String tensions

[Richard]

I came across this site the other day, ideal for those that have a period piece and afraid it may implode with a set of heavy strings on it, so just enter the info and off you go

mcdonaldstrings.com/stringxxiii.html

[Dave King]

I just had a look at this,,, be careful there are more factors involved than are being mentioned. Its the total string length thats important not the scale length. Also I do not see how they could have worked out the inner core gauges and outer core gauges on all makes of string.... some strings, take for instance a 16 can vary as much as 3Ib in tension between makes. It doesn't sound a lot but on a set of strings this would mean 18Ib difference On a total tension of roughly 180 Ib thats quite a bit....

Dave King

[Richard]

Good points and I was certainly not suggesting it be taken as gospel.

But even so, I would have thought it useful as guide to give any idea of tension even when using the stock strings as shown. For instance, just to compare the different loadings between 'average' sets of light, medium and heavy must be in itself something of a guide.

[Dave King]

my first sentence should read,,, be carefull there are some factors involved here that are not being mentioned,,, and yes Richard your right its a guide which is a good idea ,,,,
Im going to go practice spelling,,,,

Dave King

[Deleted]

Dave, with the greatest respect, the overall length of the string does not affect the string tension, that is quite wrong. The factors are scale length and the tensile strength of the string at a given pitch. The tensile strength of the string will depend on cross sectional area and the material used. To calculate the tensile stress in a string, you divide the cross sectional area by the load imposed. The length literally doesn't come into the equation. Lengthening the string under a given load does absolutely nothing to the tension set up in the string..it will stretch more, but the tension (ie the load exerted and resisted) will remain exactly the same. Increasing the 'dead' (ie non-playing length) does not affect the tension in the string, BUT a longer string may feel slightly different, that is because there is more of it to stretch (you can figure it out using Young's modulus). Stands to reason, for a particular string on a set scale length, if the tension is less, the sounding note will be lower, that's one of the immutable laws of physics. It's a commonly held misconception that string tension alters with the total string length. Please guys, get this right, because there are a lot of people out there who perpetuate this misunderstanding..it's one of my pet niggles.

[Deleted]

Hey, just checked that string tension calculator, and I say approach with caution. It's very crude because it takes no account of the material and construction used in the strings. The only reliable information is that given by testing a specific string under load. Even on plain strings there may be some difference simply due to the material used. On wound strings it gets even more complicated, as effectively they are a compound structure, with a loadbearing core, the windings, and on coated strings a further coating of polymer. So the absolute strength depends on the core wire, and the tension required to bring that string to pitch will vary depending on the size and density of that core wire and also on the gauge and density of the wrapping wire (plus any coating). Also having hex cores or round cores will also affect the actual cross sectional area of the core and therefore the load (ie tension) at which it comes to pitch on a given scale length. The notes on the calculator says they can't figure out why their figures can be 5 -10% different to manufacturers' data....still want to use it?!

[snakehips]

Hi there !

String tension ? Shouldn't it be the forces applied to the guitar ? And the dirction of the forces ? Break angle over nut and bridge - surely they are important ?

String length ? Surely the string tension on a guitar with a short tailpiece (and long "dead string" between it and the bridge) tuned to E feels different to a guitar with bridge/string retainer combo, tuned to E - as the string length is quite different ?

I've got a 27" scale-length Baritone National (Dave King special !). If I put regular guitar strings on it (13-56, like I use on my other guitars) - I reckon the cone would collapse if I tried to tune it right up to E. It feels just "right" tuned about 2-3 frets lower (D or Db).

[LouisianaGrey]

I'll quote verbatim what someone much cleverer than I am sent me (please ignore the dots in the formulas, it's the only way I can get it to space properly and it doesn't seem to want to accept the mathematical symbols):

"There is no rationale in physics I know to say that adjusting the nut and saddle height or altering anything to do with the string outside of the area vibrating to produce your note (between saddle and nut or nut) should affect string tension.

The relationship between pitch, tension, length (between saddle and nut/fret) and string gauge/weight is given by:

......1........................T
f = --- x square-root ---
......2L..................... µ

Here, f is the frequency of the note in Hertz, L is the scale length in metres, T is the tension in Newtons (divide by 9.81 to get tension in Kilograms), and µ is the mass per unit length of the string.

There is also a formula for describing how much deflection force is required - e.g. how tight or floppy a string feels. Again there is nothing in this that should be affected by saddle or nut height or string length outside of the part being played:

.....4dT
t = ------
........L

t is the deflection force (the force needed to pull out the string), d is the deflection, T is the string tension and L is its scale length.

