What is an acceptable level of intonation error?

Construction and repair of Classical Guitar and related instruments
Rasputin
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Re: What is an acceptable level of intonation error?

Post by Rasputin » Tue Mar 13, 2018 1:07 pm

simonm wrote:
Tue Mar 13, 2018 10:03 am
Electronic tuners make it much easier for people to "see" the "intonation" - what matters is what you can hear with your ears.
Well, except that if you tune with your ears you are unlikely to be tuning to the intonation you are supposed to be using. If you tune a chord so that it sounds just right you will mess up the intonation the guitar is designed for, especially on the string that is carrying the third... at least if you have not internalised the ET intervals to the point where they sound right to you. I am quite interested in whether that happens, but would guess that it doesn't - otherwise ET would sound in tune to those who are used to it, whereas what you were describing above was really the opposite of that - i.e. people coming to hear that it was out of tune.
Michael.N. wrote:
Tue Mar 13, 2018 12:29 pm
Following on from what Al said about pianos. I tried it on my digital, the intervals are off. What's odd is that I've never noticed it before even though I was perfectly aware of the piano and the issue of equal temperament.
Now all Chopin and Schumann will sound terrible for the rest of my days. :shock:
I think most digital pianos will allow you to select another temperament. I've certainly played a low end Kawai that did. Besides the temperament issue though, you have the issue of stretched tuning. As far as I understand it digital pianos do reproduce this, because it is thought to be an important part of the piano sound... so it may not be a temperament problem you are hearing, and could even be seen as part of the charm of the piano. Anyway, I would have thought you would be able to play Chopin or Schumann in a tuning very similar to the one they would have been used to.

Dr ToneControl
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Re: What is an acceptable level of intonation error?

Post by Dr ToneControl » Tue Mar 13, 2018 3:11 pm

I just fitted a set of EJ45s
30 minutes later, the problem has gone away

are polished bass strings and carbon trebles typically this problematic? I never would have guessed

Dr ToneControl
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Re: What is an acceptable level of intonation error?

Post by Dr ToneControl » Tue Mar 13, 2018 3:14 pm

Rasputin wrote:
Tue Mar 13, 2018 1:07 pm
simonm wrote:
Tue Mar 13, 2018 10:03 am
Electronic tuners make it much easier for people to "see" the "intonation" - what matters is what you can hear with your ears.
Well, except that if you tune with your ears you are unlikely to be tuning to the intonation you are supposed to be using. If you tune a chord so that it sounds just right you will mess up the intonation the guitar is designed for, especially on the string that is carrying the third... at least if you have not internalised the ET intervals to the point where they sound right to you. I am quite interested in whether that happens, but would guess that it doesn't - otherwise ET would sound in tune to those who are used to it, whereas what you were describing above was really the opposite of that - i.e. people coming to hear that it was out of tune.
Michael.N. wrote:
Tue Mar 13, 2018 12:29 pm
Following on from what Al said about pianos. I tried it on my digital, the intervals are off. What's odd is that I've never noticed it before even though I was perfectly aware of the piano and the issue of equal temperament.
Now all Chopin and Schumann will sound terrible for the rest of my days. :shock:
I think most digital pianos will allow you to select another temperament. I've certainly played a low end Kawai that did. Besides the temperament issue though, you have the issue of stretched tuning. As far as I understand it digital pianos do reproduce this, because it is thought to be an important part of the piano sound... so it may not be a temperament problem you are hearing, and could even be seen as part of the charm of the piano. Anyway, I would have thought you would be able to play Chopin or Schumann in a tuning very similar to the one they would have been used to.
my Kawai allows various temperaments, and automatically switches from stretched temperament when layering a non-piano patch on top of a piano
You can tell the difference when it is on. Personally I think I prefer it non-stretched

the temperaments for specific keys sound great though

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bacsidoan
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Re: What is an acceptable level of intonation error?

