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#631216 - 05/16/07 07:49 AM Stringing scale irregularities/Restring Questions
Ryan Marlow Offline
Full Member

Registered: 03/05/07
Posts: 21
Loc: North Wilkesboro, NC
Ok, so when I checked the sizes of the strings to mark the bridge for the approximate size of strings to replace, i noticed that the piano is very irregular in its stringing scale. I assumed it would start at a larger size in the low tenor, and then progress in steps to a smaller size in the high treble. For some reason It starts at a size (I think it may be 17) and then increases to a larger size (17 1/2), and then way down to a smaller size (14 1/2). This is a 1928 Hobart M. Cable grand. Should I be accurate in duplicating the sizes I'm finding, or should I restring with the suggested scale in "A guide to Restringing" by John W. Travis? Thanks. Oh, and by the way, Ari Isaac is duplicating my hammers and bass strings! I can't wait to install them!

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#631217 - 05/16/07 09:32 AM Re: Stringing scale irregularities/Restring Questions
Bill Bremmer RPT Offline
3000 Post Club Member

Registered: 08/21/02
Posts: 3184
Loc: Madison, WI USA
For your purposes at this point, I recommend carefully measuring each speaking length of the plain wire unisons and use the Klepec chart in Mr. Travis's book to figure a smoother scale. Keeping the tension as smooth as possible will be the most important consideration. If you use the wire sizes you found on the piano to see what the tension and other values would be from the chart, you will find that the values will be very irregular as you suspected. I had very good results back in the late 1980's using that chart to refigure plain wire scales of lesser known grands and verticals. It's best to start on note 88 and work your way down. In a few cases, scales can drop back a half wire size or so for a couple of unisons as they cross a plate strut.
_________________________
Bill Bremmer RPT
Madison WI USA
www.billbremmer.com

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#631218 - 05/16/07 12:23 PM Re: Stringing scale irregularities/Restring Questions
BDB Offline
Yikes! 10000 Post Club Member

Registered: 06/07/03
Posts: 21271
Loc: Oakland
It is difficult to determine the gauge from micrometer readings. Wire might have some irregularities, and dirt, corrosion and bends in the wire throw the readings off.

I use a spreadsheet to determine a scale with an even tension. My goal is to avoid great leaps of tension, and try to keep the difference between adjacent notes to no more than about 5 pounds, although this is not always possible. Most old pianos were not designed with this in mind, and tensions can vary wildly. I find that gauges to change too much in the treble and too little as you go to the bass.

I measure speaking lengths from a paper pattern such as used for bass strings. You can only do it to so much accuracy. Be especially careful in the treble: small inaccuracies make the biggest difference there.
_________________________
Semipro Tech

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#631219 - 05/16/07 05:48 PM Re: Stringing scale irregularities/Restring Questions
Ryan Marlow Offline
Full Member

Registered: 03/05/07
Posts: 21
Loc: North Wilkesboro, NC
Just to make sure, when you refer to the speaking length, what two points am I measuring from? Do the strings have to be tightened, or even in place? How do you get an accurate measurement with the plate in the way?

Is the Klepac Chart the recommended scale for pianos? For instance, is it strange to have a size 14 for C-88, or does it simply depend on the piano?
It would be great if my make of piano was included in the vast charts in the back of Mr. Travis' book so that I had an accurate guide to go by.

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#631220 - 05/16/07 06:22 PM Re: Stringing scale irregularities/Restring Questions
BDB Offline
Yikes! 10000 Post Club Member

Registered: 06/07/03
Posts: 21271
Loc: Oakland
The speaking length is from the front bridge point to the agraffe or capo bar. The best way to make a pattern is to start with the strings in place. Place the paper over the bridge pins and sandpaper them, so that the paper will hold in place. Then rub a pencil over the strings, so you get the direction that they go from the bridge pin. You can mark the other end of the speaking length if there are agraffes or if it is an upright. You will probably want to remove the bass strings, though. After you remove the rest of the strings, you can put the pattern back on the bridge pins, and use a pencil to mark the capo bar.

The Travis book is good for its time, but we can do better now, thanks to the computer. Since computers give quick results, I figure it out by looking at the spreadsheet, starting with the gauge of C-88 and that of the lowest plain string, although those are just guidelines. I usually start by looking for 160 lb. across the scale. It can be less for shorter pianos, and more for longer pianos. If you start with that in mind, it usually works out.

What I really want to avoid is the huge dip in tension before the wound strings start. This is the problem of the hockey-stick bridge. If there is such a bend in the bridge, you may need to change gauges at every opportunity, even skipping a wire size. If you have some idea of what the wound strings are at the break, you can come close to matching the tension across the break. Plugging them into the formula will come close enough.

The results are a a scale that stays in tune better, and more even tone, so less voicing is required. I have posted this before and after graph before, but this is how it can work out:
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Semipro Tech

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#631221 - 05/16/07 07:21 PM Re: Stringing scale irregularities/Restring Questions
Bill Bremmer RPT Offline
3000 Post Club Member

Registered: 08/21/02
Posts: 3184
Loc: Madison, WI USA
Ryan, it's been many years since I used the Klepac chart, so I looked it up. I forgot that it does not give you any direct info on the variables that there will be: pounds tension, inharmonicity and percentage of breaking point but you can still use it just as effectively as if you did have all that information. You can still come up with the exact same determination as you would if you had a computer spread sheet or another book I have which does give all of that information.

First, to answer your question about how to measure, it is actually easiest to measure speaking length with all of the strings removed. Start on note 88 and for the first several notes, just use a pocket technicians ruler or other very small ruler and measure from the forward bridge pins to the termination point on the plate. The first measurement should be about 2". As the instructions say, if it is longer than that, you will use a larger size wire.

Some pianos do have size 14 wire at the very top. Older Kawais come to mind. But if your piano has size 14 up there and your measurements are closer to what that chart has, use what the chart says. Since you won't have all of the information, you'll have to make some careful decisions but in the end, even if you could see all of the variables, you'd end up making the same decision as you would with much more information with the limited information you do have using this chart.

Most scaling decisions will run with patterns of 2, 4 or 6 unisons of the same size wire before they change to the next. As you get down further, use a long but fine tape measure. You may have to have someone help you but I have measured the longer strings by myself simply by hooking the tape measure on the forward bridge pin and pulling it taut and then finding the length at the other end, trying to estimate just where that termination point would be with an agraffe involved, etc. Patterns of 8 or more strings in a row in the tenor are common and it is also common to sometimes skip a whole wire size once you get to size 18 and larger.

It's just as well that your piano's string sizes are not listed in the book because if they were, it would just be what was found there and you would be simply repeating a manufacturer's error. Some of these pianos were made very poorly, just using a few sizes of wire. It was faster and cheaper but certainly not better. So you can make a better, more evenly tensioned scale by using the Klepac chart.

Does the piano you are working with have wound strings in the low tenor? If so, that is good but I suspect it is one of those with the "hockey stick" type bridge with plain wire down to about B2. If this is so, the best improvement you could make is to convert those flabby low tenor strings to 2 string, wound string unisons. But because you do not have that capability at this point, there is a second alternative which will be far superior to simply putting on wire which is way too low in tension (size 18 wire all the way down to B2, for example).

Convert the lowest tenor string to two string unisons but use markedly heavier wire in that area. Depending on your measurements, all the way up to size 21 for the lowest note. Sometimes, this works out to something like size 21 for B2 only, then Size 20 for C3 and C#3, then size 19 for D3 and D#3. (Then have size 18, 171/2 and 17 regular 3 string unisons on up to about C4 and higher, depending upon your determinations). In such an example, you'd have 5, 2 string, plain wire unisons. You might skip a couple of hitch pins because of that. You would still put a tuning pin in the center hole but you just leave it blank with no string on it for appearance sake. If you can and have some 2 string agraffes to put there, go ahead but it is not entirely necessary. It might even work out better if you don't. Just put the 2 strings through the outside holes and leave the center blank.

The reason why it may work out better not to convert the agraffe to a 2 string type when doing this kind of change is that this larger sized wires will be very loud and brassy sounding. That's first of all why you would only want to have two, not three. If the hammer strikes at only the edges of this very powerful wire rather than more at the center, it won't be quite as strong of a sound. You'll still need to deeply needle these hammers to take down the power. But the benefit will be that this section of the piano will stay much better in tune than it would with smaller wire. The smaller sized wire also gives off a very "wolfish", "tubby" tone that is difficult to tune. It is extremely unstable when the relative humidity changes. The larger sized wire, while still a compromise, will be a better choice in the end with respect to both tone and stability.

Many small verticals are scaled this way. I rescaled many verticals and small grands this way back in the 1980's and still tune them today and I am still quite satisfied with the results, especially considering how simple and easy a choice it was to make back then with respect to any other far more complicated conversions that may have been possible.

