"Elasticity/Compliance" and tension

Discussion in 'Luthier's Guitar & Bass Technical Discussion' started by aron, May 14, 2008.

  1. aron

    aron Member

    Messages:
    25
    Joined:
    Feb 26, 2008
    I've been searching all over for information on why some guitars feel easier to bend given the same scale length. I'm not talking about the fret height/type and other things that make sense like type of fingerboard/radius. I'm talking about when you try to pull the string across the fingerboard; some guitars just feel more slinky. Specifically, I have Strat scale length guitars and I cannot figure out why some of them really do feel like the strings are more "elastic".

    Apparently given a neck scale length and tuning, the string has a predetermined tension. This is a given. So at some point, they all have the same tension for a given scale. However, it is obvious that certain guitars feel like they require less effort to bend the string. You can grab the string and feel it. Apparently to not confuse this with tension, it's called elasticity or compliance.

    In any case, I have read that the nut break angle, saddle break angles, total string length etc.. have an effect on this. But there was a test regarding the total length of string vs... the scale that seemed to indicate that it didn't matter.

    Here is the link.

    In any case, what factors can we adjust on a Strat to affect the perceived elasticity of our strings? On a Les Paul, it's the break angle of the stop tailpiece for example.

    Any hints? Thanks in advance.
     
  2. Bob V

    Bob V Member

    Messages:
    1,191
    Joined:
    Dec 31, 2007
    Location:
    Glen Head, New York
    I'd like to see somebody measure the force necessary to bend a string far enough to get a pitch change of two half-steps, and the measurement of how far the string has to be pushed. Then lower or raise the stop tailpiece on a Gibson and measure it again. Or change the number of springs on a Fender bridge, and measure them again.

    Those of us who go by feel and what we've always believed to be true from practical empirical knowledge always seem to get slammed by the tecchies on forum pages like these (we all know the flames are coming, so damn the torpedos). So before anyone tries to debunk the setup "rules," lets see some physics lab testing. Until you show me that (and honestly, I'd like to see it so we can test our assumptions), I have to insist that a lower tailpiece makes a string less "compliant" - that it it feels stiffer and its harder to bend the note, but you don't have to bend as far to get the same pitch change. Same thing for extra springs on a Fender trem. On the other hand, if you want to run string-through ferrules in a graceful S-curve or even a "V" for design purposes instead of in a straight line, go ahead and probably no one notice the variation in compliance or elasticity.
     
  3. aron

    aron Member

    Messages:
    25
    Joined:
    Feb 26, 2008
    The tailpiece I have actually noticed and in fact is in a Gibson ad. I haven't tried the springs theory yet on a strat.
     
  4. David Collins

    David Collins Member

    Messages:
    2,253
    Joined:
    Feb 10, 2007
    Location:
    Ann Arbor, MI
    The biggest problem you'll run in to here is that "feel" is so subjective. Yes, the break angle at nut and bridge, the rigidity of the end anchor points, the string length between the saddle/tailpiece and nut/tuner, or springs of a tremolo, all these have a real influence. A key point is that if you bend to a certain pitch you will always be bringing the string to the same tension, and will require the same perpendicular force, regardless of the distance it has to be deflected to bring it there.

    So while a less rigid anchor beyond the speaking length may less force to deflect it a given length, it still takes the same end force to bring it to a given pitch. So describing the feeling of stiffness or looseness becomes a very subjective matter, just like descriptions of tone. You could qualify and quantify everything about string compliance and elasticity, but in the end you could have two players offering opposite descriptions of the same guitar. One who says it feels loose because the strings feel more compliant when fretting and strumming, another who says it's stiff because they have to bend so much farther to go up a step.

    Hand a person five pounds of iron and five pounds of feathers, and most everyone will feel that the iron is heavier. It's just such a subjective thing that relies more on perception than numbers. Just my opinion.
     
  5. testing1two

    testing1two Gold Supporting Member

    Messages:
    1,741
    Joined:
    Mar 26, 2008
    Location:
    Southern California
    +1. And since we're talking about strat-style guitars, we haven't even begun to address the impact the trem has on these perceived effects.
     
