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No different from fretting a bar chord. Nut compensation may have some effect on the whole, but mostly it's the first couple of frets that are. Beyond that, it's more of an evening factor between open and fretted strings.

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Waddy

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Waddy Thompson wrote:
" Nut compensation may have some effect on the whole, but mostly it's the first couple of frets that are. Beyond that, it's more of an evening factor between open and fretted strings."

I beg to differ. Nut compensation drops the pitches of _all_ of the fretted notes by about the same number of cents. Bridge compensation drops the pitches more the further up the fret board you go. If you plot the fretted string pitches in terms of cents, you'll see that they are a bit sharp at the first fret, and the line rises as you go toward the saddle. Compensating the nut drops the whole line, without changing the slope, while compensating the saddle decreases the slope, but doesn't change the first fret pitch much. The right combination of nut and saddle compensation can make all of the notes sound pretty close to the desired pitch. It is, of course, impossible to get a guitar to play exactly in tune for all notes on every fret, but nut compensation can help get you a lot closer on all the frets.

Your'e right, though, that putting on a capo is, or should be, equivalent to playing a barre chord. Capos are, of course, sort of ham-handed, which is probably why the pitch shifts show up more with a capo than they do when you play a barre.

Anders,
I use the Greg Byers figures for compensated nuts and saddles with ordinary nylon strings (not Carbon)
http://www.byersguitars.com/Research/intonation.pdf
works fine with a capo

This a question for Nigel. Can you explain what you gain by compensating at the nut rather than the bridge? It looks like a lot of extra wok for the same results.

Just curious,

Thanks,

Richard

Not Nigel (who hasn't been seen in these parts for a while). However, there is a basic assumption that compensating the saddle so that the 12th fret plays in tune will fix intonation on all the other frets. There's no logical reason why that should be the case and, of course, it isn't. For that to be true, for starters, it would assume that the neck relief on every guitar is the same (and "correct"), which, of course, it isn't. The typical residual errors usually result in the frets close to the nut playing sharp. Using a lot of analysis (or a lot of experimental work, depending upon where your forté lies) it can be demonstrated that these errors can be practically eliminated by compensating both the nut and the saddle, as Alan took the trouble to explain here. If you want the proverbial "chapter and verse", it can be found in "the book".

To quote the mantra: Once you've heard a properly intonated guitar, there is no going back.

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

I compensate all my nuts and haven't noticed any intonation problems with a capo fitted.
If it makes you feel better, I'd say you were wrong.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

One way to think of that is that compensating both the nut and the saddle corrects the intonation of all the notes, at least better than only doing the saddle. When a note is fretted the string doesn't 'know' whether it was done with a finger or a capo, so long as the pressure is correct. In theory, then, the intonation should be better with a capo, just as it is in normal fretting. However, when you put on a capo, you're fretting in two places rather than just one, so that's likely to have an effect. Also, of course, the capo may put on more pressure than you would. This suggests (and my experience tends to second it) that capoed intonation with a compensated nut may not be perfect, but it tends to be much better than with an uncompensated nut.

I'm surprised that nobody's yet mentioned the article in the most recent edition of "American Lutherie". It's called "Beyond the Rule of 18: Intonation for the 21st Century" and well worth reading.

Cheers,
Pat

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There are three kinds of people:

Those that make things happen,
those that watch things happen,
and those that wondered what happened.

Alan, thanks for the most excellent explanation of compensating for intonation.
I'm going to make the rig you suggest. Just wondering why the 11th fret as well? I think I would install at least 16 frets just so I could see the difference across the whole length. But your 11th fret and no mention of it in your text left me wondering.

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We are all in the gutter but some of us are looking at guitars.

The 11th fret is there to make the string displacement more 'normal' when fretting the string at the 12th. With all the other imponderables in this, it seemed a good idea to get as much as possible under control.

I went to that talk at the last GAL convention, and then got Trevor's books. The information is much the same, although with different emphasis and perspective. They leave every other treatment of the problem I've seen in the dust.

Thanks, Alan. I would never have guessed that answer!

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We are all in the gutter but some of us are looking at guitars.

Hi, I'm mainly lurking around here (and learning a lot in the process!) but now I feel I might actually have a question that I'm sure you guys could answer for me (I hope this will not be a 'thread-hijack').

First of all, many thanks for the clear explanation of how compensation at the nut should be done. I will be building the test-rig that Al suggested for sure.

