THAT MYSTERIOUS BACK CHECK (and other action parts)

Frederick G Scoles scoles@oswego.edu
Sun, 10 Nov 1996 00:05:31 -0500 (EST)



On Sat, 9 Nov 1996, Jerry Anderson wrote:

> Several years ago, in one of the Hamburg voicing rooms
> Stephan Knupfer demonstrated to me that he could get
> a noticable difference in tone quality in a Steinway D by
> changing the front rail felts.
The rest of Jerry's note has been cut to reduce the length of my
reply.

Referring to the Aug. 1996 PTG Journal, Del Fandrich's article on pages
25-31 describes hammer velocity, piano volume, "action saturation",
hammer shank flexing (and flexing of other action parts during mf to ff
playing levels). His charts show that during loud playing levels, the key
hits bottom long before the hammer hits the string (and probably even
before letoff).  These factors can have an effect on volume and
probably also harmonic content. Del mentioned that this action saturation
is more pronounced on pianos having longer keys (larger grands) since
their longer key sticks can flex more during loud playing.

Could it be that the change in tone quality that Jerry observed was also
due to the difference in "shock waves" (or the increased damping produced
by the new, more elastic front rail felts) which were traveling through
the keystick, action parts and shank several milliseconds before the
hammer ever hit the string?  If so, then a change of front rail felts
could very significantly alter tone quality, especially on a quality
grand.  It seems to me that the key thump sound that Jerry refers to will
effect the attack tone, but I don't see how it would alter the longer
sustain tone.

Mr. Fandrich said he would publish a later article describing this in
more detail, but it has not yet appeared in the journal.  (Did I miss
it?).  Has anyone else like Chris Robinson, Harold Conklin, Tom Rossing, or
the European
researchers studied changes in tone due to front rail felts or other
action parts? The articles I have seen seem to concentrate mainly on
volume, not tone.

Fred Scoles, RPT
Oswego, NY






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