The bore can have a very dramatic effect on compression, sound, and resistance. The dimensions of the bore to consider are diameter and length. Many players only talk about the diameter of the throat. The blow resistance is calculated using the length and diameter.
At clinics we often ask the question, "What is more resistant a #22 Bore or a #28 Bore?" It is not possible to answer this question unless you have the lengths as well. Yes, given the same length the #28 Bore would be more resistant. What if the #22 Bore was .250" long and the #28 Bore was .150" long? Believe it or not, the resistance is about the same! You get the picture. Both length and diameter are needed to calculate blow resistance.
The diameter is usually measured in the industry with a drill size. The #27 Bore is standard with many manufacturers.
The larger the number, the smaller the hole. Of more importance is the length of the bore. A longer bore length will help slot notes, produce a rich sound core, and aid projection. A shorter length will produce a sound that is broad and rich in lower partials, as well as, aiding flexibility. A bore can be too long or too short. Intonation will be affected as follows, too long = flat up high, too short = sharp up high. Commercial players may benefit from longer bores while symphonic players will enjoy bores that are slightly shorter, although, there are exceptions to this as well. Of course, if the length and diameter are not balanced, intonation and slotting of the notes will greatly suffer. Our Bores are matched to the cup and backbore, therefore, they are balanced for optimum results.
Throat Entrance and Exit
Other very important yet often overlooked aspects of the throat are the entrance and exit transitions. In many manufacturers' mouthpieces, these are areas of many discontinuities.
GR Technologies has eliminated discontinuities in the throat entrance and exit transitions.
Blow resistance can also be manipulated in the entrance and exit transitions. By maintaining the same throat diameter and length, a mouthpiece can be made to play more open, or tighter by changing the transition parameters.
Warning! Never drill out the Bore of a GR Mouthpiece
If your mouthpiece feels and sounds stuffy, you may likely have a problem with your gap.
The Bore must be in perfect balance with all other aspects of the mouthpiece. Blow resistance values for each mouthpiece component must be known to produce a perfectly balanced mouthpiece with an even blow, rich sound, and incredible intonation. Since GR Mouthpiece Technologies is the only mouthpiece manufacturer that calculates blow resistance, you can trust us to provide you with a Bore that is correct for you.
GR Throat Exponent
The throat exponent is the math used by GR to design the radius that enters the bore of the mouthpiece from the cup.