12th fret harmonics

[watersbluebird]

could someone settle an argument, er, discussion i have going with theodie. can a 12th fret harmonic be out of "tune" with the open string? to my crap knowledge, the harmonic will always be the same, it just might not be exactly over the 12th fret. come on, what do you think?

 

[Jeff_H]

Re: 12th fret harmonics

The open harmonic can be out of tune to the "key", but not to itself. In other words, if the open G string is "just a touch flat", the 12th fret harmonic will itself be the same degree, or "just a touch" flat.

 

[RW James]

Re: 12th fret harmonics

Yeah, you're talking about physics here - and you can't change these laws. The 12th fret harmonic will always produce a note one octave higher than the open string. The 5th fret = 2 octaves up, and the 7th fret = 1 1/2 octaves up. All in tune with the open note.

But you're right, the fret itself may not be the same note. This is one way to check if the bridge is set right - because it should be the same note.

 

[theodie]

Re: 12th fret harmonics

No, one plays the guitar 99% of the time in fretted notes. A harmonic will read different on a good tuner. If you played your guitar in harmonics, this would be the correct method to use but, you dont play mostly in harmonics do ya??????? You want the mnost accurate results dont ya????

Read this in the vault, JohnJohn and Zerberus are luthiers also,

https://forum.seymourduncan.com/showthread.php?t=21014

 

[Jeff_H]

Re: 12th fret harmonics

Yeah, but that just means that your fretted notes are out of tune from the harmonic, or vica versa. The harmonic is a function of the open string, and therefore cannot be out of tune with itself, unless the laws of physics stop working in your workshop.

"Are we to belive that boiling water soaks into a grit on your stove faster than any other place in the universe? Were these magic grits? Did you get these from the same guy who sold Jack his beanstock beans? I'm sorry, I was all the way over here...did you say your a fast cook, that's it?"

Name that movie for bonus points.

 

[SpiderVenom]

Re: 12th fret harmonics

My Cousin Vinny

 

[big_black]

Re: 12th fret harmonics

could someone settle an argument, er, discussion i have going with theodie. can a 12th fret harmonic be out of "tune" with the open string? to my crap knowledge, the harmonic will always be the same, it just might not be exactly over the 12th fret. come on, what do you think?

If you intonate your guitar to the fretted note at the 12th (which is what you should be doing), then the harmoinc at the 12th will be slightly out of tune to the open string.

 

[RW James]

Re: 12th fret harmonics

If you intonate your guitar to the fretted note at the 12th (which is what you should be doing), then the harmoinc at the 12th will be slightly out of tune to the open string.

I think you just violated the Laws of Physics.

 

[big_black]

Re: 12th fret harmonics

I think you just violated the Laws of Physics.

Don't blame me, blame the guitar. :laugh2:

Fretting a note pulls it out of tune compared to the (unfretted) harmonic note...and depending on how high your action is it can be more noticable. Go ahead an try it. It's true.

This is why you should intonate to the fretted 12th rather than the harmoinc at that fret.

 

[RW James]

Re: 12th fret harmonics

Don't blame me, blame the guitar. :laugh2:

Fretting a note pulls it out of tune compared to the (unfretted) harmonic note...and depending on how high your action is it can be more noticable. Go ahead an try it. It's true.

This is why you should intonate to the fretted 12th rather than the harmoinc at that fret.

I understand what you are saying - and you are absolutely right - IF you could hit the harmonic directly over the fret. But what actually happens is - once you get the 12th fret tuned to the octave, the harmonic point moves accordingly. You can't strike the harmonic over the fret. But if you could, it would be out of tune.

 

[big_black]

Re: 12th fret harmonics

I understand what you are saying - and you are absolutely right - IF you could hit the harmonic directly over the fret. But what actually happens is - once you get the 12th fret tuned to the octave, the harmonic point moves accordingly. You can't strike the harmonic over the fret. But if you could, it would be out of tune.

On all of my guitars, the fretted 12th and the harmonic at the 12th are two different notes. The difference is slight, but it's enough that my cheap Boss TU-70 tuner can tell the difference.

 

[RW James]

Re: 12th fret harmonics

On all of my guitars, the fretted 12th and the harmonic at the 12th are two different notes. The difference is slight, but it's enough that my cheap Boss TU-70 tuner can tell the difference.

