Mysterious unsolvable Yamaha double-striking uprights

[Geoff Sykes]

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Don --
=20
My timing must be off today. I just sent this question to the Yamaha =
email
address listed in the 2005 PTG Directory. When I clicked the =
send/receive
button, that message went out and your message came in. We'll see what =
they
have to say, but I think you have now provided me with the information I =
was
hoping for. This is very cool and gives me much to work with. I will do =
a
couple of experiments, but my guess is that since this is a regular
undocumented feature of multiple pianos your suggestion 2-1 may prove to =
be
the answer. I'll report back.
=20
Thanks --
=20
-- Geoff

-----Original Message-----
From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org] On =
Behalf
Of Donald Mannino
Sent: Tuesday, July 12, 2005 2:47 PM
To: Pianotech
Subject: Re: Mysterious unsolvable Yamaha double-striking uprights


Geoff,

This is a common problem with this style of action, and is most often =
caused
by the combination of what has been touched on already by others (a few =
less
likely causes are at the end of this message);

- The hammer springs are weak
- The hammer friction is low
- The jack springs are strong
- The damper springs are strong.

Depending on the individual piano, there are different ways to eliminate =
it.
Here are some options:

1. The damper spoon timing is causing the resistance at the key to =
become
very high at the same time that the jack spring is being compressed for
letoff.  This can be helped by weakening the damper springs or changing =
the
spoon regulation.  The test is to press the pedal and see if the
double-strike still occurs.  If not, then the damper spring / spoon
regulation will be the answer.

For spoon lift, it just depends on the piano.  I have sometimes made the
dampers lift earlier so that the spoon friction and spring resistance =
come
earlier, so that when playing the key you automatically get over that
resistance before getting to letoff.  That said, I have also made the =
lift
later and solved the problem - so it depends on the individual piano.

For damper spring tension, use your grand rep spring tool to pull back =
on a
sample spring.  Lift the damper individually by hand and feel the
resistance, then weaken the spring just enough that you can tell the
difference when pulling back on the damper head with your finger.  Then
check for the bobbling.

2. As others mentioned, friction is often set low on new actions to make
sure they are reliable.  You can try repinning one hammer center to see =
if
it helps, but I don't think that will make a difference, actually.

This can occur in  other pianos with the same basic action design.  This
design (weak hammer spring, strong jack spring) really does perform well =
and
repeat well, but is subject to this kind of bobbling when the settings =
are
just right / wrong (depending on your point of view!)  Maybe it is a =
tribute
to the consistency of the spring setting processes that all of the =
pianos in
this store are doing this!

OK, 2 more possible causes that are less likely:
1. Manufacturer's sometimes change the thickness of the butt felts in
production in order to change the "feel" of the letoff.  If they decide =
to
use a thinner felt, the letoff feel is stronger (more like a grand).  If
they make it thicker the letoff is smoother and power can be lower.  If =
you
look at the jack angle as it meets the butts, you might see a difference
between the actions and the action model you looked at.  This means that =
the
bobbling is a trade-off that the manufacturer has chosen to live with in
order to get the other performance levels they are looking for.

2. An unlikely but possible contributing factor is the angle of the =
action
as it is installed in the piano.  For this to be off in multiple Yamaha
pianos seems very unlikely, but if the base of the action is mounted out =
too
far out from the strings (usually because the case parts are not fitting
together right, or the keyboards are coming through with the capstans
mounted in the wrong place, etc) the action will be very subject to =
bobbling
on soft play.  Again, this isn't likely in this case - just something to
keep in mind for the future.

Hope this helps some!

Don Mannino RPT=20


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