Copyright © 2016
by Full-Measure Response, Inc.
All Rights reserved
Enabling your customers to experience the ultimate in keyboard continuity
The Dyna-Stat TM product
More so than any other Key Force 1 - based service, much of the hard-won
underlying technology occurs downstream, on Full-Measure Response's own
computers. It is there that the automated equation-solving engine works its
wonders. Using the mechanism-level parameters (MLPs) and many thousands
of measured forces (all acquired by the automated Key Force 1), the program
goes about its business of solving the three governing equations for each and
every note. This intense solving process is done once with the measured
MLP's, and once again with the desired
MLP's. Between these two
number crunchings, consultation occurs between us, the KF1 provider, and
the piano owner. This consultation stage is covered in a separate section below.
It must be noted here that all
of the as-is key leads remain in place, with the
vast majority staying put for the duration of the process!* All of the important
primary parameters - both static and inertial - are then measured very accurately
by the Key Force 1. And...these measurements are made autonomously, while
the operator can focus on other things! Please note that every single "as is"
note has these static and dynamic measurements made. No "as is" measurement
can be guessed or left up to chance, or else that note's IK and BF cannot be
brought into line! This is another stark contrast to what the Stanwood method-
ology advocates (only 18 notes having their Balance Weights measured).
These items, taken together, provide both the economy and the quality of the
Dyna-Stat key balancing method. The resulting continuity of both "static"
and inertial/dynamic properties across the keyboard has to be seen - and
felt - to be believed. And it can be seen...in the form of extremely transparent
graphical displays of these important mechanism-level parameters...in both
the before and after state! And yes, it can be felt too...more continuity in
both soft and aggressive playing than you or your customers have likely ever
1) focusing on the pertinent mechanism-level equations and parameters,
2) measuring those same parameters with the highly-automated
4) solving those static and dynamic equations simultaneously...twice,
in an extremely accurate and automated fashion.
The up-front technician work is fairly minimal, consisting of:
- disassembling two or three notes to get a nominal keystick mass
and center of gravity, along w/ backcheck & capstan locations, and
a couple fore-aft key measurements. A wippen should be weighed
- measuring the SW (hammermass if possible) of five or six notes
spread across the keyboard. Two or three shank masses (could
be proper spares) are determined as well.
The output of the process is a note-specific
pieces of information for each and every note. This information is:
The end result of the second number-crunching session is a revolutionary,
of piano hammer and key lead changes to be made.
Once applied, this prescription results in the important Inertia at the Key values
and the important
(balance weight) values varying continuously
across the action - something never before possible! As was mentioned in the
articles I had published in the PTG Journal in late 2013/early 2014, this means
that the Key Return Time
will also vary smoothly (as long as friction is in line).
The overall goal: smoothing energy and tone...and saving time
Minimal up-front labor required
Minimal downstream labor required
So the total amount of labor required at the back end is fairly limited, and
very targeted. Each note will likely require some amount of change, with the
changes differing from note to note. To a large degree, the Dyna-Stat system
takes what is already there, and efficiently makes something good out of it.
But not only is it efficient, it is also unprecedented in its end result of getting
the four important, mechanism-level parameters to all
a) how much the hammer head mass needs to be increased or decreased
(the changes can be enacted with the aid of simple scale measurements),
b) the mass and location of an additional key lead that is required *
The efficiency and unprecedented balancing prescription from Dyna-Stat
The consultation stage
Once the Key Force 1 measurements are made on all 88 notes, and after
the initial equation-solving is complete, we help the customer choose appro-
priate target curves. These are the curves for the three MLP's that underly the
entire Dyna-Stat process. With input from the piano owner, we choose curves
that will give him the type of "feel" he seems to be after. If he indicates no
preference whatsoever, then - within reason - target curves are chosen to min-
imize changes to the as-is hammers. Just to be clear, the "as is" hammers can
be new from the hammer manufacturer, or what had been on the action for
years. In either case, they were on the action when the Key Force 1 measured
Some special constraints on notes 67 thru 88
A little more attention is given to these 22 treble notes in the Dyna-Stat
system. These notes have higher sensitivity to pure hammerhead mass
variation than the midrange and bass notes. Reflected waves in these strings
can cause additional contacts between hammer and string, resulting in unpre-
dictable sound quality and energy transfer. The Dyna-Stat solving process
therefore maintains significantly tighter control over these treble masses. In
essence, it sacrifices some of its inherent inertia-smoothing abilities for the
sake of hammerhead mass continuity. During the final equation-solving
process, hammerhead mass for these 22 notes is allowed to vary less, while
Inertia at the Key (and thus hammer assembly inertia) can vary more. However,
Balance Force is still tightly controlled, to its best-in-class level
. Thus, a high
treble note with a relatively small AR - and/or a small shank mass - is not allowed
to have those things be fully compensated for with added hammerhead mass.
