Klarinet Archive - Posting 000794.txt from 2000/09

From: "Clark W Fobes" <reedman@-----.com>
Subj: [kl] Correlation: Tip opening and tongue speed
Date: Mon, 25 Sep 2000 17:19:52 -0400

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Let's see.. I have been working with mouthpices seriously for only 15 =
years so I have a short list of iron clad "maybies" when it comes to =
rules of mouthpiece design.

The tip area of the mouthpiece is very interesting and for the most part =
controls response. There are other factors that come into play, but the =
tip area exerts the greatest influence on response.

I have a theory that I call the "plane of resistance". I have no way to =
measure this other than through the subjective experience of trial and =
error. ( a LOT of errors).

We know that the beating reed acturally never touches the tip rail given =
a properly matched facing and reed strength. (If you play a very soft =
reed on a standard 1.00mm facing the reed will collapse, touch the rail =
and stop vibrating)

The flow of air through the tip of the mouthpiece is probably much more =
complex than what I am about to describe, but bear with me for the =
moment.

Consider that the flow of air between the reed and the tip baffle (that =
area just behind the tip rail) as a cushion of, say foam rubber. As the =
reed bends towards the mouthpiece in its cycle the cushion is =
compressed, but resists the reed. At some point the air creates enough =
resistance to help start the reed back in the opposite direction. Of =
course the reed strength and density, the loudness of the tone ( =
amplitude) also influence this point of return. BUT, at some point the =
reed must stop its movement towards the mouthpiece and begin moving in =
the opposite direction. I call this point "the plane of resistance".

There seems to be an optimal plane of resistance for each mouthpiece and =
this varies with tip opening. Response is also affected by the length of =
the facing (fulcrum point), but for simplicity let us consider that we =
are making a 17mm facing with various tip openings.

If I wish to have a similar response ( tonguing speed) I can generally =
do this with a variety of tip openings, because I understand this =
concept of the plane of resistance.

With a narrow tip opening (1.00mm) the tip baffle must be relatively =
low. As one opens the tip, there need to be a slight "roll" in the =
baffle behind the tip. As one reaches something more like 1.12 - 1.20 =
the roll becomes more pronounced and projects further into the chamber.

As the tip opening increases the plane of resistance must be moved =
closer to the reed so that it responds properly, this is the reason for =
the higher baffle design in more open facings.

Conversely, if a mouthpiece has a low baffle ( like Zinner blanks) one =
must use a very narrow tip opening and , usually, a short (15mm-16mm) =
facing to make them respond.

Of course, the quality of sound changes as well even though the plane of =
resistance may be similar. An open mouthpiece with a high baffle just =
does not sound the same as a close mouthpiece with a low baffle - but I =
can make them so that you can play the same reed on each!

Clark W Fobes

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