Post by bacsidoan » Tue Mar 13, 2018 5:01 pm

The acceptable level of intonation error also depends on where the error occurs. For example, the theoretical ET major third is already 13.69 cents wider than the 5:4 ideal ratio; any further error on the sharp side will not sound very good. By the same token, the theoretical minor third is already 15.64 cents narrower than the 6:5 ideal ratio; any further error on the flat side might be unacceptable to people with discerning pitch perception.

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Jason Wolverton
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Re: What is an acceptable level of intonation error?

Post by Jason Wolverton » Tue Mar 13, 2018 6:10 pm

The biggest problem I've noticed is the intonation issues caused by going from nylon strings to carbon strings. Obviously this only affects the trebles, but sometimes it's pretty severe. Also it seems that I get more bad carbon trebles than bad nylon trebles. I've had better luck since using Knobloch carbon treble strings.
"I have discovered (to my joy) that it is life, not death, that has no limits."- Florentino Ariza

oc chuck
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Re: What is an acceptable level of intonation error?

Post by oc chuck » Tue Mar 13, 2018 6:12 pm

Dr ToneControl wrote:
Mon Mar 12, 2018 4:39 pm
I just bought a guitar by mail, so I have a few days to return it if necessary

the intonation is out by up to 5 cents (I think) on a few strings
It has a standard straight saddle

the 2 outermost strings are OK

strings are new:
Lightly polished basses and carbon trebles
I'm sure the seller wants to sell. If you call and explain the situation
they might give you a couple extra days.
If you can't get it "fixed" would you keep it?

Alan Carruth
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Re: What is an acceptable level of intonation error?

Post by Alan Carruth » Tue Mar 13, 2018 6:16 pm

Again, 'carbon' strings stretch differently than nylon, and will require different compensation to play in tune. Compensation has to be done using the strings and setup you're going to be playing.

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prawnheed
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Re: What is an acceptable level of intonation error?

Post by prawnheed » Tue Mar 13, 2018 10:48 pm

To a large extent, it depends on the stiffness of the strings. The nut and saddle constrain the movement of the string so the effective speaking length of a string which has stiffness is shorter than the speaking length of an ideal string.

Some strings labelled as "carbon" will be stiffer than some strings labelled as "nylon".

Alan Carruth
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Re: What is an acceptable level of intonation error?

Post by Alan Carruth » Wed Mar 14, 2018 5:50 pm

OK: I see we're going be arguing the same points here as we are in another thread.

There have been several attempts made over the years to calculate the compensation needed at the nut and saddle. These go back at least to the 80s that I'm aware of. There seem to be two major reasons why strings go sharp when they're fretted: string stiffness and tension change. Byers' work addressed the first as the 'major' cause. Gore argued that Byers' model was incorrect, and did some experiments and mathematical evaluations that demonstrate that. He then went on to set up a model that allowed for calculating the correction based on tension change. I have not seen Byers' rebuttal, if any, to Gore's assertions.

I will say that I never was convinced by Byers' model, but found Gore's to be more congenial.

So far as I know, neither author denies that both causes can come into play; what's in dispute is the proper model of string vibration, and the resulting balance of the different factors.

I wrote:
"'carbon' strings stretch differently than nylon,"

and prawnhead replied:
"Some strings labeled as "carbon" will be stiffer than some strings labeled as "nylon"."

'Stiffness' is a section property, not a material characteristic. When we say that a material is 'stiffer' we need to specify that it's for a string of the same diameter. If this is the case, if a 'carbon' string at a given diameter is indeed stiffer than a 'nylon' one, it's because the 'carbon' material ha a higher Young's modulus. When either string is displaced the tension will increase somewhat. Given the same diameter and displacement the one with the higher Young's modulus will see a larger tension increase. Assuming the initial tension was similar, the one with the higher Young's modulus will thus give a larger pitch rise when fretted. This is not directly related to the stiffness, in the sense that it was not resistance to bending itself that caused the pitch rise: both stiffness and pitch rise are rather functions of the Young's modulus.

