Posted by Kenneth Sloan on March 05, 2003 at 22:45:29:
In Reply to: Re: Re: Re: on a quest posted by Rick Denney on March 05, 2003 at 12:27:18:
Here's my back-of-the-envelope mouthpiece model. It's worth what you paid for it:
a) "popping frequency" should match the middle of the range you expect to play. It gives the CENTER frequency of a RANGE of frequencies which are easiest to play.
b) popping frequency is inversely proportional to cup volume (big cup volume = low popping frequency)
c) popping frequency is proportional to throat/backbore size (bigger throat = HIGHER frequency)
d) BUT...bigger throat ALSO means that the mouthpiece has LESS influence over what's easy to play (and the tuba has more). So...bigger throat gives wider slots, and slots both higher and lower in the range. But, the slots are not as effective. So, you need more control with your lips (whereas with small throats you can wiggle your fingers and blow)
So, for a given tuba, you need to first match the popping frequency with the range you expect to play on the tuba. Then, you can change cup volume OR throat size to suit your abilities (but should change the other to compensate). Big cup/big throat is for strong players (they have the control, and need slots over a larger range). Small cup/small throat is for those who need help from the slots, but only over the middle of the range).
By this model, intonation problems crop up when the throat is too big for the player's lips - the slots are wide enough to allow the player to play all over the map. note that this is a *good* thing if you are a strong player with a strong sense of pitch and a *bad* thing if you are a weak player with a weak sense of pitch. Beginners should use small bore moutpieces (and hence, smaller cups for the same instrument). Strong players purchase scraping tools to open up the throat (which both raises the comfortable range AND allows more steering).
Knowledgable correction gladly accepted. Your milage may vary.