Reverse crown was agraffe bridges

[Delwin D Fandrich]

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  ----- Original Message -----=20
  From: DALE ERWIN=20
  To: pianotech=20
  Sent: November 18, 2001 7:19 PM
  Subject: Re: Reverse crown was agraffe bridges


     And you know the agraffes all the way to the top were not a =
detriment but I believe now that they contributed to the sustain of the =
piano by not bleeding energy away from the speaking length like modern =
FRONT duplexes do. And hey Ron N. no rear duplexes and if memory serves =
adequately long back scale.  I really learned something as to why the =
stwy piano was sooo popular even from the get go. This one was 1873.


All pianos have both front and rear duplexes. The question is how long =
they are, what the string deflection angle is (at the front), and =
whether or not they are tuned.=20

The debate over the full agraffe design vs the capo tastro design =
centers around the effective mass seen at the front string termination =
point. In theory, a greater amount of mass seen at this point will =
improve the efficiency of the speaking length termination. In practice, =
however, things aren't quite so clear-cut.=20

The agraffe system obviously presents a lower mass termination point =
than does the capo tastro bar system. This is especially true if the =
capo tastro is mass coupled to the pinblock flange as it is with the =
traditional Sohmer designs and with the current Baldwin SF-10 and SD-10 =
designs. So, in theory the larger mass of the capo tastro system should =
be clearly superior. That this superiority is not seen in practice =
should lead us to look at the other factors that affect sustain to a =
much greater extent.=20

As long as we don't deliberately bleed energy away from the speaking =
length of the string (as is the case with the tuned front duplex, or =
aliquot, designs), sustain depends more on the potential energy storage =
capability of the speaking length of the string and the design of the =
soundboard assembly than on the amount of mass seen at the front =
termination point. =20

Last Friday and Saturday evenings I attended performances in 'The Strad =
Room' (a small recital room seating 50 to 65 people). The piano in this =
room is a six-foot 1910 Geo. Steck in which I have installed a =
considerably redesigned soundboard and bridge system. (It also has =
vertical hitches and a nice, long backscale with no attempt being made =
to tune their lengths to anything.) This piano uses agraffes though the =
treble section -- in this case, C-88. I was impressed again (as were the =
musicians) with the wonderful tone dynamics and sustain of this piano. =
At least up to about A-85. The deficiencies of the agraffe really become =
apparent in the last three or four notes of this piano. Judged by =
themselves they are not so bad, it's just that, compared with the =
performance up to that point they do fall off considerably. (This piano =
does not use overhung agraffes, which would have helped considerably. =
The last few notes have a strike point problem.)

Del

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