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#1126171 - 05/04/04 10:10 AM Re: Scale Design - tension
Del Offline
5000 Post Club Member

Registered: 09/04/03
Posts: 5184
Loc: Olympia, Washington
 Quote:
Originally posted by Grotriman:


1] So I understand that the higher the bass section goes in the scale, the higher the tension. (?)

2] Also if there are wound strings in the lower tenor, there is a likelihood the scale design is higher tension.

3] I hear lots of statements about certain pianos being low tension designs. But I don't hear of any particular piano that is a "high tension" design.

4] Sometimes I get the feeling that "low tension" design is (was once) a marketing tool to give the notion that a piano was not going to go out of tune so fast (being under less stress).

5] But where is a high tension design? [/b]
1] Not necessarily. Running the bass section up some can eliminate the hockey stick effect at the low end of the tenor bridge. This is unrelated to the overall scale tension.

2] Not necessarily. This is one way to cope with extending the tenor bridge down further than is actually called for by the tenor scaling. This can be done for several reasons. Once is placement of the bass/tenor plate bracing. In a four–section plate design it is generally desirable to keep this break fairly well down in the scale to more evenly distribute the string load across the plate.

3] Certain Kawai, Yamaha and M&H scales come to mind. (Please note: I am not saying there is anything necessarily ‘wrong’ with higher–tension scales. Pianos incorporating them have a certain tone quality that is appreciated by many. My own taste has been going in different directions. Yours may not.)

4] It can be a marketing ploy. But it is easy to check. It is also easy to confuse. Just where are we to measure? Treble? Tenor? Or bass? When I speak of a high–tension or a low–tension scale I am referring to the average scale tensions used through the tenor section of a piano, disregarding the hockey stick hook. I’ve categorized the general ranges in previous posts.)

As well, just like most piano design or construction ‘features,’ the proof is in the sound. If the piano has a sound quality you appreciate then what does it matter if the scale is HT or LT? One really shouldn’t be buying a piano because it has a HT scale or a LT scale. One should be buying a piano because of its tone quality and performance.

5] See No. 3.

Del
_________________________
Delwin D Fandrich
Piano Research, Design & Manufacturing Consultant
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Stupidity is a rare condition, ignorance is a common choice. --Anon

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Piano & Music Accessories
#1126172 - 05/04/04 10:17 AM Re: Scale Design - tension
Del Offline
5000 Post Club Member

Registered: 09/04/03
Posts: 5184
Loc: Olympia, Washington
 Quote:
Originally posted by fmelliott:
Actually, Pinblocks need reform as much as anything. I have wanted to ask Del for sometime if it wouldn't be possible, and highly desireable to go to a "screw stringer" type tuning method.

Well, Del, why do we continue to use pinblocks which can be such a hassal? [/b]
Well, yes and no. The conventional tuning pin and pinblock arrangement actually works quite well. While it's not perfect it is quite inexpensive, quite functional and lasts a really long time. I've not seen any other proposed alternative that comes close.

Yes, the screw stringer system has something to offer. But its high cost will probably preclude its ever being reintroduced. It would have to be redesigned and built with somewhat more precision. And, if we expect it to last anywhere close to as long as the conventional tuning pin/wood pinblock arrangement, it is going to have to be made of considerably stronger materials than the original. Both would drive up the cost considerably.

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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#1126173 - 05/04/04 12:26 PM Re: Scale Design - tension
Calin Offline
Full Member

Registered: 09/11/03
Posts: 418
Loc: Bucharest
 Quote:
Originally posted by Del:
... You can (and usually should) drop a bit of unison tension when transitioning to the wrapped bichords, but it should be kept to no more than 10 – 20 percent. This is easily achieved by maintaining approximately uniform string tensions and this is best achieved through the use of a log scale and by keeping the length disparity between the last plain steel string unison and the first wrapped unison relatively small. ...

Del [/b]
Hi Del,

Why is it desirable to drop the tension of plain steel unisons before transitioning to wound strings?

Thanks!

Calin
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Calin

The Bechstein piano discussion group: http://launch.groups.yahoo.com/group/bechstein/
The Schweighofer piano site: http://schweighofer.tripod.com

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#1126174 - 05/04/04 12:44 PM Re: Scale Design - tension
Del Offline
5000 Post Club Member

Registered: 09/04/03
Posts: 5184
Loc: Olympia, Washington
 Quote:
Originally posted by Calin:

Why is it desirable to drop the tension of plain steel unisons before transitioning to wound strings?

