Regulating for Voice

By Jim Busby, RPT

Sponsored by Piano Technician Tutorials and published with permission from Jim Busby. The following is an excerpt from Complete Piano Voicing, Chapter 4: First, You Must Regulate and Tune. 

While everything matters in regulation, a few things are more crucial to tone than others. For practical reasons, in this article, we will call everything that is not voicing or tuning “regulation.” Here are some things to which you should pay particular attention before attempting to voice:


Letoff can make a big difference in piano tone, especially if it is “blocking” (so close that it causes the hammer to enter the path of the vibrating string). Likewise, letoff that occurs too far from the string lessens power from the keystroke, making it difficult to play pianissimo, if not impossible. Letoff should never be sacrificed to achieve better aftertouch or for any other reason. Furthermore, if letoff occurs too far from the string, it can prove difficult to mate hammers to strings because of the inability to properly block the hammers against the strings. 


There are many parts in the piano action that require alignment, but nothing affects voicing more than the hammer to string alignment. In particular, the hammer must be aligned to the strings so that the una corda pedal can be used with precision. When the una corda is used, the left side (bass side) of the hammers should all reach the edge of the left string at the exact same time. Even if you center the hammers to the strings, remember that you must check this alignment because some artists like to miss a string, while others prefer a “ghost” of a note from the left string at full shift. You should also note that not all hammers are exactly the same width. In short, always check/set to the left (bass) side of the hammer for the very best una corda accuracy.

Another alignment that can have a big effect on piano tone is the alignment of the strings under the capo bar. The strings should be in a straight line and not angled at the capo. Many times pianos that lack power have been improved by simply aligning the strings.

Hammer alignment (twisting shanks) and hammer travel should be addressed as well. This is especially important to check after the glue dries on a new set of hung hammers. The same goes for repinning and any other intensive work you may do with the action.

Blow Distance

Contrary to popular thought, slight differences (say 1-2 mm or so) don’t seem to have much effect on tone as some think. We point this out because some technicians use what is called a “blow priority” regulation sequence to maintain the blow specification at all costs. Once again, based on the spectrum studies (Editors note: the spectrum studies were conducted at BYU in conjunction with the physics department and are unpublished.), we have found that blow can vary slightly from spec with little effect on tone. Of course, with more extreme variances in blow distance, the tone will be negatively affected. 

Touchweight and Friction

Touchweight is not really a part of regulation but let’s include it here for practical reasons. Anything that does not “feel right” to the pianist may be perceived as a voicing problem. Touchweight is especially important when solving general problems in a piano. For instance, hammers that are too heavy or too light can drastically affect piano tone, besides what it may do to the touch. Therefore, if you lighten the hammers, you must also consider the downweight (DW), upweight (UW), balance weight (BW), and other aspects of the touchweight. It’s all tied in together.

Especially important is the evenness of the touch from key to key. Many times we’ve heard clients say that a piano was “too dark” or “too bright,” but upon evaluation, we didn’t find the voicing that far off. The touch, however, was like a minefield, with 70 grams DW on one key and 40 DW on the next! After we corrected the touchweight, the client exclaimed, “Wow, the piano sounds brighter and very even!” No “voicing” was done, but in fact, evening out the touchweight was what the piano needed.

Similarly, installing new key bushings is not regulation either, but technicians must “fit” the newly bushed keys to the keyframe, and this is on the periphery of regulation. If you haven’t noticed, nearly everything in piano work affects other things. That is why a good voicer is always a top-notch tuner and regulator.

Excerpt from: “Grand Piano Regulation.” For more information or to purchase the book, visit

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