Regulation is the process of creating a precise and control feel of the action. This allows the pianist to create every nuance he or she wishes to bring out of the music they are playing.
Regulation is dealing with the action. There are many points in each key mechanism (all 88) that can be adjusted. Because a piano action is mostly comprised of parts made of wood, leather, and felt, these materials can wear, shrink or swell unevenly and need to be attended to. Over time, due to compression of the felts, warping of the woods and other over all wear of the piano, the action tends to decline, and regulation is needed to bring back its beauty and sound.
My regulation process ranges from turning a small screw to sanding down a wood surface or a complete overhaul of the entire action.
The goal of regulation is to make the piano’s touch and sound consistent across all notes, allow it to comfortably achieve the widest possible range of dynamics, and make the keys responsive to even the most rapid or most subtle motions of the player.
There are many dozens of types of regulation a piano may require.
The most important include adjustment of:
- Let-off: the point when the hammer disengages from the jack and flies freely. If the let-off is too large, it can be very difficult to achieve a pianissimo, to execute rapid trills, and to play powerful fortes; if too small, notes can acquire a “pinched” sound, or even block.
- Drop: how far the hammers fall back after let-off. This affects the responsiveness of the action.
- Repetition springs in a grand piano, which allow a hammer to repeatedly strike with minimal lifting of a key. If a spring is too springy, it can cause double-strikes; if not springy enough, it becomes difficult to repeat a note.
- Key weights (and, in some actions, weight-regulating springs) control the inertia of the keys. A technician can add, remove, or change lead weights in the keys to change how light or heavy the keys feel to the player.