Thanks!

Calin
[/b]
It's not. It's the tension of the bi-chords that gets dropped. And it's the total unison tension that is under discussion, not the individual string tension.

And the amount that gets dropped depends largely on the amount of string length offset. In other words, how short the first wrapped string bi-chord unison is relative to the last tenor plain steel tri-chord unison.

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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#1126175 - 05/04/04 06:31 PM Re: Scale Design - tension
Calin Offline
Full Member

Registered: 09/11/03
Posts: 418
Loc: Bucharest
 Quote:
Originally posted by Del:
It's not. It's the tension of the bi-chords that gets dropped. And it's the total unison tension that is under discussion, not the individual string tension.

And the amount that gets dropped depends largely on the amount of string length offset. In other words, how short the first wrapped string bi-chord unison is relative to the last tenor plain steel tri-chord unison.

Del [/b]
Hi Del,

What's the relationship between the length and the tension?
You use less tension for a longer bass string or more?

Calin
_________________________
Calin

The Bechstein piano discussion group: http://launch.groups.yahoo.com/group/bechstein/
The Schweighofer piano site: http://schweighofer.tripod.com

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#1126176 - 05/04/04 11:15 PM Re: Scale Design - tension
Del Offline
5000 Post Club Member

Registered: 09/04/03
Posts: 5184
Loc: Olympia, Washington
 Quote:
Originally posted by Calin:


What's the relationship between the length and the tension?
You use less tension for a longer bass string or more?

Calin [/b]
The greater the length offset — i.e., the larger the percentage of length differential with the wrapped strings always being shorter than the plain steel strings — between the wrapped strings and the plain strings the more the tension should be dropped. I have no mathematical formula for this, it just works out better this way in terms of tone quality and power blending.

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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#1126177 - 05/05/04 12:38 AM Re: Scale Design - tension
BDB Online   content
Yikes! 10000 Post Club Member

Registered: 06/07/03
Posts: 21296
Loc: Oakland
I think what Calin wanted was much simpler:

If you lengthen a string, and you want the pitch to stay the same, you have to increase the tension if the weight of the string remains the same.

Increasing the length lowers the pitch.
Increasing the tension raises the pitch.
Increasing the weight lowers the pitch. (We usually treat weight and diameter or gauge as equivalents, which is true for a material with uniform density. There's actually slight difference with wound strings, depending on how they are made. But then, there are other imperfections in the real world.)
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#1126178 - 05/05/04 08:40 AM Re: Scale Design - tension
ChickGrand Offline
3000 Post Club Member

Registered: 05/02/03
Posts: 3202
Loc: Midwest U.S.
 Quote:
Originally posted by Del:
The greater the length offset — i.e., the larger the percentage of length differential with the wrapped strings always being shorter than the plain steel strings — between the wrapped strings and the plain strings the more the tension should be dropped. I have no mathematical formula for this, it just works out better this way in terms of tone quality and power blending.

Del [/b]
I'm a little confused by the phrasing I added italic emphasis to above, Del. It may be the phrase "length differential" that I don't grasp as it implies a relationship and I'm not sure what's relative to what. My longest wound bass string is 77" from agraffe to bridgepin and my and my longest unwrapped tenor unisons are only 65". So when you say "wrapped strings always being shorter", I'm confused. Could you clarify, please?

By the way, I'm truly enjoying your ongoing "seminar" in piano design here in the forum. You may often wonder about the futility of educating us end users a little, but I'm sure I'm not alone in finding the portion I understand fascinating and the rest intriguing, and your generosity with time and thought here a wonderful gift to us.

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#1126179 - 05/05/04 10:54 AM Re: Scale Design - tension
BDB Online   content
Yikes! 10000 Post Club Member

Registered: 06/07/03
Posts: 21296
Loc: Oakland
I think he's talking about adjacent notes. If you switch from plain gauge wire to a heavier wound string, you need to shorten the speaking length to maintain a similar tension.
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#1126180 - 05/05/04 11:30 AM Re: Scale Design - tension
Del Offline
5000 Post Club Member

Registered: 09/04/03
Posts: 5184
Loc: Olympia, Washington
 Quote:
Originally posted by chickgrand:
I'm a little confused by the phrasing I added italic emphasis to above, Del. It may be the phrase "length differential" that I don't grasp as it implies a relationship and I'm not sure what's relative to what. My longest wound bass string is 77" from agraffe to bridgepin and my and my longest unwrapped tenor unisons are only 65". So when you say "wrapped strings always being shorter", I'm confused. Could you clarify, please?
[/b]
Yes, I'm talking about adjacent notes.

