Author: Brad Behn
Date: 2007-04-20 01:10
I believe that either a perfectly flat or slightly concave table is ideal but there are mouthpieces with very deep concave or convex tables that work (to some degree), so this subject can be very tricky. The key is to make the table of the mouthpiece work in harmony with the rest of the mouthpiece’s playing characteristics (material, facing, chamber, bore).
There are three different types of tables…convex, flat and concave. Each of these types is very common but only two are considered “correct.”
The type that is frequently dismissed is the convex table, but it appears frequently for two reasons. When a mouthpiece is faced by hand the typical method of flattening the table is to draw the mouthpiece on the sandpaper, backed by a flat granite or glass surface. This technique is flawed because in most cases it actually causes a slight convexity. The problem is that a mouthpiece's table extends into the window and as the mouthpiece is drawn across the sandpaper, hard rubber is removed at two different rates because the table that is associated with the window has less surface area than the table that isn’t associated with the window. The end result is that the table that is associated with the window has had a higher rate of material removed on the same sandpaper swipe than the rest of the table, and a slight convexity appears. This convexity is VERY common on hand-finished mouthpieces. Even though this common defect may allow for a high functioning mouthpiece, intellectually speaking it isn’t considered ideal. The other reason why a convexity may appear is if a mouthpiece has been used a lot, the table can warp causing any number of issues, including convexity. This type of convexity is typically associated with other problems like rail-tilt and or asymmetry on the rails, which make the mouthpiece function poorly.
When thinking of the various types of tables, one must also think of the degree of convexity or concavity. A flat table (when rendered properly) is absolute and has no level of degree. Flat is what it is…flat.
Convex tables are typically subtle, but when a high level of convexity appears, it generally creates a difficult environment for the reed to properly mate to the mouthpiece. This creates playing characteristics that can lead to shrill, edgy sound, squeaks, difficulty to control pitch, and a sound that is generally not very warm or sweet. Tables with only a slight convexity can play almost as good as flat tables but they tend to lack the hold and warmth of sound that come from a truly flat table or slightly concave table.
Flat tables are in many ways the perfect solution because they create an honest surface for the reed to mate to the mouthpiece. Flat tables play with the least amount of embouchure pressure and with a focused sound that is flexible and clear. The one potential drawback of a flat table is that if the reed warps, the honest relationship between reed and table becomes embittered and could create issues similar to a convex table. Essentially, a flat table is less forgiving with warped reeds than concave tables.
Concave tables are most common with machine made facings because as the machine cuts the table, the rubber expands due to heat and therefore the center of the mouthpiece bulges outward creating a slight hollow after the rubber has cooled down and shrunk to its normal state. Some machine made facings are also made with a concavity on purpose. So it can be either a case of machining operations or a case of design, but in both cases, it is very common. Zinner mouthpiece have very deep concavities that do not extend to the bottom of the table, but Vandoren mouthpieces have moderate concavities that do extend to the bottom of the table. In either case, they function as mouthpieces should with correctly shaped concavities, but they both have very different playing characteristics in part due to the depth of their concavities.
In talking about concavities it is important to note the difference between a functional concavity and a non-functional concavity. When the concavity is made, it can extend into the table that is associated with the window (functional concavity) or simply be a part of the table that isn’t associated with the window opening (non-functional). The idea of a concavity comes from the old wood mouthpieces. Because wood is so volatile in nature, in the old days when mouthpieces were commonly made from wood, manufactures found that by making the table concave, it helped allow the reed to vibrate in a more stable and predictable way. The idea was if the wood mouthpiece warped while playing, the table would go convex and it would cause severe playing problems, so to help improve that problem by making the table concave, it created more “breathing room” for the mouthpiece to move while not going to the point of convex-despair. What was then discovered was when properly fashioning the concavity to extend into the window just beneath where the facing begins, this (functional) concavity created considerable influence over the playing experience. By creating a clearly defined fulcrum for the reed’s “springboard” like vibration, it made for a warmer sound that was highly responsive and three-dimensional in scope. It made for a clear and flexible soft dynamic that one could nuance with greater ease.
But the problem was how much concavity is too much. It is a subjective thing to answer, but in my opinion, to much concavity creates a lack of hold, the playing experience requires a constant bite to keep the focus, and to maintain a spread-free sound.
The correct amount of concavity, when balanced with the facing and all other elements of a mouthpiece’s design and material, allow for the reed to vibrate comfortably. You won’t be conscious of playing the clarinet any more, but you will simply make music without unnecessary interference from an otherwise less-than-ideal mouthpiece.
Some specifics: Ligatures when tightened will in effect spring the reed a little bit away from the tip and make the mouthpiece feel a little more open to play. Generally, a mouthpiece with a slight concavity will play very similarly to a perfectly flat table, but concavities that are deep will greatly change the playing experience. The vast majority of clarinetists playing on machine finished mouthpieces are experiencing concave tables.
Brad Behn
http://www.clarinetmouthpiece.com
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