However: I'm currently building a flamenco with a 655mm scale. I have decided to shorten the fretboard at the nut-end by approximately 1 mm, in an attempt to 'compensate at the nut'. Would you consider this to be helpful in terms of intonation (although probably not optimal for all strings)?
and secondly: when I glue the bridge on (this remains to be done), do I subtract the 1 mm of compensation that I 'gave at the nut' from the compensation that I normally give at the bridge? Or do I keep the normal compensation at the bridge? My guess would be to subtract it, but I'm not sure.

Strings will be D'addario normal tension, though I will probably change the G-string for a savarez alliance, since I don't particularly like the D'addario G-strings. Action at the 12th fret is 3.5mm for the low E, and 2.5mm for the high E.

Like I said: for the next guitars I will take a more thorough approach to attempting compensation at the nut, but this is my first attempt at 'eyeballing it'.

Many thanks for any replies!

Cheers
Maarten

Hi Alan, I've tried to look but can't find a decent summary of the process. The Dremel method will be much easier for me to accomplish than the drill press milling method. Do you make a jig for it?

I'm just about to cut the fretboard nut end for the small classical I'm making (actually I'm routing a shelf for the nut to sit on) so the time has come for me to decide once and for all how I'll do it and how much room I need! I was just going to go with the simple fix and cut the nut 0.8mm or so closer to the first fret, but the dremel method is within my grasp! Hopefully, maybe.

Thanks in advance and all the best,
Nick

There's another, related thread going about ukes right now citing a new process by Lanakai called "TunaUke" which compensates the nut and has adjustable saddle compensation for each individual string.

Beth, I saw that. I'd be really interested to hear Trevor and Alan's respective opinions.

Would be nice for it to all be adjustable. I'm hoping to work out how much compensation I need by bolting the neck to a dummy box with an archtop style tailpiece and a sliding saddle. Not sure how to do the nut though, not got spare bone, maybe I'll use an ebony one with a ledge for the rig.

I've got one of those StewMac jigs for cutting violin purfling grooves with a Dremel. It has a stop that sets the distance in from the edge, and you control the depth of cut by the projection of the milling cutter past the chuck. I set it up so that the cutter is down on the surface (the grooves bottom out at the fretboard level). I mark the top of the nut, double-tape it to a shelf that puts it at the same level it would be on the guitar, and have at it. It's not as precise as Trevor's rig, but given the variations I get in making the measurements to determine the offsets, I'm not sure that may 'eyeball' routing is all that much worse than any other system in practice. I do use a magnifying hood when I make the cuts.

Cool, thanks for that, Alan! I'll try to fashion something similar and practice with some ebony nuts.
I'm just trying to decide if it is really necessary to cut the full 3mm off for this one.

Lots of really good stuff posted here on intonation. Thank you dudes. Is appreciated.

Non the less to me thinking, it remains a crap shoot of educated guessing and the trial and error of ones subjective ear or an electronic gadget.. As such it appears much akin to the probability maths associated with quantum physics guessing were the electron is or ain't and the fact that wood moves. And no, me not going into all that physics....use google.

Me conclusions ...choose what ever method or technique for settin intonation you getts off on ... knowing that non of them are perfect, all be it ...some are better than others.

So with that all said ... just do the best you can, with what you got, when your setting it up, always bearing in mind that nothing is perfect, especially intonation.

With that said, now what?


Blessings
?adma

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Audiences and dispensations on Thursdays ~ by appointment only.


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Thanks for this thread guys. I have a pretty good ear and have always set up guitars the best I could. My clients have been happy with my work but after reading through this thread a few times I understand more about intonation and how to do a better job at it.

As was mentioned a few posts ago about using lighter strings. I have always put light strings on my guitars because I think they just sound better. Maybe that is why.

Cheers,
Bob

Sorry for the lame question, but what book do you refer to as "the book"?
Btw thanks for the info on this thread!

Not a lame question! Me? I ask lame questions all the time , so I know.

Contemporary Acoustic Guitar Design and Build by Trevor Gore & Gerard Gilet. You can see more about it on Trevor's site, http://www.goreguitars.com.au/main/page_the_book_overview.html.
I only got my copy in November so I'm early in my study but it is as great as everyone says. I kinda see it like the degree course to Cumpiano's diploma (not that they're in any way companion books but Cumpiano's was the one that I started with). I've already learned so much and I've only scratched the surface really.

It's actually two books, one on design and one on construction. The design one is mindblowing and I've already gleaned many a useful tip from the construction volume! In fact, I'm asking far fewer questions here now I can check in 'the book'.

Thanks so much! It seems like a very professional writing. Will do some fretwork to save up for my copy:)

Most valuable fret jobs you'll do!