For example, the lowest tenor note (F-21, a plain-steel tri-chord) in a Steinway B scale is about 1470 mm long (±5 mm or so). The highest bass note (E-20, a copper-wrapped bi-chord) is about 1025 mm long (again ±5 mm or so).

This makes E-20 approximately 30% shorter than the adjacent F-21. Te make this string configuration blend the unison tension of the highest bass string is going to have to be somewhat less than it would be if it were scaled somewhat closer to, say, 10% shorter than the F-21 length. A length discrepancy of this magnitude will make both harmonic blending (i.e., controlling the harmonic content of the vibrating strings) and inharmonicity blending somewhat problematic. These scale breaks always present difficulties, this just makes them worse.

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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#1126181 - 05/05/04 12:04 PM Re: Scale Design - tension
Grotriman Offline
500 Post Club Member

Registered: 03/07/04
Posts: 724
Loc: New York City
A pleasure to read all of this very informative stuff. Thanks Del.

Perhaps in light of the (start of an) education we've just received on scales, you can comment on the A, B, C scale designs of Steinway in light of the bass to tenor transitions.

It is curious to me that (to my ears) the A and the C scale design are really nice. But these are the models they chose to discontinue in the US. The B scale perhaps being the most problematic is the model they chose to push (though I've heard very nice B-s).

Are there structural issues that make an A or a C difficult to produce?

FWIW the transitions on the L and M from bass to treble are very problematic for me. I assumed the pianos were just too short to have a good blend between the bass and tenor sections.
_________________________
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Grotriman

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#1126182 - 05/05/04 06:09 PM Re: Scale Design - tension
ChickGrand Offline
3000 Post Club Member

Registered: 05/02/03
Posts: 3202
Loc: Midwest U.S.
Thanks for the clarification, Del.

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#1126183 - 05/06/04 10:23 AM Re: Scale Design - tension
Calin Offline
Full Member

Registered: 09/11/03
Posts: 418
Loc: Bucharest
 Quote:
Originally posted by Del:
 Quote:
Originally posted by Calin:


What's the relationship between the length and the tension?
You use less tension for a longer bass string or more?

Calin [/b]
The greater the length offset — i.e., the larger the percentage of length differential with the wrapped strings always being shorter than the plain steel strings — between the wrapped strings and the plain strings the more the tension should be dropped. I have no mathematical formula for this, it just works out better this way in terms of tone quality and power blending.

Del [/b]
Hi Del!

Thanks for answering. If you drop the tension of the first bass string at the transition, you get more inharmonicity and maybe less power. Are you thereby trying to reach the same inharmonicity as the last plain wire note?

One thing I don't really get: why lower the tension more the shorter the bass string is? A short bass string already has more inharmonicity than a longer one. So it would make more sense to me to use lower tension if it is long (close to the length of the last plain wire note), to compensate for the fact that the plain wire string has more inharmonicity and the bass string less.
Am I understanding things the wrong way?

Calin
_________________________
Calin

The Bechstein piano discussion group: http://launch.groups.yahoo.com/group/bechstein/
The Schweighofer piano site: http://schweighofer.tripod.com

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#1126184 - 05/06/04 11:56 AM Re: Scale Design - tension
Del Offline
5000 Post Club Member

Registered: 09/04/03
Posts: 5184
Loc: Olympia, Washington
 Quote:
Originally posted by Grotriman:


Perhaps in light of the (start of an) education we've just received on scales, you can comment on the A, B, C scale designs of Steinway in light of the bass to tenor transitions.

It is curious to me that (to my ears) the A and the C scale design are really nice. But these are the models they chose to discontinue in the US. The B scale perhaps being the most problematic is the model they chose to push (though I've heard very nice B-s).

Are there structural issues that make an A or a C difficult to produce?

FWIW the transitions on the L and M from bass to treble are very problematic for me. I assumed the pianos were just too short to have a good blend between the bass and tenor sections.

[/b]
None of these pianos have what I would call a transparent transition.

The Model C comes off pretty well simply by virtue of its length. It has a relatively low-tension scale for a piano of its size. And it has a relatively small hook at the end of the tenor bridge. In fact, just looking at it there doesn’t seem to be any at all; it’s not until you plot it that it becomes apparent. (These comments refer to the old, NY version of the piano. I don't know what, if any, changes may have been made to the current German version.)

