TromboneChat

What is the difference between the SM,MB,LB and XB mouth pieces

Basically, the differences are the rim sizes the cup will support. Doug notes that the XB series threads for rims and cups are incompatible with the other bass trombone series.

What Doug did was to design the rims and cups in each series so that the junction of the rim and cup is smooth, meaning that they have the same diameter and (at least) the tangents parallel to the mouthpiece axis match. (Doug may have splined the cup profile so that the second derivatives match, too. My fingers aren't that finely calibrated.)

110 rim size is available in all three cup series, but even though the threads match and you can thread an LB110 rim on an MB cup, the junction won't be smooth. (A friend and I tried the experiment: I play an MB and he plays an LB.) I don't have an SB cup to try it on, but I suspect the result would be similar if not more extreme.

The difference is the diameter at the point the rim meets the cup.

I had a LB and XB in the same cup and shank, and the XB gets a meatier sound and adds about a step to my bottom range. The heavier blank does have an effect.

So the shank actually determines the bore size then?

Trying to reduce the wind suck out of my lungs. Haven’t recovered from covid

jpwell wrote: ↑Thu Dec 28, 2023 10:18 pm So the shank actually determines the bore size then?

Trying to reduce the wind suck out of my lungs. Haven’t recovered from covid

A smaller shank will definitely help.

So a “7” shank?

Suggest getting an explanation - and guidance - directly from Doug Elliott (when he has time).

In my experience, with MB and SB, and in tenor ST, MT and LT, the smaller the series the more compact a sound it is, with an easier high range at the expense of some low range. The bigger the series, the broader the sound. That’s a very general comment, in saying that, all the combos I’ve played are easy to play, have a good sound, and respond well in all registers, and there’s also some cross over at the ends of each series (ie. you might find an SB J cup and shank with a 108 rim plays bigger than an MB with an I cup and 106 rim).

All of the answers are correct.