I get asked this question all the time, and frequently see discussions about this online. People usually have an opinion on this topic based on their own experience. As a result, opinions vary.
My opinion on this issue is based on my own playing experience, and on my observations while designing and play testing hundreds of mouthpieces since 2007.
I also have direct feedback from helping hundreds of players test mouthpieces of different cup depths. Again, results vary, but some patterns emerge.
The main effects of a shallower cup are:
- A brighter sound.
- A less resonant low register.
- More blow resistance.
- A greater tendency to split notes.
- More support in the upper register.
More support in the upper register can have different effects:
- Bigger sound in the upper register.
- Increase in range by a note or two when the chops are fresh.
- Better endurance, meaning the ability to maintain range during a long playing session.
Players experience these effects in different combinations and to different degrees. Improved endurance is the most common and significant improvement reported by most players.
Why is there so much disagreement about the effect of a shallower cup? I think there are several reasons:
- Forming an opinion based on testing cup depths for a few minutes without assessing the effect on endurance (range when you are tired).
- Different expectations about what constitutes a significant increase in range.
- Opinions formed by trying a mouthpiece that is too shallow, to the point that the potential range increase is prevented by bottoming out in the cup.
- The degree of cup depth change being considered – slight increases have less effect.
- Confounding variables such as changing cup depth along with other parameters such as rim size and shape, throat size, and backbore.
So as usual the answer to this question is more complicated than one might expect because it is subject to so many variables. Such is the nature of brass playing.
Having said that, a reasonable answer can be summed up as follows:
Most players will experience some combination of improved upper register performance (bigger sound, one or two notes of added range, better endurance) when switching to a shallower cup, if the cup is not so shallow that their chops bottom out in it when they are a bit swollen or tired.
The potential trade off is a degraded low register, more resistance, a brighter sound, and more split notes.
Dr Dave