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#909459 - 03/06/06 05:06 PM what is a high tension string scale?
iconoclast Offline
Full Member

Registered: 07/27/05
Posts: 389
Loc: Ancramdale, NY
It's always an education hitting different piano dealers. This particular one (Vogel,Schulze-Polmann) was decrying the 'high tension string scale' used on Pacific Rim pianos. Is this just sales jargon? What are the sonic tradoffs/implications of Low vs. High tension designs?

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#909460 - 03/06/06 05:12 PM Re: what is a high tension string scale?
BDB Online   content
Yikes! 10000 Post Club Member

Registered: 06/07/03
Posts: 21904
Loc: Oakland
It is a sales jargon term that has no meaning. Below is an answer I gave earlier:

I have never gotten a definition of "high-tension/low-tension" that makes any sense to me. So I am suspicious whenever anyone talks in those terms.

In general, the longer the piano, the longer the strings. It is a physical law that the longer the strings, the higher the tension the strings need to be to give the same pitch. Also, the heavier or thicker the strings, the higher the tension needs to be to give the same pitch. These are physical laws, regardless of the make of piano.

To the best of my knowledge, every piano manufacturer has used heavier strings the longer the piano. Even without that, no matter who made the piano, bigger pianos would have higher tensions than smaller pianos, just from the length of the strings.

There are a couple of rules that should be followed. The most obvious is that you do not want the tension near the breaking strength of the string. In fact, you want it under the elastic limit of the string, which is about half the breaking strength. This is usually not a problem, except that the breaking strength will usually drop considerably when you go from the plain wire strings to the overwound strings.

The other rule is that the tension should not change a lot from note to note. Everything else being equal, lower tension will not be as loud, and it can be boomier than higher tension. This may not be noticable if you have gentle transitions from one area of the piano to the next, but big jumps and rapid transitions can be heard.

Unfortunately, when calculations were more laborious than with today's computers, when most manufacturers did not see the value of designers that were as adept with the slip stick or log table as they were with the french curve, there were some seat of the pants practices that were pretty much ingrained in piano design which were not ideal, and in some cases, pretty bad. These include changing the wire size too often at the top of the piano, and not changing it enough near the transition to overwound strings. The result is a scale which is way too high in tension just below the top octave, and drops way too low in tension way too quickly near the transition.

Careful redesign should give tensions that avoid too high tensions, and in shorter pianos, drops gently to near the tension of the overwound strings, or rises equally as gently in longer pianos, and avoids any big jumps anywhere in the scale.
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Semipro Tech

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#909461 - 03/07/06 09:33 AM Re: what is a high tension string scale?
iconoclast Offline
Full Member

Registered: 07/27/05
Posts: 389
Loc: Ancramdale, NY
Thanks for the response. If I'm reading you correctly, higher string tension pretty much comes with the territory when you increase the mass of the string - either by lengthening it or by overwinding it. Since overwinding is the ONLY way to get bass strings of reasonable length (short of having a 25' grand piano) I would think that shorter string scales will by definition be higher tension than longer ones.

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#909462 - 03/07/06 10:39 AM Re: what is a high tension string scale?
Casalborgone Offline
1000 Post Club Member

Registered: 09/15/04
Posts: 1046
Loc: San Francisco Area
 Quote:
Originally posted by iconoclast:
Thanks for the response. If I'm reading you correctly, higher string tension pretty much comes with the territory when you increase the mass of the string - either by lengthening it or by overwinding it. Since overwinding is the ONLY way to get bass strings of reasonable length (short of having a 25' grand piano) I would think that shorter string scales will by definition be higher tension than longer ones. [/b]
I think you are oversimplifying the relationship in a way that is not particularly meaningful.

Saying that shorter string scales will by definition be higher tension than longer ones is only a theoretical notion. The real-world bottom line, as BDB has already said, is that describing a scale as high or low tension doesn't have much meaning. It's really just a marketing thang.
_________________________
Mike
Registered Piano Technician
Member Piano Technicians Guild
Not currently working in the piano trade.

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#909463 - 03/07/06 10:42 AM Re: what is a high tension string scale?
Happy Birthday eromlignod Offline
Full Member

Registered: 05/04/04
Posts: 379
Loc: Kansas City
It has always been my understanding that the strings in a piano are all tensioned about the same in relation to their breaking strength. Extensive experimentation in my lab has confirmed this. Ostensibly, to get the best tone and sustain, one wants to create the highest tension that is safe, which would be some small margin below the yield strength of the steel (the point where the material stops returning to its original length when released).

