Intonation Theory Question

Construction and repair of Classical Guitar and related instruments
Alan Carruth
Luthier
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Re: Intonation Theory Question

Post by Alan Carruth » Fri Nov 10, 2017 5:48 pm

Straight frets were the norm long before guitars were manufactured on production lines.

It's entirely possible to achieve intonation on most notes that is so close that most people can't hear the difference using straight frets. You need to compensate both the nut and the saddle. There are always likely to be notes that will be hard to correct because of the way the movement of the guitar top reacts back on the vibrating string. Also, whenever anybody talks about 'perfect' intonation that's always in reference to a chosen temperament: it's not a question you can dodge or finesse. In the end you will be left with the deficiencies of the chosen temperament, plus whatever residual issues the particular guitar presents.

amezcua
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Re: Intonation Theory Question

Post by amezcua » Sat Nov 11, 2017 12:21 am

I like the way Lasers can produce amazing results for very little money . There are several small firms that will do small numbers and one offs .I don`t know if lasers do metal . Water jets can cut metal to any shape .I think it would be a waste of time expecting a mass production company to do these kind of things but much smaller companies are happy to make small quantities and with great accuracy .Wider slots in a fretboard would not be that difficult for a keen guitarist .Some of the new superglue products are very precise and manageable. Bone is ideal material if you place it there or thereabouts and then adjust with all the strings in place. Allowing for the variations in string properties is one of the traps to avoid. How about a monochord to test your strings one at a time to fill out the note positions . The original question asked about theoretical solutions but practical ways will get closer to the best result .
Or simply remove the saddle bone and make an adjustable one to test the difference a millimetre at a time will make . Then write it down . It will come down to a "nuts and bolts" practical solution .Not of interest to a mass production firm but also not physically impossible .

amezcua
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Re: Intonation Theory Question

Post by amezcua » Sat Nov 11, 2017 12:56 pm

Simonm , the adjustable fret guitar photo was interesting. Understandably that temperament setting looked very difficult. There is a step after that to improve the setup . The first move is to abandon the straight Nut and try to minimise the distance between frets. It`s a worthwhile effort to make it convenient to play . Maybe Meantone spacing is one of the most awkward to arrange physically. I found the Young temperament much less out of line and that temperament was designed to allow all the various keys to be played . Kirnberger III was more out of line .It`s better to abandon any restrictions at first such as straight nuts and bridges.In the photo the 2 straightest lines of frets land in odd positions. Trying to impose any straight lines too early makes the result unpredictable . Maybe those lines were an accident of Meantone. I would like to have photos of the most well known temperaments settings on that guitar .They would be a valuable reference point for the future. The beauty of an adjustable Nut (Not allowed on that guitar ) is the player does not need to worry where the fingers land as it`s open strings . That is a very convenient point . If you examine each string in that picture you can quickly see which ones cause the most positional disruption . Those are the ones to adjust first . It`s a good example of where Iteration would be the way to go . An unusual journey to make players a little bit happier . Also allow for the player`s learning ability and familiarisation . A first impression and decision within minutes wastes the whole effort . I can see I need to make a six part monochord with everything moveable . In my crude attempts the Young temperament " pattern " (comparing notes across the fretboard with a ruler at each Position) showed a max of 2 mms out of line for the worst ones. The Kirnberger III showed a max of 4mms out of line.
A better photo of the adjustable guitar would be one showing Equal Temperament (Is that a fanfare of trumpets I hear ?) Would the frets be straight ? If not would a fret maker be able to make wiggly ones to fit in the same slots already used. Numbered sets all joined together like a row of rawlplugs ready to snap off and fit .
If you play a violin and need to adjust one semitone slightly on the A string in one particular piece of music you don`t worry about other notes on the other strings.It would not make sense to worry about them ,in that piece of music . Your hands will adjust to the different strings on a guitar . The spacing of frets changes as you play higher or lower anyway .

amezcua
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Re: Intonation Theory Question

