In a musical instrument, such as a flat top guitar, having a sound chamber defined by a back, sides, and a soundboard, a beveled portion is generally placed in the bass side of the lower bout of the instrument. 1 at a focal plane of the assembly. Sealing contact faces are preferably defined by pole faces of the second solenoid and a peripheral fluid flow passage extends through apertures defined within the second solenoid and between the sealing contact faces. A maintaining signal input end provides a maintaining signal for the first capacitor. The location and size of the crown stress reducing feature, and their relationship to one another and other club head engineering variables, play a significant role in reducing the peak stress seen on the golf club’s face during an impact with a golf ball, as well as selectively increasing deflection of the face.