Frets are off key... unsure how to explain

[Swordfish71]

So I have a Norman B-20 Cutaway. I love the sound of the guitar, I've had it for about twelve or fifteen years now.
I was never really into the technical side of guitars, be it their components and whatnot, until a few weeks ago when I told myself it might be a good idea now that I am the owner of more than one guitar.
I also just got, with my Seagull 12 string, an excellent tuner (compared to what I had), and was playing around with my Norman when I realized that when the guitar is perfectly tuned, when I play notes from the first fret to the 20th, they are all off tune... but every note by the same amount (three to four ticks on the scale of my tuner). It's not noticeable when you play one note at a time, but now I'm getting to realizing that this might be the reason why playing certain chords (namely D chord) never sounded super thrilling, unless playing with a capo... then the whole experience changes and every note is on key.
Does this have to do with the placement of the nut in relation to first fret? I would assume that a very minor adjustment to the nut would resolve the issue...

If I wasn't able to explain my issue properly, I might try making a video to show what I mean. Let me know if it would help.

[John Arnold]

Yes, nut placement is off. If the fretted notes are sharp, then the distance from the nut to the first fret is too long. If the fretted notes are flat, then the distance is too short. You can check it with a ruler or caliper. The scale is the distance from the nut to the 12th fret, multiplied by two. Multiply that number by 0.0561 to get the correct theoretical distance. I say theoretical because builders often shorten that distance by 0.02" or 0.03" to compensate for inaccuracies arising from bending the string when fretting.

[Swordfish71]

Thanks for the math!

Does this adjustment require a luthier or can I correct this by changing or reshaping the nut?

[warfrat73]

I lot of intonation problems come from the saddle. But if it's right on (or a lot closer) with a capo, it could well be the nut.

But it could also be too high action or too much relief. In either of those cases when you fret the note you can pull it past pitch. Putting a capo on has the effect of lowering the action as well.

Excessively worn frets can also cause intonation problems, after 15 years this is certainly a possibility as well.

It's also worth noting that all guitars are a compromise in terms of intonation, and none will be perfectly in tune.

[charles Tauber]

John nailed it.

I'd add only that on occasion one can find nut slots that are incorrectly shaped so that the breaking point of the string over the nut does not occur at the fretboard face of the nut. That can make the vibrating string length too long.

[Rudy4]

Great information, but don't overlook the most obvious; the nut slots not being cut low enough.

I say that because the OP says everything is fine if capoed. Although it could be the nut not placed properly, the more likely cause is the string being physically stretched as a result of the nut slots being too high.

Without having the instrument in hand it's difficult to know exactly, as there can be multiple problems that are both contributory and/ or inter-related.

Find some step by step setup information and follow it.

[Swordfish71]

Okay, so I am going to dump a few measurements I took with a feeler gauge here... Because I can't take the guitar to a pro right now, everything in Quebec is locked down (Gotta love covid).

The action at the 12th string is .100" (low E) and .096" (high E) with strings unfretted, so the action seems to be in reasonable ranges.

The scale of the guitar is 24 3/4". From nut to 12th fret (low E) is 12 3/8, minus about .015" and (high E) 12 7/16 minus about 0.025". Nut to saddle (compensated) is (low E) 24 31/32" and (high E) 24 3/4. I don't know what this says about my guitar.

Neck relief : Capo 1st fret, string held down between 12th and 13th fret, at 3rd string .009" at 6th fret. Maybe a little low? If I add a little bit of relief to bring it up to .010" or .011" as I see recommended on some websites, how much action height gain will this incur?

Nut height : (low E) .004" and (high E) .005" with capo between 4th and 5th fret. Maybe a little bit low, considering one website I was referring myself to for the measurements says he starts at .008" up to .013". However, I don't have any string buzz, so I don't know what this affects.

From what I can gather with the reading I've been doing while taking my measurements, it's down to either a badly setup compensated bridge or an improperly placed nut.

I added photos of my frets from the first two frets, they don't seem too too bad. What do you think? And, also a photo of the relief of the neck.
https://app.photobucket.com/u/swordf...0-5836772f16b9
https://app.photobucket.com/u/swordf...b-893f6d5acb3c
https://app.photobucket.com/u/swordf...9-4b237de7746d
https://app.photobucket.com/u/swordf...e-cd320af4bb18


EDIT:

Okay, so it's when you read and read and try things that you learn. I had swapped over to light strings a few years ago (was sure I was playing MLs, but I found a new set of lights in my stuff and I always buy a few packs at a time), so I tossed on a new set of mediums (that the guitar originally came with) and all my tone issues are gone. The sound is a little more mellow, less crisp I find, but the tonality is right back to where it should be. Lesson learned. Thanks for all your advice and input!

[Rudy4]

Originally Posted by Swordfish71

Okay, so I am going to dump a few measurements I took with a feeler gauge here... Because I can't take the guitar to a pro right now, everything in Quebec is locked down (Gotta love covid).

The action at the 12th string is .100" (low E) and .096" (high E) with strings unfretted, so the action seems to be in reasonable ranges.

The scale of the guitar is 24 3/4". From nut to 12th fret (low E) is 12 3/8, minus about .015" and (high E) 12 7/16 minus about 0.025". Nut to saddle (compensated) is (low E) 24 31/32" and (high E) 24 3/4. I don't know what this says about my guitar.

Neck relief : Capo 1st fret, string held down between 12th and 13th fret, at 3rd string .009" at 6th fret. Maybe a little low? If I add a little bit of relief to bring it up to .010" or .011" as I see recommended on some websites, how much action height gain will this incur?

Nut height : (low E) .004" and (high E) .005" with capo between 4th and 5th fret. Maybe a little bit low, considering one website I was referring myself to for the measurements says he starts at .008" up to .013". However, I don't have any string buzz, so I don't know what this affects.

From what I can gather with the reading I've been doing while taking my measurements, it's down to either a badly setup compensated bridge or an improperly placed nut.

I added photos of my frets from the first two frets, they don't seem too too bad. What do you think? And, also a photo of the relief of the neck.
https://app.photobucket.com/u/swordf...0-5836772f16b9
https://app.photobucket.com/u/swordf...b-893f6d5acb3c
https://app.photobucket.com/u/swordf...9-4b237de7746d
https://app.photobucket.com/u/swordf...e-cd320af4bb18


EDIT:

Okay, so it's when you read and read and try things that you learn. I had swapped over to light strings a few years ago (was sure I was playing MLs, but I found a new set of lights in my stuff and I always buy a few packs at a time), so I tossed on a new set of mediums (that the guitar originally came with) and all my tone issues are gone. The sound is a little more mellow, less crisp I find, but the tonality is right back to where it should be. Lesson learned. Thanks for all your advice and input!

It's really difficult to offer you an opinion from the photos shown. They don't really show the problem, other than one of them that show TOO MUCH relief.

Measurements don't tell the story either. Unless you're checking clearances based on the string being held down at the third fret it's somewhat meaningless.

When you relate that the problem went away when you changed to the slightly heavier gauge it again points to the slots being a bit too high. The lighter you go on string gauge the more critical this is. Here's a diagram that might help. It's for 5 string banjo, but it's the same for guitar.