Hi there
just curious about the stopper.
Different materials and shapes have a different effect on the sound?
A sound-reflective plate or something-similar can improve or change the sound?
Someone tried to use a resonator as a reflecting plate?
http://www.r5-usa.com/files/89895210.jpg
Many thanks, as usual
I’ve experimented with a few different materials, just to see if there was any effect. I had read about Robert Bigio’s practice of using various metals (and putting a groove in the face of the stopper) and how many players insist that it makes an audible difference. These are for silver Boehm flutes, mind you. I’ve tried this approach with both wooden head joints for Boehm flutes and with my own Pratten flutes. I did aluminum, stainless steel and delrin (a nice spread of different densities) and couldn’t hear the slightest difference.
That’s not to say that there is no measurable sonic difference, but my ears are not golden enough to detect it (and I’m pretty used to listening for changes of nuance in flutes that I make). I even tried them on a really nice Sankyo (Boehm) flute and couldn’t notice any advantage. As a result of those limited experiments, I chose to stick with Delrin stoppers because they are infinitely easier to manufacture. Stainless steel was very slow (being so hard and dense) and didn’t confer any special properties to my ear, and it also made the head joints a bit top heavy.
There are so many gimmicky things that are supposed to improve the sound of flutes, and there is so much placebo effect/bias involved in trying them that it is not a clear-cut sort of thing at all. But, if the player tries something like that and likes it, that justifies it. If it sounds better to you, it IS better, regardless of whether anyone else can hear it.
You can try easily yourself if you get a thin metal disc the right diameter. Try a dime or five pence or something you find around the house for a laugh. Fix to cork with Blu tac. Reset cork. Play for a while. Take it off cork face again. See if you think it improves the sound?
Many thanks
iwill try some ideas i have in mind, then i’ll let you now. I have some small saxophone pads to try, i will remove the resonators to make some experiments 
another question (i don’t want open a lot of silly topics)
“scalloping” tone holes, raises or lowers the note?
Many thanks!