Please tell us a little more about the characteristics of your piano's scale design, particularly the low tenor.
_________________________
Bill Bremmer RPT
Madison WI USA
www.billbremmer.com

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#631222 - 05/16/07 07:25 PM Re: Stringing scale irregularities/Restring Questions
Bill Bremmer RPT Offline
3000 Post Club Member

Registered: 08/21/02
Posts: 3184
Loc: Madison, WI USA
I see that BDB also answered while I was writing my message. Please read both carefully. You'll want to be able to do what he does at some time in the future. You might also be able to send him your measurements and he can send you back his suggestions for wire sizes when he runs them through his computer. Compare them to what you got by using the simple Klepac chart.
_________________________
Bill Bremmer RPT
Madison WI USA
www.billbremmer.com

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#631223 - 05/16/07 11:45 PM Re: Stringing scale irregularities/Restring Questions
BDB Offline
Yikes! 10000 Post Club Member

Registered: 06/07/03
Posts: 21271
Loc: Oakland
 Quote:
The first measurement should be about 2". As the instructions say, if it is longer than that, you will use a larger size wire.
This is an example of outmoded information. The longer the string, and/or the thicker the wire, the higher the tension you need to get the same pitch. So if the first measurement it more than 2", and you want to keep the tension reasonable, you need to lower the wire size.
_________________________
Semipro Tech

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#631224 - 05/17/07 04:00 PM Re: Stringing scale irregularities/Restring Questions
Ryan Marlow Offline
Full Member

Registered: 03/05/07
Posts: 21
Loc: North Wilkesboro, NC
Ok. I found a super-small measuring tape and was able to find that C-88 speaking length is 3 1/8" or 3.125". According to the Klepac Chart, that would be a size 14. That is what is installed. I checked the low tenor. I have plain wire strings starting at the 27th note (B3). So I have 26 unsions of copper-wound strings. The speaking length of the lowest tenor string is 37.1875" or 37 3/16". According to Klepac, a sz. 19 is suggested. That is what is installed.

The bridge curve is sort of like this:
__
\
\
\
\____
I know that's a really poor example, but that's a rough idea. Almost a backwards "S".

BDB, I'm not afraid to admit my ignorance. I don't understand how you came up with the spreadsheet. What formula is it that you refer to? Is it one of the many formulas explained in Travis' book? If I record the speaking lengths of the plain wire strings, would you be willing to enter them into your computer and figure out what wire sizes to use? I'd be intersted in comparing the outcome to what I get from the Klepac chart.

I just finished measuring the string sizes in the piano. Beginning with C-88 and going down:

-10 Unisons of sz. 14
-20 Unisons of sz. 14 1/2
-6 Unisons of sz. 16
-6 Unisons of sz. 17
-12 Unisons of sz. 17 1/2
-5 Unisons of sz. 17
-3 Unisons of sz. 19

What does that say to you experts? Seems to me that it's a poorly scaled piano. But if I knew what I was talking about, I wouldn't be on here asking for your help. ha-ha I appreciate your time and input. Thank you in advance to all.

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#631225 - 05/17/07 04:57 PM Re: Stringing scale irregularities/Restring Questions
BDB Offline
Yikes! 10000 Post Club Member

Registered: 06/07/03
Posts: 21271
Loc: Oakland
3.125" is way too long for C-88. Any string that you put in there would probably break. #14 would be 428 pounds!

It is very unlikely that you measured those gauges correctly, and you seem to have trouble measuring the speaking length as well. I do not know what piano you are working on, but designers who did not do any calculations usually followed conventional practices. If they were using only full sizes, then there would be about 6-8 notes of #13, then a similar number of #14, with maybe more for #16 and 17, and a little less for larger sizes. Incidentally odd numbers of unisons means that some strings have to be individually tied, rather than looped around the hitchpins, so 5 #17 and 3 #19 would be unusual. Designers who used half-sizes changed more often in the treble, and usually abandoned half-sizes in the tenor, which is bad practice.

The formula I used was adapted from The Piano-Its Acoustics by McFerrin. For a given pitch p, length l and tension t, the gauge is:

((SQRT(t)/(0.04796*p*l))-0.025)*500+10

You can solve for the other variables if want to guess a gauge and find out what the tension is or do something like that.
_________________________
Semipro Tech

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#631226 - 05/17/07 10:28 PM Re: Stringing scale irregularities/Restring Questions
Supply Offline
3000 Post Club Member

Registered: 09/11/06
Posts: 3919
Loc: Vancouver Island, BC, Canada
Piano scaling is really advanced stuff. With respect, if your measurement of the speaking length of C-88 comes to 3 inches, you need to let someone else check the scale and tweak it for you. Practice stringing, tuning, voicing and work your way up to higher skills.
_________________________
Jurgen Goering
Piano Forte Supply
www.pianofortesupply.com

Piattino Caster Cups distributor

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#631227 - 05/18/07 10:37 AM Re: Stringing scale irregularities/Restring Questions
Ryan Marlow Offline
Full Member

Registered: 03/05/07
Posts: 21
Loc: North Wilkesboro, NC
Well my bridge illustration didn't turn out like it was supposed to. ha-ha
I rechecked the speaking lentgh of C-88. How does slightly over 2" sound? According to the Klepac that would be a sz. 13. So, according to BillBremmerRPT, the easiest way for me to restring this 1928 Hobart M. Cable grand is to just use the Klepac chart as a guide. Correct? Especially for someone as inexperienced as me. Thank you so much for your help.

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#631228 - 05/18/07 08:33 PM Re: Stringing scale irregularities/Restring Questions
Bill Bremmer RPT Offline
3000 Post Club Member

Registered: 08/21/02
Posts: 3184
Loc: Madison, WI USA
Just as I said, Ryan but I do take BDB's comments seriously. When I read the note in Travis' book, there did seem to be something backwards about it but the hour being late, I let it go. To create wound strings is highly complex but the fact is, for the plain wire, the choices are very limited. Therefore, using that chart or this other book I have, a Handbook of Treble String Tensions, one can come up with the same results as any more advanced program. But you have to be sure about what you are doing. Measure the *speaking length* of the string only (not to the far side of the bridge). Also, the note that you identified as B3 is actually B2. The lowest B of the piano is B0.

To use #19 wire in the lowest part of the plain wire section will work, yes. But I still recommend doing what I suggested in a previous post: convert the lowest plain wire notes to 2-string unisons. Use size 21 wire for B2 only, then #20 for C3 and C#3 and then size 19 for whatever else would require size 19. That would mean just 3, 2-string unisons in this case. I think BDB might agree with me there. If you can accurately measure all of you plain wire unisons, send BDB the data. He can create a nice smooth scale for you easily and quckly.
_________________________
Bill Bremmer RPT
Madison WI USA
www.billbremmer.com

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#631229 - 05/18/07 09:32 PM Re: Stringing scale irregularities/Restring Questions
Gene Nelson Offline
1000 Post Club Member

Registered: 09/10/04
Posts: 1464
Loc: Old Hangtown California
Check this out: http://www.goptools.com/scale.htm
A freebe from Sierra Software - creator of Pscale.
_________________________
RPT
PTG Member

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#631230 - 05/19/07 01:21 AM Re: Stringing scale irregularities/Restring Questions
BDB Offline
Yikes! 10000 Post Club Member

Registered: 06/07/03
Posts: 21271
Loc: Oakland
 Quote:
I think BDB might agree with me there. If you can accurately measure all of you plain wire unisons, send BDB the data. He can create a nice smooth scale for you easily and quckly.
If you ask nicely, I might send a blank spreadsheet. Filling in 60-odd numbers is a lot of my valuable time. I think I can convert it to Excel.

Tolerances in measuring are very tight, particularly in the high treble. That glitch in the graph at B-87 is probably because I was off on the speaking length by 1/32" or so. "Slightly over 2 inches" does not cut it. You have to be within about 1/64" there.
_________________________
Semipro Tech

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#631231 - 05/19/07 08:31 AM Re: Stringing scale irregularities/Restring Questions
Ryan Marlow Offline
Full Member

Registered: 03/05/07
Posts: 21
Loc: North Wilkesboro, NC
BillBremmerRPT, I always assumed the bottom note was A1. My, my. Thanks for the correction. I believe I'll try the conversion of the lower notes to 2-string unisons.

BDB, i would greatly appreciate your sacrifice of time to provide a blank spreadsheet for me to learn to use.

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#631232 - 05/19/07 09:56 AM Re: Stringing scale irregularities/Restring Questions
Bill Bremmer RPT Offline
3000 Post Club Member

Registered: 08/21/02
Posts: 3184
Loc: Madison, WI USA
Yes, Ryan, a very important distinction. The first 3 notes, A, A# and B are the "zero" (0) octave. I ran into this problem last Wednesday when tutoring an aural tuner about passing the exam. All ETD's identify the notes of the piano using the system devised by Hermann Helmholz, a 19th Century scientist who gave us knowledge about many aspects of tuning theory. Some people still identify the notes of the piano from 1-88 but the identification by octave number and note is a lot easier to learn. The PTG Tuning Exam uses this system because ETD's are used to measure and score the exam.

So, the lowest C is C1. Middle C is C4. The very highest C is C8. The C an octave below middle C is C3 and the C an octave above middle C is C5. This is a good thing to get used to knowing whether you ever use an ETD or not. Only the Bosendorfer Imperial Concert Grand has a full octave of notes all the way down to C0. Some very old pianos stop at A7 (an 85 note keyboard instead of 88).

The piano you are working on is a classic example or "poor" scale design. But there are many of them out there. A Yamaha GH1, for example has B2 as it's lowest note in the tenor. That note has a very bad sound and is difficult to tune. No ETD calculated program will get it right. I have consistently found that it must be tuned quite a bit sharper than the C3 next to it for it to sound in tune. At one time, Yamaha supplied conversion kits to change the lowest six unisons of the tenor section to wound strings. I have one piano teacher customer who has such a piano and did the conversion. It solved the tone and instability problems in that area of the piano. Yamaha also made (and possibly still makes, I don't know for sure) the very same model with the six lowest strings in the tenor being wound, 2 string unisons.