This requires that the string weights be designed lighter (mass per unit length) as piano models grow in length. This is why longer pianos have more unwound, bare steel strings in the bass than shorter ones. If a nine-foot piano were strung with bass strings as heavy in diameter as a six-foot piano, only longer, they would certainly break long before the proper pitch was achieved, since they would be a full three feet longer. In fact, it would require a tension a full 2-1/4 times greater!

The copper windings don't add any enhanced quality to the sound of a piano. Increasing of string mass is needed to remedy inadequacies due to shorter piano lengths.

Don
Kansas City

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#909464 - 03/07/06 10:52 AM Re: what is a high tension string scale?
ejsauter Offline
500 Post Club Member

Registered: 09/19/05
Posts: 564
Loc: Michigan
Interesting thread. It seems that the ideal piano regardless of length would have nearly every string a different gauge (mass per unit length) throughout the scale. If this is even partially true, are there any pianos that come close to achieving this? Could this perhaps be a differentiator between what are the best and those less than the best?
_________________________
"The creative mind plays with the object it loves." -- Carl Jung

http://www.sauter-pianos.com

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#909465 - 03/07/06 11:06 AM Re: what is a high tension string scale?
Casalborgone Offline
1000 Post Club Member

Registered: 09/15/04
Posts: 1046
Loc: San Francisco Area
 Quote:
Originally posted by ejsauter:
Interesting thread. It seems that the ideal piano regardless of length would have nearly every string a different gauge (mass per unit length) throughout the scale. If this is even partially true, are there any pianos that come close to achieving this? Could this perhaps be a differentiator between what are the best and those less than the best? [/b]
Interesting idea. What would be YOUR notion of the ideal piano?
This needs to be nailed down. To my mind, every piano is a compromise of some sort; it is the nature of each compromise that gives different piano designs their individual character.

Yes, in good pianos the string guage changes frequently, every few notes, along the scale. Some restringers rescale pianos to increase the numbers of graduations in string guages with the notion of making the pianos easier to tune, and perhaps, in theory at least, better-sounding.

Your idea is another variation on the common theme here of trying to find out what single factor(s) are out there to define piano "quality." I don't think there are such single factors; there are multiple factors.
_________________________
Mike
Registered Piano Technician
Member Piano Technicians Guild
Not currently working in the piano trade.

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#909466 - 03/07/06 11:26 AM Re: what is a high tension string scale?
BDB Online   content
Yikes! 10000 Post Club Member

Registered: 06/07/03
Posts: 21904
Loc: Oakland
As I said, most pianos were strung according to custom, rather than science. Variations in gauge are less significant at the top of the scale than they are at the bottom of the scale, and indeed, bass strings do change at every note. A pity that scale designers did not take their cue from that, and changed their gauges more towards the bass and less in the high treble.

Pianos designed more recently tend to do better at this than more traditional designs. To my mind, traditional designs rescaled with this in mind tend to sound better than with their original scale, and need less voicing.
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Semipro Tech

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#909467 - 03/07/06 11:37 AM Re: what is a high tension string scale?
Happy Birthday eromlignod Offline
Full Member

Registered: 05/04/04
Posts: 379
Loc: Kansas City
 Quote:
Originally posted by ejsauter:
Interesting thread. It seems that the ideal piano regardless of length would have nearly every string a different gauge (mass per unit length) throughout the scale. If this is even partially true, are there any pianos that come close to achieving this? Could this perhaps be a differentiator between what are the best and those less than the best? [/b]
The strings in a piano are arguably one of its cheapest parts. Strings are largely the same between brands. Most of them are simply a piece of wire. Piano string manufacturers like Mapes will copper-wind strings any way you want for a reasonable cost. To have string designs identical to a Steinway would merely require measuring the strings and copying them. Big deal.

It seems to me that other factors are much more responsible for the quality of tone in a fine piano. The soundboard, bridge, and rim would be where the real craftsmanship takes place.