Rather, it will only be partially compensated for, as its hammerhead is not allowed
* Based on the relationship between the as-is model and the desired curves,
any outermost key leads needing removal were already removed after the
consultation stage! Key leads will only need removing in situations where
hammers are being made lighter and/or the key sluggishness is being signifi-
cantly improved (quickened).
** The exception to this are those upper treble notes (67 through 88), where
Dyna-Stat puts more restraint on how much each hammer is allowed to
change. In this region, more emphasis is given to the Balance Weight (Force)
than to the inertial properties. This is done purely for tonal reasons.
Arguably the most important capability in the Key Force 1 arsenal is the
Dyna-StatTM key action balancing system. Our goal all along - in developing
such a capability - was to somehow find a way to smooth out both the "static"
the dynamic forces across the keyboard. In other words, find a way to obtain
truly smooth note-to-note variation in key resistance across all keys. Forcing the
static (balance and friction) forces to be continuous means more consistent tone
and feel during soft play. Forcing the dynamic forces into continuity - by smooth-
ing the actual Inertia at the Key values - means extremely consistent tone and
feel during more aggressive play. As some may recall from articles I had published
in the Piano Technicians Journal, only by smoothing the static force (Up Force)
and Inertia at the Key simultaneously can one obtain smooth Key Return Times!
More about the process
More insight into all this solving & smoothing
With the as-is measurements all taken, the equation-solving program does
its thing back on our computers. The result is the establishment of behaviorally
accurate mathematical models for all 88 notes. Each and every note has four
critical parameters solved for by
the solving engine. These four - in combination
with several other "constants" across the action - define a unique mathematical
model for each note. This quadra-set of calculated as-is parameters consists of:
an equivalent "front mass" key lead configuration
Any one of these four values may not exactly
match that of the real mechanism,
but the combination
of the four together -along with those constants - does
resent the mechanism extremely well! In fact, several different combinations, or
, are inevitably calculated for each as-is note. We have shown ana-
lytically that mathematical models based on any one of these quadra-sets behave
nearly identically! That is, if 1 gram is added to the hammer, the resulting change
in IK, KRT, and BF is nearly the same...no matter which calculated quadra-set was
used in establishing/setting the as-is model! Similarly, if a 15 gram keylead is
added out front, the resulting change in IK, KRT and BF is - again - nearly the
same, regardless of which quadra-set was used for the model. This as-is quadra-
set can therefore be used to solve the equations again, when the desired
are used as inputs. Two out of the four quadra-set values (hammerhead mass
and front mass/configuration) are manipulated tirelessly and automatically, until
the three equations again solve simultaneously. The required changes in these
two items (hammerhead mass, and front mass configuration) represent the note-
specific prescription for modification.
What all this means is that our system can correct for variations in true
Inertia at the Key - and BF - from note to note, regardless of the exact source
of those variations! Whether a given note's IK value is low because of a low
hammer mass, a low shank mass, or a small AR, the resulting Dyna-Stat pre-
scription tells us exactly what changes to make to bring IK in line, while also
bringing - or keeping - the Balance Force in line! It does the same thing for
the other 87 notes, each with their own nonobvious prescription for change.
Currently, the prescribed fixes have to do with either changing the hammer-
head mass or adding a key lead mass at some location.*
Depending on custom-
er preference, a prescribed increase for the shank (a shank clip) could also be
added to the mix. If a piano is ever encountered that has note-specific AR ad-
justability, an AR change could also be part of the prescription. For now, a note-
specific combination of hammerhead change and a simple keylead change is
sufficient to bring all notes into line, on most any piano!
For each note, the program immediately examines the desired values of the
MLP's in light of the as-is mathematical model found for that note (the quadra-
set, essentially). It knows immediately if the combination of desired values
is physically possible for that note without removing the outermost key lead.
The program quickly determines any note numbers that require their outermost
lead to be removed. Those leads are removed and weighed, and their location
from the front edge is recorded. This data is fed to the solving engine on our
computer - so those removed key leads are completely accounted for (both
statically and dynamically) in the final equation-solving routine! Such key lead
removal is typically only required when the hammers are - in an aggregate sense -
being made lighter, and/or when the static forces are desired to be a lot higher.
What makes Dyna-StatTM possible?
3) the ability to only remove existing key leads if absolutely necessary, and
What about hammer assembly inertia? What about energy?
So...the randomly varying ratios have what effect?