Post by amezcua » Mon Nov 13, 2017 12:41 am

Did anyone notice in the Friedrich article there was a photo of a 1960s catalogue or advert and the picture of a guitar neck and tuning pegs ? Did you notice how the tuning shafts were placed above the worm gears ?
It was an odd start to the article as I could not see how the Japanese would honour a French man. But that was just an impression that passed through the writer`s mind .
I wonder if anyone on this forum thought to write to Friedrich and tell him off for making out of line frets.
Always remember if I mention out of line frets I am trying to minimise the inconvenience to players .It`s not done to annoy .
But the point I made about a violinist adjusting isolated notes in pieces of music is a good example of the difference between guitarists and violinists .The continuous monitoring of the intonation cannot be avoided on a violin . That means adjusting the fingertips by fractions of millimetres .In higher positions the business of thinking about positions gets abandoned and the sound is mainly what guides the hand apart from sensing the distances between finger and thumb wherever it manages to hold the violin . Added to all that vibrato . Guitarists have much of this ability there if they need to use it .It`s what hands are capable of .
In the Friedrich adjustable guitar I was surprised that each fret came to an abrupt stop . The strings would tend to catch on those edges . That`s one drawback to wobbly frets . Something I noticed myself when I tried this kind of thing .

Andrew Pohlman
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Re: Intonation Theory Question

Post by Andrew Pohlman » Mon Nov 13, 2017 10:10 pm

amezcua wrote:
Fri Nov 10, 2017 12:51 am
For Simonm .You sounded sad that a magic wand had not transformed every guitar in the world to a different tuning system .Many decisions are made to keep manufacturers happy .Happiness for them is the bottom line .It`s not always good for everyone else. Sometimes it`s very bad .Looking at guitarists statistically would we say they are overwhelmingly happy with intonation ? That would make any questions about it a rarity .
I wanted to separate the idea of "Frets out of line" from "Temperaments". They are both awkward but different .One is physically awkward and the other (temperaments) would create too many arguments as the choices are so numerous .
If a guitar was fitted with nylon and gut only would bone frets give players a chance to shape their own preferences just as they alter nuts and bridges ? Set the bone frets in wider slots and superglue any changes on top.
I was having some intonation work done by a Bay Area luthier, Lewis Santer. He told me flat out that what I was complaining about would be no big deal for most guitarists. He labeled me "very picky" ... then fixed the intonation issues. I took that perspective to heart, and it leaves me feeling very appreciative that we have luthiers capable of fixing intonation for us picky people! :D
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amezcua
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Re: Intonation Theory Question

Post by amezcua » Tue Nov 14, 2017 11:36 am

" I am meticulous. You are pernickety." Picky is too short for that saying. But what did the magic luthier actually do ?
I just thought about the metal tuners fitted on violins. The screw on most E strings works a lever that moves the end of the string It`s not a million miles from the way a steel guitar is adjusted but the guitars are shifting the bridge position. Violins have to make sure the bridge does not start tipping over or twisting . The string length should remain the same for violins but if you forced a violinist to say how long the vibrating string is on their violin they would probably not know . One of the reasons they find it hard to stay in tune .

simonm
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Re: Intonation Theory Question

Post by simonm » Tue Nov 14, 2017 12:13 pm

Andrew Pohlman wrote:
Mon Nov 13, 2017 10:10 pm
I was having some intonation work done by a Bay Area luthier, Lewis Santer. He told me flat out that what I was complaining about would be no big deal for most guitarists. ...
I suspect it was Frank Ford who had this (old) anecdote discussing repairs to guitars. A common problem is that someone comes in to the luthier and says something has gone wrong with his/her nice guitar. Recently it has been going out of tune more and is very hard to tune in general. When they bought the guitar, it was perfect and the customer thinks that maybe it needs a neck-reset or whatever.

The luthier checks it out and tells them that the guitar neck is perfect. What has actually happened is that the player over time has become more sensitive to the vagaries of our tone/temperament system. So someone without any concept of intonation assumes that the guitar is "broken". With luck the repair person can calm down the customer and also improve the intonation by adjusting, nut and saddle. The guitar is not broke, the player has just become "pernickety". :-)

Alan Carruth
Luthier
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Re: Intonation Theory Question

Post by Alan Carruth » Wed Nov 15, 2017 3:51 am

As has been pointed out at length in other threads on the subject, there is no such thing as a 'perfect' system of temperament . It's simply impossible to set up a guitar so that all of the intervals are 'pure'. Eventually, as one's hearing becomes more refined, you become more aware of the problems, and the better the instrument is, the quicker this tends to happen. Unfortunately, once it happens there's no way to make the problems disappear entirely. It is possible to minimize them, however, usually by spreading them around a bit, in a manner of speaking, so that no one interval takes the brunt of it. If you never play that particular interval some others can be sweetened up a bit more, but then it can become like the forbidden room in the Gothic novel: you end up going there all the time because you're not supposed to. It's also possible to sweeten things up 'on the fly' by stretching strings a bit as you play, and many good players become quite adept at this.

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