Strings - how?

[Steve Browning]

A while back I started a thread asking the massive how a loudspeaker works, and how it reproduces multiple frequencies. 

 

The result was a fascinating thread, which was very informative. 

 

This is about strings. What is the science around thicker strings being more full sounding and thinner strings being more twangy. I'm thinking standard bass and Fender VI, for example. 

 

How does a short scale string cover the same frequencies as a full scale string?

 

Any experts out there?

[Joe Nation]

I'm no expert, but there are several variables that change how a string sounds: length, gauge, material, tension, construction. Make a string longer, it plays a deeper sound (that's obvious to anyone that has ever fretted a stringed instrument); make it tighter, it plays a higher sound (ditto for anyone that's ever turned a tuning peg); make it thicker it plays a deeper sound (hence why we have multiple strings on one instrument). What's less obvious is how material and construction changes things.

 

I'm sure most bassists know that flatwound and roundwound strings exist - flats generally sounder softer/deeper, rounds tend to be brighter/zingier. I would speculate that that this is because the tighter fit of the flatwound binding restricts and dampens vibrations in the string, whereas roundwounds can flex just a little bit more before each adjacent wrap starts to impinge on the next. Thicker strings also resist flexion more than thinner ones, because there's more material to stretch/compress. The thickness/pitch of the binding will also change the sound, using a thicker binding with fewer wraps per unit length of string (turns per inch, TPI) will resist bending more than thinner gauge/higher TPI. You could also change the relative thickness of the core and binding, to give the same overall string gauge but a different sound (eg a 1mm core with 0.5mm binging will be the same gauge string as a 1.5mm core with 0.25mm binding, but would sound and feel different).

 

As for material, different metals and alloys have different properties. To make a guitar string, you need something that is flexible (not brittle), strong, has a high elastic limit and is ductile (can be drawn out into a wire). The higher it's elastic limit, the further it can bend/stretch and return to it's original shape. A tiny change in the level of brittleness will change just how much it will flex under a given load, ie how much it will vibrate when you pluck the string. Adding coatings, anodizing or plating to the wires will also change the properties in small but noticeable ways - black strings sound different to nickel-coloured ones.

 

It's all about resistance to bending, change that and you change the sound. As for the hows and whys, and how to get a certain sound, I'll leave that to more experienced minds.

[itu]

On 08/12/2021 at 12:41, Steve Browning said:

What is the science around thicker strings being more full sounding and thinner strings being more twangy. I'm thinking standard bass and Fender VI, for example. 

 

How does a short scale string cover the same frequencies as a full scale string?

A short scale compared to a long scale differs only a bit. If the tension and the pitch are equal, gauge has to be different and so on.

 

There are only very few materials available for stringed instrument strings (certain steels). The extra weight (what is wound over the actual string) can be nearly anything: metal, plastics... and its function is simply to make the string heavier.

 

If the tension and the length of the string are the same, but we need a higher pitch, the only way to make it happen is to reduce the weight. Piccolo strings, anyone?

 

If the tension and the weight (/ft) are the same, to change the pitch equals the change of the length of the string, take a look under the bonnet of a grand piano, or a harp.

 

Here I wrote weight/ft, because it has to be even. I would not love to play with a string that was not equal in thickness over its length. Nor would I love to adjust the fretted neck accordingly.

 

Twanginess (?) is more about the function of thickness and tension. Very thin string has to be tuned to lower tension compared to its thicker bro. If you ever tried a 30-90 set after a 45-105, you get my point.