Posted by Klaus on October 01, 2001 at 08:30:27:
In Reply to: Re: Bell creases as a sound factor posted by Matt G on September 30, 2001 at 22:29:06:
My 3 front bells are detachable. And I am glad they are. I would rather not attempt to transport neither fixed bell sousas nor a fixed front bell tuba. I am aware, that at least King has made fixed front bell tubas, but the cases must have been monsters with the the only advantage, that the musicians could use them as beds on tour.
This said I am not quite sure, that your valid considerations are giving the whole answer.
The non-ringing situation of my 40K could be found to support your point. Mounting the bell takes a very good grip. Not that it is out of round. The assembly just has a very tight fit.
But then the bell of my York Master should ring, because the fit is a good deal looser.
And the afterglowing bell of my 26K has a not particularly loose fit.
Somehow I think, that the sonic result of a too loose fit mostly would occur as a buzz, sympathetic or non-sympathetic to the tone played. In the sousa cases very noticeable to the left ear of the player. I actually have experienced this on an Eb sousa, that I once tested, but which I of course did not buy.
Loose bell rim threads have been mentioned as the culprits behind ringing bells. I am a bit reluctant to believe so, as I also think that they would give more of a buzzing sound.
I still think that the ringing sound from the bell is a BELL function (as in church bells) of the outer bell area. Initiated by the energy delivered by the airstream of the player be it transmitted by the vibrating airstream out of the bell, by vibrations from the body, or by a combination of both.
I even believe, that if these vibrations were sympathetic to the notes played, then they would not be experienced as problematic, but more as a flavour to the sound of the tuba (actually reports by RD and Lew point in that direction, so it might be a question, whether their experiences actually fit within the terms of bell-ringing/afterglow as found less pleasant by Joe S, by myself, and by others).
The annoyance comes up when the outer bell areas take up an existence as a separate (non-)musical entity somewhat comparable to a well worn rotary valve lever system, that acts as an uncalled-for percussion section.
And that the culprit is sitting in the outer bell area more or less is proven by the statements from Joe S, that he can stop the ringing by gripping the bell rim by his hand, and by me, that a more or less spongy forehead placed on the bell rim will do the same trick, when it comes to afterglows.
My original point, that creases actually stiffen up the bell, so that the BELL function is made impossible, might find support from a very unlikely place:
Some German and Czech brass instruments makers traditionally have worked out of much thinner sheets of brass, than lets say Conn did when making my two sousas from the 1920-ies.
Hence their nickel silver bell-wreaths, which I can not remember from even one single of the multitude of US and UK made instruments I have seen illustrated.
Wreaths are expensive. That might be the reason, why at least one (ex-)GDR maker offered a Jazz trumpet and a Jazz trombone with bells hexagonal (or was it octogonal) right up to the throat. Sold as a design feature. In my eyes more likely a matter of stiffening a very thin sheet of brass.