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I am involved in a discussion on Foro Flamenco Forum about the string tension of a longer vs shorter string. The discussion arose from a post recommending swapping the 6th string & 4th connection to the tuners. In other words, the 6th string would be wound aroung the roller for the 4th string & the 4th on the 6th roller. The comment was made that the 6th string feels looser in this configuration & the 4th firmer. The thread went off course when another member mentioned that "It's a simple mechanical engineering question. A cable of a given tension will deflect more at a longer length, than it will at a shorter length." This statement is true, but is assuming that the lengthened string is at the same tension as before. I commented that the longer string, 6th, would actually be tighter than before, as it is longer. We are not talking a change in the scale length of the guitar, just the string length from tie block to roller & I contend that the string tension is felt from these anchor points & not, as another member states, from saddle to nut. Bottom line, if the 6th string is moved to the 4th tuner roller & tuned to pitch, would the string be tighter? Would it feel tighter?

Thanks,
kev

The string will be at the same tension because the speaking length (the string between the saddle and the nut) has not changed. However, the string will feel a little looser because the extra length from the nut to the tuning machine adds to its ability to stretch. This assumes that the string can easily slide though the nut slot, which may or may not be the case.

I don't think so. As I see it, the string tension is registered between the anchor points, the bridge & the tuning peg. The longer the string, the higher the tension required to tune it to the same pitch.

This is a topic that has been discussed numerous times on various forums and it always makes for interesting observations.
A warning in advance, however, is that it can become a heated discussion.
I don't have any answers--just wanted to forewarn.

this is just so absurd . String tension is string tension. the only area the the tension matters is between the saddle and the nut . The theory of this is that the longer the string length the more tension .
This is a case where facts will not change opinion ,

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
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You Don't know what you don't know until you know it

Its a basic lack of understanding of simple physics.

Sorry Bugeyed but you are wrong and the other guy is right.
For tension it is the speaking length that matters (nut to saddle)
For ability to deflect the string, the added length makes it slightly easier theoretically but in tests I did with a spring balance it was not measurable.

+1

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On the side of the defense, the distance between an archtop saddle and tailpiece (afterlength) definitely has an affect on "feel". In Tom Ribbeckes "Chainsaw Lutherie" article (now in the Redbooks I think) ..."The length of the tailpiece on an archtop guitar will affect the way the guitar feels to the player, though for the same guage strings the actual tension will not change. A short tailpiece necessitates more string behind the bridge, and the added stretch ...makes the action feel softer, or looser. Conversely, a longer taipiece....no stretch...feels tighter, or firmer"
I built two very similar archtops, both with 12/52's and 25" scale

A main difference was a shorter tailpiece on the red one. It certainly feels somewhat "looser" to me. To quote Michael Lewis, "Short tailpiece means longer strings and an easier feel, long tailpiece and shorter strings emphasize brighter overtones, a more percussive response, and a stiffer feel. On some guitars the difference between a long and short tailpiece can feel like different gauge strings. "

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Dave
Milton, ON

I'm no luthier, but I've studied this quite a bit and what I've found is that as others have mentioned, string length beyond the scale length certainly contributes to feel provided that extra length is able to stretch. i.e. not binding in the nut or not a guitar with a locking nut. A guitar like a Jazzmaster that has a lot of extra string length between the bridge and tremolo certainly has a looser feel. The downward angle of the strings outside of the scale length also greatly affects feel in much the same way. The more downward angle the tighter the strings feel and vice versa.

As far as tension, as somebody else mentioned, I think it actually stays the same in the sitting position regardless of string length outside the scale length. But once you start to move/play/bend the strings, that's when you percept the change in feel. It is worth noting that with a longer string length and looser feel, you have to travel further vertically on the fretboard to reach a given pitch. Whereas with a shorter overall string length, you don't have to travel as far vertically on the fretboard to reach the given pitch, but you have to apply more pressure. I'm no physics guy but in my mind I think of it as exerting the same amount of energy just in different ways.