Don
Kansas City

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#909468 - 03/07/06 12:44 PM Re: what is a high tension string scale?
ejsauter Offline
500 Post Club Member

Registered: 09/19/05
Posts: 564
Loc: Michigan
Don, I respectfully disagree with your dismissive conclusion about the strings. The string is where the sound originates. Some manufacturers wind their own strings. Plus there is the whole metallurgy behind the strings as well as the copper winding itself. I do not disagree about the craftsmanship in the components you mentioned. The piano is after-all the sum of ALL its parts.
_________________________
"The creative mind plays with the object it loves." -- Carl Jung

http://www.sauter-pianos.com

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#909469 - 03/07/06 12:47 PM Re: what is a high tension string scale?
ejsauter Offline
500 Post Club Member

Registered: 09/19/05
Posts: 564
Loc: Michigan
Mike, I wholeheartedly agree with you about there being multiple factors.

You did ask me what my notion of an ideal piano. Since you asked, first it must be acoustic and in that fact not much different than existing technology. It must tune itself, have variable hammers (different tone), variable touch, adjustable sustain, adjustable harmonics, very durable (100 years at least), allow recording without any alteration of touch, practically infinite repeatability, etc.

My thought about the strings was one more of creating another attribute which can be used to objective compare one make against another. I will also admit that doing so probably is fruitless. ;\) I just can't get the systems analyst out of me.
_________________________
"The creative mind plays with the object it loves." -- Carl Jung

http://www.sauter-pianos.com

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#909470 - 03/07/06 02:05 PM Re: what is a high tension string scale?
Happy Birthday eromlignod Offline
Full Member

Registered: 05/04/04
Posts: 379
Loc: Kansas City
 Quote:
Originally posted by ejsauter:
Don, I respectfully disagree with your dismissive conclusion about the strings. The string is where the sound originates. Some manufacturers wind their own strings. Plus there is the whole metallurgy behind the strings as well as the copper winding itself. I do not disagree about the craftsmanship in the components you mentioned. The piano is after-all the sum of ALL its parts. [/b]
Piano wire is piano wire. It is simply high-carbon, spring-tempered steel. It was chosen because it has the highest tensile strength of any common material.

When you break a string, and your tech replaces it, he uses piano wire from a generic spool of the appropriate gauge. He puts it in and it sounds just like the old string (or better if the old one was dirty/rusty). A Yamaha sounds different from a Bösendorfer because of its design, not because they use a different type of material in their strings. Otherwise techs would have to keep special spools of wire from every piano manufacturer in the world.

I have literally broken thousands of strings in my experiments. I have had every sort of experimental string made. Strings with different windings, special coatings, etc. Good ol' bare steel with good ol' 99.99% electrolytic copper is the best. The combination is the result of 300 years of evolution and everyone does it essentially the same way.

Don
Kansas City

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#909471 - 03/07/06 02:20 PM Re: what is a high tension string scale?
ejsauter Offline
500 Post Club Member

Registered: 09/19/05
Posts: 564
Loc: Michigan
I have obviously been duped by the "German Piano Wire" marketing ploy. Thanks.
_________________________
"The creative mind plays with the object it loves." -- Carl Jung

http://www.sauter-pianos.com

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#909472 - 03/07/06 03:21 PM Re: what is a high tension string scale?
BDB Online   content
Yikes! 10000 Post Club Member

Registered: 06/07/03
Posts: 21904
Loc: Oakland
 Quote:
Piano wire is piano wire. It is simply high-carbon, spring-tempered steel. It was chosen because it has the highest tensile strength of any common material.
Not exactly. Piano wire evolved according to the needs of the piano industry. Tensile strength increased quite a bit during the 19th century. Pianos provided a good test for the quality of piano wire.

Steel is very elastic, which is another quality that is desirable. Breaking (tensile) strength should not be the limit of tension on a piano string, actually. It should be the proportional limit, the topmost tension at which string stretches proportionally to tension.

But the result of the developments in the technology is that most piano wire has very similar characteristics these days, and there is not that much difference between different manufacturers.
_________________________
Semipro Tech

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#909473 - 03/07/06 03:33 PM Re: what is a high tension string scale?
Grandpianoman Offline
2000 Post Club Member

Registered: 03/12/05
Posts: 2416
Loc: Portland, Oregon
Very good points.....actually, there is a lot more to the art of string making, especially bass strings. I have been doing some research on this very subject in reference to my M&H 7ft grand. The type of copper used for bass strings makes a difference in the sound. The type of core wire used also contributes to the overall sound because different sizes of core wire, their thickness, along with the type of copper used in the windings, the way it's wound, by hand or machine, all these factors relate to the thickness of each graduated bass string, hence you have very different "scales" for each model piano. Another factor in the core wire is how far it will stretch before breaking...the better quality wire has a higher breaking point. I have been told that for instance, Mapes Gold is a much better wire because it has a higher streching/breaking point. All these factors help contribute to the overall sound of bass strings.