  6. aron

    aron Member

    Messages:
    25
    Joined:
    Feb 26, 2008
    Wow. You are right. I didn't think about it this way. What I thought of doing was to measure how far I needed to bend to get say a whole step bend and compare that to another guitar. I suspect the distance would be different and account for the perceived difference in feel.
     
  7. aron

    aron Member

    Messages:
    25
    Joined:
    Feb 26, 2008
    OK, I would suspect that having more "looser" springs or less springs would result in a strat guitar that feels more "slinky". That it would take farther to bend to a given pitch (with the same radius).

    Interesting.
     
  8. David Collins

    David Collins Member

    Messages:
    2,253
    Joined:
    Feb 10, 2007
    Location:
    Ann Arbor, MI
    But if it takes farther to bend are you now also pushing against the B, G and D strings as to get a full step bend on the high E, instead of just running in to the the B and a little on the G? :confused:

    You can see how variables keep getting piled higher and higher that can influence a player's perception. I certainly don't claim to have any definitive answers on this.....
     
  9. GtrDr

    GtrDr Member

    Messages:
    799
    Joined:
    Apr 25, 2008
    Location:
    Central Florida
    The set up itself has a lot to do with it too. neck relief, radius, string height, the strings themselves too
     
  10. kimock

    kimock Member

    Messages:
    12,604
    Joined:
    Mar 12, 2005
    Location:
    Where the Palm Tree meets the Pine
    Re: that link. . .

    Good thing I'm not a frickin' scientist.
    Why does this guy assume that just because the total tension is the same that the distribution of tension at the bridge is the same when you bend the string over it at a different angle.

    Seems like common sense that the greater down angle you get by lowering the tailpiece is going to stress the string at that point, preloading it if you will, and that you're going to sense that additional stiffness or resistance to bending as soon as you start to push that string up.
    At some point in the bend you're going to get past that initial stiffness introduced by the bigger down angle, and the total tension at the destination pitch probably is the same regardless of the additional tension percieved to get the string moving.

    There has got to be some consideration given for the surface tension of that string at least, as it's bent over that saddle.
    C'mon, the top surface of that string is travelling a greater distance on the outside of that radius than the bottom surface, right?
    Unequal, period.
    That's basic, it's got something to do with why airplanes can fly, or why your Camaro drags one wheel around corners or something like that, but I'm pretty sure it's not rocket science. . .

    So I'm going to say that the difference in feel you get from the tailpiece height is attributable to the distribution of local surface tension at the saddle, because obviously the total string tension has to be the same.

    Kind of like the difference between a linear and audio taper pot, same off, same on, different slope in between.

    Anyway, that guy should have stayed in school for another couple of years.
    He might have gotten to the point where he knew better than to apply such a simplistic model to describe a real world scenario that any teenager with a Korean Les Paul copy and a flat head screw driver could shoot down.

    Somebody ask that guy to bend a nail. Not too hard.
    OK, bend it back. . .:cool:

    OK? Same total string tension? You bet.
    Different distribution of tension on that string?
    You bet your life.

    Not a scientist, flunked math etc.
    This one's just not that hard.

    peace sk!
     
  11. aron

    aron Member

    Messages:
    25
    Joined:
    Feb 26, 2008
    Good points Dave! For the above, rats. I would have hoped that one of the builders on this forum could just set me/us right. I'm going to try different springs and see if the perceived elasticity is altered.
    Thanks!
     
  12. walterw

    walterw Gold Supporting Member

    Messages:
    33,547
    Joined:
    Oct 16, 2006
  13. Moat

    Moat Member

    Messages:
    234
    Joined:
    Oct 17, 2004
    Location:
    Mid-Mitten
    I have a notion that it has as much - if not more - to do with the overall response/resonance/livelyness of any particular guitar, as it does anything else. Those "magic" guitars that we stumble upon far too infrequently - the ones that seem effortless, that "play themselves" - simply require less grip, or downward pressure against the frets, to transfer the "intended information" of playing... because they're simply more efficient at doing so. And a relaxed grip/less downward pressure = easier bending.

