12 fret vs 14 fret string tension

[SnowManSnow]

I'm wonder what you guys do, if anything that is different when building a 12 fret vs a 14 fret. Is the string tension enough of a difference bc of the shorter fret to make a difference in your thicknesses or bracing?
Or... Am I thinking about it all wrong?
IS there a difference in string tension at all?


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[charles Tauber]

You are confusing two unrelated things: scale length and the number of frets to the body joint.

Scale length is the theoretical vibrating string length of the open strings. One can create a guitar of any (practical) scale length and have it join the body at any arbitrary location along the neck/fingerboard. If you want to have the neck join the body at the 8-1/4th fret, for example, you can. The 12th fret, as you know, is (theoretically) half the vibrating string length and is a convenient place to join the neck to the body - not all string instruments do that (e.g. lutes). Joining the neck to the body at the 14th fret provides a little more access - two frets worth.

IF one uses the same scale length AND joins the body at a different fret, the distance from nut to saddle/bridge remains the same. If one, say, changes the neck joint from the 14th to the 12th fret, using the same scale length, the bridge moves towards the butt end of the guitar by 2 frets worth of distance. That alters where the bracing should be, the bridge plate and the soundhole.

My preference in playability and sound tends towards smaller bodied instruments with 12 frets to the body. That's what I make.


EDIT: In response to your question regarding string tension, obviously as long as the scale length is the same, so is the tension, since vibrating string length is one of the variables in string tension. As is commonly known, the longer the scale length, the higher the string tension and the further apart the frets are.

I recently completed a 12 fret-to-the-body guitar with a 650 mm scale length. It is the longest scale length I've made in a steel string guitar - standard on a classical guitar. (I know a few steel string makers who use that as their standard scale length.) It was designed and made for someone with long fingers. As a classical player, the fret spacing feels "standard" to me. I do notice a slight, but not huge, increase in string tension, not enough to really make a lot of difference to me.

In designing the instrument, the soundhole, bracing pattern, bridge plate and angle of the X brace were altered to suit, as was the top thickness. I'm very pleased with the result: https://www.youtube.com/watch?v=YwM6fp483Ds

[Halcyon/Tinker]

What Charles said...

[Mr. Jelly]

Yup. You got it.

[Alan Carruth]

One possible issue here is that many players use the word 'tension' to describe the force required to fret the string. That's related to the tension, of course, but other things get into it too, some of which we're not so sure of. For example, it's easy to see that higher action will make it harder to fret strings of a given diameter and scale length. On the other hand, many people say that a stiffer top, or more break angle over the saddle, will do that too, and it's hard to see how that could happen in some sense. At any rate, a better term for the difficulty of fretting would be 'compliance'. Tension, as has been said, is a function of string type, gauge, pitch and scale length. It's harder to figure out compliance; you need more information. Although it seems unlikely, it may be that 12-fret and 14-fret necks tend to have different compliance, all else equal.

[MC5C]

String tension is directly related to scale length, as said. When you fret a string, you push it down and lengthen it, stretching it. This raises the tension a wee bit, raises the pitch of the note, hence compensation etc. If you bend a string, ditto, the tension increases, the pitch increases. The amount of increase in tension is related to the total length of the string, string post to bridge or tailpiece. Very long total string length, combined with low friction over the nut and saddle, can be felt under the fingers as less stiffness to the string. You can find this on some vintage archtops with "compensator" or frequensator" tailpieces.

[redir]

No difference in string tension as mentioned but you do have to consider body shape and or bracing to make sure your bridge pin holes and bridge plate and all that are matched up for what ever scale you are using. Usually a 12-fret guitars bridge is going to be further in the middle of the lower bout. That's the sweet spot that gives them a different tone then the 14-fretters.

[Alan Carruth]

IMO the different sound of 12-fret vs 14-fret guitars of the same width has more to do with body length than anything else. When they went from the 12-fret 000 to the OM they more or less just chopped a couple of frets worth off length off the upper bout. This not only altered the body length, but also the box volume and the distance from the upper edge to the sound hole, all of which would alter the tone a bit. The bridge may not be any further from the lower edge at all.

At any rate, if putting the bridge in the center of the lower bout is the key to great tone, why aren't banjos made that way?