Gpman

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#909474 - 03/07/06 03:59 PM Re: what is a high tension string scale?
Happy Birthday eromlignod Offline
Full Member

Registered: 05/04/04
Posts: 379
Loc: Kansas City
 Quote:
Originally posted by grandpianoman:
Very good points.....actually, there is a lot more to the art of string making, especially bass strings. I have been doing some research on this very subject in reference to my M&H 7ft grand. The type of copper used for bass strings makes a difference in the sound. The type of core wire used also contributes to the overall sound because different sizes of core wire, it's thickness, along with the type of copper used in the windings, relate to the thickness of each graduated bass string, hence you have very different "scales" for each model piano. Another factor in the core wire is how far it will stretch before breaking...the better quality wire has a higher breaking point. I have been told that for instance, Mapes Gold is a much better wire because it has a higher streching/breaking point. All these factors help contribute to the overall sound of bass strings.

Gpman [/b]
So, you're saying that if a piano was designed for special, high-strength strings so that they could be brought to a higher tension at manufacture, then when a tech orders ordinary replacement strings for that piano, they will break?

Don
Kansas City

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#909475 - 03/07/06 04:09 PM Re: what is a high tension string scale?
Grandpianoman Offline
2000 Post Club Member

Registered: 03/12/05
Posts: 2416
Loc: Portland, Oregon
eromlignod, from what I have learned, say Maypes Gold wire was used for the core wire of all the bass strings, and then you replaced a broken bass string with a different wire that does not have the same properties, ie the stretching/breaking point is different, when you pull the sting up to pitch or past the correct pitch, it may be stretching the string past it's optimum point and it will either end up sounding dull or it may break...it will never go back to normal after stretching it past it's optimum point....that's my understanding...perhaps someone im the string making business could chime in here who knows more about this.

Gpman

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#909476 - 03/07/06 04:18 PM Re: what is a high tension string scale?
johnny boy Offline
Full Member

Registered: 01/19/06
Posts: 357
Loc: seattle
(This is from my guitar expereince, so it might not be the same) but all strigns are not created equal. Yes, the unwound strings are mostly the same and they can be interchanged very easily(made from sweedish steel for guitar), but depends on the compoisitions of the meatal and quality,it does sound very slighly different.

It is the woundstring (bass stirngs) that has the biggest effects. Whether the core is round, octagonal, how big or small makes a difference. Also the cooper wrapper material (bronze, phosphor bronze, brass, nickle, nickel plated steel, stainless steel or even gold!) makes difference. Also on whether it is flat wound vs. round wound.

Depends on all that, some strings sounds brighter and more percussive or soft and melow and etc.

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#909477 - 03/07/06 04:42 PM Re: what is a high tension string scale?
ejsauter Offline
500 Post Club Member

Registered: 09/19/05
Posts: 564
Loc: Michigan
Then perhaps I've not been duped then ;\)

I second having a real "string guy" come in here to provide more background.

Overall, in looking at the active components of the sound mechanism being the hammer, string, bridge (that being any part of the piano which transmits vibration from the string to somewhere else) and lastly the soundboard, it would be hard to imagine that some variation in the string geometry, metallurgy, gauge and length doesn't have some effect on the tone that is personality of the instrument.
_________________________
"The creative mind plays with the object it loves." -- Carl Jung

http://www.sauter-pianos.com

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#909478 - 03/07/06 04:49 PM Re: what is a high tension string scale?
ChickGrand Offline
3000 Post Club Member

Registered: 05/02/03
Posts: 3248
Loc: Midwest U.S.
 Quote:
Originally posted by ejsauter:
...It must tune itself...[/b]
I'm glad you said that so I don't have to feel guilty for asking an otherwise off-topic question of eromlignod. \:\)

Don, any news on the development of the self-tuning piano? (I was thinking about your work last week and wondering.)

