wick, Bach, and Schilke. I personally like the Wick 4A because it has an open, singing sound. However, as you sound gets more open, you will hear a little more "fuzz" close up. From the audience's seats it should not be a problem. For large shank, the model is 4AL; for medium shank it's 4AM; and for small shank it's either 4AS or 4AY (same thing).
There is also a line of mouthpieces by Wick that are made to Steven