I'm with Jeff Highland on this one, and more particularly since he's done the experiment. If you disagree with his data, go out and get some better data.

The archtop tailpiece is a red herring in this case. If the tailpiece is more or less rigidly attached to the guitar, as your first one seems to be (I can't tell about the second pic), then it becomes a fixed point, more or less. the closer that is to the bridge, the more it's likely to stiffen up the feel of it: the short backstrings can't deflect as much to allow for bridge movement. Also, you have to remember that the tailpiece will have it's own resonant frequencies, and these can react back on the guitar to alter both the timbre and feel.

And, BTW, that 'feel' is probably most properly reffered to as 'compliance': the force it takes to deflect something a given amount. It's often called 'tension', but they are far from the same thing, and the confusion is one reason why these discussions so often degenerate. I know that a lot of folks dislike technical discussions, but this is unvoidably such a one, and if we can't use the proper technical terms we are unlikely to settle anything.

I guess I am 'blissfully ignorant of any history of vehemence in this discussion, but I can certainly see how it would arise in the absence of the distinction you make here, Alan. As I consider you to be very gifted in illuminating technical principles for the less scientifically trained such as myself, it would be a real treat for me if you would expand on the difference and relationship between compliance and tension. To think of them not necessarily tracking linearly is kind of a Eureka thing for me. Pretty please?

Peace,
Sanaka

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...imagine there were no hypothetical situations...

I'm certainly not Al, but as he's not answering. Imagine you take a rubber band and hang 1lb from it. It will stretch a certain amount until it hits equilibrium. Now measure that and cut a steel rod the same length and hang one pound from it.

Both are now under 1 lb of tension and the same length. When you push on side of the rubber band, will it deflect more or less than the steel rod for a given force?

That's the difference between "compliance" and tension (although I'm not sure if it's actually called compliance in technical terms).

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Thanks Andy: I've have probably spent two pages on that.

Sanaka, your intution is more or less correct: for a given string on a given setup, compliance should pretty much track the tension. But you have to look at what happens to the tension as you fret the string, and the things that might influence that.

We see a less extreme illustration of Andy's experiment in the difference between steel and nylon strings. Nylon, with a lower Young's modulus than steel, streches more when yuou push it aside, so the tension changes less in the act of fretting the note. That's why nylon strings need less compensation than steel, and why they will feel 'softer', even when they are at pretty high tension.

Backstring length can have an effect. As has been pointed out, if the tuner is a long way from the nut, and the string slides nicely through the slot, the piece of string between the nut and post will stretch along with the part that's between the nut and saddle. Again, the string could feel 'softer', and need less compensation than a shorter one.

It's possible that a 'soft' top, one that is easy to depress at the bridge, or that allows the bridge to rock forward a lot when the tension changes, could give the strings more of a compliant feel. After all, when you push the string down you also push down on the bridge.

Among all of the other factors, we can't forget the influence of 'wetware'. We so often hear, and feel, what we expect to, that we should not discount that as a factor. That's why I was hapy to see that Jeff actually made some measurements: it's really the only way we're going to settle this sort of discussion.

There is a very simple "compliance" test that is measurable: take any guitar and bend a note then put a capo on and bend the same note and measure the difference in vertical travel required on the fretboard.

Here is a specific example I have tried in the past: I grabbed a Strat and bent the high E string up a full step at the 12th fret and noted how far I had to travel vertically on the fretboard to reach that note. I did this with an accurate tuner so I could verify when I was exactly at the F# note. Then I put a capo on the first fret with a stout capo (Kyser). The capo effectively simulates a shorter string length because it clamps the string and prevents movement of the string outside of the speaking length. Now bend the same note at the 12th fret and note how far you have to travel vertically on the fretboard. What you will find is that the string feels tighter and that you have to apply more pressure to reach the F# note. You will also find that you don't have to travel as far vertically on the fretboard as compared to when the capo wasn't on the guitar.

