Posted by jeff on November 07, 2001 at 19:36:10:
In Reply to: Doug Elliot mouthpiece question posted by Ryan on November 07, 2001 at 18:30:58:
Big mouthpieces will have an effect on the pitch of the instrument. This effect becomes more apparent in higher partials. The effect is related to the volume of air withing the mouthpiece, so the size of the backbore will also contribute somewhat. I remember reading in an acoustics book that the effect begins to become pronounced at about the 6th partial (that's a G below middle C on a CC tuba).
One thing to think about - it's very easy to swim around the true pitch of a note when using a big mouthpiece. I played for years before I realised that there is in fact a pitch center for each note which will also provide the sweetest sound. My pitch improved dramatically when I realised this and began to work on it. As an excercise, try holding a note at about mf. Hold the note for 10 seconds or so, and concentrate on hearing all the overtones in the sound. Identify the partials and their respective chord functions. Pick the two most obvious ones, such as the 3rd and 5th of the chord.
Now, breathe and bend the note down using just your lips and then bend it back up again. Listen to those 2 partials. When they line up in tune, then more partials will leap out of the sound, and there's a good chance that that is where the "true" pitch of the note is. that is also (in my opinion) the sweet spot, where the note will have the most color in the sound. On some notes on some tubas, the note will want to pitch itself flatter than the above would indicate. I don't really know whether you should try to fight it, or go with the flow and accepte that maybe that note won't sound the same as some of the other ones on your horn.
When you get the pitch centered, then not only will you have improved the pitch and the tone, but the attacks on the notes should become cleaner as well (note: this doesn't always woJr rk on particularly bad, dead notes).
This may not work, but it's been great for me. Try it and see what you think, regardless of what you decide to do about the mouthpiece.
jeff