However, converting the low tenor to wound strings is quite a complex job. You need to add extra hitch pins because each wound string as a single loop at the end. You use a smaller core wire and a fine copper winding. Only someone with a scale design program could calculate the core diameter plus the winding thickness and winding length. So by comparison, the compromise made by simply putting heavier core wire but only two string unisons is by far, easier and simpler.

I noticed immediately the scale design of the new, smaller Walter grand when I first saw one. Del Fandrich created the design. It is similar to what the smaller Mason & Hamlin and A.B. Chase pianos have. It has a separate, small low tenor bridge with 4 wound strings on it. When I played across the transition (break) from the low tenor to the bass, I heard the most even tone I have ever heard from a small piano in this area. There was, to my ear, absolutely no distinction in tone from one note to the other across this span of the scale. This is the ultimate goal.

While putting wound strings in the low tenor improves most small pianos with a long tenor bridge, there always seems to be a difference in tone across the break. Take a Steinway model M for example. The Steinway Model A also has wound strings in the low tenor. One model of the new Estonia grands also replicates this design. It seems that a better compromise for many small pianos is to simply make the bass bridge longer. This is what Kawai has done with its new baby grands. The Steinway L and O still have a low tenor with plain wire. Any experienced piano tech will tell you that this area of the piano is the most unstable and difficult to tune and voice. I would be tempted to convert the 3 lowest unisons of a Steinway L if I were to rebuild one but somehow, Steinway's designs are considered "sacred". I've never seen one that was converted but I imagine that some people have done so.

Having said all of that, the simple change from three to two string unisons with heavier wire in the three lowest notes of the tenor of the piano you are working on would be just the thing for you to do at this stage of your career as a piano technician. You won't regret it.
_________________________
Bill Bremmer RPT
Madison WI USA
www.billbremmer.com

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#631233 - 05/19/07 11:53 AM Re: Stringing scale irregularities/Restring Questions
BDB Offline
Yikes! 10000 Post Club Member

Registered: 06/07/03
Posts: 21271
Loc: Oakland
This is the spreadsheet. This has numbers filled in it, from the piano in the chart, but you can overwrite them. Do not overwrite the pitch numbers, or the formulas. Work on a copy, not the original!

Enter the speaking lengths in the column "Length 1". Enter target tensions in "Tension 1". "Gauge 1" will give the approximate wire gauge to give that tension, although in finer degrees than wire comes in. As you can see, I was aiming for about 150 lb. across this scale. In general, longer pianos will give you higher tensions. It is not necessary for the tension to be a constant. Particularly in very long pianos, you might want to have it gradually increase as the strings get longer. Even this one decreases tension somewhat, since it is a short piano.

Then you can enter the gauges you choose into "Gauge 2" and see what the resulting tension is in "Tension 2". "Length 2" is just copied from "Length 1". This helps refine the numbers.

If you are designing a new bridge, you could use the "Gauge 3" and "Tension 3" to refine the speaking lengths.

Use this at your own risk. I make no guarantees for accuracy or suitability of the results.

(I am not an Excel expert, so I cannot give instructions on how to use it, like how to fill columns. I actually use another spreadsheet application, and this is just a translation into a more common application. So do not ask me for help with that.)
_________________________
Semipro Tech

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#631234 - 05/19/07 01:15 PM Re: Stringing scale irregularities/Restring Questions
Supply Offline
3000 Post Club Member

Registered: 09/11/06
Posts: 3919
Loc: Vancouver Island, BC, Canada
Just curious BDB - how do the string length measurements come out to the ten-thousandth of an inch (e.g. 24.063")? It seems to me that it would be nearly impossible to meaure even to the 1/100 of an inch. Are you converting from a metric measurement?

Also, do I understand it correctly that inharmonicity and the loudness factor are not taken into account when coming up with a scale using this procedure?
_________________________
Jurgen Goering
Piano Forte Supply
www.pianofortesupply.com

Piattino Caster Cups distributor

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#631235 - 05/19/07 01:48 PM Re: Stringing scale irregularities/Restring Questions
BDB Offline
Yikes! 10000 Post Club Member

Registered: 06/07/03
Posts: 21271
Loc: Oakland
I am measuring to the nearest 1/64" and converting to decimals. I have another spreadsheet that has the equivalents, which I leave open when I am doing the entry.

I am not considering inharmonicity, although I have checked it and it comes out OK. Loudness is most directly related to tension, in my experience.

This may not be the most sophisticated calculation available, but it does a decent job.
_________________________
Semipro Tech

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#631236 - 05/19/07 04:49 PM Re: Stringing scale irregularities/Restring Questions
Bill Bremmer RPT Offline
3000 Post Club Member

Registered: 08/21/02
Posts: 3184
Loc: Madison, WI USA
Ryan, if BDB's offering seems a bit too overwhelming, just list your measurements, the best you can and I will calculate the pattern for you using my Treble Strings Tension Handbook as I did with so many pianos in years past. Start with C8 and list like this:

88 (C8):2
87 (B7): 2 1/32
86 (A#7): 2 1/8
85 (A7): 2 1/4

etc. down to 27 (B2) (where your plain wire ends).

From notes 88-63, to the nearest 1/32" is sufficient. From notes 62-47, to the nearest 1/16" is sufficient. From notes 48-27 (27 is B2, the lowest plain wire on your piano), to the nearest 1/8" inch is sufficient.

If there are any unisons where one string is tied off, be sure to indicate this on your chart. Example:

65 (C#6) 6 1/32 Tied Off

******************************************************************

While I can see that if using a spreadsheet, you may want to have finer measurements and when converting to metric or English decimal, you would want to have 3 decimal places, as I've said from the beginning, the end result is always going to be a decision of one wire size to the other. The final result will look like just about any other piano, merely a difference sometimes of 2 or 4 more unisons of a particular wire size and conversely, less of another. If the piano you are working on really had size 14 all the way to C8, you can certainly expect that I or anyone else would come up with something like 4 unisons of 13 and 6 of 13 1/2 for the top 10 unisons.

In a few instances, you may see a particular wire size cross over the break from the treble to the tenor and in some rare cases, you may actually see the wire size decrease slightly across that break. It all depends upon the curvature of the bridge. Look at some small recent vintage Baldwin grands and you will see that.

To answer Jurgen's question about volume and inharmonicity: I agree with BDB that maintaining the smoothest possible curve of tension is the primary goal. When this is done, the inharmonicity curve inevitably follows suit. The volume factor does as well. Volume and inharmonicity go hand in hand with tension. If you have dips and peaks in tension, you will also have dips and peaks in inharmonicity and volume. Therefore, if you build the smoothest possible tension curve, you will have the best tuning stability, ease of predictable tuning, either aural or electronic and the least amount of voicing problems.

The volume issue does however start to be a problem in the low tenor when you get to the larger sizes of wire and are trying to maintain your tension curve. That is why I am suggesting and will most likely end up suggesting a few two string unisons in the very low tenor if Ryan posts his data.
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#631237 - 05/19/07 05:51 PM Re: Stringing scale irregularities/Restring Questions
BDB Offline
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I ran the inharmonicity numbers on one scale, and there was a slight increase near the break, but it was less than 0.02%. I may be interpreting the numbers wrong, but the important thing was that it was negligible.

Remember, none of these things were calculated when the pianos were designed.
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#631238 - 05/19/07 06:17 PM Re: Stringing scale irregularities/Restring Questions
Bill Bremmer RPT Offline
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Loc: Madison, WI USA
Indeed. Many manufacturers just made some kind of curved bridge, others a kind of straight one and just laid on some wire with little more thought to it than that. When they ran out of room in short pianos, they just made the bridge take a left turn at the end and when they found that any wire heavier than size 19 sounded too loud, they just used lighter wire to the end of it. I've seen all too many pianos with size 18 wire all the way down to B2 on a 5'2" grand. Absolutely horrible sound and even worse tuning stability.

Fewer spools of wire meant a less costly inventory and less confusion for the stringer. Heavier wire sizes are harder to handle and were perhaps more expensive. Any rebuilder today can make a substantial improvement with no other alterations than carefully selected wire sizes.
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#631239 - 05/19/07 06:28 PM Re: Stringing scale irregularities/Restring Questions
BDB Offline
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As you can see from the spreadsheet, although the lowest strings of the sample piano are thick, most of the strings are thinner than usual. (There are 22 #13 notes!) This would have been much cheaper, because there is more length to the pound using thinner wire.
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#631240 - 05/22/07 03:59 PM Re: Stringing scale irregularities/Restring Questions
Ryan Marlow Offline
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Registered: 03/05/07
Posts: 21
Loc: North Wilkesboro, NC
BillBremmerRPT, would you like for me to post the speaking lengths on here, PM you, or send you an email? I have them ready. Thanks.

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#631241 - 05/22/07 06:48 PM Re: Stringing scale irregularities/Restring Questions
Bill Bremmer RPT Offline
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Any way you feel comfortable, Ryan. If you post on the Forum, I will return my caluculations here and they will be open to scrutiny which I am not afraid of but others may have slightly different opinions, so it's up to you.

