A loudspeaker has a short support post joined to the forward plate; upper end of the support post in association with the fixing post is joined to the middle part of the drum paper with the fixing post; the voice coil has the upper end thereof joined to the drum paper; when the voice coil drives the drum paper to vibrate and emit sound, the upper end of the short support post sways and generates a small offset because of the lower end of the support post being retained by the forward plate such that the voice coil moves axially in the magnetic clearance without deviation, and the voice coil is incapable of touching the yoke or the forward plate to produce noise; therefore, quality of sound output from the loudspeaker is enhanced effectively.