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Why are clarinet mouthpiece chambers square ?

Steve

Clarinet CE/Moderator
Staff member
CE/Moderator
Why are clarinet mouthpiece chambers square ?

Several times I know posters have asked why Clarinet Mouthpiece (aka "mpc") Chambers are square. Most readers are simply curious and wonder simply because they also play saxophone and notice that the saxophone mpc throat is customarily round.

If you are looking for the exact scientific, fully researched answer here .. you are not going to get it. This should hopefully make normal readers think and understand “why” it isn’t round.

Through readings, research, communications with mpc makers, clarinet makers, other repair people et all I’ve come to these following conclusions.

First, in general, the clarinet bore is a ever slightly increasing cone. So slightly increasing (okay, I’m also including polycyclindrical here) that it is considered, more or less, a cylinder and more importantly a pipe with both ends having approximately the same size openings.

But lets think of it as an ever increasing minor cone for arguments sake.

For playability, if that ever increasing cone is linear then resistance up and down the instrument would be linear. If the bore increased, decreased here and there then the resistance would change based on the variable difference at particular locations in the bore. The further up the bore the section was increased, the more resistance permutations and anomalies which would affect the entire bore and consistent playability.

So keep in mind, the mouthpiece must be of a certain volume to complete this “cone”. So if the throat increases one must decrease some other section of the mpc. And unlike the sax, the clarinet mpc goes into a barrel versus onto a neck – that neck which further reduces the cone volume in the mpc shank bore but is infinitely more adjustable than a clarinet – I could add thicker cork to the neck to allow the mpc to stick further out and increase the length of the cone

Now for an extreme, potentially unrelated example, lets think of fluid dynamics here

If you pour oil into a funnel you will notice that you can fill up the top part of the conical funnel quite quickly. But the lower part, much smaller cylinder, is a point of “resistance” of fluid flow. Now correlate that concept to a Tuba mouthpiece. But a Tuba is easily a conical bore, and the large bowl part, like the funnel is the first part of the mouthpiece to create pressure to go into the small part of the cone. So somewhat unrelated ……

Now, what if we put a smaller section before that funnel ? So how we pour oil into a small throat, which opens into a large section, which then flows into a smaller section. What happens with the fluid? Think of variations such as the first cylindrical section being larger than the bottom cylindrical section, and vice versa – we can create some serious fluid flow issues or lack thereof.

The fluid will consistently, smoothly flow into the middle section due to the pressure being exerted on it (gravity in this example). If the funnel was 100% vertical it would flow right down into the bottom, but if at an angle we could get a messy middle section. Now with air, the air is going to expand when it reaches that chamber. So with 100% air pressure consistency going from the top section into the large section we are going to get a dramatic decrease in pressure consistency, for argumentative sake, say down to 10%. Plus the airflow will be more scattered and inconsistent. Now this has to build up pressure to go into the next smaller cylinder section. Think of chaos in the part of the player having to create a consistent pressure (resistance) with the instrument at this point. I’ll leave the rest of this concept to the reader to think of the variations and problems and move on to more relevant concepts.

Upon experimentation and research (and buying a bunch of mpcs) one is easily able to ascertain (if ones ear is able to ascertain these variables) that on a french clarinet mouthpiece that the breadth of timber is related to the width, or non-width of the vertical sidewalls. The terms usually used here are “H” or “A” throat. An “H” throat being basically vertical sidewalls, and an “A” throat being sidewalls that are closer at the top, and wider at the bottom which may or may not be linear in it’s variability.

Of course, the measurement of the distance between the sidewalls also vary dependent upon the tonal qualities one is after.

Now, for french mpcs the roof of the window area directly impacts certain attributes. Let us break that roof into 3 sections. 1/3 of the section from the tip rail to the 1/3rd mark, the middle 1/3rd and the lower 1/3rd going into the throat area. In short, each section affects certain registers affecting certain harmonics, and thus affects intonation AND the timber in certain registers of sound production.

As you move to the throat you can increase the depth of the roof to give darker timbers in certain harmonic ranges.

Right after the throat in the bore, the diameter, or conical diameter greatly affects the sonority of certain registers and intonation of throat tones.

Now, although you can design a mpc with strictly a cylindrical bore (or large round throat) it is a design criteria to have the largest section of the cone either in the barrel or just below it. A round throat, would of course, change the entire internal of the mpc and affect the overall tonal quality.

Tonally, I would not sound very good. It would play. But the modal ratios for the upper twelfths would be screwed up, as well as sonority et all. One would then have to have a smaller, longer, more cylindrical barrel, which would affect other “things”. In short, you would end up redesigning the entire clarinet and probably have a clarinet in tune, though loss of sonority and tonal complexities that the current designs offer.

So as you modify that round throat to be able to affect the tonal qualities you would end up with a squarish type design.

In summary the current square design greatly affects intonation, sonority and timber of the clarinet. Creating a round throat would have to create other solutions for these areas of tone, plus it would affect the overall control and playability.
 
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