> The pin is harder, but the wood which touches the string acts like a damper > for very high frequencies. I exaggerate this to make my point, but that's > what happens. > Piano makers have long used the hardest woods in the top treble caps. I > believe they recognized the need for a very stiff material there, to > minimize energy loss. The bridge agraffe is another quite efficient) way of > reducing energy losses where it matters most. Hi Calin, I see it somewhat differently. The wood acts as a damper, yes, but not for high frequencies, but rather for bleed through. The short segments within a bridge agraffe are too short to sound audibly. They are, however, long enough to transmit string motion, via rocking on the bearing points, through to the back scale. This doesn't happen in a conventionally pinned bridge, so with bridge agraffes, you get a direct relationship between the string played, and the back scale of that note. This is the way front duplexes work, only it's on a moving bridge in this case instead of a more solid plate, and the deflection angles are typically shallower in the bridge agraffe, increasing the effect. It isn't a problem in the lower portions of the scale because the back scale is typically braided off down there already to prevent noise being generated by the long back scales. I would bet that braiding off the back scale would immediately kill that objectionable "agraffe" noise. But then you wouldn't get the sound from the open back scale of a conventionally pinned bridge, hence the rubber or felt dampers in the agraffes. They kill the bleed through noises without killing the typical and "normal" open back scale noise. My take, Ron N
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