Tension of a string on 660 vs 650

Construction and repair of Classical Guitar and related instruments
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rojarosguitar
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Re: Tension of a string on 660 vs 650

Post by rojarosguitar » Sat Apr 08, 2017 6:50 am

mikfik wrote:... is less en-harmonic and thus sounds better and feels better to both hands. Try it,you'll like it.
How do you use the term 'en-harmonic' here. Could you please explain, I don't understand. I know only enharmonic equivalents, and Wikipedia defines also enharmonic scales as being quarter tone scales.
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Re: Tension of a string on 660 vs 650

Post by rojarosguitar » Sat Apr 08, 2017 6:59 am

rojarosguitar wrote:
mikfik wrote:... is less en-harmonic and thus sounds better and feels better to both hands. Try it,you'll like it.
How do you use the term 'en-harmonic' here. Could you please explain, I don't understand. I know only enharmonic equivalents, and Wikipedia defines also enharmonic scales as being quarter tone scales.
Also we shouldn't forget that string calibres are not a continuous variable, they come in discrete jumps of diameter, so it's not necessary easy to achieve the same tension on a longer scale guitars as on 650. Also the connection between mass and stiffness (by which you probably mean here lateral stiffness) is not such a simple one. After all we don't have just some continuous mass density but rather quite complicated molecules that are highly asymmetrical and composed of long chains ...

My personal experience with apparent stiffness of strings is such that the same set on the same scale length can fell very differently, when the guitar has a different construction even with same action. It's a very complex system of variables and there is no easy telling how a certain scale length will actually feel.
Music is a big continent with different landscapes and corners. Some of them I do visit frequently, some from time to time and some I know from hearsay only ...

es335
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Re: Tension of a string on 660 vs 650

Post by es335 » Sat Apr 08, 2017 9:11 am

rojarosguitar wrote:... Also we shouldn't forget that string calibres are not a continuous variable, they come in discrete jumps of diameter, so it's not necessary easy to achieve the same tension on a longer scale guitars as on 650. ...
Ground resp. rectified treble strings are available with 0,005-0,01 mm grading for the diameter which is of course not continuous but sufficient to finetune the tension of a long scale guitar! :wink:
For instance the treble set on my 664 mm Yairi consists of La Bella rectified individuals. Delivers a very nice tension feeling and tone of course!

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Re: Tension of a string on 660 vs 650

Post by rojarosguitar » Sat Apr 08, 2017 9:44 am

Yes, sure, if you like LaBella rectified, you might be able to settle on a select set, but with many brands (like my preferred Augustin Imperials or Savarez New Crysta) you are stuck with a quite discontinuous set of choices...

But I was using the argument more for the sake of illustrating that you can't compare everything with everything ... never mind, if you are able to find a good solution for your instruments, the better!
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Re: Tension of a string on 660 vs 650

Post by mikfik » Sat Apr 08, 2017 1:57 pm

I'm sorry- the word I should have used is "inharmonic".
Here is an interesting article on the subject from. http://knutsacoustics.com/files/String-stiffness.pdf
This is a statement from the article. "When a string is plucked, the overtones will not be exact integer multiples of the fundamental frequencies (they will be "enharmonic", the stiffer the string, the more the overtones will deviate from the harmonic relation present." This is what I was trying to say.
Let me just add that as classical guitar players we are VERY fortunate to have such a great selection of string choices at very low prices because of the economy of scale.

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Re: Tension of a string on 660 vs 650

Post by rojarosguitar » Sat Apr 08, 2017 7:24 pm

Oh sure, I thought you meant that.
Actually the slight inharmonicity of the overtones (we can't say 'harmonics' here :lol: ) makes a string more interesting (like contradictory spices in food), but of course an excess of that leads to problems, and in extreme cases even to difficulties to ascertain the pitch. The most infamous example are stiff thick nylon g-strings. But this stiffness seems to be really a complex variable depending on many factors in the chemistry (of plain strings) and on winding procedures of wound strings.

BTW the so called harmonics also do not fit into tempered scales, and that makes rich sounding guitars so much more difficult to tune than dull (fundamental frequencies oriented) sounding ones.

I cant remember who, but somebody here on the forum argued that this lateral stiffness doesn't come strongly into play for the question of effort of pressing a string because the actual sidewards bending of the string is not so big. I don't know, one would have to come up with some kind of measurement device for that...

