Fred and Kevin,
Over the years I have found a strong correlation between excessive and/or very uneven downbearing and excessive tuning instability. What seems to happen is that the soundboard basically convulses in odd ways when subjected to too heavy a DB load, and then particularly so if it is unevenly loaded. This produces super-sensitivity to humidity change.
If inspecting the back side with a string shows that the crown is uneven, with obvious extra deflection behind the bridge (in the direction of "oil-canning"), I would strongly suspect excessive DB. I have been able to produce remarkably improved stability on several instruments simply by reducing and evening out the DB. I have also confirmed (to my own satisfaction when I suspect it) an oil-canned board (or close to it) on several occasions (one was a Yamaha P-22) though actually fixing the situation requires lowering the tension and lots of work.
Maybe try jamming a wedge in between the board and backpost on one of them and see over time if anything improves. If so, that could be circumstantial evidence of the problem.
Then again, it might be something else entirely.
Pwg
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Peter Grey
Stratham NH
603-686-2395
pianodoctor57@gmail.com------------------------------
Original Message:
Sent: 01-10-2019 12:10
From: Kevin Fortenberry
Subject: Yamaha U1 treble break
Very interesting observation Fred. Although admittedly I have not put a lot of thought into it, these 29 new U1s we received (through a private donor) nearly 4 years ago have honestly been a real beast to keep in tune (and the regulation also to be frank). Overall still probably THE BEST choice at the time and these are still great pianos, they just seem fairly disappointing compared to all the "old school" ones we have all (most of us!) come to appreciate.
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[Kevin] [Fortenberry] [RPT]
[Staff Techician]
[Texas Tech Univ]
[Lubbock] [TX]
[8067783962]
Original Message:
Sent: 01-10-2019 11:12
From: Fred Sturm
Subject: Yamaha U1 treble break
I have noticed recently that the new Yamahas have a much worse tuning issue right above the treble break than the old ones. The notes right above the break go way sharp or flat in response to humidity change, and this is far more pronounced than in my 30-year-old Instruments. I took a couple photos of the break, and wonder if this is why. It seems that the newer ones have a jog in the rebar, probably for some good reason, but it has this bad side effect.
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Fred Sturm
University of New Mexico
fssturm@unm.edu
http://fredsturm.net
http://www.artoftuning.com
"We either make ourselves happy or miserable. The amount of work is the same." - Carlos Casteneda
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