String through, tuner extensions, pc board spacers, etc.

Discussion in 'Hardware, Setup & Repair [BG]' started by silky smoove, Jun 14, 2005.

  1. silky smoove

    silky smoove Supporting Member

    May 19, 2004
    Seattle, WA
    This seems to be something that comes up quite often and has recently come up a lot on another forum where I'm a member. I thought I would post my theory here as well. I'm highly against the idea that changes beyond the bridge saddles or string nut actually affects string tension while maintaining a specific tuning and string gauge (obviously if you make those change and also tune up with heavier gauge strings you'll have a resultant increased tuning). At any rate, here's what I came up with and posted in another forum, please tell me if you agree or disagree, and if you disagree, please explain why:

    Okay, this is either going to answer a lot of questions, or open up a serious can or worms. There has been a lot of discussion lately over the questionable benefits to string tension by adding string length beyond the nut or bridge saddles, or both. I’ve made a few diagrams to illustrate my point as to why this is not true and does not yield any benefits to string tension. Also, please note a couple of key concepts to understanding this thing:

    Distance: The measurement between two points in a straight line.

    String Distance: The measurement along the centreline of a string, which is not a perfectly straight line, nor can it be.

    String Gauge: The material thickness about the centreline of a string.

    Scale Length/Speaking Length: The distance between the nut and the 12th fret multiplied by 2 (essentially the distance from the bridge saddles to the nut, but you use the previously referenced equation due to the fact that to allow for perfect intonation of each string, the distance will be slightly different for each string).

    Tension: The applicable string length along its speaking length given a specific tuning and a specific string gauge.

    Here we go:

    Diagram 1:

    As you can see, this is a (very rough) sketch of the layout of a bass guitar’s string as it is anchored at the bridge and at the headstock to a tuning machine, and as it passes over the string nut and bridge saddles.

    In this diagram, the string is stretched between two points, the nut and the saddles. This defines the speaking length of the string, i.e. the scale length. The string gauge and desired tuning for this string determines the string distance between the nut and the saddles. As you decrease tension (i.e. down tune) the distance between the two points, along the string becomes greater and therefore tension is reduced. As you increase tension (i.e. tune up) the distance between the two points along the string becomes shorter and therefore tension is reduced.

    Diagram 2:

    As you can see, this is a (also very rough) sketch of the layout of a bass guitar’s string as it passes through the body and is anchored to a tuning machine that is further down the headstock (which would be congruent with a left handed neck on a right handed body, adding PC board spacers after the nut, etc. etc. etc.).

    In this diagram, as compared to the first diagram the TOTAL string length is noticeably longer. Does this equate to higher tension if the distance between the nut and the bridge saddles remains the same as in the first diagram? Absolutely 117% correct.

    What? Didn’t you just argue otherwise? Silky? Are you smoking crack?

    What people are forgetting in this argument is that while the total string distance has changed, and the distance between the nut and the bridge saddles has remained the same, the STRING distance has now become shorter and therefore the note is now sharp of its intended tuning. Therefore, you must down tune (i.e. reduce tension, increase the string length between the nut and bridge saddles, etc. etc.) in order to achieve the correct string tuning.

    So, in a nut shell, give a specific string gauge, a specific scale length and a specific tuning, no change in tension will occur when ANY change is made outside of the speaking length (i.e. scale length, area between the bridge saddles and nut) of a string.
  2. Silky, I applaud your work. You've done a yeoman's job of explaining a difficult to grasp concept. I totally agree with you but I've sort of got to - you are absolutely correct!

    I have a small addition to your definitions for the sake of clarity and that is that "tension" in this case is a measurable containment of energy between two points. The scale of measurement being pounds and the two points being, as you've described, the nut and the saddle. Without the ability to measure the tension, which your explanation leaves out, there isn't much reason for the rest of the excercise.

    Way to go :bassist:
  3. silky smoove

    silky smoove Supporting Member

    May 19, 2004
    Seattle, WA
    Thanks Hambone, coming from you that means a lot!