Abstract: Improved dynamic-acoustic system of guitar (X) with soundbox (184), creates a better scheme of dynamic forces cooperating with soundboard (168) of guitar (X). This system makes it possible for the top to vibrate more freely, producing a full, open tone. Through the use of additional energy, resulting from moving the string attachment from soundboard (168) onto acoustic arm (10), the soundboard (168) is not put under string tension, as in standard flat top, classical, or arch-top guitars. Allowing much lighter braces to be used without a imploding or exploding soundboard (168). Acoustic arm (10) is a simple mechanical element attached to neck (82) of guitar (X), creating its extension inside soundbox (184). Neck (82) with attached acoustic arm (10), is installed in top block (74). Next, neck (82) attached with two bolts (100) and (124) to soundbox (184), creates a separable, rigid construction of guitar (X).