Tuning a guitar to a keyboard or another guitar

[Hawk]

Sometimes I get asked, when a guitar player is matching a string (note) to a note on a keyboard, if the note is in tune. Most of the time it is not perfectly in tune. If you hear any beating (pulses) at all, it's not in tune. Even if the pulse is slower than 1/4 of a beat per second, it's not in tune.

There are "tests" to measure the difference. For instance if a guitar is tuning to A440 (A4 on a piano) F2 is a 17th (interval) below A4 (A440). One of the harmonics of F2 is A4. However because of equal temperament the A4 harmonic of F2 if slightly flat of the A4 note. Therefore when F2 and A4 are played at the same time you hear "beats".

If you play F2 with A4 on the keyboard and listen to the speed (beat rate) of the beats, then play F2 on the keyboard at the same time the guitar player plays A4 (A440) on his guitar, the beat rates should be exactly the same.

If the guitar (when played with F2 on the keyboard) has a slower beat rate than F2 to A4 on the keyboard it is flat. If the guitar (when played with F2 on the keyboard) has a faster beat rate than F2 to A4 on the keyboard it is sharp.

It's really quite simple. If you compare the beat rate of a 17th from a common source and the beat rate is the same, it's in tune.

[floodcitybrass]

What I think you are getting at is the fact that your notes can be in tune pitch-wise but when you start playing chords, the intonation is slightly out because the harmonic overtones do not match up.

So you can have an instrument perfectly in tune pitch wise, but when you play certain intervals (say fourths or fifths), the intonation of the harmonic overtones do not match up. So yes, even though you are perfectly in tune, it might not sound like it depending on what you are playing.

Depending on the instrument, you may be able to compensate for this while playing.

This article explains it. \

http://www.justonic.com/history.htm

[bassist_25]

Keep in mind that the fingerboard works on a logarithm principle. It's near impossible for a guitar to have perfect intonation throughout the entire fingerboard. I have heard a few guitars and basses with near perfec intonation - or were at least the minimal amount of cents out to trick most ears - but they were definitely at the extremely high end of price.

As far as tuning, I like my Korg Pitchblack. *lol*

Edit: Above post already said pretty much what I said.

[Hawk]

What I think you are getting at is the fact that your notes can be in tune pitch-wise but when you start playing chords, the intonation is slightly out because the harmonic overtones do not match up.

So you can have an instrument perfectly in tune pitch wise, but when you play certain intervals (say fourths or fifths), the intonation of the harmonic overtones do not match up. So yes, even though you are perfectly in tune, it might not sound like it depending on what you are playing.

Depending on the instrument, you may be able to compensate for this while playing.

This article explains it. \

http://www.justonic.com/history.htm

Two different things.

Equal temperament dictates that there are beats in major 3rds, and therefore 10ths and 17ths. Equal temperament means every 1/2 step is the same distance apart. Or spaced by the 12th root of 2. For instance, multiply 440 times the 12th root of 2 and you get the next 1/2 step up.

In many historical temperaments like mean tone temperaments they had 3rds with no beats. Along with some other pure (or just) intervals like 4ths and 5ths.


You are in part considering inharmonicity. Harmonmics are exact multiples of the fundamantal pitch. "Partials" are NOT exact multiples of the fundamantal. Both "partials" and "harmonics" ARE overetones. But the ones called "partials" are out of tune with the fundamental

For instance if A4 vibrates 440 Hz and the string dividesds itself by 2 the harmonic should be 880. But that's not often the case. It might be 880.1 Hz. Therefore no longer called a harmonic but is now called a "partial". When a harmonic ios out of tune relative to the fundamental pitch of the same string it is refered to as "inharmonic". Not "enharmonic", which is something different.


Then there is a third consideration of the fretted guitar neck. Which rearly gives perfect placement of the fundamental note. A fretless neck can be much more precise in the hasnds of a good musician. But then again, consider the inharmonicity of the string itself.

[lonewolf]

Maybe we should create a new genre of rock using just intonation...or did somebody already do that?

Everybody can get a new fingerboard for their guitars.

[Hawk]

Maybe we should create a new genre of rock using just intonation...or did somebody already do that?

Everybody gets to re-fret their guitars.

I've been studying just intonation lately. A mean tone tempeament sounds so different than equal temperament but isn't "balanced" in all keys. Your stuck playing in a few keys. But when you do change keys you get copmpletely different "colors". Equal temperament came into fashion so one could play a given tune in any key.

There are some Yamaha keyboards with some mean tone temperaments built into them.

[Hawk]

Regardless of inharmonicity, the A - B 17th test is always perfect.

[floodcitybrass]

Everybody can get a new fingerboard for their guitars.

That's exactly not my point. It has nothing to do with fingerboard.

The point is that you *need* two different pitches of a note for intonation to be accurate.

[Hawk]

Everybody can get a new fingerboard for their guitars.

That's exactly not my point. It has nothing to do with fingerboard.

The point is that you *need* two different pitches of a note for intonation to be accurate.

I think you might be a bit confused. I was talking about tuning the fundamental pitch to another fundamental pitch - a unison. Two fundamentals can be identical. That is not two different pitches but one pitch on two sources.

Notes have what are called "coincidental harmonics" or "coincidental partials".

We lable the fundamental pitch (Hz) as "1". When the string divides itself by two it creates the 2nd partial. When the string divides itself by three it creates the 3rd partial. And on and on.

For instance a major 3rd has 2 very audible coincidental partials, the 5th partial of the bottom note and the 4th partial of the top note. On F2 the 5th partial is = to A4. On the major 3rd F2 to A2, the fourth partial of A2 also is = to A4. In other words the third is a 5:4 ratio with A4 being the copincidental partial of F2 to A2. Equal tempearment dictates that this third is "wide" and therefore produces "beats".

In JUST tuninmg the third might be tuned pure with no beats, but then it would NOT be equal tgempearment like we tune today.

Same for 4ths and 5ths. 4ths are a 4:3 ratio and are tuned "wide" in equal temperament - but just in some mean tone temperaments.

5ths are a 3:2 AND a 6:4 ratio, meaning they have TWO coincidental partials. 5ths are tuned "narrow" in equal temperament but may be tuned "just" or "perfect" in some mean tone temperaments.

[lonewolf]

Everybody can get a new fingerboard for their guitars.

That's exactly not my point. It has nothing to do with fingerboard.

The point is that you *need* two different pitches of a note for intonation to be accurate.

If you went to "just" intonation, you most certainly would need a new fret arrangement. The changes would be subtle, but necessary.

[Hawk]

Everybody can get a new fingerboard for their guitars.

That's exactly not my point. It has nothing to do with fingerboard.

The point is that you *need* two different pitches of a note for intonation to be accurate.

If you went to "just" intonation, you most certainly would need a new fret arrangement. The changes would be subtle, but necessary.

You are correct. Again, is there any subject that you can't converse in ? Smart man, you are...

Just intonation is a way of tuning with certain intervals being tuned perfectly (just). That belongs to tuning methods back in history, not the tunings of today (for the most part). But the modern accepted tuning is equal temperament or equally spaced 1/2 steps, which dictates imperfect intervals like major 3rds (wide rather than just), 4ths (wide rather than just) and 5ths (narrow rather than just).