If you send them by private e-mail, you may use an attached file. Put the words "piano scale data" in the header. If you respond privately, I can still post an abbreviated summary such as "6 unisons of 13, 4 of 13 1/12, etc. My e-mail address is Billbrpt@aol.com.
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#631242 - 05/22/07 07:11 PM Re: Stringing scale irregularities/Restring Questions
BDB Offline
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If you want to enter them into my spreadsheet, I can go though my process. Send me a message when you are done, and I will give instructions.
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#631243 - 05/22/07 07:29 PM Re: Stringing scale irregularities/Restring Questions
BDB Offline
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Oh, and be sure to let us know which notes do not share a string with an adjacent note. Otherwise I will assume that they all do, in which case there needs to be an even number of notes with each wire gauge.
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#631244 - 05/23/07 12:18 AM Re: Stringing scale irregularities/Restring Questions
Bill Bremmer RPT Offline
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It's not a bad idea at all to let both me an BDB do it and you can choose whichever design you feel most comfortable with.
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#631245 - 05/23/07 01:48 AM Re: Stringing scale irregularities/Restring Questions
Supply Offline
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I am playing around wih a scaling spreadsheet these days. Unless it is some kind of a secret, I would be interested in seeing the raw data (speaking lengths and, if available, original wire gauges) and run the numbers through the sheet I have, in order to compare with other programs.

We could have a whole re-design committee for Ryan's piano!
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#631246 - 05/23/07 08:16 AM Re: Stringing scale irregularities/Restring Questions
Bill Bremmer RPT Offline
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But Ryan should also be wary of "design by committee" and choose the design he feels most comfortable with and not make a composite one or take all results and average them.
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#631247 - 05/23/07 10:04 AM Re: Stringing scale irregularities/Restring Questions
Ryan Marlow Offline
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Registered: 03/05/07
Posts: 21
Loc: North Wilkesboro, NC
Alright, here it goes:

88 (C8): 2 1/8 2.125
87 (B7): 2 7/32 2.21875
86 (A#7): 2 5/16 2.3125
85 (A7): 2 13/32 2.40625
84 (G#7): 2 17/32 2.53125
83 (G8): 2 5/8 2.625
82 (F#7): 2 3/4 2.75
81 (F7): 2 29/32 2.90625
80 (E7): 3 1/16 3.0625
79 (D#7): 3 7/32 3.21875
78 (D7): 3 3/8 3.375
77 (C#7): 3 17/32 3.53125
76 (C6): 3 23/32 3.71875
75 (B6): 3 29/32 3.90625
74 (A#6): 4 1/8 4.125
73 (A6): 4 5/16 4.3125
72 (G#6): 4 17/32 4.53125
71 (G6): 4 25/32 4.78125
70 (F#6): 5 1/32 5.03125
69 (F6): 5 9/32 5.28125
68 (E6): 5 7/8 5.875
67 (D#6): 6 3/16 6.1875
66 (D7): 6 1/2 6.5
65 (C#6): 6 13/16 6.8125
64 (C5): 7 1/8 7.125
63 (B5): 7 7/16 7.4375
62 (A#5): 7 27/32 7.84375
61 (A5): 8 7/32 8.21875
60 (G#5): 8 21/32 8.65625
59 (G5): 9 1/8 9.125
58 (F#5): 9 21/32 9.65625
57 (F5): 10 3/16 10.1875
56 (E5): 10 7/8 10.875
55 (D#5): 11 1/32 11.53125
54 (D5): 12 1/4 12.25
53 (C#5): 13 13.0
52 (C4): 13 11/16 13.6875
51 (B4): 14 1/2 14.5
50 (A#4): 15 5/16 15.3125
49 (A4): 16 7/32 16.21875
48 (G#4): 17 9/16 17.5625
47 (G4): 18 5/16 18.3125
46 (F#4): 19 1/4 19.25
45 (F4): 20 1/8 20.125
44 (E4): 21 1/16 21.0625
43 (D#4): 22 1/8 22.125
42 (D4): 23 1/8 23.125
41 (C#4): 24 13/32 24.40625
40 (C3): 25 23/32 25.71875
39 (B3): 27 1/32 27.03125
38 (A#3): 28 7/16 28.4375
37 (A3): 29 7/8 29.875
36 (G#3): 31 5/16 31.3125
35 (G3): 32 3/4 32.75
34 (F#3): 34 3/16 34.1875
33 (F3): 35 9/32 35.28125
32 (E3): 36 1/8 36.125 (tied off)
31 (D#3): 36 29/32 36.90625
30 (D3): 37 1/4 37.25
29 (C#3): 37 3/8 37.375
28 (C2): 37 11/32 37.34375
27 (B2): 37 5/16 37.3125 (tied off)

I'm anxious to see the results you guys come up with. I'm very anxious to get started on the piano.

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#631248 - 05/23/07 06:44 PM Re: Stringing scale irregularities/Restring Questions
BDB Offline
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Roughly speaking:

1 - 21
2 - 20
2 - 19
1 - 18
2 - 17
4 - 16-1/2
4 - 16
2 - 15-1/2
16 - 15
4 - 14-1/2
10 - 14
4 - 13-1/2
6 - 13
4 - 12-1/2
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#631249 - 05/23/07 11:23 PM Re: Stringing scale irregularities/Restring Questions
Bill Bremmer RPT Offline
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Ryan,

This was indeed a very interesting project and puzzle to solve. I used the Piano Rebuilder’s Handbook of Treble String Tensions (and Other Characteristics) compiled by James H. Donelson RPT, published in 1977. It is a table of numbers that I used to rescale over 20 pianos back in the late 1980’s and early 1990’s.

What I gathered about the piano you are working with is that it has some unusually long speaking lengths in its hi-mid and low treble sections. Therefore, smaller than usual wire is recommended than for most pianos in these areas (as BDB pointed out in contradiction to what the Klepac chart suggests). Also, at the very top, the speaking lengths were slightly long and could have even used some #12 and #12 ½ wire but with the size #13 and #13 ½ wire that I suggested, the tensile strength lies still well below the maximum of 70% which is recommended. I have seen many scales with even higher tension in this area.

The “%tensile” figures indicate the percentage of tension at theoretical pitch before the string would break. Since most people will tune these highest strings considerably sharper than that, one would certainly not want to exceed the 70% limit. Although I did not look up what size #14 would have provided in the areas where I suggest #’s 13 & 13 ½, I can well imagine that the tension would have been dangerously high. These wire sizes will also produce a good, strong sound whereas #’s 12 & 12 ½ may sound a little on the weak side. It is normal for most scales to have slightly higher tension in the highest part of the high treble.

The Inharmonicity column indicates the amount of difference between the 1st and 2nd partials, (one octave higher than the fundamental). You will note that the 4 highest strings have 1st partial inharmonicity of over ¼ of a step. This is normal in this area of the piano but if size #14 wire had been used, the inharmonicity would have been all the more exaggerated.

From the notes 80 all the way down to 30, I was able to keep the average tension hovering around 150 pounds as BDB has suggested. This should provide you with a light sounding and easy to tune piano with relatively low inharmonicity compared to many others. Only at the lowest end does the inharmonicity start to climb again but just very slightly. Also, at the lowest end, any wire size above #19 would tend to sound very loud and brassy, this is the reason for dropping back to a bichord (2 string unison). You will notice in looking at the figures, in spite of increasing dramatically the size or wire, the pounds of tension and % tensile drop off precipitously but the inharmonicity rises slightly. This is entirely due to insufficient speaking length and why some kind of compromise is called for. If #19 wire were used in this area, the tension would drop very low indeed and tunings would be very unstable in this area, responding dramatically to the least rise and fall in relative humidity. The tone would also be weak and “wolfish” sounding.

Do not be alarmed by the words “estimate” you see beginning at note 62 and below. This certainly does not mean I merely estimated which wire size should be there. The very fine measurements you took from notes 62 and below sometimes fell in between the figures that are in the table I have. The author noted that these fine increments were passed over to keep the table of figures from being too cumbersome since such small increments make literally no difference in determining which wire size to use in this area.

However, if one uses a computer spreadsheet and calculations, having such small distinctions does make for an even smoother looking curve. Therefore, I estimated what those figures would be for you. The estimates are merely the very insignificantly small differences in tension, % tensile and inharmonicity. If I had used either the next fraction up or down, it would have made no difference whatsoever in the choice of wire size.

I noted that you identified C4 as C3 but I corrected that in the chart you offered. I placed asterisks (***) to help the figures I supplied line up better so you could more easily see the curves of all four characteristics: wire size, pounds tension, % tensile and inharmonicity.

You will notice that at note #68, I made the notation “back-up/break”. I assume this is the break between the high treble and the treble. In many pianos, the bridge goes straight across this break but I imagine that on your piano, the bridge continues to curve. Therefore, there is a noticeable “jump” in length between notes 68 & 67, which calls for a smaller wire size. So, the pattern of wire sizes takes a step back from 14 ½ to 14 which is unusual, virtually never seen in finer pianos. But in this case, it provides for the smoothest curve possible. I have done this a number of times before on smaller, lesser quality pianos. Trust me; it is an improvement, not a mistake in judgment.

