To: Jim Bryant Jim, It sounds like you may have somewhat more experience than I do with the Sohmer agraffe bridge design. I have a couple of questions that perhaps you—or anyone else out there?—could help me with. We’re putting a new soundboard into an 8’ 4" Sohmer using this bridge design. For a variety of reasons the original bridge design is being retained, complete with its agraffes. Hence, I read with some interest your comments about these bridges. First, about the sound. I agree, but I do wonder how much of the tone difficulty can be blamed on the agraffe bridge design. I measured the scale in this piano and found that the overall tension was just under 64,000 pounds. Assuming I had made a serious mistake somewhere, I measured it again and ran the numbers through my computer a second time. Same results. In the tenor section there was a stretch of about an octave where the individual string tensions were in the 300 to 333 pound range (yes, that is per string, not per unison). Are these scale tensions typical of these pianos? If so, this by itself would cause their sound to be “nasal” I should think. Regardless of the bridge design. Second, to my surprise the bridges on this piano were in EXCELLENT condition. I’ve rarely seen a conventional bridge looking this good even in relatively new pianos. Despite the string tensions used, there was no evidence of any bridge roll or soundboard damage of any kind. The bridge agraffes have threaded shanks that are 25 mm long through the top two sections and 32 mm long through the tenor section. The last three notes on the tenor bridge and all of the bass bridge use conventional bridge pins. There was a maple piece approximately 8 to 10 mm thick glued to the bottom of the soundboard that closely paralleled the tenor bridge. (A sub-bridge?) The agraffe shanks are long enough to go all the way through the bridge and soundboard and about 1/2 to 2/3 of the way through this piece. The ribs were notched to fit around this sub-bridge. I suspect this sub-bridge saved the structural integrity of the bridge, but notching the ribs close to their centers surely couldn’t have done much for the tone quality of the instrument. My question is: How does one go about setting bearing on this thing? You speak of up bearing on the agraffe, which there certainly would be. But there would be quite a lot of down bearing on the back scale. Do you—does anyone!—have any idea how these boards were originally loaded? Since Mr Sohmer’s design could not change the laws of piano acoustics I still need to end up with positive overall soundboard loading. Any thoughts and/or suggestions will be greatly appreciated. It's pianos like this that keep life interesting. Yes? Thanks—ddf
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