When playing any wind instrument it is obvious that the most important aspect of playing is great air support. A simple rule to remember is the larger the instrument the more air that is needed. When playing tuba after coming from trombone or baritone you are literally playing on a metal tube that is two times larger than what you are used to. Two times the horn means two times the air. Also there is less resistance with the tuba mouthpiece than there is with a smaller trombone or baritone mouthpiece. That means that the mouthpiece will blow more freely and subsequently you will run out of air quicker. Make sure you pace yourself in this first step. Please remember to stay relaxed in your breathing. As Pat Sheridan says "Tension is the enemy of tone." Do not start your tone with a tense breath!!!! Stay relaxed when breathing and remember to keep your tongue low. Arnold Jacobs used to say, "Breath to expand, don't expand to breath." When breathing the throat should stay relaxed and be in an "Oh" position.
When forming the embouchure be sure to follow the following steps:
Make an "OH" vowel.
Make an "oo" vowel.
Then squeeze the tube. Imagine there is a straw in between your lips and you want to squeeze so it crushes down a little but not so much that you flatten it.
The tuba embouchure may feel a little "looser" than the trombone/baritone embouchure. In actuality a good tuba embouchure has some similarities to a well formed trombone/baritone embouchure. Both embouchures have: 1. A Firm Flat Chin 2. Have Firm Corners 3. Use a relaxed tongue/throat when breathing in 4. Involve leaving plenty of space between the teeth and inside the mouth to create a dark sound.
Sound is produced by air moving between the lips and vibrating. Because the lips are vibrating slower to produce a lower pitch, the embouchure feels like it is looser.
NOW FOR MOUTHPIECE PLACEMENT!!!
The mouthpiece should fit comfortably over the lips comfortably below the nose. The student should get a small mirror, like a locker mirror, and make sure that when putting the mouthpiece over the embouchure that it is in the center of the face and, if possible, with a lips in the center of the mouthpiece. If it is a student with a smaller set up then fit the tuba mouthpiece over the lips as comfortable as possible. Below are three pictures, the first two are incorrect and the last is a picture of correct placement.