TromboneChat

If you switched from your mouthpiece to one with a reduced throat diameter, but a more open backbore, how would it affect your playing? What about the opposite?

There are MANY different ways to accomplish either of those things.
The effect depends on the details.

Are there simple rules, such as "deeper cup=darker sound" and "bigger throat=requires more air"?

In general, deeper cups resonate lower frequencies better and shallower cups resonate higher frequencies better, so that translates into darker and brighter sound. But the shape of the cup also influences that.

And in general, a larger throat uses more air. But that also depends on the backbore.
Using more air can also be inefficiency, as in mismatched designs that don't work right.

Flow and resonance are not the same thing, but they are often confused.

Harry Reed did a test where he had 2 mouthpieces made with equal rims and cups, but one had a large throat with focused backbore, other had focused throat with open backbore. He can talk more on that subject if he sees this thread.

BrianJohnston wrote: Tue May 19, 2026 6:59 pm Harry Reed did a test where he had 2 mouthpieces made with equal rims and cups, but one had a large throat with focused backbore, other had focused throat with open backbore. He can talk more on that subject if he sees this thread.

Thanks Brian! Yeah, this formed the basis of my L1 and L2 mouthpiece designs. The L1 has the focused throat / open backbore, the L2 has the (very) open throat / focused backbore. Both share a medium cup (where the 5G is "deep").

Each has things they do better than the other:

The L1 has a dark sound in the mid and low register, easy and brighter upper register, and really helps with endurance. You use finesse to accomplish technical challenges.

The L2 has an even sound throughout all registers, even access to all registers, and a much greater dynamic range. You use air to accomplish technical challenges.

The L1 beats the L2 for endurance, but both help with endurance vs a deep mouthpiece. It has more character.

The L2 beats the L1 for the total control you have of the dynamic range, and the low register is less about finesse and more about air. It has more presence.

There is some terminology confusion, I think. Throat is the geometry between the cup and bore, bore is the cylindrical hole (drilled then reamed), back bore is the conical opening. Resistance would be, in part, a function of the diameter and length of the bore. This has always been my understanding.

NathanSobieralski wrote: Wed May 20, 2026 4:34 pm There is some terminology confusion, I think. Throat is the geometry between the cup and bore, bore is the cylindrical hole (drilled then reamed), back bore is the conical opening. Resistance would be, in part, a function of the diameter and length of the bore. This has always been my understanding.

Bore and throat are interchangeable terms. Most manufacturers seem to use the term throat diameter to describe what you are calling the bore. The interface of the throat to the cup, what you are calling the throat, is usually called the throat entrance or shoulder.

Length of the throat has an effect on resistance, yep!