"double striking" problem

[Barrie Heaton]

hI aVERY,

I was preparing a grand for a concert last year, in Blackburn Cathedral
it was a hire a piano a brand new Yamaha.  The pianist came in and said
there was a problem with the treble when you played soft it was weird he
said and a clicking damper.

The problem was similar to yours, three notes just above  the treble
break can't remember which ones not important.  When played hard hammers
o.k. when played soft hammers double sriked.  This was a well regulated
piano factory set spring tension,  I stripped the action down when
through the whole thing couldn't find anything... was fast running out
of time.  So I went down the road, you went down, dropped the set off
and the drop screw.  This cured it but I wasn't happy.  I thought right,
just time to sort out the clicking damper.  This is where my problem
was,   how it got there I don't know.  There was a little plastic straw
stuck to the damper slap rail.  With its tail protruding along and
catching the edge of one of the notes on the next break this was the one
what was clicking, so I dismissed this one in my initial search for the
bouncing hammers fool.  What was happening when the key was pressed hard
the straw was collapsing but when the key was played softly, there was
just enough resistance to stop the check from catching the tail of the
hammerhead.

Not saying you have a straw in your piano,  but you may have some fluff
on your damper slap rail.  Or the rail may have slipped down,
*unlikely*.

Hope this is of some help.

Kind regards,

Barrie.
#
In article <v01530500af278786bd3f@[129.7.16.129]>, Avery Todd
<atodd@UH.EDU> writes
>List,
>
>   I had a problem yesterday with our Hamburg D. One of our piano faculty
>gave a recital last night and had been talking to me about notes "double
>striking" (his term) on very soft playing. It was a VERY soft, but
>noticeable, double strike on some notes (hammers not going into check and
>bouncing back into the string), primarily notes in the middle third of the
>piano.
>   I was able to solve the problem to his satisfaction but I don't *really*
>understand what caused it in the first place so it was pretty much a trial
>and error kind of thing. I just now talked to him on the phone and
>everything worked out very well. He said he felt very comfortable with the
>piano. So, I guess all's well that end's well, but I need to understand
>what causes this type of thing so I can prevent it from happening in the
>future.
>   It's very difficult to explain this problem in words, but here are some
>questions and some things I did to try & solve the problem.
>
>   What really controls how much upward "throw" (I can't think of a better
>term) the hammer does when adjusting the repetition? Is it strictly how high
>the hammer catches on the backcheck? Does the amount of let-off or drop
>affect it also? I know that key dip would also affect where the hammer is
>caught in relation to the strings, of course.
>   The repetition spring tension is what "seemed" to be causing the problem.
>I had to play at least mp to get the hammer to go into check but most
>hammers had very little lift at all. Certainly not strong enough to cause
>any kind of bounce at the top. I even had to increase the tension the
>smallest amount possible to ensure repetition without getting a bounce back
>on very soft playing. I brushed the hammer tails with a suede brush to get
>any residue out the grooves on the tails to try to improve checking.
>   Also the backchecks. They're Hamburg backchecks, about 1-1/2 yrs. old,
>having been replaced when new hammers, shanks and flanges were installed. I
>regulated them as high as possible without getting a rub on the hammer tail
>
>on a hard blow. This also seemed to help some.
>   I even increased the aftertouch a little by raising the hammer line
>slightly, trying to insure that the jack was completely escaping from under
>the knuckle. Yes, I lubed them, too. I did notice that the knuckle leather
>is starting to get slightly loose around the core, so I guess I'll have to
>do that correction as soon as I can put the piano out of commission for a
>bit. Could that looseness have any affect on this?
>   I normally regulate with a very close let-off, especially on our
>performance pianos and have never had a problem. This time, I increased the
>let-off and the drop, very slightly, to see if this would help stop the
>hammers from bouncing back into the strings but I would like to put the
>let-off back at 1/16" without having this problem recur. The bedding was
>also checked.
>
>   Sorry this is so long but I'm trying to give all the information I can
>in hopes someone can explain this to me. I hope I've explained it clearly
>enough for you to understand what I'm talking about. Any comments to help
>me understand the "whys and wherefores" of this problem would be greatly
>appreciated. Thanks.
>
>Avery
>
>_____________________________________
>Avery Todd, RPT
>Moores School of Music
>University of Houston
>713-743-3226
>atodd@uh.edu
>_____________________________________
>
>
>





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Barrie Heaton                                  |  Be Environmentally Friendly
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