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  #1  
Old 02-19-2019, 12:42 PM
Silly Moustache Silly Moustache is offline
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Default IS THIS TRUE??

Looking for some info on YouTube yesterday, and found a chap talking about guitar set ups.
He said "New strings are at the highest tension then lose tension as they age!"

Really?

Whadya think?
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Old 02-19-2019, 12:47 PM
zmf zmf is offline
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If you turn the little knobby things at the top of the neck, the tension will come back, if indeed it went away.

Or am I missing the intent?
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Old 02-19-2019, 12:50 PM
charles Tauber charles Tauber is online now
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Theoretically, yes, practically, probably not enough to make ANY difference.

The Mersenne's Law relates the vibrating frequency of a string to its length, mass and tension. As a string stretches, its cross section is reduced in some proportion to its stretch. As given by Mersenne's Law (for ideal strings), if the mass goes down - due to a reduced cross section - the tension will also go down in order to have the same vibrating frequency. (The vibrating string length is given by the nut and saddle positions that do not change when altering the tension on a string.)

The reduction in cross section of a stretched guitar string over time is likely negligible. So, in theory, yes, in practice probably not enough to make any difference. In short, not true enough to bother even mentioning.

https://en.wikipedia.org/wiki/Mersenne%27s_laws
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Old 02-19-2019, 12:51 PM
Glennwillow Glennwillow is offline
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Well... I have trouble believing that. Slack in the windings around the tuning posts gets taken up on new strings in the first day or so after putting new strings on. And because of that, the tuning pegs have to be retightened to bring a string back up to pitch on the guitar. But that series of actions should not suggest that a string is literally being stretched beyond its elastic limits, as if we were pulling putty apart.

A particular diameter string has to be brought up to a particular tension to generate a specific frequency on the guitar. If the string literally kept stretching to reduce tension, as if it were being stretched beyond its elastic limit repeatedly over time, it would soon break.

A guitar string under tension is certainly being stretched a very small amount, but not beyond its elastic limit, at least not normally. An old string is not being stretched any more than a new string.

I could be wrong, but to me, this claim does not sound right.

- Glenn
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Old 02-19-2019, 12:54 PM
Silly Moustache Silly Moustache is offline
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mmm, A little while ago Murrmac (where are you?) reprimanded me on one of my videos because I said that after restringing you should ul them to stretch them ..he said "strings don't stretch, but they do settle" or something similar.

I doubt the guy in the video but I suspect he's as wrong as I was.
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Old 02-19-2019, 01:03 PM
charles Tauber charles Tauber is online now
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Quote:
Originally Posted by Glennwillow View Post
A particular diameter string has to be brought up to a particular tension to generate a specific frequency on the guitar. If the string literally kept stretching to reduce tension, as if it were being stretched beyond its elastic limit repeatedly over time, it would soon break.
And, that is exactly what happens.


Quote:
A guitar string under tension is certainly being stretched a very small amount, but not beyond its elastic limit, at least not normally.
It is beyond its elastic limit into the range of plastic deformation. In the plastic deformation range, "work hardening" of the metal occurs making the metal increasingly more resistant to further stretching. The work hardening also increased the brittleness of the metal, one of the reasons that repeatedly bending and unbending a string - such as often occurs as the string leaves the tuning post - causes it to break. In short, it does stretch "a lot" initially, and progressively less and less.

It's an easy experiment to verify. Put on a new set of strings. Tune it to pitch and immediately put a mark on the string at the nut using a felt tip marker. As the strings stretch, and the guitar goes out of tune, subsequent retuning back to pitch will see the position of the marker move over time: it will move closer and closer to the tuning peg post. Removing the string tension does not return the mark to its original location. That is plastic deformation. Eventually, beyond a certain point, the mark won't move appreciably further.
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Old 02-19-2019, 01:03 PM
zmf zmf is offline
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A tangential question.

I've heard it often opined that one way to tell if your strings need replacement is that the guitar becomes harder to tune. The above would suggest that this is not the case.
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Old 02-19-2019, 01:05 PM
Manothemtns Manothemtns is offline
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Quote:
Originally Posted by charles Tauber View Post
Theoretically, yes, practically, probably not enough to make ANY difference.