As mentioned before, I don't know the technical term, but to me it requires the same amount of energy. With longer string length a guitar will play softer, but if you bend much you will have to push further. With the shorter string length the guitar will play tighter but if you bend a lot you won't have to push the strings as far.

An example to describe how length can influence compliance: take a piece of spaghetti 1/2 inch long and apply enough force to break it. Now take a full length piece and apply the same force to the middle. See what happens here?

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http://banduramaker.blogspot.com

So to summarize, there are two physical properties at play: tension and compliance.

As far as compliance, for a longer and looser feeling string, is it correct to say definition-wise that string is less compliant?


Also, when looking at those two physical properties with regards purely to scale length: the longer string length inside the scale length should create a looser feel due to compliance. However, more tension is required to reach the same given pitch on a longer scale. Therefore, is it accurate to say that the tension physical property has more affect on feel than the compliance physical property when looking at scale length?

Chad asked:
"As far as compliance, for a longer and looser feeling string, is it correct to say definition-wise that string is less compliant?"

It's MORE compliant: it 'complies' better with your efforts to push it aside.

"Therefore, is it accurate to say that the tension physical property has more affect on feel than the compliance physical property when looking at scale length?"

Probably, but I'd want to see some data to be sure. It's one of those 'balance' sorts of things.

Sometimes It's better to do a little number crunching than use analogies
Lets consider this

Scale length 25"
String tension 30 lbs
deflect string 1/2" at the centre

Ignoring for the sake of this calculation string bending stiffness (assume the string is flexible)

Firstly let us disregard end conditions

the deflected string and it's original position forms a shallow triangle with sides 12.51, 12.51 and 25. do the statics of this and the force required to deflect the string to this position is 30x2x0.5/12.51 = 2.4lbs

Regardless of the length beyond the nut and saddle you are going to have at least this resistance to deflecting the string by 1/2 inch

Now consider the fact that in deflecting the string, its length has increased to 25.02 from its original.
If the string was locked at nut and saddle this would produce an additional strain of .020/25=.0008

If you have an extra 6" total beyond nut and saddle and the string is free to move across these points then the additional strain is .020/31=.00065

Now these strain figures will convert proportionally to increased tension dependent on modulus of elasticity of the string and diameter of the core, and this increased tension will increase the force required to deflect the string
I am not going to do the calcs but the trend is clear, increase the length of the string beyond the nut and saddle and you make the string slightly easier to displace and therefore easier to fret. If bending up to a note however you will need to displace the string further to get the same pitch increase

Alan and everyone: awesome! Those illustrations make it easy to see the difference. I would enjoy seeing data as well, but Chad's idea that tension seems to contribute more to 'feel' than compliance, all else equal, goes along with the conventional wisdom that shorter scale lengths are easier to play.

Peace,
Sanaka

_________________
...imagine there were no hypothetical situations...

Of course immediately after typing the above I run across Liutaio Mottola's article referencing an experiment by Bob Benedetto that would seem to disprove that people can feel a difference between scale lengths.

This doesn't jibe with me at all though. Here is recent experience of mine that is not terribly scientific, but I think is valid enough: I'm helping a family friend to learn guitar. She is a petite teenage girl, just starting out. My dreadnaught, with 25.4" scale length and strung .012-.052, is really difficult for her to play - she simply cannot fret an F chord (and the dread is comically huge for her to hold). She got a new guitar for Christmas, a parlor with shorter scale length, and she's all over it - it is indeed like playing melted butter compared to my dread. This is with the same gauge strings, and both guitars are similarly and well set up, with similar action. I thought this is why different scale lengths even existed. What gives (pun intended )?

Feel free to ignore this post if I'm just starting a whole fruitless discussion all over again

Peace,
Sanaka

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...imagine there were no hypothetical situations...

I don't agree with the test that is referred to in that article. The article even says that further research is needed. That is happening in this thread. Mathematical proofs are cool, but stories like your family member's are totally on the mark.