One of the advantages of 'carbon' strings is that they tend to be denser than 'nylon', so a thinner string can be used to achieve a given pitch and tension. Since the stiffness of a plain string goes as the fourth power of the diameter and the Young's modulus, a thinner 'carbon' string with a higher Young's modulus could actually be less stiff than a nylon string for the same tension and pitch. Even if the stiffness does not affect the intonation directly, a more flexible string will tend to sound better. It will tend to have a more 'true' overtone series and possibly lower losses, both of which are also issues with plain 'nylon' G strings.

Again, I'm not as qualified as I'd like to be to argue the math behind all of this. I'm simply putting forth the case as I understand it.

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prawnheed
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Re: What is an acceptable level of intonation error?

Post by prawnheed » Thu Mar 15, 2018 1:27 pm

Alan,

My post was not a response to yours, but directed at the OP.

However, yes both factors are important. Which is greater depends (among other things) on the strings (material and gauge) used and the scale length and action of the guitar. For example, on a steel string with a low action the stiffness issue will be proportionally greater than on a nylon string with a high action.

I agree that the stiffness of the string is not the cause for the stretching effect - that is due to the geometry where a fretted string (two sides of a triangle) is simply longer than an unfretted string (the hypotenuse of the same triangle). How big this is depends on the scale length (the length of the base of the triangle) and the action (the height of the triangle).

However, stiffness is the primary cause for a shift in the virtual node at the bridge - a boundary effect which is present as much on open strings as it is on fretted notes.

The stiffness is characteristic of both the material (its Young's modulus) and the size/shape of the section. For example, a round steel bar of a given diameter is much stiffer than a soft plastic rod of the same diameter. Ask your wife/girlfriend for other examples.

So, which one of two strings is stiffer will depend on the composition and size of the strings in question and whether this is of great importance will depend on the guitar they are fitted to - one cannot easily tell from the label.

riffmeister
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Re: What is an acceptable level of intonation error?

Post by riffmeister » Thu Mar 15, 2018 1:35 pm

I usually play 5ths and octaves to judge intonation.....with my ear as the guide.

Alan Carruth
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Re: What is an acceptable level of intonation error?

Post by Alan Carruth » Thu Mar 15, 2018 3:10 pm

prawnhead wrote:
"However, stiffness is the primary cause for a shift in the virtual node at the bridge - a boundary effect which is present as much on open strings as it is on fretted notes. "

This was the issue Gore investigated, and more or less dismissed. As I say, we have conflicting 'authorities' here. The question has not been finally settled, if, indeed, it can ever be, given the differences between strings and guitars. I will agree that there can be a shift in the fixed end point of wound strings when they break over the saddle hard: the windings pack together at the bottom and prevent free motion of the string, in the 'vertical' direction at least. You can see that the string rises in front of the saddle in that case.

Alan Carruth
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Re: What is an acceptable level of intonation error?

Post by Alan Carruth » Thu Mar 15, 2018 3:16 pm

Please see Trevor Gore's recent post in the thread" At the 12th fret the G sting is not sharp, the A string is flat"

Stephen Faulk
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Re: What is an acceptable level of intonation error?

Post by Stephen Faulk » Fri Mar 16, 2018 8:17 am

The foolproof method of guitar intonation is to switch to violin, viola, bass or cello. People who have picky ears can work that out better without frets.
Patience at the bending iron pays in rounded dividends!

amezcua
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Re: What is an acceptable level of intonation error?

Post by amezcua » Wed Apr 25, 2018 10:35 pm

The perfect pdf for this subject is by Beverly Jerold ....Intonation Standards and Equal Temperament . The pdf code does not seem to be automatic on this but the title will find it. Rasputin will relish the details of bad intonation throughout the ages and it gives a more balanced reason why ET was adopted so widely . Maybe it was to stop musicians going crazy .
upers.kuleuven.be/sites/upers.kuleuven.be/files/page/files/2007_2_3.pdf.
The topic starts off with flutes but persevere with this pdf it is very informative and entertaining if you imagine the problems most musicians used to have .

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