What is an acceptable level of intonation error?

Construction and repair of Classical Guitar and related instruments
Dr ToneControl
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What is an acceptable level of intonation error?

Post by Dr ToneControl » 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

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

Post by JohnB » Mon Mar 12, 2018 4:59 pm

I know this might seem a silly thing to say, but the first thing I would do is to swap the strings for a set that I know have a good reputation for intonation. For me that would be the D'Addario EJ45 strings. They are a starting reference point for many (including a number of luthiers). Admittedly the strings will take time to settle which might take you to your deadline.

Perhaps you have already done that.
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Dr ToneControl
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Re: What is an acceptable level of intonation error?

Post by Dr ToneControl » Mon Mar 12, 2018 5:16 pm

JohnB wrote:
Mon Mar 12, 2018 4:59 pm
I know this might seem a silly thing to say, but the first thing I would do is to swap the strings for a set that I know have a good reputation for intonation. For me that would be the D'Addario EJ45 strings. They are a starting reference point for many (including a number of luthiers). Admittedly the strings will take time to settle which might take you to your deadline.

Perhaps you have already done that.
the strings fitted on delivery are basses from EJ45 LP, plus trebles from Savarez 540R carbon

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Steve Ganz
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Re: What is an acceptable level of intonation error?

Post by Steve Ganz » Mon Mar 12, 2018 6:00 pm

Most important: Is it out of tune to your ear?
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Re: What is an acceptable level of intonation error?

Post by vesa » Mon Mar 12, 2018 6:25 pm

Savarez Alliance have very often intonation issues, try some others.
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Alan Carruth
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Re: What is an acceptable level of intonation error?

Post by Alan Carruth » Mon Mar 12, 2018 6:48 pm

This is a vexed question.

People usually won't hear a difference of three cents or less, so that's a sort of acceptable first target: if you can get it that close it's 'good'. But there are complications.

Precision has to be in reference to some standard. Since guitars are usually set up in 12-tone Equal Temperament that's the usual reference. As with any temperament it's a compromise: there are no 'pure' beatless intervals except for the octave, and some intervals are very far from 'pure'. Major thirds are off by 14 cents, iirc. For the most part you get used to the issues, but the further from 'pure' the intervals are the harder the problems are to ignore. If you add a three cent deviation to the 'normal' fourteen cent out-of-tuneness of the third it's certainly likely to be grating.

There are various tuning schemes that will 'sweeten up' the usual guitar keys. Of course, you pay for that in that the less-used keys sound worse. Equal temperament became popular because it allows for free modulation from one key to the next without a change in affect; each major or minor key is 'out' in the same way as every other. It's also the only temperament where all the semitones are equal in size, which means that you can use straight frets. 'Wiggly' frets are another way to get 'better' intonation at the cost of free modulation. There have been several threads on all of this recently.

Most intonation issues these days are caused by changes in string tension when you fret notes. You very seldom see misplaced frets on newer guitars, as you sometimes did in the old days. One of the problems here is that 'nylon', like 'wood', is a class of materials. Just as oak and rosewood and spruce differ from each other, the various types of nylon do too. Each string maker chooses a nylon that gives them the sound they like, and one brand of string can stretch very differently from another.

It's become more common in the last fifteen or twenty years to 'compensate' nylon strung guitars by moving the bridge saddle to take the stretch and tension change of the strings into account and correct the intonation. More recently luthiers are also shifting the nut for the same reason. Each different brand and type of string can require different adjustments, which should also take things like the action height into account. This is not something that a manufacturer can do, since they don't know in advance what strings and action a particular guitar will end up with. Properly done this can usually get you to well within the 3-cent guideline.

A secondary source of intonation errors is the vibration of the top of the guitar itself. If this reaches a relatively high amplitude at or very near a played pitch, or an overtone of one, it can cause intonation errors. Usually this is more common on 'better' guitars, since what makes them better, in part, is that they tend to vibrate more easily. This will alter the pitch of specific notes, and, again, it can't be predicted, only measured in the final product. Some makers will fine tune the compensation of the nut and saddle to achieve a compromise that minimizes the problems.

As you can see, that word 'compromise' comes up a lot. If it's any consolation, a well set up guitar with a good set of new strings can be about as close to 'perfect' in intonation as it's possible to get except in electronic instruments. This will be far better than, say, the average piano.

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Re: What is an acceptable level of intonation error?

