Duplex scale

The back portion of the string, known as the resonator, is isolated from the part of the string hit directly by the hammer. The resonator vibrates in sympathy to the note struck, this is called the duplex scale.
In Fazioli pianos, the duplex scale is completely adjustable because of a system that enables the length of the resonator to be modified.
This system enables the resonator to be tuned to the finest detail.