With the Model A it depends on which version you’re referring to. Some were less bad than others. There were three substantially different designs for this piano. The piano being built in Germany is, I think, a descendent of what we call the A-2, a 6’ 1”. It would benefit from a well-designed transition bridge.

There is no inherent reason why the bass/tenor transition cannot be, for all practical purposes, acoustically transparent even in a short piano. We’ve done this quite successfully in grand pianos as short as 4’ 5”. By comparison, pianos in the 5’ 7 ½” to 5’ 10 ½” pose little challenge. It’s just that it does take some creative design manipulation of the various string scale and soundboard assembly parameters. It is easier to accomplish this starting with fresh design but it is also possible through the careful redesign of existing product as well.

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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#1126185 - 05/06/04 12:11 PM Re: Scale Design - tension
Del Offline
5000 Post Club Member

Registered: 09/04/03
Posts: 5184
Loc: Olympia, Washington
 Quote:
Originally posted by Calin:


Thanks for answering. If you drop the tension of the first bass string at the transition, you get more inharmonicity and maybe less power. Are you thereby trying to reach the same inharmonicity as the last plain wire note?

One thing I don't really get: why lower the tension more the shorter the bass string is? A short bass string already has more inharmonicity than a longer one. So it would make more sense to me to use lower tension if it is long (close to the length of the last plain wire note), to compensate for the fact that the plain wire string has more inharmonicity and the bass string less.

Calin [/b]
The issue is not inharmonicity, it is the tonal, or acoustical, blend. We don’t really hear inharmonicity. Yes, it affects tuning but, on it’s own, we don’t hear it. What we do hear is the relative power and the harmonic mix in the acoustic waveform produced by the strings associated with adjacent notes. Of these, power is considerably less important than is the harmonic mix in the acoustic waveform. Which is why we can get by with the moderately lower unison tension (the individual string tensions are, of course, higher) on the excessively shortened wrapped bi-chord notes.

I’m not yet prepared to try to explain just why this tension drop is desirable. From experience I know it to be the case, from theory I’m not sure just why. I’m contemplating some experiments that should cast some enlightenment on the question.

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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#1126186 - 05/06/04 04:00 PM Re: Scale Design - tension
Eric F Offline
500 Post Club Member

Registered: 10/23/03
Posts: 518
Loc: La Quinta, CA
[highly desireable to go to a "screw stringer" type tuning method.

I'm sorry to dig backwards into the discussion, but I'm not sure what a "screw stringer" type of pin is and does. Larry Fine says they are machine screws, but how do they hold the tension of the string? Did any other manufacturer besides M&H use them? Thanks.
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"Music comes first from my heart, and then goes upstairs to my head where I check it out." - Roberta Flack

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#1126187 - 05/06/04 07:41 PM Re: Scale Design - tension
dbm Offline
Full Member

Registered: 03/24/04
Posts: 166
Thanks to Del and other experts for providing invaluable seminar like discussions on piano design.

I am interested in sustain because almost anything hit producing a sustaining tone sounds good. (Short sustaining instruments may sound good as well,like drums and certain makes of pianos.)

I'd like to know which are the dominant factors in determining sustain in descending order: The string tension, the strings themselves, the soundboard, the inner rim wood hardness, and the outer rim wood hardness.

I read C.C.Chang's piano webpage and I think that he mentioned that the initial fast decay was due to the vertical mode of motion of the strings while the ensuing singing tone with slower decay was due to the horizontal mode of string vibrations. The coupled motions of the strings also have to be such that there are no net twisting or shifting effect on the bridge thus two strings are only allowed out of phase motions horizontally and in-phase motions vertically. I'd like to hear from industry experts if these are accepted theory.

I also noticed that in tuning unisons, there seems to be a spot where the tone appears to be dead with fast decay. Moving slightly away from this point yields a much more pleasant tone to my ears. Some people referred them as in-phase or anti-phase coupled motions of the strings but from what I read from Chang's site anti-phase vertical motions of two strings are not allowed as well as the in-phase horizontal motions of two strings.

Also no matter what wood is used for the rim, to me they should be all hard enough compared to the vertical suppleness of the soundboard to cause near 100% reflection. Could energy loss due to radiation and friction be more dominant than the hardness of rim wood in determining sustain?

Sorry for all the technical questions not necessarily related to string tension but I work with electromagnetic waves and equations and can't help to draw some analogies in an attempt to understand more about pianos.