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#909479 - 03/07/06 04:49 PM Re: what is a high tension string scale?
Happy Birthday eromlignod Offline
Full Member

Registered: 05/04/04
Posts: 379
Loc: Kansas City
 Quote:
Originally posted by johnny boy:
(This is from my guitar expereince, so it might not be the same) but all strigns are not created equal. Yes, the unwound strings are mostly the same and they can be interchanged very easily(made from sweedish steel for guitar), but depends on the compoisitions of the meatal and quality,it does sound very slighly different.

It is the woundstring (bass stirngs) that has the biggest effects. Whether the core is round, octagonal, how big or small makes a difference. Also the cooper wrapper material (bronze, phosphor bronze, brass, nickle, nickel plated steel, stainless steel or even gold!) makes difference. Also on whether it is flat wound vs. round wound.

Depends on all that, some strings sounds brighter and more percussive or soft and melow and etc. [/b]
Guitars are a little different than pianos. You don't replace all the strings in your piano on a whim to get a different sound. If a piano string breaks, you call a tech and he simply replaces and tunes it.

My point is that the tensions of piano strings can't vary too wildly from design to design since this would necessitate special proprietary materials for each type, which isn't the case. I don't have my notes with me now, but I believe that the tension of piano strings is around 150 lbs. across the gamut.

Don
Kansas City

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#909480 - 03/07/06 05:18 PM Re: what is a high tension string scale?
Happy Birthday eromlignod Offline
Full Member

Registered: 05/04/04
Posts: 379
Loc: Kansas City
 Quote:
Originally posted by ChickGrand:
 Quote:
Originally posted by ejsauter:
...It must tune itself...[/b]
I'm glad you said that so I don't have to feel guilty for asking an otherwise off-topic question of eromlignod. \:\)

Don, any news on the development of the self-tuning piano? (I was thinking about your work last week and wondering.) [/b]
Actually, I should have some very exciting news shortly. I am currently in the process of changing manufacturers.

QRS just couldn't keep the project on track. Every time they said it was active again, they would put it right back on the back burner. The last straw came when I received a shareholders' report that announced some of the new products that they were introducing (that had been preempting my invention). One of them was a keyboard that had black keys that "light up" when you play them...oh brother.

The vice president of a large piano company that you all know quite well (no hints just yet!) is coming out for a demonstration in the next week or so. He is very excited about the project and I'm sure he will be duly impressed with the prototype.

Ironically, since the project has sat dormant for these four years, I have continued to improve it just to fight the boredom! As of last night, I can tune a string that is 45 cents out of tune in nineteen seconds (five seconds to bend 45 cents, and fourteen more seconds to stablize). The accuracy is plus or minus one-sixth of a cent. Interestingly, I can actually measure and control the pitch much more precisely than that, but the string has a natural tendency to fluctuate by a few tenths of a cent anyway, so you really can't tune it much more accurately even if you wanted to.

After my upcoming meeting I'll make an announcement in the group. Thanks for your continued interest.

Don
Kansas City

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#909481 - 03/07/06 05:21 PM Re: what is a high tension string scale?
ChickGrand Offline
3000 Post Club Member

Registered: 05/02/03
Posts: 3248
Loc: Midwest U.S.
I'll look forward to the announcement, Don. My only reservation about the idea previously was that I wished it were being implemented on a better line of pianos. \:D

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#909482 - 03/07/06 05:23 PM Re: what is a high tension string scale?
Happy Birthday eromlignod Offline
Full Member

Registered: 05/04/04
Posts: 379
Loc: Kansas City
 Quote:
Originally posted by ChickGrand:
I'll look forward to the announcement, Don. My only reservation about the idea previously was that I wished it were being implemented on a better line of pianos. \:D [/b]
Oh, it's a better line of pianos all right... ;\)

Don
Kansas City

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#909483 - 03/07/06 05:25 PM Re: what is a high tension string scale?
Grandpianoman Offline
2000 Post Club Member

Registered: 03/12/05
Posts: 2416
Loc: Portland, Oregon
Sorry, but am not familiar with your work Eromlignod..what is it that you are working on?

Gpman

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#909484 - 03/07/06 05:33 PM Re: what is a high tension string scale?
Happy Birthday eromlignod Offline
Full Member

Registered: 05/04/04
Posts: 379
Loc: Kansas City
 Quote:
Originally posted by grandpianoman:
Sorry, but am not familiar with your work Eromlignod..what is it that you are working on?