[murrmac123]

Originally Posted by MC5C

String tension is directly related to scale length, as said. When you fret a string, you push it down and lengthen it, stretching it. This raises the tension a wee bit, raises the pitch of the note, hence compensation etc. If you bend a string, ditto, the tension increases, the pitch increases. The amount of increase in tension is related to the total length of the string, string post to bridge or tailpiece. Very long total string length, combined with low friction over the nut and saddle, can be felt under the fingers as less stiffness to the string. You can find this on some vintage archtops with "compensator" or frequensator" tailpieces.

I also tend to believe that greater total string length increases string compliance, but is there any controlled scientific experiment documented anywhere which actually proves this ? It would be a very simple matter to set up a rig to test the hypothesis.

[Mr. Jelly]

Originally Posted by redir

Usually a 12-fret guitars bridge is going to be further in the middle of the lower bout. That's the sweet spot that gives them a different tone then the 14-fretters.

For some reason some people resist this fact. It sure is evident to me. I'm sure there are some guitars made that all they do is change the upper bout but for most others, like Martins and Santa Cruz, the bridge and bracing are completely different and moved more into the middle of the lower bout on 12 fret 00s.

[murrmac123]

Originally Posted by Mr. Jelly

for most others, like Martins and Santa Cruz, the bridge and bracing are completely different and moved more into the middle of the lower bout on 12 fret 00s.

There are several better qualified than I to comment, and hopefully they will comment, but my understanding is that the bridge location on a 12 fret and 14 fret Martin is virtually identical , taken as a measurement from the end graft to the saddle.

The 12 fret was the original model, and when they changed to 14 fret necks, the upper bout was shortened, and the fretboard length was increased by one fret, which required the soundhole to be moved nearer the bridge.

The bridge , however, stayed where it was AFAIK.... it certainly wasn't shifted into any perceived "sweet spot".

[redir]

That's what I meant by saying you would have to change the body shape or bridge position. My preference is to change the bridge position. I don't know what it is but it is clearly different and to my ears sounds better especially on small parlor guitars, I don't have any experience at all with 12 fret dreds.

I do absolutely agree thought that body shape and dimensions is a leading factor, if not the thing that determines most, the difference in tone from guitar to guitar.

[Mr. Jelly]

This is from the Taylor guitar website

What exactly is a 12-fret?

It refers to the position where the neck meets the guitar body. On other Taylor steel-string models, the neck meets the body at the 14th fret. A 12-fret neck is also slightly shorter than our 14-fret necks, with two fewer total frets (18 versus 20). The different positioning of the neck relative to the body shifts the bridge location away from the soundhole, closer to the center of the lower bout. This gives the guitar a distinctive musical personality.

[Pat Foster]

On guitars whose upper bouts are quashed to accommodate a 14th fret body join, there is little or no change in the bridge position compared to an equivalent 12-fret. In other words, the upper bout is moved 2 frets toward the bridge, but the bridge position has little or no change of position. A careful evaluation of Martins, for example, comparing the 14-fret OM and 12-fret 000, and others, bears this out.

However, there is a change of bridge position between 12- and 14-fret guitars if the same body shape is used, such as the Martin Norman Blake, which is an OM body with a 12- fret neck. On those guitars, the bridge would move the equivalent of the distance between the 12th and 14th frets.

Pat

[Alan Carruth]

I have made guitars with 14 fret necks using my 12-fret 000 size box. They sound as much like their 12-fret brothers as any two different guitars do.

The 'sweet spot' on the top is not a function of the outline geometry so much as it is of the bracing and top thickness. Certainly there are limits as to how close to the bottom edge you can make the bridge before you start to run into problems, but it would be hard to get close to those in any more or less 'normal' guitar design. Early guitars tend to have their bridges 'way down on the top, and still sound like guitars. Most of the differences there stem, IMO, from the fact that they tend to be ladder braced, and very small. I once built a guitar on commission that had a 20" scale length. Given the choice I used a 14 fret neck, simply because a 12-fret neck would have looked like Thor's hammer. The bridge ended up about 2" below the sound hole, and it worked fine once you got the hang of playing the slack strings.