String Tension Rant!

“String tension” is one of the most misunderstood of all scientific realities of lutherie. Many luthiers do not understand the term, and I dare say most guitarists and other fretted instrument players are utterly clueless when it comes down to what it really means. String tension is NOT the feel of how slinky a string is. It is NOT related to string afterlength…the string length between the nut and tuner posts or bridge and string anchor point or tailpiece. It is NOT related to the break angle of the string over the bridge or over the nut. A given string at a given vibrating length at a given pitch has an absolute tension. The formula for this is based on the linear density of the string…for instance, how much an inch of the string weighs. This factor can be expressed in a number of ways, and it seems that each string company has their own take on it, but it all comes down to the same basic thing. When people talk about “string tension”, they are very often actually talking about the stretch factor…how the string feels when fretted or a note is bent. While the string may have an absolute scale length, those after bits of the string also stretch a bit and greatly affect the feel of the string. Were you to lock down a Floyd Rose “trem” (it’s really a vibrato…) and lock down the strings at the nut with the strings tuned at pitch, you’d have the shortest stretchable length of string possible, and you’d find the strings feeling stiff, but changing in pitch with relatively small sideways bending movements. If you have a guitar with long afterlengths from nut to tuner post and bridge to tailpiece, you’d find that if you had the same scale length (nut to bridge saddle) and same string gauges, you’d find the strings felt slinkier (NOT lower tension!), and you’d have to move the string farther to get the same pitch raise as with the double locked down guitar. Also, changing the break angle of the strings from nut to tuner post or bridge to tailpiece (if any) does NOT affect tension, though friction may affect the stretch feel. So many myths, so little understanding.

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