Gpman [/b]
The self-tuning piano.


http://tech2.nytimes.com/mem/technology/...B63&oref=slogin

http://www.npr.org/templates/story/story.php?storyId=878091

http://www.newscientist.com/article.ns?id=dn3143

Don
Kansas City

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#909485 - 03/07/06 06:07 PM Re: what is a high tension string scale?
Grandpianoman Offline
2000 Post Club Member

Registered: 03/12/05
Posts: 2416
Loc: Portland, Oregon
Thanks, and the best of luck with it! I wish it could be installed in an existing piano \:\)

Gpman

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#909486 - 03/07/06 10:12 PM Re: what is a high tension string scale?
Del Offline
5000 Post Club Member

Registered: 09/04/03
Posts: 5325
Loc: Olympia, Washington
The relationship between scale tension and timbre is not quite as indefinable as some would have us believe.

BDB is right when he points out that many, if not most, of the string scales found on pianos in use today—including some very highly regarded pianos in current production—were developed empirically by designers who had only a vague idea of the scale tensions they were ending up with. By the time the meetings that formed the basis for the book, Piano Tone Building, however, at least some designers had a pretty good grasp of the relationship between string scale tensions and the voice of the piano. They were also aware that a change in scale tensions required appropriate changes in the soundboard design.

When considering just what effect variations in scale tension might make to the overall voice of a piano it is important to understand that changing the tensions of one or two notes in the tenor (say, by replacing the original strings with wire a half-size larger or smaller) is not going to make much difference. Restringing the whole piano and raising or lowering the average tenor string tensions by 10 or 15 lbs. probably will. (If you’re raising the tensions by that much you might also want to consider where you want to be when the plate lets go!)

Many scales in use today are hard to classify in terms of scale tensions. For example, C-52 in one version of the Steinway Model D has a tension of 166 lbs. (343.5 mm, #16 ½ wire). That is just on the high side of what I would call a low-tension scale. One octave down, (C-40) we find a tension of 179 lbs. (660 mm, #18 wire). That’s toward the high-end of what I would call a mid-tension scale. Going one more octave down, (C-28) we’re up to 206 lbs. (1291 mm, #20 wire). Now that is high-tension in most everybody’s book. So what do we call this piano? From C-52 going up to C-64 we find tensions also going up, this time to 172 lbs. (184.5 mm, #15 ½ wire). At C-76 we’re all the way up to 186 lbs (98.6 mm, #15 wire). And, finally, at C-88 we find the tension back down to 154 lbs. (49 mm, #13 ½ wire). So, this scale is all over the map. If we sum and average all of the unison tensions in the piano we come up with a total scale tension of 45,700 and an average of 188 lbs.—definitely a high-tension scale.

In terms of how scale tensions affect the voice of the piano, however, the strings that lie on the long bridge have the greatest effect. In the case of the Model D this averages 179 lbs., still quite high.

Nor can we say categorically that long pianos have high-tension scales and short pianos have low-tension scales. While a Steinway Model M would probably average out around 150¬–155 lbs., I have a 5’ 2” Knabe in my shop which averages 170 lbs., and that includes the top treble section where tensions are down in the 120 to 130 lb. range. The tensions through the tenor section of this piano average 178 lbs. Just one pound shy of the Steinway D average.

Does this mean the scaling of the 5’ 2” Knabe equal to the scaling of the 8’ 10 ½” Steinway? Not really. C-40 in the Knabe is 665 mm long and uses a #18 ½ wire for a tension of 190 lbs. Not all that much different. But in the Knabe C-28 is only 1025 mm long and uses two wrapped strings.

So, what does all this mean? In general, if all other factors are equal—string length, hammer density and resilience, soundboard design and construction, etc. [/b]the sound envelope generated by a low-tension scales will have more energy in it fundamental and lower partials. The sound envelope generated by a high-tension scale will have less energy in the fundamental and more energy in the upper partials. Also, very generally, strings at a higher tension will have the capability of storing more energy so they have the potential for more sustain.

However, all other factors are rarely, if ever, equal![/b] String lengths can vary. A high-tension scale might use relatively short strings with large diameter wire. Or it might use relatively long strings with smaller diameter wire. And a low-tension scale also might use relatively short strings with larger wire or relatively long strings with smaller wire. Each will produce a different sound envelope.