    It can be a rather subtle difference, and the player adjusts to it (relaxes grip) automatically, without even thinking - so it leaves the overall impression of ease, "slinkyness", or elasticity.

    I have a buddy with a Sadowski hardtail Strat - strung with .011's and very high action... yet plays and bends sooo much easier than any of my super-low action, strung with .010", big fret Strats. Why?? All I can figure is because this Sadowski is super-light, lively and resonant - it just "zzshinggs" and sings at the slightest brush of the strings. Quite unlike any of my guitars... :bkw

    Fret height/shape, alloy (hard/slippery vs. soft/bitey), and fretboard "drag" beneath the fingertips (finish, wood grain, etc.) all contribute, too.

    IMHO, anyways.
     
  14. merkaba22

    merkaba22 Member

    Messages:
    1,163
    Joined:
    Dec 27, 2007
    Location:
    Hollywood, CA
    There are a couple of factors I always consider in understanding this (IMHO):

    The length of string that is available at the time of stretching is important: for example, for a strat-type guitar with a Floyd Rose locking setup, the effective length where the string can be stretched is a little over scale length @ 25.5" compared to a reg. strat having the scale length of 25.5" + the distance to the bottom of the spring block (approx. 2") + the distance past the nut to the tuner (in the case of the 1st string, 6") -- accordingly, it is much easier to bend a string that has an effective length of 34" v. 25.5". To make a more dramatic example -- imagine a string @ 20 lbs extending a mile in length, an ant on it would bend it somewhat -- on the other hand, a string @ 20 lbs that is one inch, would be very difficult to move at all ....

    This observation would take into account when there is a steep rake of the string extending past the bridge to the tailpiece on a Gibson -- shortened length that can be stretched means harder to bend. To some degree having a "sticky" nut can be a factor -- one where you can hear the string pop or ping when you tune -- probably minor, but minor things can add up.

    Another factor is that I have found different strings form different manufacturers have different feels - maybe subjective, but varying alloys could explain variation since the way the string slips over them is varied; for example, stainless steel is very slippery compared to plain steel -- take a loose guitar string and run it over a stainless steel salad bowl to see how slippery it is -- bending could be easier in one case over another.

    To a lesser degree, there is the height of the fret (since downward pressure can create part of the desired pressure to bend to pitch but is easier than across the fretboard -- think sitars and scalloped fretboards).

    Further, there is the fingerboard itself and how its finished -- I find that finished maple fingerboards are "sticky" compared to say, ebony, and that affects how much strength is used to move the string sideways for bending.
     
  15. edgewound

    edgewound Gold Supporting Member

    Messages:
    5,373
    Joined:
    May 20, 2008
    Location:
    Southern California
    Some things I've learned throughout the years on string tension...from both building my own guitars and playing them, and experience with other designer/builders....I worked for Charvel/Jackson back in the 80's. I was in sales, but I do alot of repair work on speakers for a living now, and have a pretty good handle on how things work after some experience.

    The geometry/profile of the neck relative to the body has the first-most influence on string tension where the string seems to react faster to a bend up note.

    Look at the stock difference of a Les Paul vs a Strat by laying it on the floor or a table.

    The Les Paul's neck and headstock has a negative tilt to it relative to the front of the body. The Strat has either no tilt or in some cases a positive tilt toward the front of the body. This positive tilt angle and the straight headstock on the Strat can lead to a "bow" effect where the neck is actually bending forward with the string bend and requires more force and bend distance to get up to the note you're searching for. The negative tilt on the Les Paul, PRS, etc. has a much more rigid foundation for the string to react to, which makes for less force needed to bend up to the note...because the neck isn't flexing too. Notice that a Les Paul doesn't need string trees to hold the strings in the nut. Warmoth now makes a Strat neck with an angled headstock...no trees required.

    That, in addition to the angled head stock gives the strings on the LP, PRS, etc. more perceived tension and in return "corners" faster.

    The standard tremolo on a strat also tends to add to this sluggishness in bending tension.
     

Share This Page