My Sabine can pick up that difference as well. But it should mean that the fretted note is wrong. The harmonic note, by law, MUST be one octave higher than the open string.

 

[big_black]

Re: 12th fret harmonics

My Sabine can pick up that difference as well. But it should mean that the fretted note is wrong. The harmonic note, by law, MUST be one octave higher than the open string.

If your tuner picks it up as well, doesn't that prove my point? :smack:

Think about a scalloped neck...you press too hard, the note goes out of tune. The length of the string changes when you fret...and the degree that it is noticable depends on the height of the frets, action, etc.

 

[RW James]

Re: 12th fret harmonics

If your tuner picks it up as well, doesn't that prove my point? :smack:

Think about a scalloped neck...you press too hard, the note goes out of tune. The length of the string changes when you fret...and the degree all depend on the height of the frets, action, etc.

No - read what I said - the fretted note is out of tune - NOT the harmonic. It can't be.

 

[big_black]

Re: 12th fret harmonics

No - read what I said - the fretted note is out of tune - NOT the harmonic. It can't be.

What I am saying is that if you intonate to the fretted note, the harmonic will be out of tune to the open string. The harmonic will move as the intonation does.

 

[Amateur]

Re: 12th fret harmonics

According to physics, the harmonics should happen right at the mid point of the supported portion of the the string. The 12th fret should theoretically at the middle between the nut and the bridge. However, since the wound strings are not exactly solid, they have to be compensated some what. There is also the difference of height on both ends with the bridge side ususlly set higher. This usually means the nut side will be a little bit shorter when the string is pressed at the 12th fret, and hence the movable bridge for intonation for the fretted string. The problem is that the none of the scale the human ear has accustomed to is of perfect proportion. If we tune the piano perfectly according to mathematics, it will sound awful. That's why the piano tuner just tunes the "A" to 440 HZ and then tune the rest of the keys by ear. Base on that, I usually just tune the open strings once when I had intonated the strings unless I happen to change the strings to a different gage or a different made. I have a pianist in my band and all I can do is get in tune with the piano. No sense arguing with those 88 keys.

 

[emilio]

Re: 12th fret harmonics

:blackeye: I'm trying really hard to understand this but i get lost.

 

[WhoFan]

Re: 12th fret harmonics

this is pretty involved, and way over my head.... all i know is at the local shop they taught me to intonate useing open string and the fretted 12th fret.... no harmonics at all....

 

[joeydude]

Re: 12th fret harmonics

What I am saying is that if you intonate to the fretted note, the harmonic will be out of tune to the open string.

no no no no no no no no no NO!!

if you intonate to the fretted note, the harmonic may be slightly out of tune to the fretted note. but it will be in tune with the open note because THE 12TH FRET HARMONIC IS NEVER OUT OF TUNE TO THE OPEN NOTE. heres why:


when you pluck an open note the whole string gose back n forth. when you hit the 12th fret harmonic whats hapening is one half of the string is going in one direction while the other half is going in the other direction. this makes for twice as many hertz (cycles per second), hence the octave up. The perfect halfway mark along the string dose not move, this is why your finger sits there to get the harmonic going to begin with.


so you see a harmonic has nothing to do with the frets, it has evrything to do with the open note. now your gonna say "but but...

The harmonic will move as the intonation does.

"

yes. yes this is very true the position of the harmonic will move as you change intonation because the string length has been changed. but the open note will change by the exact same amount because its on the same friggin string! the same string whose length has just been changed, therefore changign both the harmonic and the open note arrrrrrrgggg!!!!! understand allready!!!!!!****in hell!!!!!!!

ok im done now

 

[watersbluebird]

Re: 12th fret harmonics

well this has been great fun to read. so even though i'm not a luthier and theodie is, from what i've just read, i'm right and he's wrong. i get a bit cheesed off when luthiers assume they are more knowledgable than the average joe on matters such as these. my ears, i think, are pretty good. i know when things are not right, and when they are. being a luthier makes no difference to these matters. of course they have skills and training that i will never get, fair enough. but that doesn't mean they can play a guitar better, that they can hear differences in notes, sounds etc better. so stop being so up yourself, theodie. and eat some humble pie, while you're at it.
(i can't wait for your response!) man, i love these forums.