Soundboard cracks are one of the most common - and most misunderstood - findings when inspecting a used grand piano. Wood shrinks and expands with humidity changes over decades, and a crack simply means the wood has moved more than it could stretch.
Usually harmless
- Thin, stable hairline cracks that run with the grain and don't buzz when notes are played.
- Old cracks that have clearly not widened over time (visible from touch-up finish or age-matched discoloration inside the crack).
Worth investigating further
- Cracks near ribs (the wooden braces glued to the underside) that have caused a rib to separate - this can cause buzzing and does affect tone.
- Wide, fresh-looking cracks, especially several appearing close together, which can suggest the piano was kept in an unusually dry environment.
- Any crack accompanied by an audible buzz on specific notes - this is the practical test that matters more than the crack's appearance alone.
A soundboard doesn't need to be replaced just because it has cracks; the real question a technician assesses is whether it has lost its crown (the slight upward arch that provides string downbearing) and tone quality, not the cosmetic crack count.
