Set-up question - notes are sharp when fretted

Braintree56 · #1 10-11-2021, 08:30 PM

When I tune my guitar perfectly with a tuner, the fretted notes are sharp. The most noticeable is the B string. I've tried adjusting the truss rod, but it doesn't seem to fix the issue. I understand there are probably a zillion different reasons for this and it's hard to diagnose over a forum... BUT... Any suggestions for what to try next?

This is a beat-up Martin D-15m that is a decent guitar, but I'm comfortable learning how to do maintenance/set-up on. It's been fixed and serviced by a handful of "professionals" through the years and some did a better job than others.

I have a nicer guitar and don't want to spend money to have this serviced. I want to learn to do it myself.

YamaYairi · #2 10-11-2021, 08:49 PM

Usually when fretted notes sharp close to the nut, the nut action is too high, but you need to learn how to do a proper setup.
Go to www.frets.com and learn how.

Brucebubs · #3 10-11-2021, 11:09 PM

Is the saddle compensated?

In simple terms - if the string notes SHARP move the saddle BACK - INCREASE the string length.

If the string notes FLAT move the saddle FORWARD - DECREASE the the string length.

Here's a compensated saddle I made from a bone blank.

Talldad · #4 10-12-2021, 06:51 AM

When you press the B string at the first fret you make the whole string longer, this changes the pitch of the string. The further down you have to press it the longer the stretch becomes the higher the pitch.
If you can get the nut down lower then there will be less stretch in the string and consequently less pitch variation.
If this is happening near the middle of the fretboard (12) then it maybe that the action is high.
As previous posts have suggested, do a search on setting up a guitar properly on this forum. There are some amazing resources.

MC5C · #5 10-12-2021, 08:54 AM

When fretted notes are sharp compared to the open note, the issue is usually either nut height (if the note at the 12th fret is correct) or bridge saddle compensation if the note at the 12th fret is sharp, or both. The issue in both cases is the string gets stretched down to the fret, that increases tension and makes the note sharper. What we do is move the bridge saddle back to compensate for that by making the string a little longer when fretted.

Step one is tune your open string and then play the same string at the 12 th fret. If it's sharp, the bridge saddle needs to be moved back, making the string longer and flattening the fretted note. If it's flat, the bridge saddle needs to be moved forward, closer to the nut, and that sharpens the fretted note.

The B string is normally the most out of tune of all, simply because of it's size and the effect that fretting it has on it's tension. In the electric guitar world an unwound G strings will need even more compensation than the B string, but acoustics usually have a wound G string which needs about the same compensation at the high E string. That's because the compensation is based on the diameter of the core wire on wound strings, and a G string has about the same diameter core wire as the high E string.

Older acoustic guitars, including Martins and other factory made guitars, are notorious for getting the saddle in the wrong spot, and the guitars play slighly out of tune up the neck. They also don't have additional compensation for the B string - there is an excellent photo of a saddle with added compensation up this thread. There are lots of ways to get the guitar in tune, starting with finding a luthier that you can discuss this with and who can do a fresh setup, and evaluate the whole bridge/saddle location thing for you.

The other thing often overlooked is the nut action. If the nut slot is too high, you're going to press the string down at the first, second and maybe third fret and those notes will sound sharp even with correct compensation at the sadddle, because the string is getting stretched down even more than normal. You can have the nut action adjusted so the nut slot height is the same as a fret height would be, or a wee tad more, to minimize the distance the string is stretched when fretted.

Braintree56 · #6 10-12-2021, 09:19 AM

Thanks for all the good leads. I'll definitely check out frets.com and this site for resources.

My saddle is compensated.

I'm wondering if the nut slots are actually too low and the last guy who did the set-up just raised the action to take out the buzz rather than replacing the nut - thus making the action too high.

After posting this, I measured the action and it was much greater than 7/64". I adjusted the truss rod to bring it down to 7/64. It seems to have helped the problem, however now the guitar buzzes like crazy.

Does replacing the nut seem to make sense?

Thanks.

MC5C · #7 10-12-2021, 10:07 AM

Adjusting the truss rod "affects" the action but it does not "adjust" the action. The truss rod sets the neck relief - how straight the neck is. To set the truss rod correctly you fret at the first fret and the 14th fret, and look at the height of the string (any string but I usually use the G string) over the 6th fret. There should be a tiny bit of clearance, around the thickess of a business card. Or around .005" if you can measure that. I just look for the string to be able to sound out if I pluck it between the 1st and 14th fret, barely... If the there is too little relief, even with OK action heigth and everything perfect otherwise, the strings will tend to buzz near the nut. With too much relief (and again proper action height) the strings will tend to buzz around the 6th fret - too much bow, the 6th fret is too low compared to the higher frets, so when you fret there you get a buzz. The correct amount of relief lets the string vibrate in it's arc, but not touch a fret to buzz.

