aftertouch

[Delwin D Fandrich]

Stephen Birkett wrote:

> ....
> Interesting to compare the Bluethner patent action, which is specified to
> have no aftertouch, with the Erard, or modern, action, which is supposed
> to have a spec. amount of aftertouch. Why is is a requirement for Erard
> or modern? What makes aftertouch necessary for proper function of the
> action?

-------------------------------------------------------------


Stephen, et al,

Basically aftertouch is required in the "modern" action to allow the jack to escape. It
must rotate enough so that the tip of the jack avoids the hammershank knuckle as the
hammer rebounds away from the string set after impact. If it does not rotate enough it is
quite possible that the knuckle will bounce against the tip of the jack and cause the
hammer and shank assembly to oscillate -- repeatedly and rapidly impacting the strings.
This phenomenon generally called "bobbling." Aftertouch can be viewed as insurance. It is
insurance against hammer blocking and bobbling. However! How much insurance is actually
required is really the question.

Back when I was doing a lot of concert tuning and prep work I spent some time working with
several different performing pianists trying to figure out just what it was that they
wanted out of a performance piano action. Sadly, the first thing nearly all of them said
was that they wanted them to work! Always during these conversations I was told the horror
stories of the many so-called "concert" pianos simply didn't work very well. Beyond that,
they wanted the action to feel uniform and consistent, both in tactical response and in
voicing. Solid tuning was a given. They mostly expected -- and got -- that. Most of those
horror stories were about action performance, often on very well tuned and voiced
instruments.

Getting into the details of regulation preferences, most of them wanted jack letoff to be
as close the the string as possible without making the hammer block on very soft blows.
They wanted "dynamic" touch weight to be absolutely consistent. I found that many, if not
most, of those I queried could definitely feel -- and they did not like -- the
inconsistent key leading most modern actions are plagued with. I.e., there couldn't be
four leads in one key and five in the next and then three or four in the next, etc. This
meant there must be an engineered and uniformly tapered leading scheme. No "individually
weighed off" keys for these folks! Irregularities in static touch weight had to be tracked
down and fixed. Rarely was aftertouch mentioned as such. They wanted key travel -- i.e.,
key dip -- to be as short as practical and as uniform as possible. And they really meant
uniform! More often, if it was used at all, the word "aftertouch" was used in a way that
really meant key travel.

After playing around with different regulation parameters a bit I came to the conclusion
that what was really desired was as shallow a key dip as was practical.  This meant that
with a hammer travel distance of 45 mm and a key travel distance of 9.5 mm, the actual
key/hammer lever ratio should be no more than 1:5.4 and 1:5.1 would be even better. There
should just enough key travel and/or aftertouch to trip the jack and rotate it far enough
out of the way so that the tip of the jack would almost, but not quite, fully clear the
knuckle on a very soft blow when the key bottomed out. The returning knuckle would
complete the job of pushing the jack out of the way. For an action to work reliably in
this manner it requires that relative thin and firm front rail punchings be used. Which
was a good thing, since the pianists also wanted the key to bottom and stop moving with
some authority. Actions regulated this way demanded a fairly precise touch on the part of
the pianist -- generally this was not a problem. They appreciated the challenge and the
control. Ah! The control! The action might seem a bit overly sensitive at first, but the
pianist soon adapted and would soon start trying things they hadn't attempted before.
Actions set up this way also required slightly -- only slightly -- more touch-up
regulation to keep them working reliably. But my, were they ever quick.

All of this does make me kind of wonder why current action configuration and set-up is
going the way it is. It seems to me that using heavier hammers along with the requirements
of additional key leading and/or lower (numerically) key/hammer travel ratios is leading
us away from this quick and responsive type of action feel. Key travel is increasing --
10.5 to 11.0 mm is no longer unusual. How far can the human finger move with the speed
required for some of the faster virtuoso performances? It seems to me we should be trying
to set up actions to make these performances easier, not harder. When I started in this
business, a key travel of 9.5 mm was considered the norm. Probably 8.5 or 9.0 mm would be
even better. (Stephen, what is the key travel on some of these early actions?)

Well, I fear I'm beginning to ramble and it's been a really long day. If anyone else has
any thoughts and/or experience with this type of action set-up and regulating I'd be
pleased to hear about it.

Regards to all,

Del