Piano World Home Page Forums Our Most Popular Forums Piano Forum FAQ - Piano Forum what is a high tension string scale?

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?

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.

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.

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.

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

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?

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.

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.

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

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.

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.

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

I have obviously been duped by the "German Piano Wire" marketing ploy. Thanks.

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.

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

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

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

(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.

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.

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.)