The Mersenne's Law relates the vibrating frequency of a string to its length, mass and tension. As a string stretches, its cross section is reduced in some proportion to its stretch. As given by Mersenne's Law (for ideal strings), if the mass goes down - due to a reduced cross section - the tension will also go down in order to have the same vibrating frequency. (The vibrating string length is given by the nut and saddle positions that do not change when altering the tension on a string.)

The reduction in cross section of a stretched guitar string over time is likely negligible. So, in theory, yes, in practice probably not enough to make any difference. In short, not true enough to bother even mentioning.

https://en.wikipedia.org/wiki/Mersenne%27s_laws
Great response. I'm an engineer and was going to try to tackle the question but you said it better than I ever could!
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Old 02-19-2019, 01:05 PM
mr. beaumont mr. beaumont is offline
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Can a string actually "stretch" though? They're metal...
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Old 02-19-2019, 01:07 PM
charles Tauber charles Tauber is online now
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Quote:
Originally Posted by Silly Moustache View Post
mmm, A little while ago Murrmac (where are you?) reprimanded me on one of my videos because I said that after restringing you should ul them to stretch them ..he said "strings don't stretch, but they do settle" or something similar.
That'd be wrong. They do stretch and they do settle. Prove it to yourself with the experiment I suggested previously.

Tune up a nylon string guitar and watch the fun. The strings do "settle", but they also stretch like crazy and do so for several days. One of the ways of speeding the process of both settling and stretching is to pull on them. Common practice by classical guitarists.
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Old 02-19-2019, 01:07 PM
Manothemtns Manothemtns is offline
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Quote:
Originally Posted by mr. beaumont View Post
Can a string actually "stretch" though? They're metal...
Absolutely...but they will be thinner the further they're stretched. Same as a climbing rope.
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Old 02-19-2019, 01:08 PM
charles Tauber charles Tauber is online now
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Quote:
Originally Posted by Manothemtns View Post
Great response. I'm an engineer and was going to try to tackle the question but you said it better than I ever could!
Thank you. I'm also an engineer.
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Old 02-19-2019, 01:11 PM
woodbox woodbox is offline
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I'm going with Glenn on this one.
(edit: while I was writing, I see others agree with him too)
Why?

Well, his many years as an accomplished guitar player, added to his highly respected career in engineering,
tells me he would know more than most about this.

My vote:
What Glenn said above.

(second edit: Glenn is in good company with a couple more engineers on board... I'll be still)

Last edited by woodbox; 02-19-2019 at 01:20 PM.
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  #14  
Old 02-19-2019, 01:15 PM
charles Tauber charles Tauber is online now
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Quote:
Originally Posted by zmf View Post
A tangential question.

I've heard it often opined that one way to tell if your strings need replacement is that the guitar becomes harder to tune. The above would suggest that this is not the case.
That's true, but not really for the reason you are suggesting.

As strings get "old", they play "un-true". That is, the intonation of them - their ability to play in tune - isn't consistent. That can be due to two primary things. One is if the string stretches and doesn't change cross section uniformly - it has a different diameter at different places in the string. I'm not sure how much that happens, but is possible.

The other, that is common, is that the strings become "damaged", particularly where they contact the frets. Repeated fretting of as string against a string can locally flatten the string, changing its cross section. That can influence how well - and consistently - it plays in tune. Corrosion, sweat and dirt can have a similar influence for similar reasons.

As we have all experienced, strings change their sound as they age. Some of that has to do with the above and some of that due to the strings becoming work hardened from extended stretching.
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Old 02-19-2019, 01:15 PM
rick-slo rick-slo is offline
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"Elastic limit. Elastic limit, maximum stress or force per unit area within a solid material that can arise before the onset of permanent deformation. When stresses up to the elastic limit are removed, the material resumes its original size and shape. Stresses beyond the elastic limit cause a material to yield or flow."

Guitar strings aren't tune up to or above their elastic limit. There might be points of wear from friction but doubtful that lowers required tuning tension. Also strings can get grime build up but that would raise required tension if anything.
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