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#1126188 - 05/07/04 12:23 AM Re: Scale Design - tension
BDB Online   content
Yikes! 10000 Post Club Member

Registered: 06/07/03
Posts: 21296
Loc: Oakland
Screw stringers were the first Mason & Hamlins. They held the string by a metal hook, rather than a tuning pin. The hook had a screw thread at the other end, which went through a hole in a ridge in the plate. There was a nut on the other side of the hole, which was what you turned to tune the piano. One revolution of the nut was about a 24th of an inch at the end of the string, as opposed to over 3/4" on a tuning pin. This was slower during manufacture but easier to tune once you got it up to pitch. However, the hooks were held in position by a slotted piece of brass, like a comb, and the teeth would tend to break off, making them difficult to tune.
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#1126189 - 05/07/04 10:22 AM Re: Scale Design - tension
Calin Offline
Full Member

Registered: 09/11/03
Posts: 418
Loc: Bucharest
 Quote:
Originally posted by Del:

The issue is not inharmonicity, it is the tonal, or acoustical, blend. We don’t really hear inharmonicity. Yes, it affects tuning but, on it’s own, we don’t hear it. What we do hear is the relative power and the harmonic mix in the acoustic waveform produced by the strings associated with adjacent notes. Of these, power is considerably less important than is the harmonic mix in the acoustic waveform. Which is why we can get by with the moderately lower unison tension (the individual string tensions are, of course, higher) on the excessively shortened wrapped bi-chord notes.

I’m not yet prepared to try to explain just why this tension drop is desirable. From experience I know it to be the case, from theory I’m not sure just why. I’m contemplating some experiments that should cast some enlightenment on the question.

Del [/QB]
Hello Del, and thanks for sharing your knowledge!

Here are a few more questions:
How does lowering the tension influence the harmonic mix of a wound string?
I read that generally higher tension gives more poreminent harmonics in a string. Is this so?
When you are lowering the tension of the first bass string, are you trying to make it have more or less harmonics?
Is there a formula of calculating/predicting the harmonic structure of a string's tone (such as for inharmonicity)?

Calin
_________________________
Calin

The Bechstein piano discussion group: http://launch.groups.yahoo.com/group/bechstein/
The Schweighofer piano site: http://schweighofer.tripod.com

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#1126190 - 05/07/04 12:34 PM Re: Scale Design - tension
Del Offline
5000 Post Club Member

Registered: 09/04/03
Posts: 5184
Loc: Olympia, Washington
 Quote:
Originally posted by dbm:


1] I am interested in sustain because almost anything hit producing a sustaining tone sounds good. (Short sustaining instruments may sound good as well, like drums and certain makes of pianos.)

I'd like to know which are the dominant factors in determining sustain in descending order: The string tension, the strings themselves, the soundboard, the inner rim wood hardness, and the outer rim wood hardness.

2] I read C.C.Chang's piano webpage and I think that he mentioned that the initial fast decay was due to the vertical mode of motion of the strings while the ensuing singing tone with slower decay was due to the horizontal mode of string vibrations. The coupled motions of the strings also have to be such that there are no net twisting or shifting effect on the bridge thus two strings are only allowed out of phase motions horizontally and in-phase motions vertically. I'd like to hear from industry experts if these are accepted theory.

3] I also noticed that in tuning unisons, there seems to be a spot where the tone appears to be dead with fast decay. Moving slightly away from this point yields a much more pleasant tone to my ears. Some people referred them as in-phase or anti-phase coupled motions of the strings but from what I read from Chang's site anti-phase vertical motions of two strings are not allowed as well as the in-phase horizontal motions of two strings.

4] Also no matter what wood is used for the rim, to me they should be all hard enough compared to the vertical suppleness of the soundboard to cause near 100% reflection. Could energy loss due to radiation and friction be more dominant than the hardness of rim wood in determining sustain?

[/b]
1] The dominant factor? There are several including the harmonic mix in the vibrating string. But the principle factor is the impedance relationship between the strings and the soundboard assembly. In very general terms, and assuming a given set of strings on a given piano:
-- A ‘light’ soundboard assembly will absorb high frequency energy at a faster rate than will a ‘heavy’ soundboard assembly.
-- A soundboard assembly with ‘low’ stiffness will absorb low frequency energy at a faster rate than will a ‘stiff’ soundboard assembly.

Generally speaking a piano with a ‘low-impedance’ soundboard assembly — i.e., relatively light and flexible — will have a powerful, percussive attack with shorter sustain. A piano with a ‘high-impedance’ soundboard assembly — i.e., relatively heavy and/or stiff — will have a less percussive attack and a longer sustain.

