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Inharmonicity nightmare - an old baby grand Ruch

  • 1.  Inharmonicity nightmare - an old baby grand Ruch

    Posted 02-11-2019 19:10
    Whilst normally dealing with well behaved concert instruments in best condition, sometimes I do favours for friends. Today's instrument was a nightmare in France - a baby grand by Ruch of Paris. It was only afterwards I learned that it had been given to the friend at Christmas after having been stored unplayed untuned in a garage up a mountain for five years.

    I use Kellner universally as a viable alternative to ET for everything. For speed I normally use the CTS5 tuner to set the scale over the central three octaves without any stretch and checking the 7 perfect fifths on each as I go. The lack of stretch is critical so as not to widen the tenor C# to treble F fifth harmonic, as exemplified by the opening chord of the Raindrop prelude. My method then is to tune the bass below with a best fit of octave, 3rd harmonic and 5th harmonics to the relevant scale notes in the middle and tenor octave and the result tends to be coherent, solid and very musical.

    But this didn't work on the Ruch. The tuning was all over the place and sounded hideous. Years ago I used to use the shareware version of Tunelab but haven't had need of it for years, my current technique in every other instance giving better results than standard inharmonicity measurements and curves. But newly having the trial version of Tunelab on my Android I thought I'd do the inharmonicity measurements to see what might be wrong and measured every note up to treble C.

    The strings are old and weren't cooperative in moving with the pin movement and two broke on me just at the start of the coils on the tuning pins. As the graph shows, the inharmonicity was all over the place.

    Screenshot from Tunelab
    As an aside, I'm not sure of what the green and blue graphs are on the Tunelab display, so any enlightenment from anyone would be really appreciated.

    But I explained to the owner that it was the random variation of inharmonicity which made the instrument not sound nice, and I redid the tuning entirely using Tunelab to navigate the mess as probably the easiest way to get the most acceptable result in the circumstances.

    The instrument has had new hammers and the action is in very good condition therefore. But the stringing . . .

    Were I to tell the piano's owner that the instrument should have a restring, would a new set of strings overcome the inharmonicity variations? And we certainly shouldn't get the existing strings sent off for patterns for the new strings. How might one specify the new strings appropriately and would they make a great difference?

    I'd rather stick to concert instruments ;-) but sometimes one can't evade getting one's arm twisted.

    Best wishes

    David P

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    David Pinnegar BSc ARCS
    Curator and House Tuner - Hammerwood Park, East Grinstead, Sussex UK
    antespam@gmail.com

    Call for papers - Seminar 6th May 2019 - "Restoring emotion to classical music through tuning."
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  • 2.  RE: Inharmonicity nightmare - an old baby grand Ruch

    Posted 02-11-2019 19:32
    I suggest contacting Stephan Paulello in France. He can rescale the piano and provide the wire. He may just give you the specificatons for the wound strings and you can get them made.  Just Google his name and go to his website.
    Ed

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    Edward McMorrow
    Edmonds WA
    425-299-3431
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  • 3.  RE: Inharmonicity nightmare - an old baby grand Ruch

    Posted 02-11-2019 20:08
    That's brilliant - many thanks

    But I wonder if anyone has experienced this sort of problem and has had magically brilliant results upon restringing, and upon which an example my friend would have confidence in investigating further?

    Best wishes

    David P

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    David Pinnegar, B.Sc., A.R.C.S.
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    +44 1342 850594





  • 4.  RE: Inharmonicity nightmare - an old baby grand Ruch

    Posted 02-11-2019 21:47
    I have rescaled many pianos since first studying piano scaling in the mid 1970's. The Hybrid Wire Scales Protocols that the varieties of high carbon steel wire annealing points Paulello has made has allowed scale designers to develop the most robust realm of scaling choices in history to solve both low break point, inverted inharmonicity slopes and Longitudinal mode strength issues that plauge small piano scales.

    What I and other students of scale design have discovered is many of the tonal issues with low break point portions of scales are Longitudinal mode issues. The "softer", weaker wire types Paulello sells can be used in the portions of the scale that are placed at too low a break strength for fully modern wire to sound best.

    Too high inharmonicity affects tuning more than tone. If you want to improve the inharmonicity curve, you may need to explore switching plain wire unisons to wound. This can be done by using type O core wire for making wound trichord strings. Also the lowest single notes in small piano bass scales can be made using Type O core for much greater clarity without sacrificing warmth.

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    Edward McMorrow
    Edmonds WA
    425-299-3431
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  • 5.  RE: Inharmonicity nightmare - an old baby grand Ruch

    Posted 02-12-2019 14:07
    Edited by Anthony Willey 02-12-2019 14:09
    David,
    Responding to your initial post, I'm fairly certain the two graphs you shared above do not represent the inharmonicity of the piano, and I would be hesitant to make any big decisions on the basis of those. The green graph seems to be showing the tuning curve itself: that is, the offsets of various partials (in cents) from flat equal temperament. The blue graph I believe is showing how wide or narrow various intervals (in your case 2:1 octaves and 4:2 octaves) are being tuned, I think, again in cents.

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    Anthony Willey
    Coralville IA
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