From the above equation you can see that longer strings need to be under higher tension in order not to feel floppy.

Cheers - hope that helps. But you'll still find many guitarists who like to believe other factors matter (e.g. I've heard it said that the longer nut to tuner distance on Fender bass strings affects the string tension which appears to have no basis in physics (and you can imagine - you can adjust the string on a strat and then use a locking nut which clamps the string at the nut, and then cut off the string behind the nut - would that change how the string feels? No!)."

[Richard]

Maybe I should not have mentioned this in the first place but, from little acorns etc etc

Anyway, whilst on this subject can we go orff on a slight tangent and have a lucid explaination of the theory behind the break angle of the said strings over the bridge ..

[snakehips]

Hi again !

I've just realised or remembered what it is I had in my head about guitars with/without tailpieces and resulting extra string length or not ( extra dead string length) - here it is :

Bending strings !!

I imagine the force required to bend a string up, say a full tone in pitch, may be different on a guitar with a tailpiece than on one without a tailpiece. This is because you are trying to bend more string.
Either "force" or "distance the string needs to be pushed sideways" - I'm not sure which is more important - probably they are both important.

I believe this is one arguament used to explain some areas of Jimi Hendrix's guitar playing, string bending on a Fender Strat. The "dead string" lengths at the headstock get progressively longer as you go up the strings (from 6th to 1st) - USUALLY !!
As Hendrix played a right handed guitar strung left handed, it was the opposite way round - the 1st string had the shortest "dead space length" at the headstock, the 6th string the longest.

(Mind you, I think he would be just as good on any guitar he was given !!!!!!!!!)

Perhaps I am confusing the whole arguament ?
I hope I am helping to clear up (or differentiate) some issues ?

[blueshome]

Louisiana Grey makes the point that only the distance between nut and saddle affect the deflection force needed - ie how light or heavy the action of a guitar and how easy to bend a string. This is only true if the string cannot move over the nut or saddle (as with a locking nut etc), in practice the string can stretch, hence the "softer" feel of guitars with an end tailpiece (eg National, archtops etc).
This does not affect the overall tension applied to the guitar by the string as is correctly noted.

[LouisianaGrey]

But you're ignoring the friction element, Phil. In practice I don't believe the strings move much across the bridge when bending. If they did I guarantee they would hang up in the string slots and the guitar would be out of tune after the bend. That's why the Hipshot Trilogy needs slippery material for the nut and bridge for it to work properly. I speak from experience on that one.

[Dave King]

The length of the string DOES effect the tension, are you saying that the string between the nut and the tuning heads is not under tension ? the reason for headless guitars and basses was indeed to help with this problem,,,,,, I have made a very simple jig to measure string tensions. If anyone is not sure on the physics please feel free to pop round for a demonstration. A couple of extra turns around the tuning head makes a surprising difference.....

[Deleted]

Great, at last, some real logical rational discussion about this subject..well done chaps! In the past I've seen some real nonsense spouted by so-called experts writing in guitar magazines on this one. If you think about strings 'hanging up' in the nut slots, bending notes is only an extension of tuning the guitar higher using the machineheads. With a properly cut nut, the string should not be meeting excessive resistance in the nut slot. When you get that dreaded creaking or pinging when tuning up...that's usually the string sticking in the nut slot, but otherwise, the string will be sliding ever so minutely over the nut as tension is altered whether by the machineheads or by stringbending with fingers or whammy bar (except in a locking nut of course). On the other point of bridge/nut height, this could have some effect on the feel of the guitar, but NOT the (technically defined) string tension. The amount of break over the nut and bridge will affect the downforce exerted by the string..the greater the break angle, the greater the force and therefore the greater the friction between string and nut slot. An excessive amount of friction could contribute to strings sticking over the nut, but in reality the break angle at nut and bridge is a matter of stopping the strings from jumping out of the nut slots or off the saddle, and also exerting enough downforce to drive the cone of a reso guitar, or the top in the case of an acoustic.

[Dave King]

Well I just hate this, this only normally happens when I argue with my wife. Ive just got the said jig out and tried it again to prove that I was right,,, and I'm totally wrong I even tried to double the length of the string in the hope that it would show a small increase in tension and make me feel better... but nope nothing 626 826 no difference,

My Apologies,,,,, Dave King