This characteristic can vary across the soundboard assembly. I.e., the soundboard assembly might exhibit high impedance characteristics in the bass and low tenor region, low impedance characteristics in the upper tenor/lower treble region and, again, high impedance characteristics in the upper treble. In fact, this scenario is not at all unusual and is found in many pianos. Especially as they age a bit.

2] This theory gained some popularity a few years back with an article that appeared in Scientific American magazine. There were several problems with the factual base of the article and several unsupportable assumptions made. (It’s been a few years and I’m not about to try to dig it out and study through the thing again. So please don’t as for specifics. If you’re interested it appeared about 20 years or so back.) Whether the conclusions of this original article are valid or not they only partially explain what happens within an individual unison; they do not explain the general tonal character of the piano. For that you have to consider #1, above.

3] I have not read Mr Chang’s web site so can’t comment specifically on what he writes. However, all of these theories consider only the specific unison being examined or tuned, not the overall function of the piano. For that you have to go back to #1, above.

4] The rim supports the soundboard assembly. The soundboard assembly is vibrating. Therefore energy is being felt at the parameter of the soundboard panel at the junction between it and the inner rim. If the inner rim (or the whole rim assembly, for that) is relatively light and flexible it will readily absorb energy from the vibrating soundboard assembly. This energy is, for the most part, lost within the rim assembly as heat. If the rim assembly is relatively dense and massive it will not readily absorb energy from the soundboard assembly. More energy will then remain in the soundboard assembly where it is converted into sound.

There noticeable, and often significant, difference in both the quality of tone and the useable sustain time between pianos with different types of rims. I have personally observed this difference between otherwise identical instruments side by side. Some years back Baldwin was attempting to save a few dollars and switched from hard maple to poplar in the rim assemblies of their three smaller grand pianos, the models M, R and L. The difference in performance was immediately noticeable and unacceptable. The tone in the pianos using poplar rims was conspicuously sharper and shorter. They switched back to hard maple for the inner rims which, in the opinion of some, was an acceptable compromise. I’m told they are now back to maple for both the inner and outer rims.

Yes, there are energy losses within the soundboard assembly. But this is also true within the rim assembly. Most of the energy coupled to the rim assembly is also lost due to the internal friction of the wood.

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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#1126191 - 05/07/04 01:02 PM Re: Scale Design - tension
Masonite Offline
Junior Member

Registered: 03/29/04
Posts: 14
Loc: New York
Regarding Del's previous post:

First of all, thanks for your insightful and informative posts.

So, a point-of-information question: what do you mean by soundboard assembly? Is that the bridge crown, bridge, soundboard, and ribs?

Could you give your opinion as to choice in design of each of the elements for impedance characteristics? What issues are there with using different materials in each phase in terms of energy loss (impedance mismatch)? Also, if you're also including the ribs in your consideration, I'd appreciate your opinion on the use of different woods for the ribs in different sections of the soundboard.

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#1126192 - 05/07/04 03:23 PM Re: Scale Design - tension
Del Offline
5000 Post Club Member

Registered: 09/04/03
Posts: 5184
Loc: Olympia, Washington
 Quote:

Originally posted by Calin:


Here are a few more questions:
How does lowering the tension influence the harmonic mix of a wound string?

I read that generally higher tension gives more prominent harmonics in a string. Is this so?

When you are lowering the tension of the first bass string, are you trying to make it have more or less harmonics?

Is there a formula of calculating/predicting the harmonic structure of a string's tone (such as for inharmonicity)?

Calin
[/b]
I’ve gone into most of this in the not-so-distance past. At least I think I have. But to repeat:

Lower tension scales tend to develop more energy in the lower partials. Hence more potential energy in the lower harmonics of the sound wave envelope.

In general strings with relatively higher tension tend to develop more energy in the higher partials, less in the fundamental.

In developing a scale with generally lower tension I would be trying to emphasize the energy content in the fundamental and lower partials and, by extension, in the acoustic energy waveform.

There is no mathematical formula available to predict this that I am aware of.

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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#1126193 - 05/07/04 03:44 PM Re: Scale Design - tension
Del Offline
5000 Post Club Member

Registered: 09/04/03
Posts: 5184
Loc: Olympia, Washington
 Quote:
Originally posted by Masonite:

So, a point-of-information question: what do you mean by soundboard assembly? Is that the bridge crown, bridge, soundboard, and ribs?

