DAVID ABDALIAN wrote: > I have a client with a Hoffman 190 manufactured in 2002, sold new in > 2003 with tuning instability problems. The piano has not stayed in > tune since the start. It has Dampp-chasers complete six part system. > Multiple experienced RPT’s have tuned this piano since new. Chinese built, Delignit block, you can probably turn the pins far enough for the pitch to change 30 cents before the bottom of the pin moves in the block. >The piano > goes out of tune in sections as would be expected with a gap between the > pinblock and the plate flange. The gap is about .003 - .020 inch gap > which is present from note F1 – F2, from note E3 – C5 and from B5 – F8. How would it be expected to go out "in sections" with that gap? For that matter, what tuning instability would you expect and why would expect it, from the gap? Define "goes out". Goes sharp overall? Goes flat overall? Random? By section, or string to string? > It is difficult to tune also. The strings don’t seem to render well > especially at the capo bar. Another RPT technician claims that it could > be the Roslau wire also. Any comments would be appreciated. Sounds like a lot of random guessing going on. Maybe it's the casters, or lid prop? Has anyone made any attempt to isolate cause and effect, such as pitch response from intentionally flagpoling pins (without turning) to verify rendering problems? How much understring felt is the string being dragged across? What are the counter bearing angles at the capo? How does this differ from the agraffe section where you don't seem to have the problem - or do you? Does the piano have plate bushings? The clue is in the observation that it's both difficult to tune, and won't stay in tune. That means it's not getting in stable tune in the first place. I'd suggest some attempt to isolate and verify where the problem actually is before starting to apply suggested fixes. My first assumption is that it's NOT the Roslau wire. Ron N
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