参考までに http://www.floydcooley.com/ より
Searching for ways to improve on the classic Helleberg mouthpiece
so many players use, I worked with well-known German mouthpiece maker
Joseph Klier to develop the FC Helleberg. This mouthpiece is similar
to the smaller Helleberg mouthpiece such as the Conn Helleberg 7B,
but has a differently shaped backbore which results in a much more
resonant sound. I use it on my new Nirschl York CC tuba and it helps
to produce a strong, well-centered sound on this large horn. It is
also an ideal choice for use on F tubas, as it helps to open up the
sound of the lower register. Any player currently using a Conn
Helleberg 7B or similar Helleberg mouthpiece, who is looking for
a more resonant, centered sound, will want to try this new mouthpiece.