Only down at notes 31 and below do I run into a dilemma. I imagine this is where the bridge takes a “left turn” and creates the “hockey stick” appearance. The speaking lengths increase very little for each successive note when they should increase a whole inch or so for plain wire to be effectively and best used this low in a scale. This is where specially designed wound strings would best be used but that would require adding hitch pins, replacing agraffes with 2-string types, etc. So, where you see the words, “bichord”, simply guide your plain wire through the outside holes in the agraffes and bridges and leave the centers blank. Put in a tuning pin in the center hole but just leave it blank. If in the end, you don’t like the outcome, you can always use size #19 to the bottom, possibly putting size #20 on the lowest, tied off unison.

It is unfortunate that you must buy some sizes of wire for only one or two unisons. Just buy the smallest quantity you can for those sizes. Also, you’ll note that I skipped size #18 wire entirely. This is just how it worked out. I also used size 19 ½ and 20 ½ wire when most pianos skip half sizes anywhere past size #18. Again, this was the best compromise. You certainly can choose to use size #19 from note 32 all the way down using 3 string unisons if you so choose. Many pianos are built this way and apparently so was this one. The compromise I offer is in my opinion a better solution, however.

Here is a summary of the scale design I came up with for you:

Scale design for 1928 Hobart M. Cable Grand

88-87: 13.0 (2 unisons)
86-79: 13.5 (8 unisons)
78-73: 14.0 (6 unisons)
72-69: 14.5 (4 unisons)
68-65: 14.0 (4 unisons) (note unusual reversal of pattern)
64-63: 14.5 (2 unisons)
62-59: 15.0 (4 unisons)
58-45: 15.5 (14 unisons)
44-41: 16.0 (4 unisons)
40-39: 16.5 (2 unisons)
38-35: 17.0 (4 unisons)
34-33: 17.5 (2 unisons)
32: 19.0 (1 tied-off unison) (Note that size #18 is skipped entirely)
31: 19.5 (1 bichord unison)
30: 20.5 (1 bichord unison)
29: 21.0 (1 bichord unison)
28: 21.0 (1 bichord unison)
27: 22.0 (1 bichord unison) (no need for tie-off, skip last hitch pin)

Here are the complete details:

Note//Speaking length//wire diameter//lbs tension//%tensile//Inharmonicity

88 (C8):***** 2 1/8 2.125//13.0//175.12//63.912//57.02
87 (B7): **2 7/32 2.21875//13.0//170.08//62.074//53.85
86 (A#7): **2 5/16 2.3125//13.5//175.39//60.481.//54.58
85 (A7): *2 13/32 2.40625//13.5//169.18//58.340//52.26
84 (G#7): 2 17/32 2.53125//13.5//166.79//57.515//47.91
83 (G8): *****2 5/8 2.625//13.5//159.81//55.106//46.49
82 (F#7): *****2 3/4 2.75//13.5//156.25//53.880//43.32
81 (F7): *2 29/32 2.90625//13.5//155.47//53.612//38.99
80 (E7): ***3 1/16 3.0625//13.5//153.81//53.037//35.49
79 (D#7): *3 7/32 3.21875//13.5//151.36//52.195//32.65
78 (D7): *****3 3/8 3.375//14.0//157.67//51.359//32.24
77 (C#7): 3 17/32 3.53125//14.0//153.78//50.090//30.20
76 (C6): *3 23/32 3.71875//14.0//151.93//49.490//27.56
75 (B6): *3 29/32 3.90625//14.0//149.35//48.649//25.41
74 (A#6): ****4 1/8 4.125//14.0//148.38//48.331//22.93
73 (A6): ***4 5/16 4.3125//14.0//144.48//47.062//21.55
72 (G#6): 4 17/32 4.53125//14.5//150.85//58.468//21.07
71 (G6): *4 25/32 4.78125//14.5//149.63//46.040//19.07
70 (F#6): *5 1/32 5.03125//14.5//147.61//45.481//17.46
69 (F6): **5 9/32 5.28125//14.5//144.90//44.584//16.14
68 (E6): *****5 7/8 5.875//14.0//150.49//49.019//11.15 back-up/break
67 (D#6): **6 3/16 6.1875//14.0//148.71//48.441//10.17
66 (D7): *******6 1/2 6.5//14.0//146.21//47.625//9.37
65 (C#6): *6 13/16 6.8125//14.0//143.08//46.607//8.72
64 (C5): *****7 1/8 7.125//14.5//148.01//45.543//8.68
63 (B5): ***7 7/16 7.4375//14.5//143.69//44.211//8.21
62 (A#5): 7 27/32 7.84375//15.0//151.00//44.000//7.75 (estimate)
61 (A5): **8 7/32 8.21875//15.0//147.00//43.000//7.00 (estimate)
60 (G#5): 8 21/32 8.65625//15.0//145.00//42.500//6.50 (estimate)
59 (G5): *****9 1/8 9.125//15.0//144.38//42.094//6.09
58 (F#5): 9 21/32 9.65625//15.5//152.00//42.400//5.78 (estimate)
57 (F5): **10 3/16 10.1875//15.5//151.12//41.861//5.23
56 (E5): ****10 7/8 10.875//15.5//153.41//42.497//4.52
55 (D#5): 11 1/32 11.53125//15.5//153.00//42.50004.00 (estimate)
54 (D5): *****12 1/4 12.25//15.5//154.50//42.798//3.54
53 (C#5): ********13 13.0//15.5//155.02//42.941//3.13
52 (C4): *13 11/16 13.6875//15.5//153.097//42.409//2.86
51 (B4): ******14 1/2 14.5//15.5//153.068//42.401//2.55
50 (A#4): *15 5/16 15.3125//15.5//152.079/42.127//2.30
49 (A4): *16 7/32 16.21875//15.5//152.00//42.000//2.05 (estimate)
48 (G#4): 17 9/16 17.5625//15.5//158.783/43.984//1.67
47 (G4): **18 5/16 18.3125//15.5//153.80//42.604//1.59
46 (F#4): ****19 1/4 19.25//15.5//151.41//41.941//1.46
45 (F4): ****20 1/8 20.125//15.5//147.43//40.840//1.37
44 (E4): **21 1/16 21.0625//16.0//143.50//39.800//1.29 (estimate)
43 (D#4): ***22 1/8 22.125//16.0//149.40/39.315//1.25
42 (D4): ****23 1/8 23.125//16.0//145.40/38.263//1.18
41 (C#4):24 13/32 24.40625//16.0//144.50/38.000//1.06 (estimate)
40 (C4): *25 23/32 25.71875//16.5//150.00//37.500//1.03 (estimate)
39 (B3): **27 1/32 27.03125//16.5//148.50//37.000//0.93 (estimate)
38 (A#3): **28 7/16 28.4375//17.0//146.00//36.500//0.86
37 (A3): *****29 7/8 29.875//17.0//151.316//36.114//0.84
36 (G#3): **31 5/16 31.3125//17.0//148.00//35.300//0.77 (estimate)
35 (G3): ******32 3/4 32.75//17.0//144.33//34.446//0.73
34 (F#3): **34 3/16 34.1875//17.5//147.00//33.200//0.72 (estimate)
33 (F3): ***35 9/32 35.28125//17.5//140.00//31.500//0.71 (estimate)
32 (E3):36 1/8 36.125 (tied off)//19.0//150.95//29.950//0.85
31 (D#3): *36 29/32 36.90625//19.5//147.00//33.150//0.91 bichord
30 (D3): *******37 1/4 37.25//20.5//145.78//30.435//1.08 bichord
29 (C#3): *****37 3/8 37.375//21.0//136.50//27.083//1.25 bichord
28 (C2): **37 11/32 37.34375//21.0//121.00//24.000//1.41 bichord
27 (B2):37 5/16 37.3125(tied off)//22.0//117.25//21.575//1.72 (estimate) bichord

I have this record on file and can send it to you as an attached, MS Word document if you wish by e-mailing me at Billbrpt@aol.com. I will post some first time stringing tips for you tomorrow.

My best regards and wishes for success in this project,
_________________________
Bill Bremmer RPT
Madison WI USA
www.billbremmer.com

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#631250 - 05/24/07 12:56 AM Re: Stringing scale irregularities/Restring Questions
BDB Offline
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I started by looking at a scale around 140 lb., but saw that there would be a problem with the lowest plain string. So I went with a linear increase from 125 lb. up to about 150 lb. at the top. I was not willing to share a hitchpin between two different gauges of wire, and took an average when necessary. The result actually goes from about 108 lb. to about 160 lb.

So it is a little lower tension than Bill's, and it is not terribly different from other scales, except that the area where the gauges stay constant are higher than is traditional. There are not any sizes skipped, other than half sizes in the tenor, which is traditional. It uses the existing hitchpins as it was designed. So it is a reasonable scale, which will not throw someone else who works on it.
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#631251 - 05/24/07 02:05 AM Re: Stringing scale irregularities/Restring Questions
Bill Bremmer RPT Offline
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Registered: 08/21/02
Posts: 3184
Loc: Madison, WI USA
I noticed also that the area where there are many of the same size wire in a row was higher than usual too. This usually occurs in the #17 wire size area. I have done the sharing of two wire sizes on one hitch pin a few times. I found it was possible to put two strings together and create a single tie-off with them, for example. In one instance of an older Baldwin grand, I hid the splice between two strings beneath the string braid. I didn't find these kinds of tricks necessary in this case, however.

