The sound post is the heart of the double bass. The location and fit of the sound post is directly proportional to how your bass will respond tonally. At Upton Bass String Instrument Company, we hand-turn EVERY ONE of our own spruce bass sound posts in-house from top quality spruce tonewood imported from Germany. Our sound posts are straight grained, with no grain run out. We hand-select logs of seasoned spruce- age lofted for seven years- and turn them into our premium sound posts. Our sound posts are available in 19, 18, 17, 16, and 15mm. We can custom make a sound post to fit any double bass.