Post by Scott Phillips » Mon Mar 12, 2018 10:04 pm

I’ve heard other forum members in other threads say that they had intonation problems with the polished sets. Hopefully you have time to try a different set of strings in time to return the guitar. What kind of guitar is it? I had a $200 Lucero, that was only 2cents off on the low E and A strings. The other 4 strings were perfect.

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

Post by souldier » Mon Mar 12, 2018 10:19 pm

The simple test I apply is that I play some of my repertoire that utilizes the upper positions near and past the 12th fret. If it sounds good to my ear, then I'm happy. I personally don't think merely using a tuner is the best way to go about it as being in tune is different from sounding in tune.

Practically every guitar I've owned from cheap factory to expensive luthier has been slightly off. Things change big time also when you go from nylon to carbon strings which it seems you have done. I would simply suggest you play the guitar in the upper positions and see if it sounds in tune to your ear (assuming you have some level of pitch recognition). If it sounds good, I'd be happy and wouldn't lose sleep over a few cents. If things sound out of tune with carbon, try switching to normal tension nylon strings like D'addario EJ45's to see if it improves.
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Steve Ganz
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Re: What is an acceptable level of intonation error?

Post by Steve Ganz » Mon Mar 12, 2018 10:28 pm

It's important, but subtle, to note that a guitar string can be in tune at the octave, but be out of tune on many other notes. So saying something like "The B string plays out of tune" leads to the question "Where?"
I'm guessing that the OP was referring to the octave, but that could be deceptive. Often times the octave may sound OK, but other places, especially low down the neck, or high chords with open strings ringing, can be out of tune.
To believe that a string plays in tune (with itself) I would have to tune the string, then measure with a tuner all the fretted notes. If not all, at a minimum 3 5 7 9 and 12.
Or the original question that I asked, "How does it sound to you?"
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Re: What is an acceptable level of intonation error?

Post by astro64 » Mon Mar 12, 2018 10:30 pm

How thick is the saddle? You can probably get a new compensated saddle that can fix that level of intonation issues. But I also agree that an Alliance treble set is not the one to test intonation with. Put on nylon trebles and see what that produces. Odds are the third string will be sharp if the saddle has no compensation. But that can often be fixed if the saddle is not too narrow in thickness.

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

Post by Dr ToneControl » Mon Mar 12, 2018 11:46 pm

I'm mainly checking the 12th fretted note against the harmonic there
the G string is a bit sharp, the D is a bit flat, the others are not much out. To play the E at the 14th fret on the D string with the top E requires a bit of a bend to stay in harmony, but frankly checking a few of my guitars, plenty of them have a bit of trouble

(btw I noticed the saddle was a little moved over to the bass side, and correcting that lessened some of the issues)

I notice that my cheap £400 Yamaha is quite sharp for most strings

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Steve Ganz
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Re: What is an acceptable level of intonation error?

Post by Steve Ganz » Tue Mar 13, 2018 1:18 am

It sounds like you are coming around. Another quick check is to tune it up, then test the fretted high E for octive of open B... pairs of notes that should be octave. G on B string against open G, etc.
Good luck deciding.
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Re: What is an acceptable level of intonation error?

Post by simonm » Tue Mar 13, 2018 10:03 am

Alan gave the details. A couple of people gave the summary: "how does it sound to you." Is it more or less "in tune" that other guitars you have played.

Marcelo Kayath in a masterclass (on YouTube) explained to one of his students "you can't tune a guitar, all you can do is get it less out of tune".

Frank Ford on his Frets site, says that it is not uncommon to have someone come to him asking him to fix the guitar which keeps going out of tune. The guitar was perfect when they bought it. In fact there is nothing wrong with the guitar: what has happened is with time the player has developed a more discrimination sense of "in tune" and has begun to hear the difficiencies of Equal Temperament.

Electronic tuners make it much easier for people to "see" the "intonation" - what matters is what you can hear with your ears.

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

Post by Dr ToneControl » Tue Mar 13, 2018 10:22 am

This guitar sounds good to me.

I would be less happy on an cutaway instrument on which I planned to use DADGAD - on which I often use high-voiced chords with open strings. It's more important on electrics for the same reason.
I have an electric with a true temperament fretboard, so I am quite familiar with fine-tuned variations on just intonation

Some of my high-level acoustics also have intonation errors, even with compensated saddles

On this classical guitar I don't really plan to be using frets past the 12th other than on the top 2 strings
I am going to try different strings next

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Re: What is an acceptable level of intonation error?

Post by Michael.N. » 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:
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