Still, while it is impossible to categorize these things absolutely, it is possible to put forth some broad generalizations. If a designer wants to create a piano with a warm voice with broad timbre dynamics he or she will probably chose a relatively long, low-tension scale. This will work against a relatively low-mass soundboard of medium to low stiffness. If a designer wants to create a piano with great power he or she will use a higher-tension scale working against a more massive and stiffer soundboard system.

Some final thoughts.
Except in an abnormally long high treble and in a poorly designed bass scale string tensions will not approach a strings tensile proportional limit.
Generally, when a company announces that they have “increased scale tensions for more power,” they have done just that. Depending on how creative they are this will be done by going to larger wire sizes through some parts of the scale or by making the strings through all or part of the scale longer. Occasionally, both. Whether this actually gives them more power is another issue. If things are going to be kept in balance ribbing will have to be slightly stiffer, they might have to increase the thickness of the soundboard slightly and they may need a slightly more massive hammer (along with the resulting deformation of action parts). The higher tension scale will also tend to resist soundboard mobility (think of it as pushing against a stiffer spring). More than one pseudo-designer (usually someone in the marketing department) has been surprised to find out that simply increasing string tension does not yield the intended results.

Del
_________________________
Delwin D Fandrich
Piano Research, Design & Manufacturing Consultant
ddfandrich@gmail.com
(To contact me privately please use this e-mail address.)

Stupidity is a rare condition, ignorance is a common choice. --Anon

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#909487 - 03/08/06 12:35 AM Re: what is a high tension string scale?
Grandpianoman Offline
2000 Post Club Member

Registered: 03/12/05
Posts: 2416
Loc: Portland, Oregon
Del, thanks for your great explanation. What you are saying follows the logic of the string maker I was talking to.

In doing research as to what the best bass strings would be for my 1925 M&H RBB, I was told that having the exact string specs from a 1925 BB would be the most beneficial and that M&H had a certain bass string core wire and outside diameter wire in mind when they were designing the piano? I was able to find the exact specifications of a set of original strings on another 1925 BB, thanks to an owner of a 1929 BB who has the these exact size strings, core diameter, outer diameter etc. I have sent those to the string maker. For the most part, he says they are good, and he is only going to change a few of the parameters, including a smoother transition between unicords and bi-chords.
The new set of bass strings that are on my RBB now do not sound good, giving a thin, hollow sound. When my rebuilder measured the core diameter of the lowest note, it was .048. The lowest core diameter from the original set of 1925 strings was .059, that is quite a difference. In fact, all the core diameters of the current set of bass strings are smaller than the original specs...I suspect that is contributing to why the bass does not have a rich, robust sound?

I guess M&H knew what they were doing back then and knew what bass string specs would sound the best with their soundboard design.

I know there are string makers out there that design "scales" for these older pianos, changing the original specs, thinking they will sound better than the original scales...and sometimes they are not successful....interesting!

Del, have you used a lot of original bass string specs in your rebuilding of older pianos, and if so, have you found they sound optimum?

Gpman

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#909488 - 03/08/06 02:09 AM Re: what is a high tension string scale?
BDB Online   content
Yikes! 10000 Post Club Member

Registered: 06/07/03
Posts: 21904
Loc: Oakland
There are a variety of ways of computing averages, including average tensions. Adding all of them up and dividing is one way, but it tends to throw things off if some numbers are way out of whack. If you graph the tension of note 88 and the tension of the first overwound string, and draw a straight line between them, and take the midpoint of the line, you probably get a better idea of what the ideal average for a given scale would be. Of course, many pianos are nothing like that.

The model that I was using is based on this straight-line method, and in this model, the line for a short piano tends to decline a bit towards the bass, while in longer pianos, it rises.

In the case of Del's Steinway D, the tension probably conforms reasonably closely to this model. In the case of the Knabe, the tension undoubtedly steps up in random jumps according to changes in wire gauge until it nose-dives to, or more likely well below, the tension of the first wound string. (Whenever I hear people say that the new Knabes use the scale of the old ones, I cringe, knowing that they could, and probably do, do better!)

A bad break more than likely comes from diverging too much from a straight line or a reasonably smooth curve. A lot of other problems do, too.
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