AR Resonance Trumpet BackboreSIZING CHART For decades we have been told a wider rim and a deeper cup is the way to achieve a bigger sound. Or that a shallower, smaller cup is what you need for a lead sound. This is not our philosophy. At AR Resonance we believe the most important element in a mouthpiece is the backbore, then comes the throat, then the rim and finally the cup. Follow us and you'll see why. The most important and often totally neglected parameter each player needs