String Tension... What affects what?
Bonus Footage on the Video!!!!! Les Paul Top wrapping... Yes, No?
String tension is something we might take for granted once we have been playing for a while.
The string of a particular mass being stretched tightly to a given tension over a calculated distance is what gives us our note. You can see the math to the right.
In real terms, The longer the scale of the guitar, the tighter the string needs to be pulled to get a given note if all other factors are the same. A 25.5" scale requires a higher tension overall than a guitar with a 24.75" scale. These are the most common. The shorter scale guitar, if everything else is the same will feel "slinkier" and easier to play.
"Lowering" String Tension....
We hear people say this a lot. "I did _______ modification on my guitar and lowered the string tension." This is because there are a couple of other factors involved. First lets make one thing clear. The tension of a string between the nut and the bridge (the tonal area) will always stay the same (as long as the scale and string weight stay the same) Otherwise..... you would be out of tune.
Most of the "string tension" mods that we do to our guitars are doing two things.
1. Changing the length of the string outside the tonal area
2. Changing the "break angle" of the nut, the bridge, or both.
When we bend a string, we are actually pulling on the entire length of the string. Most of the time this is from the tuning key to the ball end of the string. When we lengthen the string outside the tonal area, we don't "lower" string tension.
Instead, we give ourselves more string to stretch as we bend. If there is only a little bit of string between the nut and the tuning key... it won't stretch very much when we bend. If there is more, that area stretches and slides across the nut.... allowing for an easier bend. In the illustration to the right, Example A will be easier to bend than Example B.
The other factor is "break angle." The steeper the angle of the string as it goes over the nut and the bridge, the higher the downward pressure on the contact point..... The harder it is to bend because of increased friction.
Common modifications to play with all these factors are "top wrapping" on a LP style guitar, and removing string trees from a Strat or Tele style guitar. Locking nuts also affect this. Check out the bonus footage in the video below to learn more.