This is the last installment of my trilogy containing the "composite saddle bone", the "spruce bridge plate" and now the "nut compensation". These three things works in harmony on my restored old guitars and to my ears gives them a way better sound than expected :-)
Intonation is a field with many theories and opinions. Here I describe a practical way to use the nut and not just the saddle to improve intonation on any fretted instrument. The information found in the site setitupbetter.com is the base for the method.
To use the nut for intonation purposes gives the possibility to have almost "perfect" intonation on two different spots on the fretboard. With standard intonation the intonation will be great at the 12'th fret only. The intonation in the upper fret area of the fretboard are really bad indeed. Incidentally, that's where the majority of all guitar players play their chords ;-)
The main problem is that all fretted notes have a higher pitch than the open strings due to the stretching of the fretted strings. Another major problem is the need to have the nut a bit higher to avoid fret buzz from open strings (they are longer, vibrates more and are often played harder than fretted notes, back buzz behind a capo is another problem). Chords with a blend of fretted notes and open strings will sound out of tune with the standard intonation, especially the chords taken near the nut.
After reading the info on the site mentioned above, I came up with a way to measure the intonation points in the nut and the saddle. Using the measures I then cut the fingerboard shorter (around 1 mm shorter) at the nut and use a dremel and files to shape the nut and saddle so the string leaves the nut/saddle at the measured intonation points.
I use a stroboscope tuner and use it to make sure that the open string, the fretted third and 12'th notes on each string is in tune. I do this by moving the intonation points at the nut and saddle to a forth (retuning after every movement) until the equation is solved and all the three notes on the string is in tune. The positions are measured and written down.
While measuring, the "nut" consists of small bits of tangless frets acting as an adjustable "zero fret" and the "saddle" is the back ends of drills rolling on top of the bridge. A temporary tailpiece is used to fasten the strings. A small piece of spruce is used to make the fretboard a bit longer at the nut to make room for the movable frets, a 0.15 mm feeler gauge gives the "nut" a bit more height to emulate the optimal string height at the 1'th fret. Another piece of spruce is needed to fill out the saddle slot if there is one.
I measure the distance from the back side of the 1'th fret to the middle of the "zero" fret for each string with a digital caliper and the distance from the same backside of the 1'th fret to the intonations point at the saddle with a ruler. I put the measurements in a table (mm and cm).
It's important to check the string height at the 12'th fret, it shall be the one used when playing. For the electric guitar I use a standard 2,5/1,5 mm between the top of the fret to the underside of the string. Having the stringset that the player likes and will use is another good thing to make the intonation as good as possible. The tuning shall be the one most used when playing. The fretboard should have the right relief too. In a nutshell, all the setups and choices should be done before the measuring for intonation.
By cutting the fretboard shorter at the position for the intonation point closest to the 1'th fret, the nut can be rectangular and all the other intonation points can be reached with a dremel. The nut looked like this when cut. Only with a close inspection of the nut you will notice the jagged cuts.
Not a great example, the G and D came close and I decided to leave both of them uncut when measuring the nut blank on the guitar... I should have cut in 0.16 mm on the G string...
Every guitar have small variations of the intonation points. There is no "one size fits all".
On acoustic guitars I have noticed though that it's the A or b strings that usually comes closest to the 1'th fret. At the saddle the strings G-e is often a straight line and the E-D strings can vary a lot. The electric guitar example above is not typical, the variations at the nut is usually bigger.
I made a special tool to shuffle the fret bits at the nut like this.
I found a drill bit set with drills in steps of 0.1 mm between 6 mm to 0.1 mm. Very handy to adjust the string height at the 12'th fret with a radiused fretboard. I mark the position of the intonation point on the nut blank with small bits of tape to make it easier to cut in to the right spot.
Doing a nut compensation like this makes the guitar chords near the nut play beautifully in tune. I believe that even a capo will play better since the saddle is only intonated for fretted notes (as the capo is) instead of a blend of fretted notes and the problems at the nut!
Without a nut compensation, every fretted instrument WILL be out of tune when playing chords near the nut. The difference is is a major one.
The nut intonations is quite stable. The intonation is very good even when a different set of string gauges or alternative tunings are used. I for one is not as sensitive to pitch as the stroboscope tuner is! On an electric guitar it's always a good thing to intonate the "good old way" for the new set of strings, that will make the guitar play cleaner in the lower part of the fretboard. There are always variations between different sets of the same string brand, but most of the time the difference is small.
The measuring process usually take me one hour. Making the compensated nut and composite saddle another couple of hours. All in all, it's about a half a days work if nothing goes wrong. The upside is the result obviously, but the measurements also makes it impossible to cut the saddle slot in the wrong position :-)
I've been playing and working on guitars for a long time, and I find that with a properly cut nut and a good setup, open chords sound in tune when played with proper technique. So I'm not as convinced as you are of the necessity or effectiveness of a compensated nut for a skilled player. However, players with a heavy handed technique, or those who use strings that are too light, can benefit from a compensated nut.
I commend your effort, but I would suggest a more elegant approach, which requires no permanent alteration to the instrument, would be to render your nut material into a radiused "shelf" nut, as I have with the bone blanks pictured below (PS how do I display these pics?):
You can get a "good enough intonation for rock'n roll" moving the whole nut closer to the 1'th fret (I used to do this), but the individual and measured compensation for each string IS the better method. That way each string has the optimal distance from the 1'th fret. So why not do it the optimal way? Looking at the last slide I see that you actually intonate each string. Good work, the compensation is looking right to me!
To preserve things original when the original is not worth preserving is not how I like to do it. Not everybody will agree, I guess I am a bit uncompromising that way. In the beginning I did make shelf nuts, but the extra work (especially with a radiused fretboard) and the less pleasing esthetics was the reason I simply cut the fretboard about 1 mm now. Well done it's very hard to see that the fretboard is about 1 mm shorter.
