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Repeated String Breakage Yamaha C7X

  • 1.  Repeated String Breakage Yamaha C7X

    Registered Piano Technician
    Posted 13 days ago

    Hi Everyone,

    I'm looking for your advice regarding string breakage in a several note section in the lower treble section of a Yamaha C7X. There were no issues the first couple years. then strings began breaking in the several note section just after the tenor/lower treble break. Strings are not breaking anywhere else on this piano. In my view this is not a warranty issue, as I see nothing unusual or abnormal about the capo, string rests, etc. in this section. My client is a faculty member, and this is her personal piano at home. She truly is a "monster" pianist (as in hugely talented and wonderful), and she performs contemporary works as part of her concert schedule. I have lovingly told her "just don't play like that" (kidding), but that hasn't gotten us very far. She loves her piano, and would really like to keep it. But this problem is annoying (to us all!).

    I have already made sure the hammers are filed and well-voiced in that section, and I have altered the regulation in the two treble sections to reduce power. She is ok with this. What else might you suggest I do? I am primarily interested in any suggested alterations of the capo itself in this several-note section, and the possibility of raising or lowering the counterbearing angle to the string rest. Does a broader capo surface promote string breakage? Does a sharper counterbearing angle help prevent it or aggravate it? Thank you for sharing your thoughts! Please feel free to refer me to articles about this, or to reply privately.

    Teri

    email:  teri22ns@att.net

    cell:  310-702-2389



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    Teri Meredyth RPT
    Harbor City CA
    (310) 702-2389
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  • 2.  RE: Repeated String Breakage Yamaha C7X

    Registered Piano Technician
    Posted 12 days ago
    Terri

    Where are the strings breaking?  If they are breaking at the agraffs, then it's her playing. As you mentioned, she's monster player. Combine the hard touch with a lot of right pedal, and strings are going to break. 

    You can try reducing blow distance and even key dip. It might also help if you put a monitor behind her so she can hear how loud she's playing.  

    Just some ideas

    Wim





  • 3.  RE: Repeated String Breakage Yamaha C7X

    Registered Piano Technician
    Posted 12 days ago

    I would first increase lefoff. Then address hammers. Are they excessively hard and non-resilient?  That would tend to increase string breakage. What about

    keyset?  Are keys loose?  Good advice on capo and Paulello wire.



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    Parker Leigh RPT
    Winchester VA
    (540) 722-3865
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  • 4.  RE: Repeated String Breakage Yamaha C7X

    Registered Piano Technician
    Posted 12 days ago
    All Don says... we had this exact issue at Texas Tech on a Yamaha, but especially the Paulello XM wire seemed to be a HUGE help. 








  • 5.  RE: Repeated String Breakage Yamaha C7X

    Registered Piano Technician
    Posted 12 days ago

    Awesome... thanks Kevin.

     

    Teri

     






  • 6.  RE: Repeated String Breakage Yamaha C7X

    Registered Piano Technician
    Posted 12 days ago

    Hi Parker,

     

    As I said in my message, this has all been done already.

     

    Teri

     






  • 7.  RE: Repeated String Breakage Yamaha C7X

    Registered Piano Technician
    Posted 12 days ago

    Thanks Wim... they are breaking at the capo.

     

    Teri

     






  • 8.  RE: Repeated String Breakage Yamaha C7X

    Registered Piano Technician
    Posted 12 days ago
    Teri,

    A few thoughts:
    • Yamaha capo bars are sometimes VERY hard.  They heat treat them to the point where they are hard to file them!  So the in those pianos the strings don't dig into the V, but the hardness can contribute to the wire weakening.
    • A smaller radius on the contact area actually encourages the pivoting action of the wire during hard playing.  This slightly reduces metal fatigue.  So if you are replacing the wire in the affected area, check the radius of the V-bar underneath.  If the width of the V is around 4mm, that is a 2mm radius which is good.  If it seems larger, see if you are able to file it smaller. If there are deep grooves in the iron from the wires, then the capo is not too hard - file it front and back first, then smooth the bottom to get rid of the grooves.  Those grooves become 'saddles' that actually grab the wire, making it harder to tune and also forcing the wire to flex on the speaking side instead of pivoting as it should.
    • I have had excellent luck with Paulello 'XM' wire.  You can order it online from France and they will ship it direct.  It really is stronger.  Of course, just having fresh wire in the entire section combined with shaping the hammers nicely usually completely stops the string breaking for a while anyway, but with the Paulello wire it will hold up longer.  
    • One last minor tip I have used in some pianos: I raise up the balance rail glide that is closest to the breaking wire. Screw the glide bolt up as high as they can go so that they don't knock.  This really takes away a lot of the attack  - and it will weaken the tone of course and the pianist might complain about the feeling.  Don't do multiple glides - just the closest one.  And of course, never do this on a performance instrument!

