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Yamaha U1 treble break

  • 1.  Yamaha U1 treble break

    Posted 6 days ago
    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. 
    thumbnail image
    New U1
    thumbnail image
    Old U1 (1970s)


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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
    ------------------------------


  • 2.  RE: Yamaha U1 treble break

    Posted 6 days ago
    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]
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  • 3.  RE: Yamaha U1 treble break

    Posted 6 days ago
    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
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  • 4.  RE: Yamaha U1 treble break

    Posted 5 days ago
    Glad to know it's not just me: my own piano is a 6-year-old U1 and it does seem pretty unstable.

    I haven't yet installed a Damp Chaser system. Would my own piano be a good place to start, and would it help newer U1s?

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    Scott Cole, RPT
    rvpianotuner.com
    Talent, OR
    (541-601-9033
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  • 5.  RE: Yamaha U1 treble break

    Posted 5 days ago
    I find dampp chasers in uprights 
    work amazingly in keeping it
    stable.  It's an enclosed box with
    It's own microclimate. 

    Debbie Cyr
    Registered Piano Technician 
    508-202-2862 cell

    Sent from my iPhone





  • 6.  RE: Yamaha U1 treble break

    Posted 5 days ago
    I am a strong proponent of the system.

    Pwg

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    Peter Grey
    Stratham NH
    603-686-2395
    pianodoctor57@gmail.com
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  • 7.  RE: Yamaha U1 treble break

    Posted 5 days ago
    Do you have a picture of the bridge across this strut?

    ddf

    --
    Delwin D Fandrich
    Fandrich Piano Company, Inc.
    Piano Design and Manufacturing Consulting Services -- Worldwide
    6939 Foothill Ct SW -- Olympia, WA 98512 -- USA
    Phone 360.515.0119 -- Mobile 360.388.6525





  • 8.  RE: Yamaha U1 treble break

    Posted 5 days ago
    Hi Del,
    It is troublesome to photograph, as it is right behind the keybed. The notching is done in such a way as to make the curve of speaking lengths pretty even, seemingly more even with the change in the V bar curve. So the fact that tuning skew is worse is surprising. I have the impression that some of the odd tuning behavior at breaks has to do with the plain wood, not being strained by strings at tension going between bridge pins. 

    In any case, the newer design does seem to exacerbate the tuning issue just above the treble break, pretty consistently. Similarly with the P22, which has the same V bar design.
    Regards,
    Fred Sturm
    "I am only interested in music that is better than it can be played." Schnabel






  • 9.  RE: Yamaha U1 treble break

    Posted 5 days ago
    Is the bridge cut out for the strut? If so, would a brace at that break on the back of the sounding board help to stabilize the section?

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    Regards,

    Jon Page
    mailto:jonpage@pianocapecod.com
    http://www.pianocapecod.com
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  • 10.  RE: Yamaha U1 treble break

    Posted 6 hours ago
    I asked because, usually, when this V-bar configuration is seen it is because the bridge is "continuous" rather then adjusted to maintain a logarithmic speaking length scaling progression. 

    Assuming the designer knew something about striking points along the speaking length of the wire this would be the only reason to offset the V-bar in this manner. That is a rather extreme offset. 

    Tension variations that occur when wire diameters are changed are in the order of 8 - 10 lbf (give or take depending on the length of the scale). But when a bridge keeps a continuous sweep across a strut break it can be upwards of 75 lbf (depending on the distance between the bridge pin fields). The first is not acoustically detectable by most people, the second is. 

    So, my question is, does the sweep of the bridge actually change across this strut break or do they just offset the pinning a bit?

    ddf

    --
    Delwin D Fandrich
    Fandrich Piano Company, Inc.
    Piano Design and Manufacturing Consulting Services -- Worldwide
    6939 Foothill Ct SW -- Olympia, WA 98512 -- USA
    Phone 360.515.0119 -- Mobile 360.388.6525





  • 11.  RE: Yamaha U1 treble break

    Posted 4 days ago
    Hi Fred,
    Have you taken scale measurements in that area on both old and new? It might be interesting to see if they have changed the scale. P-22's are lousy across this strut as well. Put those measurements into scaling software and see what differences there may be regarding Break % and tension.

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    Alan McCoy
    Spokane WA
    ahm2352@gmail.com
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  • 12.  RE: Yamaha U1 treble break

    Posted 3 days ago
    Maybe some day. I noticed the difference in the U1 V bar a few years back, and speculated that it might be the reason for the few notes above the break being so crazy, so when I had a new one apart, I took measurements. There was nothing that would have led me to believe there would be any issue. In fact, I suspect they improved the evenness of the scale.

    Tuning one of each back to back prompted me to take photos and post them. I'll leave it to someone else to investigate further.
    Regards,
    Fred Sturm
    "Art is not a mirror held up to reality, but a hammer with which to shape it." Brecht