Could you give your opinion as to choice in design of each of the elements for impedance characteristics? What issues are there with using different materials in each phase in terms of energy loss (impedance mismatch)? Also, if you're also including the ribs in your consideration, I'd appreciate your opinion on the use of different woods for the ribs in different sections of the soundboard.
[/b]
By ‘soundboard assembly’ I mean the assembly comprised of the soundboard panel, the ribs, the bridges, all of the incidental hardware such as screws, pins, etc., and how the system is assembled to form crown. In other words everything having to do with the soundboard and how it reacts to the strings.

As to the second part of your questions — I give all-day seminars on this subject and barely scratch the surface. (Which, by the way, you are welcome to join when and where they are presented.) The issues you raise are far more complex that I’m prepared to even attempt to answer within the context of this list. At least not all at once. Break them down into bite-sized pieces and I might be able to handle them over a period of weeks, perhaps months.

That, or wait for the book (which is what I should be working on right now).

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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#1126194 - 05/07/04 04:24 PM Re: Scale Design - tension
Calin Offline
Full Member

Registered: 09/11/03
Posts: 418
Loc: Bucharest
 Quote:
Originally posted by Del:

That, or wait for the book (which is what I should be working on right now).

Del [/b]
Hello Del!

Can you give us some details about your book?
When is it going to appear and maybe what chapters you plan on including?

Calin
_________________________
Calin

The Bechstein piano discussion group: http://launch.groups.yahoo.com/group/bechstein/
The Schweighofer piano site: http://schweighofer.tripod.com

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#1126195 - 05/08/04 03:03 AM Re: Scale Design - tension
katie_dup1 Offline
1000 Post Club Member

Registered: 02/27/03
Posts: 1838
Loc: Canada
I just thought I'd pop in & thank Del and others for their excellent explanations concerning elements of design that tend to mystify mere mortals, such as myself. The ability to articulate (as text) such complexities so others can understand the subject matter is a talent few possess .... Del, I hope you've had opportunities to mentor young techs .... You appear to me to be a very good teacher.

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#1126196 - 05/08/04 03:57 AM Re: Scale Design - tension
BDB Online   content
Yikes! 10000 Post Club Member

Registered: 06/07/03
Posts: 21296
Loc: Oakland
Of the similar pianos I was dealing with this week, the most pronounced hockey-stick hook was the Bechstein E, a very old-fashioned design. The Steinway Ds and the Yamaha CFIIIs were much less so, even though D and the E which are in the same building are probably contemporaries. I suspect that the Yamaha theoretically has the best design, but I think that there is a gap between the theory and the practice. After all, it was the first Steinway A that had the intermediate bridge. The later versions did away with it. I don't think Steinway would have removed it if they didn't feel that it was an improvement. It just shows that there are different tastes in these things.

I also spent a lot of time with a Steinway B. Not much of a hook there, either.
_________________________
Semipro Tech

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#1126197 - 05/08/04 06:00 AM Re: Scale Design - tension
JPM Offline
1000 Post Club Member

Registered: 02/24/03
Posts: 1010
Loc: NM, GE & Wash. DC
I would like to echo Katie's sentiments. On topics such as this, when Del, BDB and the rest of you smart folks start dialoging, I invariably get educated.

I appreciate the time and effort required to pen clear and concise answers to tough questions on a highly complex subject. Speaking for myself at least, I assure you it is not an easy task to do well.

Del, please do write that book some day. Undoubtedly, it will be of great interest to all that love pianos and an enduring legacy that will remain useful and relevant for a very long time to come.
_________________________
"Piano music should only be written for the Bechstein."
-- Claude Debussy

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#1126198 - 05/08/04 10:52 AM Re: Scale Design - tension
Del Offline
5000 Post Club Member

Registered: 09/04/03
Posts: 5184
Loc: Olympia, Washington
 Quote:
Originally posted by BDB:


1] Of the similar pianos I was dealing with this week, the most pronounced hockey-stick hook was the Bechstein E, a very old-fashioned design. The Steinway Ds and the Yamaha CFIIIs were much less so, even though D and the E which are in the same building are probably contemporaries. I suspect that the Yamaha theoretically has the best design, but I think that there is a gap between the theory and the practice.

2] After all, it was the first Steinway A that had the intermediate bridge. The later versions did away with it. I don't think Steinway would have removed it if they didn't feel that it was an improvement. It just shows that there are different tastes in these things.

