What is the difference between the underdamper and overdamper piano? The underdamper piano has its dampers (the soft white or yellow cushion looking things that lift when u press a key or press the right pedal) placed underneath the hammers (the things that hit the strings). The underdampers genrall damp the sound better when the pedal or keys are lifted. The overdampers are situated on top or over the hammers, the overdamper mechanism is as*embled and connected to a beam that basically blocks you from seeing much of the action in the piano. The overdamper on the other hand does not damp the sound that well. If your piano is worn and old when a note is played and the key and pedals are released the sound tends to carry on as if the piano was placed in a big concert hall.