The damper arm on a Rhodes piano is the mechanism for each note that allows the damper felt to rest against the tine. When the note is pressed the damper arm lifts and removes the damper felt from the key allowing the note to sustain. This is achieved by the bridle strap coming under tension and pulling the damper arm. The damper arms are also lowered simultaneously when the sustain pedal is pressed, giving the Rhodes piano an expressive sustain like an acoustic piano.
Damper arms are made of aluminium, and depending on the year of Rhodes manufacture are either individual for each note or come in a comb of 12. These damper arms assemblies are typically found in Rhodes pianos made after 1974. They are configured in three difference sizes: bass, mid, and treble for the respective areas of the piano.
Process:
Damper arms are naturally under tension against the tines. This eliminates unwanted sustain at rest position. When the key is pressed key pivots on the balance rail, lifting the key pedestal. This in turn pushes the hammer cam towards the time. At the same time, the bridle strap attached to the hammer cam is put under tension and pulls the damper arm down. This happens just before the tine is struck by the hammer tip, allowing the note to sustain.
When the key is released the key pedestal moves downwards, releasing the hammer cam from stop-lock. In turn this releases the tension on the bridle strap, causing the damper arm to rise and press against the tune, dampening the note.
With the sustain pedal pressed the same process occurs, but because the dampers arms are already lowered by the damper lift rail , the bridle tapes are never put under any tension.
Regulation:
Damper arms can be adjusted in two ways: the first is the correct timing of the damper lifting before the hammer tip strikes the tine. This should be even throughout the whole keyboard. By undertaking this regulation, lost motion can be introduced into the note, reducing the tension, and creating a slightly lighter touch. This is measured by seeing at what point the damper lifts when the hammer moves towards the tine. The damper should lower when the tip is halfway towards the tine. Adjusting this is mainly done at the centre point of the smaller arm. Finer adjustment of the damper tip can be achieved by adjusting the arm just below the damper felt as seen in this diagram.
The second aspect of regulation is adjusting all damper arms so that when the sustain pedal is pressed they all lift evenly. This is a less important aspect of regulation for touch, but is important for even dampening of the dampers when the sustain pedal is released.
For beginners to the regulation process, firstly ensuring the damper actually dampens, the time, and then ensuring the damper does not obstruct the vibrating tine are the most important concern. The optimal damper clearance between the damper and the tine when the note is struck should be 3/8” to 1/2” (9 to 13mm).
