Moving nut for perfect intonation?

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Several of my guitars have the pattern where when they are intonated perfectly at the 12th fret, they will be slightly sharp by the 22nd or 24th fret.

These guitars play well and stay "in tune" up the neck, but I read that to solve this problem, the nut would need to be moved back slightly. In practice its not a problem when playing 17th fret and below.

I also read that the nut is often compensated because it is higher than the first fret, so that they make it closer for this reason so it will be in tune lower on the neck. On some of my guitars I lowered the nut so this distance is less, but I think I may also need to move the nut back.

Is there a procedure for finding the perfect nut distance besides shimming, retuning, and intonating to find the perfect distance? I was thinking about folding aluminum foil to create shims of the correct size. Seems really labor intensive.
 
Re: Moving nut for perfect intonation?

There is no real 'solution' or silver bullet with varying compensation in one area without effecting it in another. Move the nut forward and you flatten the lower frets while sharpening the uppers. Move it back and it will have the inverse effect (assuming you keep intonation constant at the 12th). In the end you will just be sweeping problems in to different corners of the room, and it becomes a choice of pushing them around to where they have the least impact in context of performing.

Generally, a bit sharp on the uppermost frets will not have a negative impact in actual performance, unless you are looking at a tuner or going out of your way to try hard to hear a problem (in which case you would probably never be contented with the equal tempered scale we use to begin with). Some actually find a bit of sharpening on the upper frets to be preferable.

For calculating changes in pitch with changes in nut compensation, yes it can be done reliably by numbers rather than repeated repositioning trial and error. I have a very comprehensive spreadsheet that includes this function, but I'm not aware of any simple online calculators. As you alluded to however, it's just one small piece in a much bigger puzzle, and the first step should be making sure you are not overcompensating in nut and saddle positions for errors caused by less ideal adjustments in other factors of setup (nut height, relief, saddle height, pickup height, fret crown, etc).

In the end though, there will always be imperfections. Judging where flaws are better left to preserve integrity of more important areas where errors will be more noticeable is a choice better made by a good ear than with a tuner.
 
Re: Moving nut for perfect intonation?

Thanks David.

It is something which comes into play on long runs that span the neck. It may require a different intonation or tuning strategy.
 
Re: Moving nut for perfect intonation?

If it's something significant enough to need addressing, then I would examine all options such as action, fret dress, pickup magnet pull, etc, before adjusting the intonation at the saddles if it's good everywhere else. It's very unlikely I would advocate moving the nut back unless it were already forward shifted, as this change will affect notable changes all across the board.

I find it very rare for upper fret sharpening to be an issue of much consequence. Sequential notes often have to be drastically off before any negative effects can be heard by anyone not specifiacally seeking them out. Concurrent notes on the other hand, complex chords played against open strings (especially within proximity of an octave or two) are where smaller errors can jump out to catch your attention as noticeable. Play a run of single notes of short duration on upper frets though, and most people wouldn't notice a change of 10-15¢ until you started hanging on long duration chords.

Of course in this range of upper frets you can very easily shift 10¢ sharp or flat with a bit of finger pressure, so often it's better to work on techniques to intonate with your fingers (a discipline traditionally emphasized in the classical world, but often neglected in the realm of folk and rock players). Trying to make all notes land perfect without any intentional control by the player though, will be a long journey of chasing the wind. It's a very imperfect system, and any correction I've seen which purports to solve one problem without creating others has just never really added up.
 
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Re: Moving nut for perfect intonation?

David Collins said:
If it's something significant enough to need addressing, then I would examine all options such as action, fret dress, pickup magnet pull, etc, before adjusting the intonation at the saddles if it's good everywhere else. It's very unlikely I would advocate moving the nut back unless it were already forward shifted, as this change will affect notable changes all across the board.

I find it very rare for upper fret sharpening to be an issue of much consequence. Sequential notes often have to be drastically off before any negative effects can be heard by anyone not specifiacally seeking them out. Concurrent notes on the other hand, complex chords played against open strings (especially within proximity of an octave or two) are where smaller errors can jump out to catch your attention as noticeable. Play a run of single notes of short duration on upper frets though, and most people wouldn't notice a change of 10-15¢ until you started hanging on long duration chords.