3] I also spent a lot of time with a Steinway B. Not much of a hook there, either.
[/b]
1] It’s been a while since I’ve analyzed a Yamaha CF, but the last one I took a serious look at was fundamentally a Steinway D. Cleaned up in a few places, but still . . . .

2] Yes, the original Model A used a transition bridge that was later removed. But — and this is a really big ‘but’ — it transitioned from tri-chord plain steel strings to MUCH shorter tri-chord wrapped strings. About the worst transition you can make from a scaling standpoint. When properly designed and scaled the transition bridge is a very effective method of blending the low tenor with the bass. Effective enough that I’m coming to almost prefer it in shorter pianos.

3] Visually, your observation is correct — there doesn't appear to be much hook to the low tenor bridge of the Model B. But from a scaling standpoint the hook is both evident and tonally significant. The scale is pretty good down to about F-33 and then begins to shorten up significantly. If it maintained essentially the same length multiplier on down the lowest tenor strings (F-21) would be about 1850 mm (72.8 mm) long. As it is F-21 has a speaking length of approximately 1475 mm (58.1”). The hook is there, it’s just masked by the length of the piano.

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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#1126199 - 05/08/04 11:05 AM Re: Scale Design - tension
Grotriman Offline
500 Post Club Member

Registered: 03/07/04
Posts: 724
Loc: New York City
 Quote:
Originally posted by JPM:

Del, please do write that book some day. Undoubtedly, it will be of great interest to all that love pianos and an enduring legacy that will remain useful and relevant for a very long time to come. [/b]
If only so you don't have to spend so much time responding to our requests for more information!

BTW - Where are your seminars given?

Thanks.
_________________________
Regards,

Grotriman

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#1126200 - 05/08/04 11:28 AM Re: Scale Design - tension
Del Offline
5000 Post Club Member

Registered: 09/04/03
Posts: 5184
Loc: Olympia, Washington
 Quote:
Originally posted by Calin:
 Quote:
Originally posted by Del:

That, or wait for the book (which is what I should be working on right now).

Del [/b]
Hello Del!

Can you give us some details about your book?
When is it going to appear and maybe what chapters you plan on including?

Calin [/b]
It was prompted by a little book I pulled, wet and mangled, out of a trash pile at a company I used to work for. Titled “Piano Scale Making” it was published in 1927 and in about 80 pages of sparse, but mostly concise prose, it explains how to ‘design’ and build a 5-foot piano. “A sample of which has been built and pronounced good.”

Now, I’m a sucker for old books — especially old books about pianos — so I rescued the poor thing. As I gently separated the old, yellowed and disintegrating pages I became increasingly intrigued with the piano being described. I had the growing impression that I’d rebuilt one just like it. It represented the culmination of the simplification and homogenization that had been taking place over a period of some ten to twenty years within the piano industry leading up to mid-1920s.

I was particularly interested because I have long considered the very small piano to be one of the greatest challenges facing the piano industry. And one that has not been well met. We have lots of cheap very small pianos (we did in 1927 as well — it’s not a new phenomena) but we have no really good very small pianos.

When one considers the challenges of piano design it is common to immediately consider the king of instruments; the concert grand. But, by comparison it is easy to design a large piano. There is so much forgiveness in those great, long strings. It is, by comparison, much more difficult to design a truly musical very small piano. (By my definition this means a piano 160 cm [5’3”] or shorter.) It is difficult enough that to date no one has done it. Oh, there are very small pianos that are less bad than others but none that are really great musical instruments. Still, it is possible. At least within the context of the musical scale normally used by good pianists. We have come very close through extensive remanufacturing but there are limitations to what can be done with existing design.

Unfortunately it seems to be easier to buy up instant heritage and move production to regions of ever-lower labor costs than to aggressively investigate and develop the fundamental design of the piano. So. I decided to tackle the subject of piano design from the perspective of the very small piano. It is here that we encounter all of the challenges of piano design. A tiny design error in a large piano becomes a major issue in the very small piano. And, because piano design principles remain the same regardless of size what I write about in describing and explaining the design and construction of the very small piano is also applicable to the larger piano.

I am currently about 2/3rds to 3/4ths of the way through the book. It covers most everything I can think of from developing the shape of the rim and developing a string scale to designing the plate. It is not intended to be a step-by-step instruction book but a treatise on both how and why things are done. I am trying to pass on a practical basis for understanding how the piano works more than a tutorial on piano design. The book is intended more for the piano technician and interested piano amateur than for the university piano researcher. At least this is my goal.
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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