As I already wrote, the real marvel here is that the same string set can feel so different on two guitars of basically same geometrical properties (scale length, action) and brought to same tuning.
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Re: Tension of a string on 660 vs 650

Post by mikfik » Sat Apr 08, 2017 8:59 pm

I agree completely with remarks of "rojarosguitar". When it comes to the feel of one's guitar, scale length is only one of many variables, but it's the one variable that is constant and we can discuss it's properties and effects in general. The way a string vibrates is a very complicated subject and it takes a much smarter person than me to fully understand it.
mydres-4.jpg
The 5 long strings running along the side of the neck range from 85cm - 90cm in length and are tuned from EE (one octave below guitar) through BB, yet they are pretty thin. They sound so much better than any 10 string guitar I've ever heard. When played they do NOT go plunk like a big fat string at 65cm. They sound more piano-like and sustain in a nice manner.
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Re: Tension of a string on 660 vs 650

Post by rojarosguitar » Sat Apr 08, 2017 9:07 pm

That one looks really interesting ... a moded 6 string or an entirely different beast?
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Re: Tension of a string on 660 vs 650

Post by mikfik » Sun Apr 09, 2017 3:11 pm

The photo shows my Dresden 13 string guitar built by Michael Thames. He used to post here at Delcamp a few years ago and I miss his input on these pages. This guitar was his answer to the many problems we modern guitarists have with the Baroque lute used to play Weiss's music. This Dresden guitar has 64cm scale for the 8 strings on the fretboard and the diapasons (the 5 strings that run next to the neck) run from 82cm - 88cm in length. She has an all wood lattice under her top.
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Re: Tension of a string on 660 vs 650

Post by rojarosguitar » Wed Apr 19, 2017 9:24 pm

I have done a little calculation with a slightly simplified geometrical model: I assume that the 12th fret is a corner of an equilateral triangle with the action height as the orthogonal height, which assumes a bit more symmetry than there really is, but I believe the deviations are really small. Also the actual lateral stiffness of the strings is not being included here, but this should also be only a small contribution...

According to this simplified model when the material, gauge and the pitch of the string is kept same, the necessary pressing force to rich the fret increases by approx. 1,54%.

For sending a pdf of the calculation please PM me witgh your e-mail adress, if you're interested...
Music is a big continent with different landscapes and corners. Some of them I do visit frequently, some from time to time and some I know from hearsay only ...

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Re: Tension of a string on 660 vs 650

Post by rojarosguitar » Thu Apr 20, 2017 5:12 am

If you want to look into my handwritten notes:

https://www.dropbox.com/s/mtg4sewaii15i ... 1.pdf?dl=0


An analogous calculation for the transition from 640 to 65o yields an increase by 1.56% in pressing force (for an nylon e-1 string of 0.7mm diameter and an action of 4mm at 12th fret).
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Re: Tension of a string on 660 vs 650

Post by rojarosguitar » Thu Apr 20, 2017 6:52 am

I have verified through a simple experiment that the calculations I have done in my notes are roughly OK. On my Stenzel 650mm with New Crystal NT e-string and an action of app. 3.5 mm above the 3d fret I have measured app. 0.245 kg as pressure force. In my model I had calculated 0.24 kg.

If I take the dimensions straight from the Stenzel, I calculate 0.242 kg (under the assumption of a density of 1000kg/m^3 as for nylon, which is probably too low, because the New Crystal feels a bit denser than normal nylon). So the error is here around between measurement and calculation is here around 1.15% (fairly Ok for an ad hoc experiment).

My conclusion is, that my model is fairly OK for the situation. One thing I wasn't certain of was the last step of doubling the pressure force because of the pull from two sides. My measurements seem to confirm that.
Music is a big continent with different landscapes and corners. Some of them I do visit frequently, some from time to time and some I know from hearsay only ...

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Re: Tension of a string on 660 vs 650

Post by rojarosguitar » Thu Apr 20, 2017 8:20 am

Here I provided a general calculation of the pressure force at the 12th fret for any scale length, any frequency, any diameter and any density of the string (the density of traditional nylon is quoted as 1000kg/m^3, that of fluorocarbon is quoted with 1791kg/m^3 at Arto's String Calculator).

https://www.dropbox.com/s/2h3m2okszplqr ... s.pdf?dl=0

So when I calculate for the same Stenzel the pressure force when using a 0.6mm fluorocarbon string I obtain 0.289kg instead of 0.223kg when using a nylon 0.705mm string (at 12th fret e-1). That is an increase of almost 30%.
Music is a big continent with different landscapes and corners. Some of them I do visit frequently, some from time to time and some I know from hearsay only ...

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