The Regulation Triangle Method

I have developed this method to help me quickly analyze an action and know how to improve it.

The following is a reply to a member of another forum when he asked about grand regulation. Some of the specific values refer to grands.

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Hi Ian,

I have developed a model of regulation that may help you. I call it the Regulation Triangle.

I mention it because your comment seems to show some confusion (either by you, or me! LOL)

Anyway, on a grand, capstan adjustment affects blow distance, which does not affect let off, but does affect aftertouch.

Here’s how the Regulation Triangle basically works:

Consider three adjustments we set directly – Blow, Dip, and Let Off.
Consider this element that is set indirectly – Aftertouch. Proper aftertouch is used to create optimum feel in the piano.

To know how aftertouch is affected by the triangle elements, consider each triangle element and how a change in its setting affects the piano’s feel and ability to perform. (These relationships are not 100% accurate all the time, they are just used to envision how the action responds to adjustments)

Using a golf term called the “Pro Side”, we will identify the specification of each element and the pro side, that is, which side of that specification we would want, if we had a choice.

The adjustment of each element is identified as affecting a certain musical quality. Again, this may not be accurate, or the whole story, but the purpose of the model is to create a method of quickly knowing how one adjustment affects another within the piano.


Blow / 1 7/8″ / Power / More is better
Dip / 7/16″ / Speed / Less is better
Let Off / 1/16″ / Sensitivity / Less is better*

*Careful of burbling or double striking.

Here are some way to “measure” aftertouch:
– The jack should escape the knuckle when the key is all the way down, and settle halfway between the knuckle and the back of the repetition window.
– You should be able to “feel” that there is a little room for the key to move after let off.
– After let off, the hammer should rise about 1/16″
– There are spacers like plastic feeler gauges, that you can put under the key. The thickness of spacer that just produces the start of let off, requiring a firm press to achieve let off, is considered a measure of aftertouch.

There is a range of possible measurements for that. Pianos Inside Out suggests 0.040″ (1mm) but you can buy a variety of these feeler gauges to set aftertouch where it feels right for you.

Anyway, here is the process that I go through when analyzing an action’s regulation settings, assuming all the other non-variable* specifications are set properly, like proper repetition spring tension, jack knuckle alignment, drop, etc.

*Non-variable, in the way I am using it, means there is only a narrow acceptable window of settings that produce desired results.

Measure aftertouch.

Excessive aftertouch? I do the “Woo Hoo” dance because I can “soup up” or improve the action’s feel by:
– Reducing let off (more sensitivity)
– Increasing blow (more power)
– Decreasing dip (more speed)

Not enough aftertouch? I do the “Bummer” dance because I have to rob from the triangle.
– Increase let off (less sensitivity)
– Decrease blow (less power)
– Increase dip (less speed)

Blow seems to be the most “rubbery” specification, and therefore the one I choose to adjust most of the time to get good aftertouch.

I hope that helps. It is a holistic view of the action behaviour and it has allowed me to quickly analyze an action without trying to envision how all the little parts are connected and how each separate movement affects another within the chain. Maybe I just have a small brain. 🙂

Remember, the judgements of quality of musical characteristics’ effect by changes in regulation triangle adjustments, are just made to help me quickly analyze the action using the triangle method. As I already said, the comments made about them are not to be inferred that the effects are written in stone, only useful in that they help with the analysis, even though I have found them to be accurate almost all the time.

The Regulation Triangle

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