WindWorks Trumpet Academy Forums WindWorks Mouthpiece physics

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    • #12939
      JuttaC
      Participant

      Can anyone tell me why a cornet (and presumably trumpet) mouthpiece has to have such a small bore just beyond the cup? (I am genuinely intrigued!) Just after the cup, there is a narrow orifice, then the mouthpiece widens again within the shank until the bore is that of the leadpipe (more or less).

      I am having serious problems with a “strangled feeling” in the throat. Today I got my “magnifying glass” out. Without the mouthpiece, I could blow (all passive, honest!) through the instrument very easily. Blowing through the mouthpiece is a lot harder. Blowing through the mouthpiece and instrument is, unsurprisingly, harder still. What makes it hard is the orifice just downstream from the mouthpiece cup. (I believe flow rate changes with the square of the bore, so this makes a big difference.) Why does the bore have to be so much smaller just beyond the cup than at the (instrument) end of the mouthpiece? What’s the physics behind this?

      I think I am currently trying to force way too much air through the instrument, so I’m putting in enormous effort to build up pressure and the throat just closes. Think I understand the problem and will experiment further, but I’m now wondering whether there is actually a mechanical solution, or at least a mechanical change which may help.

    • #13002
      mjn
      Participant

      Hi Jutta, I am sure Greg will have a better answer, but the throat design on a trumpet mouthpiece helps create the overtones that you hear from the instrument.. a tighter throat will create roughly a brighter sound (more high overtones)(think a roger ingram lead piece with a #29 drill) and a larger throat will typically create a more broad and darker sound (bach 1.5C with a #24 drill). there are too many variables these are just the basics when talking about throats and backbores, which is what i think you are talking about. about the choking off feeling: yes you are blowing way too much air into the mpc. try this: eyes closed, then blow really hard into mpc. then same thing but blow really softly into mpc. notice the difference in feeling between the two extremes. do this a few times. then start blowing air softly into mpc and gradually increase. as soon as you feel the air backing up into your throat you have gone too far. the point where you can blow air and it doesnt back up is roughly how much air you need to be blowing into mpc at any given time based on loudness of course. any more than that leads down the windy road of too much tension.. etc.. which is why we are here! hope this helps.. and as i said Greg will probably have a better answer…

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