    I've worked through this issue quite a few times with multiple piano brands - good luck!

    Don Mannino





  • 9.  RE: Repeated String Breakage Yamaha C7X

    Member
    Posted 12 days ago

    it may be a good idea to use an inspection scope that can take pictures of the various string contact points at the capo to see if there are cuts , too much contact etc. I suspect it is not any one problem but hard hammers , heavy playing, monster mashing , holding down the sustain pedal , and needed tweaks in the regulation are all factors. I have had broken strings in church pianos especially in the bass when Gospel singers and pianists go for volume. 

    lots of good suggestions here. Its also a distinct possibility that the pianist has some hearing loss and is playing much harder on the piano. Don't forget= Franz Liszt had to have several pianos for his concerts he was so heavy a player



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    James Kelly
    Owner- Fur Elise Piano Service
    Pawleys Island SC
    (843) 325-4357
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  • 10.  RE: Repeated String Breakage Yamaha C7X

    Registered Piano Technician
    Posted 12 days ago

    Thank you so much Don! This is exactly the kind of information I was after. I will get some of the Paulello wire, check the capo again and raise that glide. Much appreciated.

     

    Teri

     






  • 11.  RE: Repeated String Breakage Yamaha C7X

    Registered Piano Technician
    Posted 12 days ago

    Ditto to what Don has suggested with regard to the Paulello wire.  At the U of Oregon we have had our share of string breakage.  We had one player who could, at will, break any string on any piano.  It was quite the chase after he was done and he is now at another university (Thank goodness!!)  In the past few years I have restrung several of our Steinway grands that were notorious string breakers and replaced strings in the "breaky sections" on others.  In most cases this encompasses the C6-E/F7 area.  The conversion takes about three hours to accomplish including dressing the capo a bit.  One Steinway B that was restrung with Mapes strings was the worst and I was replacing strings on a weekly basis.  The XM wire was clearly the answer and we now enjoy an instrument that is stable and serviceable.  Of course the ONE STRING that broke after the repair was just below the new wire.  Ya just can't win!!  Sheesh.  After several years all of the pianos with the XM strings in the problem areas have performed well.  Doing this on many of our pianos, and not done yet, I can say without qualification that it works as Don described.  In addition I have noted that along with the enhanced durability that there is little to no difference in the voicing and even using the original tuning scheme on CyberTuner that it was not necessary to change any of the values in that section.  It's a win all the way around for us with minimal fuss to accomplish.  

    One additional note--I find that the Paulello wire seems to settle out a bit faster that other strings and not just the XM.  A spot replacement before a performance will yield a bit more stability that most other products.   I also find that the false beats are a bit better as well.  

    When I arrived at U of O there was a whole house full of pianos that had hammers not shaped in many years.  I made the commitment to correct that and the reward was pianos with reduced string damage.  It wasn't eliminated but certainly going the right way as far as string breakage.  Nicer to listen to and tune as well.  

    I am preparing the restring one of our Hamburg Ds using the Paulello strings including the XM wire.  We noticed that the capo was heat treated and even a file barely touched it.  Both pianos have been habitual string breakers.  When we get the strings on I'll report back on the results and am looking forward to a bit more stability and less string damage on these wonderful pianos

    Mike Reiter

    U of Oregon  (go Ducks!!)



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    Michael Reiter RPT
    Eugene OR
    (541) 515-6499
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  • 12.  RE: Repeated String Breakage Yamaha C7X

    Registered Piano Technician
    Posted 12 days ago
    Terri

    How old is this piano?  There is a C7 at the university I work at which has been breaking strings for the past 3 years. Last year I replaced the hammers and did all the prepping on them, but the strings are still breaking. I was blaming it on some heavy handed students, but perhaps it's this vintage Yamaha. Perhaps replacing the strings with Paulello is the answer. 