What I do is this - I set the nut action first, because it's totally relative to the plane of the frets near the nut and nothing else. It's kind of stand-alone. Then I adjust the neck relief with the truss rod. Again, it's not related to anything else, neither nut height or action height, it's stand-alone. It's neck straightness only. Then I adjust the action height at the 12th fret. I like 1/16" for the high E string and 3/32" for the low E string, but it can go up or down from there depending on the player. It's related to both nut height and neck relief, so you do them first and then you adjust action height with the height of the saddle only. Don't adjust neck relief to adjust the action height when the neck relief is already set and correct. The final step is compensation. That's because compensation is related to all of the other steps, mostly action height and string gauge to be fair, but as we saw action height is related to the other two steps. So when you have the setup almost done, you can evaluate compensation and see if you need to move the saddle break point (where the string hits the saddle) or even move the saddle. You can't assume it's in the right place, both Martin and Gibson had periods where they got their templates wrong and made a ton of guitars with the bridge in the wrong spot. Anyway, it's step one, two, three, four and then look at what you've got. Anyway, that's Brians setup guide 101...

MC5C · #8 10-12-2021, 10:16 AM

I wanted to add how to evaluate and adjust nut action. There are different techniques, but what I do is easy, fast and needs no tools to just check it out. I string the guitar and tune it to pitch. For each string, I fret at the third fret so the string is touching both the second and third fret, and then I look at the string height over the first fret. You check to make sure the string isn't touching, first of all. You can do that by tapping on the string over the first fret and see if it "clicks", or you can pick the string betwee the second fret and the nut, and see if the pitch changes if you do that while fretting at the second fret. You want the string to be oh-so-slightly above the first fret when you are fretting at the third fret. I like to have a tiny amount of space, enough for that click, or a piece of regular paper to slip under. I like to set up for a little more space under the larger wound strings than under the unwound strings, since they tend to vibrate more and in a larger arc. If you find you have no space at all under the strings at the first fret, it's perfectly OK to pop the nut out (usually it's not glued in and just a friction fit, or it's glued lightly so you can tap it sideways carefully to release it) and put a shim of paper or card or even wood veneer under it to raise it a bit. Making a new nut is always an option, but shimming a nut is way easier and works just as well.

rick-slo · #9 10-12-2021, 10:16 AM

Consider a compensated nut. Why that is not more of a standard practice beats me.

Example:

Braintree56 · #10 10-12-2021, 10:21 AM

Great. Thanks.

Step 1 - I need to confirm that my nut height is in the right spot.

To do this, I need to press down at between the 2nd and 3rd fret and judge the distance between the string and the 1st fret. Do I have that right? Is there a measurement I should aim for - perhaps using a feeler gauge?

Braintree56 · #11 10-12-2021, 10:23 AM

Quote:

Originally Posted by rick-slo

Consider a compensated nut. Why that is not more of a standard practice beats me.

Example:

This is a good idea. I have a feeling that my guitar has other issues that need to get resolved first though. Once everything else checks out - I'll look into this!

Braintree56 · #12 10-12-2021, 10:32 AM

Quote:

Originally Posted by MC5C

I wanted to add how to evaluate and adjust nut action. There are different techniques, but what I do is easy, fast and needs no tools to just check it out. I string the guitar and tune it to pitch. For each string, I fret at the third fret so the string is touching both the second and third fret, and then I look at the string height over the first fret. You check to make sure the string isn't touching, first of all. You can do that by tapping on the string over the first fret and see if it "clicks", or you can pick the string betwee the second fret and the nut, and see if the pitch changes if you do that while fretting at the second fret. You want the string to be oh-so-slightly above the first fret when you are fretting at the third fret. I like to have a tiny amount of space, enough for that click, or a piece of regular paper to slip under. I like to set up for a little more space under the larger wound strings than under the unwound strings, since they tend to vibrate more and in a larger arc. If you find you have no space at all under the strings at the first fret, it's perfectly OK to pop the nut out (usually it's not glued in and just a friction fit, or it's glued lightly so you can tap it sideways carefully to release it) and put a shim of paper or card or even wood veneer under it to raise it a bit. Making a new nut is always an option, but shimming a nut is way easier and works just as well.

Great. I'll try this and report back as soon as I'm home!

DickHutchings · #13 10-12-2021, 02:16 PM

Quote:

Originally Posted by rick-slo

Consider a compensated nut. Why that is not more of a standard practice beats me.

Example:

For one thing, it looks like a difficult thing to do. I'll give it a try someday.

Braintree56 · #14 10-12-2021, 02:48 PM

So I just took a closer look. The nut is definitely too low. The strings touch the 1st fret when held in between the 2nd and 3rd fret.

My action measures just over 6/64s on the low E at the 12th fret and about 4/64s on the high E.

I'm going to try shimming the nut as a start, but I might be interested in buying a blank and shaping. If for no other reason than learning how to.

Please give me any more advice/suggestions/thoughts you have!

cliff_the_stiff · #15 10-12-2021, 03:01 PM

Quote:

Originally Posted by Braintree56

Thanks for all the good leads. I'll definitely check out frets.com and this site for resources.

My saddle is compensated.

I'm wondering if the nut slots are actually too low and the last guy who did the set-up just raised the action to take out the buzz rather than replacing the nut - thus making the action too high.

After posting this, I measured the action and it was much greater than 7/64". I adjusted the truss rod to bring it down to 7/64. It seems to have helped the problem, however now the guitar buzzes like crazy.

Does replacing the nut seem to make sense?

Thanks.

If the nut is too low, your going to get buzz when playing open chords. that goes away when fretting.
Guitars aren’t perfect intonation instruments. Lots of information about that here on the forum.