The conversion or the lowest tenor strings to wound bichords is commonly done these days. Sometimes, a rebuilder fills in the center tuning pin hole and finishes over it. The wire sizes need to be marked on the piano one way or the other such as a neatly written number on the plate by the tuning pins or on the bridge itself. I used to use number decals that I bought at an art store. I don't really see the minor alterations I suggested as being a problem for anyone. If a string should break and it needs to be replaced but the wire gages are plainly marked, there should be no question about what goes where. While plain wire bichords in the low tenor may surprise someone who has never seen such an alteration before, even a visually impaired person can easily detect which wire goes to a pin and that there are only two strings, not three.

Some scales do skip wire sizes but they are usually whole sizes past #18. In this case, some of the higher half sizes worked out better. I noted that BDB used only one #18 but also that the original also skipped that size.

-12 Unisons of sz. 17 1/2
-5 Unisons of sz. 17
-3 Unisons of sz. 19

I would not insist upon, just recommend the bichords and the sizes I suggested. For the lowest 3 notes, the original design of 3 #19 would not be very good. However, I would say that what BDB suggested:

Roughly speaking:

1 - 21
2 - 20
2 - 19

...would also be quite reasonable and could also use 3 string unisons without skipping any holes or hitch pins. But these 3 lowest notes would be quite loud and brassy sounding, so very aggressive hammer voicing would be called for, especially for the very lowest note. Another alternative could be to make only that lowest note a bichord, skipping the last hitch pin (but using #21 wire, not #22). These lowest strings would still have extremely low tension however and would have more trouble staying in tune but not as much and as extremely so as the original design, just in between what I suggested and the original.

I'll take back the comment I made about making a composite. I think substituting BDB's idea for the lowest 5 notes as I mentioned above is a perfectly reasonable idea. I just think it's important to consider all the benefits and consequences. While I don't see a problem with the conversions/alterations I suggest, BDB seems to think there is that possibility. So, in the end, Ryan the final decision will be up to you but whatever decision you make, there is always the possibility of changing it. None of what was proposed by either of us will lead to a point of no return.

One final comment I would have about the original design: the large number of 17 and 17.5 wires are in the usual area that they occur except that the sizes are curiously reversed (unless Ryan mistakenly listed them that way). This would in this case however, be very poor design indeed. The tension would go from extremely low to very high and then back to low again, so would the volume and so would the inharmonicity except in the lowest strings where it would remain about as high or higher than in my design. I don't know what any of the figures would be for note 27 (B2) with #19 wire because that is considered so unreasonable as to be off the chart! No calculated ETD program could deal with it very well at all.
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#631252 - 05/24/07 02:24 AM Re: Stringing scale irregularities/Restring Questions
BDB Offline
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I doubt Ryan measured the original wires correctly. It is not easy to do even if you are skilled with the use of a micrometer. Sometimes you have to look more for changes, than accurate measurement, and base it on your knowledge of past scaling practices. The numbers Ryan gave were so at odds with those practices that I never considered that they were accurate.

I have also considered that it is possible he has not measured the lengths as accurately as I might like. I am more certain that the scale design was not particularly good. If I were to consider changing hitchpins, I would probably use overwound strings on the lowest 5 notes. But this piano is probably not worth the effort.

I also suspect that the lowest notes will not be ideal. But I bet they would be better than they were originally. It is probable that the lowest strings were thinner than either Bill or I suggested, which would mean that they would have very low tension. (If the piano has agraffes, make sure the holes in them are big enough! You may need to ream them.) So whatever you do is likely to be an improvement.
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#631253 - 05/29/07 04:19 AM Re: Stringing scale irregularities/Restring Questions
Michael Payne Offline
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Registered: 05/28/07
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Loc: San Francisco
I reingineered the strings of an old 1895 Sohmer Grand (original strings) using the Travis book. Took me all day but I think it was worth it. A few observations: Most of the original string gagues were beyond their flexibility for the note they were supposed to produce at that length given the necessary tension required, therefore the wrong strings (possibly due to A435 original calculations versus A440); My range ended up being much greater, starting with 11 at the top instead of 12, and 22 at the bottom instead of 20; I also added several half steps in string sizes that were not originally there; Note that when old strings stretch they are actually thinner in the middle of the string than toward the ends - so measuring near the far ends are closer to the original size; I found a cheap electronic tape measure online for about $14 that had decimal places for measuring; I think next time I will use the excel spreadsheet, but cross reference it against the Travis scale to make sure they are within flexibility range; The Travis book does not work on the bass strings so make sure you send the last string length and diameter to the base string company so they can make a smooth transition between the bass strings and the treble; Some pianos have a crooked bridge, I assume to make some compensation, but the tension must vary in an odd way, as I have seen several later Sohmer pianos (1930-1940) with cracks in the sound board near the crook.
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#631254 - 05/29/07 12:39 PM Re: Stringing scale irregularities/Restring Questions
BDB Offline
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Wire strength has improved over the years. Unless there is some real anomaly with the scale design, there should be no problem staying within the proportional limit of the strings. Besides, there is nothing that you can do about it, short of redesigning the bridge. It changes with the wire gauge: If you decrease the wire gauge, you decrease the tension and the proportional limit. The only place it would be a problem is with the bass strings, and that is up to the bass string designer.
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#631255 - 06/24/07 01:09 AM Re: Stringing scale irregularities/Restring Questions
Michael Payne Offline
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Registered: 05/28/07
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Loc: San Francisco
I just ran some scenerio comparisons for the 1906 Crown upright originally engineered at A435 with the "Calculating Technician" spreadsheet by Dave Roberts (converted to excel by Douglas K. Rhodes, RPT).

They state that the three critical factors are, in priority, Volume; Breaking point; and Inharmonicity.

What I found was that in the string range #27 to 88, when the original string dimension range #18 down to #12 wire was tuned up from A435 to A440, that the volume decreased by almost 50% -- primarily in the #27 to #37 keys, as they transition to the bass section.

When I expanded the wire diameter range going from #22 down to #12 the pattern of volume replicated the original chart, but with the only difference being the pitch, as I converted to A440.

I tried to post the three charts on this BBS (original strings at A435, original strings at A440, and new broader string range at A440) but could not figure out how to do it.

If anyone is interested I can send it to you in a word document, just e-mail me.

Volume range on the first chart (original strings, A435) is from about 260 to 120.

Volume range on the second chart (original strings, A440) is from about 150 to 120.

Volume range on the third chart (expanding new strings from original #18-#13 up to #22-#12 at A440) is again from about 260 to 120 like the original chart.

Keeping the string range the same, the volume gap increased between the bass section as volume decreased -- the change narrowed the volume difference between the bass section and treble making it a smoother transition.

Tension, breaking point, and inharmonicity all remained within parameters on all three charts.

I did find someone who is winding the new bass strings in Canada in Iron instead of copper, like the original. He double-winds and says the bass will be "booming." He had to order the iron wire from England. The first ten strings are copper-wound. Starting at #18 in the treble section, together with a timid single-wound copper bass section may be appropriate, but I am taking painstaking measures on this piano, which is in some ways somewhere between an exact restoration, and a renovation to modern. "Same sound but modern key." I want Debussy to send shivers up your spine, and lift you up to the top of a spire of a cathedral!
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#2028343 - 02/06/13 08:15 PM Re: Stringing scale irregularities/Restring Questions [Re: Ryan Marlow]
NCP Offline
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Registered: 01/29/13
Posts: 7
I have studied this entire thread and attempted to re-scale a 1949 Lester 6'2" grand using the spreadsheet of BDB and input from Bill Bremmer RPT as they attempted to assist Ryan Marlowe.

In the past, I have replaced many broken wires, and have replaced full sets of wound bass strings, but am now attempting to help a beloved aunt restore her grand piano to "better than new" condition. I am not certain, but believe the piano may have been restrung before. The original wires measured from 18 to 12 1/2.

Using the spreadsheet, I added my measurements and then tried to "tweak" the wire sizes to attain as close to a uniform 160 pounds across the scale. I ended up with a scale ranging from 156 to 165 pounds of tension.

Am I on the right track, or am I missing something here ?
I will appreciate any opinions or criticism !!

Many thanks,
ncpianoman

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#2028673 - 02/07/13 10:43 AM Re: Stringing scale irregularities/Restring Questions [Re: Ryan Marlow]
Olek Online   content
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"Volume range on the first chart (original strings, A435) is from about 260 to 120.

Volume range on the second chart (original strings, A440) is from about 150 to 120."

Any explanation to this counter intuitive fact ?

more tension mean less iH and more elasticity, how does it relates to volume ? I have the Travis book but did not remind the way he compute volume, it should be related to mass and tension, and I see no reason it lower with more tension, unless it is about the harmonic content and that volume is only the first partial (?)


Edited by Olek (02/07/13 10:44 AM)
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#2028705 - 02/07/13 11:49 AM Re: Stringing scale irregularities/Restring Questions [Re: Ryan Marlow]
BDB Offline
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It sounds like you are on the right track. A variation of 9 lb. in the tension is pretty uniform. Many original scales vary more than that much between adjacent notes.

Isaac is wrong. Tension has nothing to do with elasticity and more tension can increase inharmonicity.
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#2028722 - 02/07/13 12:20 PM Re: Stringing scale irregularities/Restring Questions [Re: BDB]
kpembrook Offline
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Originally Posted By: BDB
It sounds like you are on the right track. A variation of 9 lb. in the tension is pretty uniform. Many original scales vary more than that much between adjacent notes.