    Wim





  • 13.  RE: Repeated String Breakage Yamaha C7X

    Registered Piano Technician
    Posted 11 days ago

    I installed all XM wire for the top two sections of a Steinway O grand used for concerts due to potential heavy use.  Not only is it stronger, but it will also lower the breaking percentage in areas where the BP is steadily higher.  I think the tone sounds a bit more relaxed, in a good way.  What I did is what Paulello recommends for concert use.  

    If the string is breaking at the V bar, what is happening to the string to cause that to occur?  What is changing in the string?  How is that related to hardness?



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    William Truitt RPT
    Bridgewater NH
    (603) 744-2277
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  • 14.  RE: Repeated String Breakage Yamaha C7X

    Registered Piano Technician
    Posted 11 days ago

    "If the width of the V is around 4mm, that is a 2mm radius which is good."

    Don, by "width of the V", do you mean the width of the surface of the V that contacts the string?

    Thanks much,

    John Pope



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    John Pope
    University of Kentucky School of Music
    Lexington, KY
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  • 15.  RE: Repeated String Breakage Yamaha C7X

    Registered Piano Technician
    Posted 11 days ago
    The contact surface should be shaped something like a half round rod.  If the width of a half round is 4mm, that equals a radius of 2mm

    2mm to 3mm is considered a good size from treble string contact, but for me smaller is better - unless the iron is super hardened. 

    Don Mannino 
    Sent from my phone. 





  • 16.  RE: Repeated String Breakage Yamaha C7X

    Posted 11 days ago

    Quite some time age when Ron Overs first brought his piano to convention, I seem to remember that there was a recipe for heat treating the capo bar to alleviate work hardening. Has this concept been able to be tested out? I surmise that this would have to be performed while the plate is out of the piano and before finishing. The process would require a series of torch tips ove the area at one time to bring up the temperature to a light cherry red and allowed to cool ... by air, by quenching I have not been able to determine.



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    Garret Traylor
    Trinity NC
    (336) 887-4266
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  • 17.  RE: Repeated String Breakage Yamaha C7X

    Registered Piano Technician
    Posted 11 days ago

    You would need to pre-heat the plate to 800 degrees F and cool very slowly. Otherwise you risk cracking the plate.



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    Parker Leigh RPT
    Winchester VA
    (540) 722-3865
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  • 18.  RE: Repeated String Breakage Yamaha C7X

    Posted 10 days ago

    So heating the area to a "dull red" in daylight would be conceivable? 

    I wonder if the iron can be aneled at a lower temperature or would it have to be at around this 800°



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    Garret Traylor
    Trinity NC
    (336) 887-4266
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  • 19.  RE: Repeated String Breakage Yamaha C7X

    Registered Piano Technician
    Posted 10 days ago
    • A number of years back (1970's) I owned a Yamaha C7 (7'4") where the capo/string buzz was becoming intolerable. Being mildly educated in metallurgy I knew that heating the capo to the temperature needed to re-format the hardness would be extremely risky. Heating cast iron is susceptible to breakage, due to the fact that heating in one area causes the metal to expansion disproportionately as a whole -- hence cracking. It is common knowledge that as metals cool, the outer surfaces cool faster. The faster the cooling process the harder the surface area. I remember visiting a manufacturing company that made large gears in transmissions used in cargo ships propulsion systems. As I was watching the gears being removed from the casting, a worker used a gas torch to apply heat to the outer edges of the teeth to slow down the cooling process. That prevented the teeth from becoming too hard and brittle. That is the case with piano plates. The rate of cooling of the capo will determine the hardness of the surface. Fortunately, in our case with capo hardness, as with any metal, that hardness is "skin" deep. The better, and safer, alternative is to grind the capo down past the outer hard surface with a die grinder. That process poses its own problems as the depth can be difficult to control resulting in different hardnesses throughout the capo. I'm not advocating anyone approach this process impetuously as there are many variables. Fortunately, using a die grinder on Yamaha pianos is relatively easy as you can remove the keybed and approach your work without much physical hinderance.


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    Roger Gable RPT
    Gable Piano
    Everett WA
    (425) 252-5000
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  • 20.  RE: Repeated String Breakage Yamaha C7X

    Posted 10 days ago

    Thank you  Roger!
    Well put, your comments make perfect sense to me. 



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    Garret Traylor
    Trinity NC
    (336) 887-4266
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