Abstract
This study aims to be improved classical guitar's sound quality. We are studying for an adjustment in the guitar's volume, power and expression. In particular, we noted surface plate, because the plate affects greatly sound quality. In previous study, we forwarded to design best structure. The plate stretches bracing on the reverse plate. We searched the best layout, and designed good idea. However, there are some problems in these prototypes. Surely, the envelope became gentle slope then the guitar sound was more high quality. The low tone sounds good, though the high tone sounds little harsh. This target is to control, and to amend high tone sound from sharp to soft. Hence we put the magnet near the bridge; moreover we analyzed new model vibration and frequency characteristic. As a result, we decided the good position. It should put near the 1, 2, 3 strings and near the sound hall. When we put there, the guitar became soft sound. Therefore we can control the classical guitar's high order ingredient.