Isaac is wrong. Tension has nothing to do with elasticity and more tension can increase inharmonicity.


Correct about tension variation.

correct about elasticity, but more tension does not increase inharmonicity. Higher tension makes the wire "seem" thinner.
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#2028749 - 02/07/13 01:03 PM Re: Stringing scale irregularities/Restring Questions [Re: Ryan Marlow]
BDB Offline
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If you have a fixed speaking length, in order to increase the tension, you have to increase the diameter of the string, which increases the inharmonicity. Assuming that you want to tune each note to pitch, of course!
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#2028756 - 02/07/13 01:10 PM Re: Stringing scale irregularities/Restring Questions [Re: Ryan Marlow]
Olek Online   content
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It is a little difficult to get but if you increase the diameter of course, you get more iH
but if you change the pitch your raise the elasticity of the wire then the iH lowers. Call that anything, it seem like elasticity (faster return to original dimension in cas eof deformation)


So assuming you keep the same diameters and you raise the tension, why would the volume lower ? just because of less parsing of the partials ? Is not volume a global energy measure ? is it just for the fundamental ?
In that case I can understand, as more partials mean less fundamental probably (?)


Edited by Olek (02/07/13 01:13 PM)
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#2028766 - 02/07/13 01:28 PM Re: Stringing scale irregularities/Restring Questions [Re: Ryan Marlow]
BDB Offline
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If you want to keep the same diameter and raise the tension, go ahead, but I prefer my pianos tuned to a chromatic scale!
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#2028897 - 02/07/13 05:42 PM Re: Stringing scale irregularities/Restring Questions [Re: Ryan Marlow]
miscrms Offline
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Posts: 187
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BDB, the link to your spreadsheet seems to be broken (I know its an old thread smile ). If you would be willing to repost or email me (miscrmsATgmail.com) a copy I would be very interested to play around with it. Probably won't be restringing any pianos any time soon, but its very interesting stuff!

Also noticed the local library has the Travis book mentioned, so I'll have to swing by sometime and pick that up unless there's something better/more recent you all would recommend.

Thanks,
Rob
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#2028939 - 02/07/13 07:00 PM Re: Stringing scale irregularities/Restring Questions [Re: BDB]
NCP Offline
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Registered: 01/29/13
Posts: 7
Many thanks BDB and all!

Just for fun, the original strings amounted to these unisons:
8 @ #18
12 @ #17
17@ #16
7 @ #15
4 @ #14
5 @ #13 1/2
4 @ #13
3 @ #12 1/2

The new scale worked out to this:
9 @ #17
7 @ #16 1/2
9 @ #16
3 @ #15 1/2
1 @ #14 1/2
7 @ #14
3 @ #13 1/2
2 @ #13


I am assuming I will have to tie off a few strings to attain this scale exactly ? Does this seem reasonable ?

One last question.... if the goal is 160 pounds of tension, why does the Excel chart start at 150 pounds ? Just curious ?

Thanks again for sharing the spreadsheet. Any input or criticism from anyone will be appreciated !
ncpianoman

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#2028956 - 02/07/13 07:21 PM Re: Stringing scale irregularities/Restring Questions [Re: Ryan Marlow]
NCP Offline
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Registered: 01/29/13
Posts: 7
OOPS ! The "new scale" above is NOT correct ! That was the wire size list based on the 150 pounds default on the spreadsheet.

Here is the actual "tweaked" scale I created as I attempted to attain a steady 160 lbs. tension:
4 @ #18
8 @ #17 1/2
8 @ #17
6 @ #16 1/2
7 @ #16
5 @ #15 1/2
7 @ #15
3 @ #14 1/2
3 @ #14
4 @ #13 1/2
5 @ #13

Please excuse my error in the previous post !
ncpianoman

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#2028992 - 02/07/13 08:36 PM Re: Stringing scale irregularities/Restring Questions [Re: miscrms]
BDB Offline
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Originally Posted By: miscrms
BDB, the link to your spreadsheet seems to be broken (I know its an old thread smile ).



The link is almost the same. I guess I took the space out of the name.
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#2029075 - 02/08/13 12:12 AM Re: Stringing scale irregularities/Restring Questions [Re: BDB]
miscrms Offline
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Registered: 12/29/12
Posts: 187
Loc: Phoenix, AZ
Originally Posted By: BDB

The link is almost the same. I guess I took the space out of the name.


Awesome, thanks!
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#2029109 - 02/08/13 02:23 AM Re: Stringing scale irregularities/Restring Questions [Re: Ryan Marlow]
Supply Offline
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Loc: Vancouver Island, BC, Canada
Originally Posted By: NCP
OOPS !
...
7 @ #16
5 @ #15 1/2
7 @ #15
3 @ #14 1/2
3 @ #14
4 @ #13 1/2
An un-even number of unisons of any given gauge always calls for a tied off string. In most pianos, tied strings occur only at a few special places. For the vast part, there are even numbers of unisons of a given gauge, which allows for the string to loop around the hitch pin and come back to the next tuning pin.

Unless you begin to pull out hitch pins, and drill holes for new ones, you will not have the luxury of plopping any given spreadsheet-generated scale onto an existing piano plate.

Remember: piano design is all about compromise (in the right spots, of course)
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#2029139 - 02/08/13 03:48 AM Re: Stringing scale irregularities/Restring Questions [Re: NCP]
Olek Online   content
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Registered: 03/14/08
Posts: 7185
Loc: France
Originally Posted By: NCP
I have studied this entire thread and attempted to re-scale a 1949 Lester 6'2" grand using the spreadsheet of BDB and input from Bill Bremmer RPT as they attempted to assist Ryan Marlowe.

In the past, I have replaced many broken wires, and have replaced full sets of wound bass strings, but am now attempting to help a beloved aunt restore her grand piano to "better than new" condition. I am not certain, but believe the piano may have been restrung before. The original wires measured from 18 to 12 1/2.

Using the spreadsheet, I added my measurements and then tried to "tweak" the wire sizes to attain as close to a uniform 160 pounds across the scale. I ended up with a scale ranging from 156 to 165 pounds of tension.

Am I on the right track, or am I missing something here ?
I will appreciate any opinions or criticism !!

Many thanks,
ncpianoman


As I see it the stretch of the wire is important too, hence the BS relation hich is not only there as a security, but as a tone quality parameter. But first tension of course (while on old pianos the tension curve (never find a flat tension scheme) is lowering in the high treble, while in modern ones it raise.

We could say that the yeld stretch is raised in the treble region, to compensate for our human ear that hear less good that frequency range. So the raise in tension as well as in stretch seem a good reason. it also fight the iH rise
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#2029141 - 02/08/13 03:57 AM Re: Stringing scale irregularities/Restring Questions [Re: Michael Payne]
Olek Online   content
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Registered: 03/14/08
Posts: 7185
Loc: France
Originally Posted By: Michael Payne
I just ran some scenerio comparisons for the 1906 Crown upright originally engineered at A435 with the "Calculating Technician" spreadsheet by Dave Roberts (converted to excel by Douglas K. Rhodes, RPT).

They state that the three critical factors are, in priority, Volume; Breaking point; and Inharmonicity.

What I found was that in the string range #27 to 88, when the original string dimension range #18 down to #12 wire was tuned up from A435 to A440, that the volume decreased by almost 50% -- primarily in the #27 to #37 keys, as they transition to the bass section.

When I expanded the wire diameter range going from #22 down to #12 the pattern of volume replicated the original chart, but with the only difference being the pitch, as I converted to A440.

I tried to post the three charts on this BBS (original strings at A435, original strings at A440, and new broader string range at A440) but could not figure out how to do it.

If anyone is interested I can send it to you in a word document, just e-mail me.

Volume range on the first chart (original strings, A435) is from about 260 to 120.

Volume range on the second chart (original strings, A440) is from about 150 to 120.

Volume range on the third chart (expanding new strings from original #18-#13 up to #22-#12 at A440) is again from about 260 to 120 like the original chart.

Keeping the string range the same, the volume gap increased between the bass section as volume decreased -- the change narrowed the volume difference between the bass section and treble making it a smoother transition.

Tension, breaking point, and inharmonicity all remained within parameters on all three charts.



Hello thanks for chiming in, any reason why the volume should lower with more tension ? (435 to 440 ?)

Older wire could have alower breaking strain and can be tense more in the good constrain one with less tension.
Modern wire oblige to make much compromizing as it is more hard. I have seen numerous old instruments that had definitively lost their original tone because of new strings.
SOme colleagues even keep the old wire find in some old Erards going to dump, so they can keep the original wire. I never heard a modern replacement with such a tone quality.

On the contrary, unless you have along enough scale you are in trouble with older designs.

Some reasearch pretend than the old wire had phosphorous traces and that this is why the tone was so particular. Today no string maker will accept to have phosphorous in their batches so we cannot have that done again.
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#2029201 - 02/08/13 08:25 AM Re: Stringing scale irregularities/Restring Questions [Re: Ryan Marlow]
Olek Online   content
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I believe that the wire sollicitation is taken in account in order to keep the stretch of the wire in correspondence with the frequencies, then the piano cna stay in tune longer.

in the mediums , where the soundboard change are the most noticeable, is suppose that a maximum of tension is also expected so to limit tone changes with the soundboard shape changes.
It does not happen really with old panels so this may not be a problem.