I might add that I will do a shelf nut if the guitar is valuable and a collector item, it's not that hard to do.
Many (most) players don't want their guitar altered - especially if it's vintage. In my opinion, it is ideal for a repairman to retain originality whenever possible. For this reason, a properly compensated shelf nut is the more responsible approach.
How do you do the compensation? Is it a standard shape or do you measure it individually for each guitar? The one on the picture is a very good approximation (as long as the overall distance from the 1'th fret is right), but every now and then I get surprised by a different compensation pattern when doing the measuring. On thing I would do different is to have the A string closer to the 1'th fret than the E string, that is almost always the case.
One drawback with a shelf nut is that the thickness of the nut becomes greater and the string may get stuck in the string channel when tuning. Can be hard to source thick enough bone blanks too.
I have not done many of these (only when someone asks for one). The way I look at it, is that a compensated nut "compensates" for poor technique, so I try to get a feel for how badly the player is mashing his chords out of tune, and I try to approximate their technique (or lack thereof), while checking the pitches of the fretted notes of the open chords on a strobe tuner. I'll lay it out by placing sections of drill rod or fretwire with the tang shaved off on the surface of the fingerboard, and i'll scoot these pieces around until it plays reasonably in tune according to my strobe tuner. I then measure the distance to the edge of the nut slot, and rough in the nut compensation (conservatively). I do the final compensation by checking tuning with the actual nut in place, filing a little off at a time until my tuner says it's just right.
Regarding a the string getting stuck, this is not a problem if you use the appropriate sized files. Regarding larger bone blanks, cow femurs are abundantly available anywhere there's cows or butcher shops. Just cut the bones to the dimensions you want.
Not so different to what I do then.
My philosophy don't include the individual player, I do the compensation using a light touch when pressing down the strings. I leave it to the player to use a good playing technique instead of adjusting the intonation to a bad one. The compensation is needed on every guitar regardless, even when the player practices a good technique as the site I mentioned describes in detail.
That said, to much pressure on the strings will change the pitch a great deal. Better learn the right way to do it!
Just to humor you, I just removed two guitars from their cases and plugged them into my Peterson digital strobe. The first is a Les Paul. I just dressed frets on and set it up for a customer, so I know for a fact that it's in good playing condition. With proper technique, the fretted notes are all perfectly in tune according to my tuner, which indicates that it does not need a compensated nut if it's played with good technique. I am confirming this right now with my tuner in front of me and the guitar in my lap - the guitar plays in tune without a compensated nut.
The second guitar I'm testing is one of my own. A Framus Missouri archtop with a zero fret, also in good playing condition. Once again, according to my tuner, it plays in tune without the aid of a compensated nut.
Of course, this is under controlled conditions and I am conscious of finger pressure and I'm being careful not to strike the sting too hard while checking tuning. My own experience with crafting compensated nuts is that it tends to "sweeten" the tuning somewhat if you play with a heavy handed technique, and you can play much more aggressively without it sounding sour. In other words, it makes up for sloppy technique.
That said, I prefer to not have a compensated nut on my own guitars, partly because if I play with other guitarists who don't have compensated nuts, our tunings might not agree as well. I won't say a compensated nut is "cheating", but I like the challenge of making a traditional guitar play in tune. Furthermore, none of my favorite guitarists used compensated nuts, and those are the guys I'm trying to sound like.
For whatever reason, the luthiers on this forum don't seem to advocate the use of compensated nuts either. It's not a new thing at all, and it still hasn't really caught on among the top players and luthiers who set the trends. It's the mediocre players who need a compensated nut to sound in tune, but the best luthiers are not building for mediocre players - they're building for great players, and great players don't need a compensated nut to sound in tune, therefore the best luthiers don't bother with compensated nuts because their customers don't need them.
The major problem comes with chords, small differences between the pitch of the strings will be audible and hard to compensate. Single notes can be compensated by the skilled player if the correct pitch is possible to get with the right finger pressure.
Many of my customers (some of them great musicians) who are very sensitive to the pitch don't have to tune, and retune all the time with an intonated nut. They can concentrate on the music and not the built in faults of the instrument. For them the intonated nut is a revelation. Average Joe's will not benefit the same way.
To make a compensated nut is more time consuming and most people don't know the benefits you get from it. And some don't even hear it. The look of the intonated nut is not as pretty as the standard one and the sound is slightly different, not good for the big crowd of traditionalists.
For me this is a simple way to make the guitar a better sounding instrument. Why not use it.
Why not use it? Because I like my guitars better with a traditional nut. They sound fine that way. Why is it that all the best guitar virtuosos in the world don't use compensated nuts? Maybe it's simply because they prefer a traditional nut - and they still manage to sound beautifully in tune. Why is it that the best luthiers in the world build their guitars with un-compensated traditional nuts? Maybe it's because their guitars sound better that way, or their clientele prefer them that way, or both. Can you name any top players or luthiers who endorse the use of compensated nuts? There's some great luthiers on this Forum. I'd like to hear what they have to say on the subject, but if you haven't noticed, they're not on this thread clamoring to extol the virtues of compensated nuts.
I'll start pitching compensated nuts to my clients and using compensated nuts on my own guitars when Tommy Emmanuel starts using them, and when Bruce Sexauer begins installing them on his guitars. Until then, I'll just consider it a crutch to help mediocre guitarists to sound less out of tune.
We have different opinions.
Very interesting to see that Musicman does intonated nuts! Very much like the ones I make too. I'm convinced that a mean value of the compensation from say five similar instruments will make a much better intonation on the same model. But as I said, there is no "one size fits all", every individual instrument will benefit from a measurement of the true intonation points.