Floyd, you could help us out here by giving us a few stats about the tenor part of the piano, since that is where your greatest concerns lie. Can you share the speaking lengths and wire diameters for the first plain wire and the 20 - 25 notes above that? That way, myself and probably some others can throw the data into our own scaling programs and give some commentary based on more data.
Given the low tension scale this piano has, it just seems ripe for rescaling using hybrid stringing. Most likely the breaking percentages (or Practical Breaking Load percent PBL%) as the typogram is referring to) are too low for much of the piano, and the substitution of Type 1 in the very low tenor, and type O for much above that will result in a substantial improvement in tone by raising the breaking percentage.
Moreover, hybrid stringing allows you to have your cake and eat it too. While your impulse would be to bring the tension up by increasing the wire diameter, that comes at a cost in these small pianos. Once the wires get to a certain size, the tone sounds choked and not so pleasant. Along with that, increasing the wire size will lower the breaking percentage - going in the wrong direction away from good tone.
Where the rebuilder has only one wire type (as in Roslau or Mapes for us), there aren't many other choices. In the very low tenor, you can add wound bichords. The plate won't allow you very much to increase speaking lengths that would be meaningful.
The focus on tension in smaller pianos here leads one away from the most effective method, which is hybrid wire. I will briefly make my point with a 5' 2" Baldwin M that I rescaled a while back, using the first plain wire (note 30) as my example, with a SPL of 906 mm.
Original stats were 21.5 gauge wire diameter, with a PBL% of 32.49, string tension of 62.85 DaN, blank inharmonicity of .33.
What was substituted was 19 gauge Type 1 Paulello wire, with a PBL% of 48.75, string tension of 50.44 DaN, blank inharmonicity of .26.
This was an experiment for me, based on using PBL% as the most important consideration in scaling. I knew that if I had used Type M at 19 gauge (or Mapes or Roslau) it would sound like flabby garbage. Had I dropped the tension too low, which went from in the 140's to about 111 lbs.?
The result was rather startling. The PBL% of 48.75 put the note solidly in the goldilocks zone of good tone regarding breaking percentage, the inharmonicity had dropped from .33 to .26 AND it sounded great - open, free, and sustaining, and more in character with the notes above and below it. I similarly made changes throughout the low tenor, tapering off to about the original around note 50. This was also transformative. I heard greater clarity and body and a better voice. It was a remarkable change that demonstrated what a powerful tool hybrid scaling can be, really the most powerful tool of all, as it can be combined with the other things that we do in scaling.
I calculated all this using Arno Patin's Abacus spreadsheet, which is set up to be used with Paulello wire.
As Chris says, smooth lines are not enough. The ear is the ultimate arbiter, it either sounds good or better, or not.
Chris, if you want to write your own scaling programs, do so by all means. For myself, I know that there are people out there who have considerably more expertise than I in most any area of piano work. That includes people who write scaling software. If I can buy a program that makes me better at what I do, I am all for it. I don't need to be the smartest man alive, just one who is wise enough to work around my own limitations in this journey of discovery. I will say that in the 6 plus years that I have been doing hybrid stringing using dedicated software, there is no doubt in my mind that it has greatly elevated the quality of my finished rebuilds, and that starting this work was a seminal moment for my work.
Will Truitt
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William Truitt
Bridgewater NH
603-744-2277
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Original Message:
Sent: 12-06-2017 22:07
From: Floyd Gadd
Subject: Rescaling Early 20th Century Grand
When this piano was built, Heintzman & Co. and Gerhard Heintzman were distinct companies. The Gerhard Heintzmans were of reasonably good quality, but the Heintzman & Co. pianos were definitely superior. I suspect the data you have posted is from a better piano than what I am working with.
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Floyd Gadd
Regina SK
306-502-9103
Original Message:
Sent: 12-06-2017 16:32
From: Chris Chernobieff
Subject: Rescaling Early 20th Century Grand
A great designed little piano with tons of potential. But, you're not going to improve the scale too much. It's pretty darn good as is . Heintzman knew what he was doing.
Here it is on a spreadsheet. Tension, InHarmonicity, and Impedance.
The problem with the piano is the soundboard Rib scale. IT'S HORRIBLE!! It might as well be a dining room table in there. The panel was a non tapered solid 3/8 through and through.
Notice in the diagram that the largest rib #7 is not the longest rib #8. Just one of its many problems. Plus, I suspect that their procedure of installation is faulty. At least the board I removed was. It was flat as a pancake in the piano, but crowned up significantly when removed.
I made a new soundboard with a classical structure and Improved the rib structure. Incredible sounding piano now.
Putting a hybrid rescale on a terrible rib scale don't make sense to me.
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My philosophy on restringing software is to not use them. Better to make your own. Learn the math formulas and how they work first, then create your own speadsheet with the proper knowledge to back up your rescale. Rescaling is NOT just looking at smooth lines on a computer screen. My 2 cents.
-chris
#caveman
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I have a piano in my Nuclear Fallout Shelter, and my competitors don't. How silly is that?
chernobieffpiano.com
865-986-7720
Original Message:
Sent: 12-06-2017 15:39
From: Floyd Gadd
Subject: Rescaling Early 20th Century Grand
I am preparing to restring a 1925 Gerhard Heintzman 5' 4" grand piano. The existing scale averages about 130 pounds tension per string in the tenor, around 140 in the low treble, and under 120 in the high treble.
I have used Scale Ripper in the past to even out scales, but have never encountered a scheme like this one. The string lengths are short -- significantly shorter than the 5' 2" Knabe I restrung two years ago.
If I evaluate the existing setup in PScale, I find that the first 16 notes of the tenor are slightly above what Parsons has identified as the preferred range for inharmonicity. Adjusting the stringing scheme so that the tension averages 140 pounds across the plain wire area raises the inharmonicity slightly further in the tenor, and drives the inharmonicity in the top octave-and-a-half of the treble quite a bit beyond what Parsons indicates as the preferred upper limit.
If I play with the original scale in Paulello's Typogram, I can bring stress percentages into the ranges Paulello suggests by substituting wire types in the low tenor and the top octave of the treble. It looks like there might be something worth exploring here.
What I do not know is whether I should simply smooth the tensions of the existing scale (the stringing has no half sizes), or whether I should follow my usual procedure of bringing some degree of overall evenness to the tension levels across the whole plain wire section, and then explore how the different wire types can be used to achieve appropriate stress percentages (% of break point)
There are clearly some gaps in my knowledge!
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Floyd Gadd
Regina SK
306-502-9103
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