Anyway low level of solicitation provide that flacid tone with proeminent partials and too much iH, that can be noticed on some old pianos stringed with modern wire, it is sensitive with american wire in the treble of a Steinway I have seen lately, that treble is all but elegant (5th octave) . did not check the wire diameters but I can hear the lack of solicitation there, because I am acustomed to that kind of flaws in the tone on old pianos.

Moaning a lot and difficult to make a nice tone with tuning; Harsh, give an impression of power but non musical one, When you voice down the tone get just more accepteable.

too much iH = the spectra is unclear the fundamental is perturbated, pitch refernce is not evident.
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#2029214 - 02/08/13 09:01 AM Re: Stringing scale irregularities/Restring Questions [Re: Supply]
NCP Offline
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Registered: 01/29/13
Posts: 7
Thank you Supply, BDB and Oleg !

This is exactly the information I needed to hear ! SO, if I understand correctly, I should make adjustments to my "tweaked" scale, to a "final" scale using even numbers of unisons while still attempting to retain the most even pounds of tension, right ?

What about the post by Oleg ? Should I attempt to raise the tension in the treble in a smooth curve toward a certain tension in the treble ? What would be that ultimate tension on note 88 ? And, if so, at which note should I begin that upward curve ?

I truly appreciate all this kind and helpful assistance from ALL !!

ncpianoman

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#2029244 - 02/08/13 11:01 AM Re: Stringing scale irregularities/Restring Questions [Re: Ryan Marlow]
BDB Offline
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I try to keep note 88 close to 160 lb. The problem is the transition from the highest wound note to the lowest plain note. You could plug in the diameter of the highest wound note to get an approximation of the tension on that string. It has to be converted to a gauge. The conversion factor that I use on the spreadsheet is that the diameter in thousands minus 5 divided by 2 is the gauge. So for .031 inch diameter, that is (31 - 5)/2 = 13 gauge. That conversion works for the usual gauges used in pianos, but it is not accurate for much smaller and larger gauges.
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#2029260 - 02/08/13 11:30 AM Re: Stringing scale irregularities/Restring Questions [Re: NCP]
Olek Online   content
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Registered: 03/14/08
Posts: 7185
Loc: France
Originally Posted By: NCP
Thank you Supply, BDB and Oleg !

This is exactly the information I needed to hear ! SO, if I understand correctly, I should make adjustments to my "tweaked" scale, to a "final" scale using even numbers of unisons while still attempting to retain the most even pounds of tension, right ?

What about the post by Oleg ? Should I attempt to raise the tension in the treble in a smooth curve toward a certain tension in the treble ? What would be that ultimate tension on note 88 ? And, if so, at which note should I begin that upward curve ?

I truly appreciate all this kind and helpful assistance from ALL !!

ncpianoman


Hello NCP, if you have an even tension you cannot really be wrong at the base, what I refer to is the level of solicitation the wire is subjected to. AN accepted rule is to avoid too low levels (the computing in Europe differs from the way it is seen in the Travis book , as a security 25% lowering is used on the real breaking strenght before computing how much % is allowed)

This to take in account "at large" the fragility induced by bends and coils.

Then not less than 40% in the first plain notes, raising to 80% BS in the last treble notes, and you have aneat moderate scale.

Original tension in many old scale make a hop on the first 10 notes then lowers sligthly toward the high treble.
SO if you can raise it possibly you will have a better result in the end, as modern wire ask more tension to tone well than the one availeable at older times (in my opinion)

so in the mediums, the goal is to have around 50-60% solicitation. It is just that the mechanical behaviour of the wire is better in those limits, and can raise with thinner wire. The optimum tone for treble being not far from the end of the elastic zone of the wire.

Recent proposals from Paulelo, that are pplied with good results whatever wire is used. I also know at lat one manufacturer that use more solicitation even in the mediums, and I also have senn thos high levels of BS attained in the mediums by some old high tension scales (Pleyel, 1915)

But for instance Bechstein pianos of today have a little tension in the low mediums that raise toward the treble...

You have differnt types of scale, it should be interesting to determine what kind of scale your instrument had, as it may relate with the resiliency and the weight of your soundboard.

The last being now old, some corrections can be envisaged so you dont ask too much of the panel...

Here is a graf of the plain wire of an old 1860 piano Erard

https://docs.google.com/file/d/0B6GjQDkF_AMQM25FSHpSRmV1bEk/edit?usp=sharing

tensions in the 415-500 N range for the plain wire and 500-360 N for basses. of course soft wire is used here. the strings are not long

AT some point this begin to be a tad complicated. SO at last trying to have tension without jumps is yet a good thing.

Old pianos also had what I consider registers, considering a zone for the treble, another for the mediums, tension wise (if not some of the designs I see are a mystery)

The idea that we need more power and more partials in the treble is from Jean Louchet and seem to corrobore the audition curve, that is less sensitive in that region.

I like to be sure of something :

are more partials giving an impression of more power or no ?


Edited by Olek (02/08/13 12:21 PM)
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#2029293 - 02/08/13 12:57 PM Re: Stringing scale irregularities/Restring Questions [Re: Ryan Marlow]
Olek Online   content
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Registered: 03/14/08
Posts: 7185
Loc: France
What helps to ascertain the scale is a comparison of the string's lenght progressiveness on a spreadsheet in logarithm display mode :
the original frequency (f) in HZ, multiplied by the string length (speaking length) in meter

(direct display of the lenght give not as much information)

You can see where the lenght reduction begin on the scale, how is the bottom of the long bridge.

here is the original BS% of a 1925 Pleyel 3B (small grand 1.64 m)



https://docs.google.com/file/d/0B6GjQDkF_AMQNmdvWEhJMXNBSTA/edit?usp=sharing

Here are the tensions, that look strange at first sight (but typical on an old scale)

https://docs.google.com/file/d/0B6GjQDkF_AMQRHh2a3J3bnVCSU0/edit?usp=sharing

Compare them with BS% you will notice that 80% is kept as a limit in the high treble.

I believe that the last notes are less tense by fear of blocking the soundboard on its edge , but ther may be another reason


Edited by Olek (02/09/13 01:08 AM)
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#2029360 - 02/08/13 03:11 PM Re: Stringing scale irregularities/Restring Questions [Re: Ryan Marlow]
Olek Online   content
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Registered: 03/14/08
Posts: 7185
Loc: France
Here you can see the tension of a 1925 grand piano Pleyel
mod 3 -1925

A high tension scale mounted with a softer wire than Roslau

See how the solicitation lower (but stay accepteable) with modern wire

https://docs.google.com/file/d/0B6GjQDkF_AMQOUhkOG1RNjFjc2c/edit?usp=sharing

Then, a Boesendorfer 190 - year 1915

https://docs.google.com/file/d/0B6GjQDkF_AMQV2JrOWlrZkRrLTg/edit?usp=sharing

less long strings, moderate tension , no correction of the plate breaks on the bridge


Edited by Olek (02/08/13 03:50 PM)
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#2029759 - 02/09/13 09:09 AM Re: Stringing scale irregularities/Restring Questions [Re: Ryan Marlow]
NCP Offline
Junior Member

Registered: 01/29/13
Posts: 7
Thank you BDB and Olek ! I have SO much to learn !

I will mic the uppermost wound string and apply that equation and respond after work today if I can.

The other question I asked was this:
This is exactly the information I needed to hear ! SO, if I understand correctly, I should make adjustments to my "tweaked" scale, to a "final" scale using even numbers of unisons while still attempting to retain the most even pounds of tension, right ?

I hope that is the correct theory, but any input would be very much welcomed and appreciated!

Thank you ALL for your help !
ncpianoman

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#2030005 - 02/09/13 06:02 PM Re: Stringing scale irregularities/Restring Questions [Re: BDB]
NCP Offline
Junior Member

Registered: 01/29/13
Posts: 7
OK.... using your wound string conversion, my uppermost wound string is .0575 (57.5 - 5)/2 = 26.250 gauge. With my string length for that note and this 26.25 theoretical guage, the spreadsheet shows 165.148 pounds. The first wire @ #18 shows 162.305 pounds. As I said before, the tension only varies 9 pounds from bottom to top wire (29 - 88).

Does that suggest I am there and ready to string this piano? I think I am to that point, but just wanted your professional opinion.

Again, thanks for sharing the spreadsheet and for all of your advise !

ncpianoman

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#2030027 - 02/09/13 07:09 PM Re: Stringing scale irregularities/Restring Questions [Re: Ryan Marlow]
BDB Offline
Yikes! 10000 Post Club Member

Registered: 06/07/03
Posts: 21271
Loc: Oakland
That looks good. It is hard to get that close on many pianos.
_________________________
Semipro Tech

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#2030043 - 02/09/13 07:48 PM Re: Stringing scale irregularities/Restring Questions [Re: BDB]
NCP Offline
Junior Member

Registered: 01/29/13
Posts: 7
Thank you very much for your help and patience ! I could never have done it without the spreadsheet !

As it turned out, I had to adjust the scale slightly to gain an even number of unisons with each wire size and ended up with a variation of 13.3 pounds from top wire to smallest wound string, but I trust that will suffice.

Once again, thank you to all who assisted me with this learning process !

ncpianoman

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