Of course in this range of upper frets you can very easily shift 10¢ sharp or flat with a bit of finger pressure, so often it's better to work on techniques to intonate with your fingers (a discipline traditionally emphasized in the classical world, but often neglected in the realm of folk and rock players). Trying to make all notes land perfect without any intentional control by the player though, will be a long journey of chasing the wind. It's a very imperfect system, and any correction I've seen which purports to solve one problem without creating others has just never really added up.
Click to expand...

I started "fretting" over this because I lowered the nuts on a few of my guitars and feel that if they were compensated to begin with, that maybe they should be less compensated with the nut action very low over the first.

It may also have something to do with how I intonate. I have heard that intonating the G-string sharp is a good idea.

I have been intonating for years but recently realized there are different strategies and it makes a difference in the kind of playing I do, the ability to hear a shift in intonation when a lick spans 12 or more frets. I will have to examine all my guitars and see why some of them sound better. Cursory examination showed general sharpness on top on the guitars I checked but I suspect it may have to do with the fact that an imperfect crown up there represents a larger % of the string length. One thing I want to do is form some sharper/better crowns to see if that affects it.
 
Re: Moving nut for perfect intonation?

If frets 1-12 are correctly intonated then moving the nut is obviously not the way to go if frets 13-21 are not.
 
Re: Moving nut for perfect intonation?

I would be interested as to which particular instruments seem to intonate more agreeably, and which tend to be a bit more stubborn. Guitars like PRS do come with a modest amount of nut compensation from the factory, while others like Gibson and Heritage use a different fret spacing system all together which pushes the upper frets sharper compared to a standard board layout. Then of course others simply have inconsistent nut positions with compensation occurring occasionally be error rather than intention.
 
Re: Moving nut for perfect intonation?

The short answer you will NEVER EVER have perfect intonation on any guitar. Now yes their are methods that help improve intonation but then you start getting into temperaments and very fine tuning.

Also using a wound G-string will help cure those intonation problems on the third string.
 
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Re: Moving nut for perfect intonation?

Out of curiosity, did you make a complete table of how off each note is.

Compensated nuts are also a source of trouble and can mess you how 1-3rd frets behave. Double edged sword.
 
Re: Moving nut for perfect intonation?

uOpt said:
Out of curiosity, did you make a complete table of how off each note is.

Compensated nuts are also a source of trouble and can mess you how 1-3rd frets behave. Double edged sword.
Click to expand...

Yeah, I'm probably taking alot for granted. The open positions and frets 1-12 are all very good.

The problem is when you play a sweep arpeggio in 17th position, you an hear its off. And if pitch is higher, vibrato can only do so much.

Maybe I should correct this in Samplitude. I guess thats easier than obsessing about intonation.
 
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Re: Moving nut for perfect intonation?

Rockstar216 said:
You might want to look at this site. They offer guitar necks that give closer to perfect intonation as one can get.

http://www.truetemperament.com/site/index.php?go=4&sgo=0#A1
Click to expand...

I don't like that they use the word "perfect".

Most players make notes quite a bit sharp from pressing hard. That isn't easily to avoid but the point it, unless you use very small frets you won't get perfect intonation no matter where the fret sits.
 
Re: Moving nut for perfect intonation?

uOpt said:
I don't like that they use the word "perfect".

Most players make notes quite a bit sharp from pressing hard. That isn't easily to avoid but the point it, unless you use very small frets you won't get perfect intonation no matter where the fret sits.
Click to expand...

I totally understand that and I accept that the guitar is not a perfect instrument but I'm still intrigued by their different temperament necks.
 
Re: Moving nut for perfect intonation?

I think it's cool that we can mess with this stuff and sweeten certain intervals at the expense of others. As much as I sometimes wish it were simpler, that a guitar would either be in tune or not, I think it's more fun this way.
 
Re: Moving nut for perfect intonation?

I did some more work with my guitars. I found that the difference between guitars is largely user error, although they all exhibit a light trend towards sharpness in the upper registers. I had been using various stage tuners and software to set intonation, but found an app called "Pitchlab" for android which has more accuracy. When I was able to see the (slight) difference between open string and 12th harmonic, I had a new degree of accuracy. (Interesting that these will differ, must have something to do with width of string or amplitude of vibration).

One of the online dealers gives advice to intonate the 12th against the 24th fret, but given the slight trend towards sharpness, this creates less than ideal results. I think intonating at the 12th is best overall.

ALSO, I found that tightening the floyd saddle can introduce error - what intonates perfectly can be knocked out when tightening the allen, so I need to double and triple check. Obviously still not perfect intonation, but I have a handle on it now.
 
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