More on Piano Action Regulation
The goal of regulation is to make the piano as responsive as possible to the pianist's input. To do so, the piano has to respond consistently and accurately at all dynamic levels and tempos. If you've ever played a piano that seemed to respond telepathically to your input, then that gives you an indication of what a good regulation can do for a piano. A piano that is well regulated is easier and more enjoyable to play, and that makes it easier to get lost in the music.
Each key in a grand piano has over 35 points of adjustment, from the height of the key (down to the thousandth of an inch!) to the distance from the hammer to the strings. The technician's job is to make those adjustments over the entire keyboard, so that each note responds predictably, accurately and consistently. Over time, as the wood, felt and metal action parts wear, compress and shift, your piano will become less responsive. If you've noticed that:
- It's more difficult to play evenly on your piano than it used to be
- You don't have as much dynamic range as before (You can't get softer than a mezzopiano and/or can't seem to get louder than a forte)
- It's more difficult to play softly (not all notes sound, or they aren't evenly soft)
- It's harder to play very quickly (fast repeating notes don't always sound out every time)
- Visually, the hammer line is uneven (hammers aren't all a uniform distance from the strings)
- The keys themselves are uneven heights (especially noticeable on the white keys)
Then your piano would definitely benefit from having the action regulated. If you bought your piano used, then you won't have a frame of reference of the idealized "before," but a qualified technician can inform you of the condition of the action and whether it would benefit from a regulation.
As for how often your piano should be regulated, that depends on usage, climate and your personal preference. As with tuning stability, pianos that are kept in well controlled environments will hold their regulation better than pianos in environments where temperature and humidity fluctuate greatly. If you bought your piano new from a reputable dealer, then they should have done a basic regulation before the piano was delivered to your home. It would still be a good idea to ask your technician to check the regulation at the first tuning, just to ensure that it's where it should be as the piano starts its life with you. If your piano isn't played often and/or is in a steady climate, then once every 5 years might be all that's needed. If you are an advanced player who practices for hours a day, then it might be worth having the action checked over once a year. If your piano is a concert instrument with regular public performances, then your technician should ensure that the regulation is always kept to a high standard.
For more information on regulation, read the PTG's Bulletin on Action Regulation.