24.75 Gibson Scale - Or is it?

We all commonly think of Gibson guitars using the 24.75" fret scale. This is the fretscale Gibson officially claims to use.  This sugguests that the fretscale on a Gibson guitar is 24.75" all the way up the fingerboard in every position -- a unified fretscale.  However, this is actually not the case.  Guitarsmith Richard Stanley has worked on guitars for several decades. The emperical evidence Richard  has gathered over the years from working on guitars from all eras from the 1950s to present, suggusts that Gibson fingerboards employ what he calls a multi-theoretical string length scale or a multi scale.  That is, several fret scales applied to one single fingerboard.

The easiest way to understand this situation is to read an excerpt of the interview I did with Richard on this topic.

Stanley: When I started looking at the fret scale issue (on all guitars), I found two distinctly separate deviations:
  • randomized errors over a period of time where no two are the same
  • non-unified theoretical string lengths, which appear to be intentional modifications of the fret scale. These take the form of scales having more than one theoretical string length within the fret scale, some with as many as five different theoretical string lengths incorporated in one single fingerboard.

DRG: Well, when you have a bad fret scale, whether it's randomized error, or a non-unified scale, it can seem like it's not staying in tune. You can tune it for one position or another, but you cannot get it to play in tune all over the neck.

Stanley: Right. You can't. Interestingly, many players contending with faulty scales think that they are dealing with a pitch stability problem -- string slippage, sloppy tuners, etc. rather than intonation.

DRG: So if a board is supposed to be 24.75 how do you determine what the scale really is?

Stanley: I pull out about a half dozen templates and start throwing them down on the fingerboard. I also use a (magnifying) loupe with a reticule graduated in five thousandths of an inch to actually survey these boards. So what you'll see is one group of frets will agree with 24.75, and another group correlates with 24.6 and so forth. 

Here are surveys from a 60s SG and one that is practically new SG.

 Look at how similar they are. They aren't exactly the same, but they're close. And that's how (all Gibsons) tend to look. The first four frets are typically 24.5, and the upper end somewhere around 24.75, sometimes runs out as high as 24.85. And where a random scale is all over the place, this is purposeful. There's no two ways about it. You can't look at guitars made over a 40-50 year period and continue to see this pattern without realizing that they meant to do it.

DRG: Here's the old board from my 1954 Les Paul.

 

Stanley: Right. You can see from the survey that from frets one to five, the fret scale is 24.5, from frets five to 12, the scale is 24.6, from frets 12 to 16, it's 24.7, and (finally) from frets 16 to 22 the scale is 24.75.

DRG: And 24.75 is what we think all Gibson fret scales are supposed to be. But on that board it was only that scale from 16 to 22. And the rest of the board was segmented into four different, non-unified scale lengths.

Stanley: Exactly, and this form of deviation is readily distinguishable from the random error examples by the fact that many, many different samples having this form of error are exactly the same, repeated time and again. I refer to this type of segmented scale as a multi-theoretical string length scale or just multi scale.

The practical effect is that the string lengths cannot be set up so that all areas of the neck play reasonably in-tune. The way this affects intonation is that when you try to set up the bridge saddles, if you set it up for the octave, you find that the 19th fret is sharp. Or if you set it up off the 19th fret, you find the octave is flat.

DRG: And this will show up when you check it with a strobe tuner, right?

Stanley: You can see it using a cheap quartz tuner, but, most importantly you hear it. I got into this before I owned any kind of pitch reference other than a 440HZ tuning fork and found that players were pointing out areas where they heard intonation issues that had errors of just 1% of the distance between adjacent frets.  It is important to remember that I didn’t go looking for this issue, it took many players expressing dissatisfaction with the intonation characteristic of their instruments over a period of several years to attract my attention.

And the way people react to this discussion they think I've got a bug up my butt about fret scales, and I wouldn't overemphasize it. To me this is just an issue of basic design that needs to be right for the instrument to used without presenting unnecessary hurdles for the player. I should point out that this is not a major part of what I do anymore.  Nearly all manufacturers and builders except for these folks have come to recognize the validity of the unified scale based on the 12th root of 2.

DRG: But you're saying "these folks" still have not caught on to that.

Stanley: No. About two to three years ago, I saw a Les Paul Studio that had a unified scale on it, and I said: well they finally came around! But I never saw another one.

Editors Note

The preceding discussion on fret scales is designed to promote awareness of issues that may or may not effect you. It is important to note and remember that rock music history has been made, recorded with, and played live, with thousands of guitars that likely had "imperfect" fret scales. Millions of musicians and fans never noticed or heard a problem, much less complained about it. Probably because guitarists who hear or experience incorrectible tuning/intonation problems severe enough to bother them don't typically dwell on the reasons why it is happening they usually just get rid of the particular guitar and replace it with one where such issues are imperceptible. This is a perfectly valid solution.

The key thing to take away from this discussion and Richard and I can't emphasize this enough is this: If you don't hear a problem, you don't have a problem.