Plastic mouthpieces rattling / buzzing in receiver?

[MartyNeilan]

I have a plastic (Lexan) mouthpiece that is good for casual uses except for one problem: The tip of the mouthpiece shank often rattles or buzzes in different tuba mouthpeice receivers. I keep this piece in my bag and mostly use it at schools, so the school tubas may be partly to blame. However, it seems to happen on a lot of different horns. One of my students, so enamoured with the clear appearance, borrowed it the other day but had the same problem. I DO NOT want to sound like I am bashing the company that makes these, because I feel it is a good and innovative product, especially for outdoor uses. However, I would just like to know if others have had this problem and if there might be a simple solution.

[MartyNeilan]

Well, the piece appears to be made correctly, no obvious construction flaws. It also inserts firmly into the receiver, the seal appears snug from the outside. The part that seems to be buzzing is the end (tip) of the shank, all the way inside the receiver.

[Bob Mosso]

Could it have too much taper on the shank?

[Rick Denney]

Could it have too much taper on the shank?

No, the Kellyberg I just bought for cold-weather outdoor playing has a standard taper on the shank, and it fits fine with no rattling.

But the shank will not be as stiff as a metal mouthpiece shank, and it will therefore vibrate with more deflection for a given energy. Just the nature of the beast.

Rick "whose Kelleberg glows in the dark" Denney

[Tubaryan12]

Are those plastic mouthpeices any good, other than the fact there is rattling?

Yep

[Dan Schultz]

Plastic shrinks directly after the molding process and there is a chance the shank might be slightly undersize... causing it to seat further into the receiver. The injection molding process has a couple of factors that can create size problems.... the injection temperature, and the injection pressure. Either can cause the product to be small.

I have a large variety of mouthpieces including Conn-Hellebergs, Helleberg 7B, Schilke-Helleberg, Bach 18, Yamaha Roger Bobo Solo, yada yada yada.. but I find myself using a Kelly 18 more than anything else. Yup! ... the Kelly's seem to be good.

[Leland]

Are those plastic mouthpeices any good, other than the fact there is rattling?

As has been said, "Yup."

I was using one almost exclusively for the past year (at least until I got my Bayamo). The Lexan is much nicer to the lips than the standard nylon or Delrin, and it's actually a good shape.

Plus, it has all the benefits of any other plastic-rimmed mouthpiece, namely not sucking the heat away from your chops like metal mouthpieces do. It was no longer a temperature-induced problem to stand around for half an hour and immediately try to play -- even room-temperature metal is 15-20 degrees colder than a warm face.

[Lee Stofer]

Schlepporello,
If THAT's the case, remind me to NEVER EVER play a crystal green one! The crystal red Kellyberg continues to be my favorite.