The violin’s soundpost is a small cut and fitted approximately 1/4” spruce dowel that sits inside the violin strategically placed for optimal sound. Its function is to carry vibrations from the top plate to the bottom plate. Optimal fitting and placement of the soundpost will make your instrument sound much better.
When cutting a new soundpost, bare in mind that the end grain should run perpendicular to the violin’s top grain. A perfect fit on both surfaces is essential to a great result. It’s better to cut a slightly too long soundpost to allow for mistakes and tone adjustment which can easily be shortened, than to make the post too short. Longer posts will locate closer to the center of the instrument whereas shorter posts will locate closer to the E string f-hole side. Longer posts tend to favor darker deeper tones, whereas shorter posts favor brighter higher tones.
Moving the post closer to the bridge usually produces more power, whereas moving the post away from the bridge will give less power and a form of richness.
The tightness of the post also has an effect on the violin. A post that is set too tightly will choke the violin and require more bow pressure, whereas a loose soundpost will lack quality and be at risk for falling.