This is a multi-part message in MIME format. ---------------------- multipart/alternative attachment ----- 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 ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/fa/bb/c3/45/attachment.htm ---------------------- multipart/alternative attachment--
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