We've described how we can efficiently and confidently smooth the true feel
(touchweight) of the action, across all notes. This is done by smoothing the
IK and BF (balance weight) values. Of course, this feel includes continuously-
varying "key sluggishness" properties too, since Key Return Times are also made
smooth. This means that, for any given key speed, the final energy in the entire
key mechanism will vary smoothly from note to note. To a huge extent, it also
means that the hammer assembly rotational energy values will vary smoothly
Each different ratio requires a different value of hammer assembly Moment
of Inertia (MI-Hmr), in order for that hammer assembly to have the same kinetic
energy. Those notes with slow-moving hammers (low AR's) must have higher
values of MI-Hmr. Those notes with faster-moving hammers (high AR's) must
have lower MI-Hmr values. But the total hammer assembly energy - for any given
key input - stays nearly the same. Whether the AR is deviant or not, a low ham-
mer or shank mass is determined by the solving engine, leading to a Hammer
Mass Add (HMA) prescription. When a low AR is determined, this also leads to
an HMA prescription. Similarly, a high hammer or shank mass - or a high AR -
tends to lead to a Hammer Mass Remove (HMR) prescription. The three simul-
taneous equations take care of any such situation or combination thereof (e.g. a
heavy hammer, with a light shank and low AR). The front mass prescription is a
bit less straightforward, since "too much" front mass lowers BF, while raising IK a
tiny bit. But again, the three equations take care of all of this automatically
resulting in note-specific prescriptions for all 88 notes!
So, randomly varying AR's prevent the hammer assemblies from having contin-
uously-varying moments of inertia. However, we can safely say - to a huge degree -
that the hammer assemblies' rotational energy
indeed vary smoothly
from note to note, for any given final key speed. This is exactly what our Dyna-Stat
system does! This is what produces smoothly-varying tone and sound power.**
In short, smaller AR's require larger MI-Hmr values; larger AR's require smaller
MI-Hmr values. In either case, hammer rotational energy is made continuous.
This was a tremendously difficult proposition. But if it could be done, we would
be talking unprecedented stuff, whether it be for the piano repair, action compon-
ents, or piano manufacturing industries. The ability to do this while also saving
time and money would be even more of a game changer. Thanks to a combination
of the Key Force 1 and the Dyna-StatTM system, this has indeed finally been attained!
This accomplishment now gives you, the piano technician, a new array of tools to
best respond to your customers' requirements. No matter how involved you had
been in action balancing before, you now have every reason to participate in this
groundbreaking Dyna-Stat technology. If you did very little - or no - balancing
before, you can now offer it to more of your customers. If you do quite a bit of it
already, you can now do it much more accurately, and more inexpensively! In
either case, with a modest change in your normal routine and business model, you
can soon be offering some of your customers the finest action balancing - of both
touch and tone - in the world.
The Key to all this: Proper Physics and Mechanism-Level Parameters
After 12 long years of development, it is hard to choose any two or three break-
throughs as having "made the difference" in arriving at the Dyna-Stat level. It goes
without saying how instrumental the revolutionary Key Force 1 equipment itself
has been to the endeavor. Aside from that, a huge part of Dyna-Stat's ultimate
success stemmed from careful formulation - and efficient solving - of three
governing equations (one "static", two dynamic) for each note across the piano.
Once the proper equations are focused on and formulated, mechanism-level
parameters (MLP's) make their appearance elegantly and almost effortlessly.
These MLP's are essential if the ultimate goal is an automated, non-invasive,
and extremely efficient way of assuring smooth variation in the important
playability parameters, all the way across the keyboard. In essence, the key is
that these MLP's not only appear in the equations to be solved, but that these
same MLP's are actually measured on the piano action itself! This fact is what
ultimately completes the circle as it were, allowing the technology to spring
forth. Here is a quick visual sample of the "as is" output and display of some of
these MLP's, from actual piano measurements:
The solving engine can also solve the equations using shank clips
, rather than
adding mass at the hammerhead. This reduces the labor some, and results in a
more reversible product, if the customer finds the end result to be too light or too
5) the unprecedented accuracy with which the pure static forces are measured.
Again, there is very little labor price to pay for all this meticulousness in meas-
urement, as the measurements are made autonomously by the Key Force 1
machine. Not only are the measurements autonomous, they are also the most
accurate and precise measurements available anywhere! We can't stress enough
the importance of assuring truly accurate "static" forces (Balance and Up Forces)
in a world-class action balancing product. While we are finally bringing the true
dynamic equations into the balancing mix, no one should discount the importance
of simultaneously assuring smooth Balance Weights (Forces) across the keyboard.